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A Madman Dreams of Tuning Machines: The Story of Joseph Weber, the Tragic Hero of Science Who Followed Einstein’s Vision and Pioneered the Sound of Spacetime
…and a remarkable letter from Freeman Dyson on the difficult, necessary art of changing one’s mind.
By Maria Popova
In his groundbreaking 1915 paper on general relativity, Albert Einstein envisioned gravitational waves — ripples in the fabric of spacetime caused by astronomic events of astronomical energy. Although fundamental to our understanding of the universe, gravitational waves were a purely theoretical construct for him. He lived in an era when any human-made tool for detecting something this faraway was simply unimaginable, even by the greatest living genius, and many of the cosmic objects capable of producing such tremendous tumult — black holes, for instance — were yet to be discovered.
One September morning in 2015, almost exactly a century after Einstein published his famous paper, scientists turned his mathematical dream into a tangible reality — or, rather, an audible one.
The Laser Interferometer Gravitational-Wave Observatory — an enormous international collaboration known as LIGO, consisting of two massive listening instruments 3,000 kilometers apart, decades in the making — recorded the sound of a gravitational wave produced by two mammoth black holes that had collided more than a billion years ago, more than a billion light-years away.
One of the most significant discoveries in the history of science, this landmark event introduces a whole new modality of curiosity in our quest to know the cosmos, its thrill only amplified by the fact that we had never actually seen black holes before hearing them. Nearly everything we know about the universe today, we know through five centuries of optical observation of light and particles. Now begins a new era of sonic exploration. Turning an inquisitive ear to the cosmos might, and likely will, revolutionize our understanding of it as radically as Galileo did when he first pointed his telescope at the skies.
In Black Hole Blues and Other Songs from Outer Space (public library) — one of the finest and most beautifully written books I’ve ever read, which I recently reviewed for The New York Times — astrophysicist and novelist Janna Levin tells the story of LIGO and its larger significance as a feat of science and the human spirit. Levin, a writer who bends language with effortless might and uses it not only as an instrument of thought but also as a Petri dish for emotional nuance, probes deep into the messy human psychology that animated these brilliant and flawed scientists as they persevered in this ambitious quest against enormous personal, political, and practical odds.
Somewhere in the universe two black holes collide — as heavy as stars, as small as cities, literally black (the complete absence of light) holes (empty hollows). Tethered by gravity, in their final seconds together the black holes course through thousands of revolutions about their eventual point of contact, churning up space and time until they crash and merge into one bigger black hole, an event more powerful than any since the origin of the universe, outputting more than a trillion times the power of a billion Suns. The black holes collide in complete darkness. None of the energy exploding from the collision comes out as light. No telescope will ever see the event.
What nobody could see LIGO could hear — a sensitive, sophisticated ear pressed to the fabric of spacetime, tuned to what Levin so poetically eulogizes as “the total darkness, the empty space, the vacuity, the great expanse of nothingness, of emptiness, of pure space and time.” She writes of this astonishing instrument:
An idea sparked in the 1960s, a thought experiment, an amusing haiku, is now a thing of metal and glass.
But what makes the book most enchanting is Levin’s compassionate insight into the complex, porous, often tragic humanity undergirding the metal and glass — nowhere more tragic than in the story of Joseph Weber, the controversial pioneer who became the first to bring Einstein’s equations into the lab. Long before LIGO was even so much as a thought experiment, Weber envisioned and built a very different instrument for listening to the cosmos.
Weber was born Yonah Geber to a family of Lithuanian Jewish immigrants in early-twentieth-century New Jersey. His mother’s heavy accent caused his teacher to mishear the boy’s name as “Joseph,” so he became Joe. After he was hit by a bus at the age of five, young Joe required speech rehabilitation therapy, which replaced his Yiddish accent with a generic American one that led his family to call him “Yankee.” As a teenager, he dropped out of Cooper Union out of concern for his parents’ finances and joined the Navy instead, where he served on an aircraft carrier that was sunk during WWII. When the war ended, he became a microwave engineer and was hired as a professor at the University of Maryland at the then-enviable salary — especially for a 29-year-old — of $6,500 a year.
Eager to do microwave research, he turned to the great physicist George Gamow, who had theorized cosmic microwave background radiation — a thermal remnant of the Big Bang, which would provide unprecedented insight into the origin of the universe and which Weber wanted to dedicate his Ph.D. career to detecting. But Gamow inexplicably snubbed him. Two other scientists eventually discovered cosmic microwave background radiation by accident and received the Nobel Prize for the discovery. Weber then turned to atomic physics and devised the maser — the predecessor of the laser — but, once again, other scientists beat him to the public credit and received a Nobel for that discovery, too.
Joe’s scientific life is defined by these significant near misses… He was Shackleton many times, almost the first: almost the first to see the big bang, almost the first to patent the laser, almost the first to detect gravitational waves. Famous for nearly getting there.
And that is how Weber got to gravitational waves — a field he saw as so small and esoteric that he stood a chance of finally being the first. Levin writes:
In 1969 Joe Weber announced that he had achieved an experimental feat widely believed to be impossible: He had detected evidence for gravitational waves. Imagine his pride, the pride to be the first, the gratification of discovery, the raw shameless pleasure of accomplishment. Practically single-handedly, through sheer determination, he conceives of the possibility. He fills multiple notebooks, hundreds of pages deep, with calculations and designs and ideas, and then he makes the experimental apparatus real. He builds an ingenious machine, a resonant bar, a Weber bar, which vibrates in sympathy with a gravitational wave. A solid aluminum cylinder about 2 meters long, 1 meter in diameter, and in the range of 3,000 pounds, as guitar strings go, isn’t easy to pluck. But it has one natural frequency at which a strong gravitational wave would ring the bar like a tuning fork.
Following his announcement, Weber became an overnight celebrity. His face graced magazine covers. NASA put one of his instruments on the Moon. He received ample laud from peers. Even the formidable J. Robert Oppenheimer, a man of slim capacity for compliments, encouraged him with a remark Weber never forgot: “The work you’re doing,” Oppenheimer told him, “is just about the most exciting work going on anywhere around here.”
Under the spell of this collective excitement, scientists around the world began building replicas of Weber’s cylinder. But one after another, they were unable to replicate his results — the electrifying eagerness to hear gravitational waves was met with the dead silence of the cosmos.
Weber plummeted from grace as quickly as he had ascended. (Einstein himself famously scoffed at the fickle nature of fame.) Levin writes:
Joe Weber’s claims in 1969 to have detected gravitational waves, the claims that catapulted his fame, that made him possibly the most famous living scientist of his generation, were swiftly and vehemently refuted. The subsequent decades offered near total withdrawal of support, both from scientific funding agencies and his peers. He was almost fired from the University of Maryland.
Among Weber’s most enthusiastic initial supporters was the great theoretical physicist Freeman Dyson. Perhaps out of his staunch belief that no question is unanswerable, Dyson had emboldened Weber to attempt what no one had attempted before — to hear the sound of spacetime. But when the evidence against Weber’s data began to mount, Dyson was anguished by a sense of personal responsibility for having encouraged him, so he wrote Weber an extraordinary letter urging him to practice the immensely difficult art of changing one’s mind. Levin quotes the letter, penned on June 5, 1975:
I have been watching with fear and anguish the ruin of our hopes. I feel a considerable personal responsibility for having advised you in the past to “stick your neck out.” Now I still consider you a great man unkindly treated by fate, and I am anxious to save whatever can be saved. So I offer my advice again for what it is worth.
A great man is not afraid to admit publicly that he has made a mistake and has changed his mind. I know you are a man of integrity. You are strong enough to admit that you are wrong. If you do this, your enemies will rejoice but your friends will rejoice even more. You will save yourself as a scientist, and you will find that those whose respect is worth having will respect you for it.
I write now briefly because long explanations will not make the message clearer. Whatever you decide, I will not turn my back on you.
With all good wishes,
But Weber decided not to heed his friend’s warm caution. His visionary genius coexisted with one of the most unfortunate and most inescapable of human tendencies — our bone-deep resistance to the shame of admitting error. He paid a high price: His disrepute soon veered into cruelty — he was ridiculed and even baited by false data intended to trick him into reaffirming his claims, only to be publicly humiliated all over again. In one of the archival interviews Levin excavates, he laments:
I simply cannot understand the vehemence and the professional jealousy, and why each guy has to feel that he has to cut off a pound of my flesh… Boltzmann committed suicide with this sort of treatment.
Here, I think of Levin’s penchant for celebrating tragic heroes whose posthumous redemption only adds to their tragedy. Her magnificent novel A Mad Man Dreams of Turing Machines is based on the real lives of computing pioneer Alan Turing and mathematician Kurt Gödel, both of whom committed suicide — Turing after particularly cruel mistreatment. Levin’s writing emanates a deep sympathy for those who have fallen victim to some combination of their own fallible humanity and the ferocious inhumanity of unforgiving, bloodthirsty others. No wonder Weber’s story sings to her. A mad man dreams of tuning machines.
Without diminishing the role of personal pathology and individual neurochemistry, given what psychologists know about suicide prevention, social support likely played a vital role in Weber’s ability to withstand the barrage of viciousness — Dyson’s sympathetic succor, but most of all the love of his wife, the astronomer Virginia Trimble, perhaps the most unambivalently likable character in the book. Levin writes:
She called him Weber and he called her Trimble. They married in March 1972 after a cumulative three weekends together. She laughs. “Weber never had any trouble making up his mind.” Twenty-three years her senior, he always insisted she do what she wanted and needed to do. Perhaps trained in part by his first wife, Anita, a physicist who took a protracted break to raise their four boys, the widower had no reservations about Virginia’s work, her independence, or her IQ. (Stratospheric. In an issue of Life magazine with a now-vintage cover, in an article titled “Behind a Lovely Face, a 180 I.Q.” about the then eighteen-year-old astrophysics major, she is quoted as classifying the men she dates into three types: “Guys who are smarter than I am, and I’ve found one or two. Guys who think they are— they’re legion. And those who don’t care.”)
Trimble was the second woman ever allowed at the famed Palomar Observatory, a year after pioneering astronomer Vera Rubin broke the optical-glass ceiling by becoming the first to observe there. Levin, whose subtle kind-natured humor never fails to delight, captures Trimble’s irreverent brilliance:
In her third year, having demonstrated her tenacity — particularly manifest in the fact that she still hadn’t married, she suspects — she was awarded a fellowship from the National Science Foundation. When she arrived at Caltech, she was delighted. “I thought, ‘Look at all of these lovely men.’” In her seventies, with her coral dress, matching shoes and lip color, Moon earrings, and gold animal-head ring, she beams. Still a lovely face. And still an IQ of 180.
This fierce spirit never left Trimble. Now in her seventies, she tells Levin:
When I fell and broke my hip last September, I spent four days on the floor of my apartment singing songs and reciting poetry until I was found.
It isn’t hard to see why Weber — why anyone — would fall in love with Trimble. But although their love sustained him and he didn’t take his own life, he suffered an end equally heartbreaking.
By the late 1980s, Weber had submerged himself even deeper into the quicksand of his convictions, stubbornly trying to prove that his instrument could hear the cosmos. For the next twenty years, he continued to operate his own lab funded out of pocket — a drab concrete box in the Maryland woods, where he was both head scientist and janitor. Meanwhile, LIGO — a sophisticated instrument that would eventually cost more than $1 billion total, operated by a massive international team of scientists — was gathering momentum nearby, thanks largely to the scientific interest in gravitational astronomy that Weber’s early research had sparked.
He was never invited to join LIGO. Trimble surmises that even if he had been, he would’ve declined.
One freezing winter morning in 2000, just as LIGO’s initial detectors were being built, 81-year-old Weber went to clean his lab, slipped on the ice in front of the building, hit his head, and fell unconscious. He was found two days later and taken to the E.R., but he never recovered. He died at the hospital several months later from the lymphoma he’d been battling. The widowed Trimble extracts from her husband’s tragedy an unsentimental parable of science — a testament to the mismatch between the time-scale of human achievement, with all the personal glory it brings, and that of scientific progress:
Science is a self-correcting process, but not necessarily in one’s own lifetime.
When the LIGO team published the official paper announcing the groundbreaking discovery, Weber was acknowledged as the pioneer of gravitational wave research. But like Alan Turing, who was granted posthumous pardon by the Queen more than half a century after he perished by inhumane injustice, Weber’s redemption is culturally bittersweet at best. I’m reminded of a beautiful passage from Levin’s novel about Turing and Gödel, strangely perfect in the context of Weber’s legacy:
Their genius is a testament to our own worth, an antidote to insignificance; and their bounteous flaws are luckless but seemingly natural complements, as though greatness can be doled out only with an equal measure of weakness… Their broken lives are mere anecdotes in the margins of their discoveries. But then their discoveries are evidence of our purpose, and their lives are parables on free will.
Free will, indeed, is what Weber exercised above all — he lived by it and died by it. In one of the interviews Levin unearths, he reflects from the depths of his disrepute:
If you do science the principal reason to do it is because you enjoy it and if you don’t enjoy it you shouldn’t do it, and I enjoy it. And I must say I’m enjoying it… That’s the best you can do.
At the end of the magnificent and exceptionally poetic Black Hole Blues, the merits of which I’ve extolled more fully here, Levin offers a wonderfully lyrical account of LIGO’s triumph as she peers into the furthest reaches of the spacetime odyssey that began with Einstein, gained momentum with Weber, and is only just beginning to map the course of human curiosity across the universe:
Two very big stars lived in orbit around each other several billion years ago. Maybe there were planets around them, although the two-star system might have been too unstable or too simple in composition to accommodate planets. Eventually one star died, and then the other, and two black holes formed. They orbited in darkness, probably for billions of years before that final 200 milliseconds when the black holes collided and merged, launching their loudest gravitational wave train into the universe.
The sound traveled to us from 1.4 billion light-years away. One billion four hundred million light-years.
We heard black holes collide. We’ll point to where the sound might have come from, to the best of our abilities, a swatch of space from an earlier epoch. Somewhere in the southern sky, pulling away from us with the expansion of the universe, the big black hole will roll along its own galaxy, dark and quiet until something wanders past, an interstellar dust cloud or an errant star. After a few billion years the host galaxy might collide with a neighbor, tossing the black hole around, maybe toward a supermassive black hole in a growing galactic center. Our star will die. The Milky Way will blend with Andromeda. The record of this discovery along with the wreckage of our solar system will eventually fall into black holes, as will everything else in the cosmos, the expanding space eventually silent, and all the black holes will evaporate into oblivion near the end of time.
Published April 25, 2016 | 0.848164 | 3.632688 |
For decades, ever since the Pioneer and Voyager missions passed through the outer Solar System, scientists have speculated that life might exist within icy bodies like Jupiter’s moon Europa. However, thanks the Cassini mission, scientists now believe that other moons in the outer Solar System – such as Saturn’s moon Enceladus – could possibly harbor life as well.
For instance, Cassini observed plume activity coming from Enceladus’ southern polar region that indicated the presence of hydrothermal activity inside. What’s more, these plumes contained organic molecules and hydrated minerals, which are potential indications of life. To see if life could thrive inside this moon, a team of scientists conducted a test where strains of Earth bacteria were subjected to conditions similar to what is found inside Enceladus.
The study which details their findings recently appeared in the journal Nature Communications under the title “Biological methane production under putative Enceladus-like conditions“. The study was led by Ruth-Sophie Taubner from the University of Vienna, and included members from the Johannes Kepler University Linz, Ecotechnology Austria, the University of Bremen, and the University of Hamburg.
For the sake of their study, the team chose to work with three strains of methanogenic archaea known as methanothermococcus okinawensis. This type of microorganism thrives in low-oxygen environments and consumes chemical products known to exist on Enceladus – such as methane (CH4), carbon dioxide (CO2) and molecular hydrogen (H2) – and emit methane as a metabolic byproduct. As they state:
“To investigate growth of methanogens under Enceladus-like conditions, three thermophilic and methanogenic strains, Methanothermococcus okinawensis (65 °C), Methanothermobacter marburgensis (65 °C), and Methanococcus villosus (80 °C), all able to fix carbon and gain energy through the reduction of CO2 with H2 to form CH4, were investigated regarding growth and biological CH4 production under different headspace gas compositions…”
These strains were selected because of their ability to grow in a temperature range that is characteristic of the vicinity around hydrothermal vents, in a chemically defined medium, and at low partial pressures of molecular hydrogen. This is consistent with what has been observed in Enceladus’ plumes and what is believed to exist within the moon’s interior.
These types of archaea can still be found on Earth today, lingering in deep-see fissures and around hydrothermal vents. In particular, the strain of M. okinawensis has been determined to exist in only one location around the deep-sea hydrothermal vent field at Iheya Ridge in the Okinawa Trough near Japan. Since this vent is located at a depth of 972 m (3189 ft) below sea level, this suggests that this strain has a tolerance toward high pressure.
For many years, scientists have suspected that Earth’s hydrothermal vents played a vital role in the emergence of life, and that similar vents could exist within the interior of moons like Europa, Ganymede, Titan, Enceladus, and other bodies in the outer Solar System. As a result, the research team believed that methanogenic archaea could also exist within these bodies.
After subjecting the strains to Enceladus-like temperature, pressure and chemical conditions in a laboratory environment, they found that one of the three strains was able to flourish and produce methane. The strain even managed to survive after the team introduced harsh chemicals that are present on Enceladus, and which are known to inhibit the growth of microbes. As they conclude in their study:
“In this study, we show that the methanogenic strain M. okinawensis is able to propagate and/or to produce CH4 under putative Enceladus-like conditions. M. okinawensis was cultivated under high-pressure (up to 50 bar) conditions in defined growth medium and gas phase, including several potential inhibitors that were detected in Enceladus’ plume.”
From this, they determined that some of the methane found in Enceladus’ plumes were likely produced by the presence of methanogenic microbes. As Simon Rittmann, a microbiologist at the University of Vienna and lead author of the study, explained in an interview with The Verge. “It’s likely this organism could be living on other planetary bodies,” he said. “And it could be really interesting to investigate in future missions.”
In the coming decades, NASA and other space agencies plan to send multiple mission to the Jupiter and Saturn systems to investigate their “ocean worlds” for potential signs of life. In the case of Enceladus, this will most likely involve a lander that will set down around the southern polar region and collect samples from the surface to determine the presence of biosignatures.
Alternately, an orbiter mission may be developed that will fly through Enceladus’ plumes and collect bioreadings directly from the moon’s ejecta, thus picking up where Cassini left off. Whatever form the mission takes, the discoveries are expected to be a major breakthrough. At long last, we may finally have proof that Earth is not the only place in the Solar System where live can exist.
Be sure to check out John Michael Godier’s video titled “Encedalus and the Conditions for Life” as well:
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Planetary Distance Formula
A large scale model explaining the formation of the Solar System
By Sollog Immanuel Adonai-Adoni
AKA Dr. Sol Adoni
July 11th 2002
Edited October 8th 2002
Edited February 22nd 2004
This simple model is based upon something we have tried to observe for quite some time. That is the carbon 12 atom. Yes, my solar model resembles in great detail a carbon 12 atom.
Can it be that humans, a complex carbon life form, actually live on a planet within a solar system designed to resemble a carbon 12 atom?
My model explains such anomalies as the asteroid belt, the formation of huge gas giants and the abnormalities of Venus and Neptune to other planets in our known solar system at this time.
The most important PROOF to show that this model is correct; is there will in the very near future be several discoveries of new planets in our solar system.
The orbits of these unknown planets will align correctly to my theorized orbits. This is the only PROOF that can really validate a theoretical work such as this.
If the known qualities of the solar system fit the model and it predicts accurate future unknown variables but probabilities correctly, then such a model can be considered correct.
Some long held truths will be completely shattered in my work. New ideas about the solar system and the universe will be put forward that will become accepted facts in the future as my model is validated by the discovery of new planets that fit my model precisely and invalidate other models as incorrect.
A few theories such as Titius-Bodes (an old planetary distance law see footnotes) will be completely rebuilt to explain a doubling law that is built into most if not all life.
Titius-Bodes is slightly incorrect in the big model of the solar system that I am revealing here. However, it did serve its purpose in trying to explain a key to my model, which is a doubling law. A variation of Titius-Bodes aligns two of the three sets of numbers I use.
Titius-Bodes is to me nothing more than a doubling law that I call 1 3 7 (the “fine-structure constant” of quantum electrodynamics – see footnotes). Physicists will immediately smile and say, okay an attempt to explain 137.
My theoretical doubling law that I call the Law of 1 3 7 is a universal constant that explains planetary distance formation. It also explains why Titius-Bodes works to some degree.
The reason Titius-Bodes cannot fully explain the solar system is that the solar system is actually built around three separate groups or sets of numbers that are simply aligned to each other. Such an ordered alignment for three types of particles/planets does exist within a carbon 12 atom, and it is a key part of my model of our solar system. The similarities are clear.
The reason no one has seen this alignment of orbital numbers before, is that many of the key planets needed to prove that this alignment of orbital numbers was real no longer exist. So my theoretical orbits must for now show the alignment of the three groups of numbers. However, the discovery of new orbital numbers from unknown planets in the future will correctly align to the sets I explain in this work, and that will validate that my theorized missing orbits must have existed in the distant past when the solar system was very young.
Our solar system is now very mature and the orbits are quite stable, however as simple observable models show, a newly established gravitational field is quite unstable in the beginning until a certain synchronization manifests aligning the various parts. I will explain this a little more in just a bit.
Some of my earlier work such as the Creator Formula (Circumference Ratio Earth Aligned To Orbital Ratios – see foot notes) and my recent PROOF for the Creator Formula (a clear ratio relationship between Earth to Mercury/Mars/Jupiter/Saturn) are validated in this work.
A problem some found with my earlier work the PROOF for the Creator Formula is the Venus exception or anomaly. This exception rule is now easily explained. Venus should not align to Earths orbital ratios as the other inner planets do! The PROOF for the Creator Formula just explained that Venus is an exception to an observable ratio relationship between Earth and the majority of the inner planets.
The PROOF of the Creator Formula shows the same type of alignment ordering of numbers similar to what occurs within a carbon 12 atom to the Earth’s inner planets perfectly.
My solar model creates three sets of numbers that are all aligned to a simple doubling law that I call 1 3 7. It resembles Titius-Bodes, but only in the fact it uses doubling.
Titius-Bodes observed a possible doubling rule of order but it never theorized that three sets of numbers for this rule existed in our solar system.
Now that I have discovered that three separate sets of orbital alignments exist in our solar system, the concept of Titius-Bodes can be easily understood.
Pi is also a key in my model, and part of the reason is that our planets create in some instances near perfect circles in their orbits. So a bunch of circles should have some type of Pi ratio just by the geometrical properties inherent in circles.
I have divided this model into several parts, the first three parts deals with the clear alignment of numbers in the orbits of 18 planets. You might be saying how can I use 18 orbits when we only know about half that many.
My model theorizes orbits that don’t exist any longer and it also theorizes orbits of planets that we have yet to discover.
While I cannot empirically prove an orbit once existed in the asteroid belt, it will be accepted in the future that several most likely did as other orbits of unknown planets are found that validate my solar model.
A few other orbits that also no longer exist are in my solar model. They no longer exist due to the simple fact the planets that once held those orbits were absorbed into young gas giants like Jupiter and Saturn.
I have never read any major works on astro-physics, since I have my own understanding of the quantum mechanics of our universe. So what I know of other theories about the idea that planets may have collided is little more than some have theorized some planets may have formed by slow collisions and other planets may have collided to form the asteroid belt.
These ideas could have been taught to me in school as a child or I may have been exposed to these ideas via shows on PBS or whatever.
My interests in life were never astro-physics related. So I didn’t research the whole gamut of ideas out there. My interests in the past 7 years have been geared toward theology and occult knowledge. I use some of this esoteric knowledge to fully explain certain numbers where chosen as starting points in my formulas!
I have always enjoyed playing with numbers, but I don’t really make it a hobby.
I am interested in the truth, and what is observable in our solar system has lead me to explore within my own database of knowledge a method to explore and explain all of these numbers.
This all being said, my model suggests not only an asteroid belt from the collision of two young planets, but also planets that had to have once orbited near the gas giants that no longer exist. Where did these missing planets go? They were merged or absorbed into the young gas giants like Jupiter and Saturn!
This may or may not be an earth shattering idea. However, the location of these missing planets is something I don’t believe anyone has ever put forth in a solid solar model to explain this theory.
When outer planets are found that align to planets such as Neptune and Uranus, then my missing planet orbits have to be accepted as factual. So here are my three sets of orbits. The numbers I use for known planets are correct as of today since they are the numbers supplied to me by NASA. While you can look up the actual numbers for our known planets for yourself at sites like NASA, the numbers I use for the missing planets are figures for planets that are long gone. But, there will soon be several new planets found in our solar system that align to my model and thereby validate the whole work!
Three Numerical Sets of Orbits
The first set of orbits that are aligned to each other is the easiest to verify since four of the planets still exist.
These planets that are aligned to each other are
Mercury/Earth/Mars/Planet X – Niribu/Jupiter/El-Sollog
The orbit of Planet X is in the asteroid belt. Ancient Myths say this was Niribu. So I will call Planet X Niribu. The orbit of the theoretical planet El-Sollog is near the orbit of Saturn. This is a missing planet that merged with Saturn.
When I set out the relationship of these planets we will have a theoretically orbit for Niribu that is aligned to the other five planets in a simple doubling law similar to Titius-Bodes but not exactly Titius-Bodes. I have modified their so-called n set of numbers.
The rule of doubling and adding a variable might have been first theorized by Titius-Bodes. However, long before I had ever heard of Titius-Bodes I had theorized the law or rule of doubling for 1 3 7.
The best way for me to explain what 1 3 7 means to physicists is that it is the “fine-structure constant” of quantum electrodynamics. It is considered by some to be almost the glue that holds atoms together.
While I make no claims to be an expert on quantum electrodynamics, I will admit that I have written many computer programs over the years, since I spent most of my adult life running a computer programming company.
When I was quite young, someone bought up the concept of 1 3 7 to me as in an argument, “Okay you’re so smart with numbers explain 1 3 7 to me.”
I probably had to ask in what manner were the numbers being used. I most likely would have noticed a relationship to my birth date of 7/14 or 14/7 in Euro dating. I knew from my father’s mother that 1 4 7 was her lucky numbers. She told me as child she started playing them after I was born in the so-called daily number and at the track. She said they always seemed to hit for her.
So as a child I was indoctrinated in how 1 4 7 were lucky numbers.
Anyway, at that point in the argument I was probably given a simple overview of 1 3 7.
I do remember what my reply was. “It’s simple, it’s a law of double add one. You start with ONE, you double and then add one, then double then add one. This simple statement produced 1 3 7 and I thought nothing much of it again for many years other than whenever someone seemed to comment on the mysteries of 1 3 7 I would say, “Haven’t you heard of the law of double and add one?” I would then explain what I theorized at around the age of 13 to whoever was discussing the great significance of 1 3 7 to me at that time. I’d had maybe a few dozen discussions before I theorized my PDF formula in my lifetime, where I explained the law of doubling or 137 to someone.
When I was first exposed to Titius-Bodes, all of less than a week ago, I immediately saw my 1 3 7 Law in it. At first I tried to tweak what some considered some great secret of the solar system. At first I was impressed with how close Titius-Bodes was. I then realized it was totally wrong and would not correctly locate future orbits without more manipulation of my addition variation to Titius – Bodes (a simple variable I created to improve Titius-Bodes a few days ago – see foot notes).
I use the law of 1 3 7 in all two of the three sets of my orbital numbers in my model. It is not pure 1 3 7 as I knew it originally, but it is a simple double a number to start and then add a constant variable. Some will say it is Titius-Bodes. It is not. It is the natural law of doubling inherent in all living things.
It is 1 3 7 with perhaps a dash of Titius-Bodes.
This first set of six orbits starts like Titius-Bodes with two numbers. The first number adds the variable to create the first orbit or Mercury. Then like Titius-Bodes the first number is not doubled. My other two formulas that create sets of orbits are slightly different. One starts with a number and then keeps doubling. While another one subtracts a fraction of 2/3 to create the numbers for orbits. So one may say Titius-Bodes is 1/3 relevant to my model.
Titius-Bodes starts with 0 and 3 as the first two numbers. Once three is in the picture Titius-Bodes starts doubling and adding .40 or 4/10.
My first set of numbers like Titius-Bodes contain a zero as a starting point, but my second number is not 3 or .3 (I use fractions so I don’t have to divide by 10 as Titius Bodes does) it is .60. As in 60 the year I was born. As in 60, the base math of the Babylonians.
My variable in the first set of numbers is .40 like Titius-Bodes, so my variable and .60 make unity or one. “ONE is all there is”, is a favorite saying of mine. So what better place to start than a couple of numbers that make unity. Seems simple enough right? Oh, the first number becomes .40 due to adding the variable of .40 to zero. So the total sum of the first number and the variable of .40 by adding the second number to it is once again unity or one.
Titius Bodes originally looked like this.
= (n + 4)/10
where n = (0, 3, 6, 12, 24, 48, 96, 192, 384)
My first set formula is very similar
= n +.4
where n = (0, .6, 1.2, 2.4, 4.8, 9.6)
Titius bodes does not try to explain why 0 and then 3. As I explained above unity is the basis of my first formula.
By deleting 3 from my first formula I am excluding the backwards planet Venus from my first aligned set of numbers. This validates my PROOF of the Creator Formula. Venus does not belong in any formulas that try to align earth to other inner planets. Venus is actually part of another set of numbers aligned to Neptune and a doubling of Pi.
With my numbers above I create near perfect orbits for the first six planets of my model. Earth and Jupiter are perfectly aligned with this formula based upon earth as 1 AU. These are the larger two of the four still existing planets created by the first formula. The reason Earth and Jupiter are still perfectly aligned could be due to how much bigger than the other planets they are. Also the moon of earth could be a reason the earth has stayed in the original orbit designed for it. It is theorized that with time most or all of the planets will gravitate closer if not into the sun.
2.80 (Planet X – Niribu – Asteroid Belt)
10.00 (El Sollog)
Titius-Bodes never tried to explain why certain orbits were slightly off in their theory. Titius-Bodes also tried to align Saturn to this formula. Saturn is aligned to a third set of numbers. If we did not use the Titius-Bodes variable of .4, then Saturn is perfectly aligned to 9.6 AU.
However, in Titius-Bodes you have Saturn lumped into a simple group of all the planets. Saturn merged with the original planet in my first set of planets, a planet that once existed close to Saturn at 10 AU.
That planet is El-Sollog. El is the ancient name of GOD in Hebrew. El is the number 31 in Kabbalah. 31 is Pi^3 with a remainder of .00006.
I have chosen to append my own name to this planet named for GOD, since it is my belief GOD inspired me to create this correct model for our solar system. It is my belief my model demonstrates clearly that an intelligence designed the solar system. I won’t debate that point in this work, but I will in a later work.
So I am giving GOD credit by naming the planet that was in a PERFECT 10 orbit EL-Sollog. I as a mere servant of GOD get a footnote.
The theoretical orbit of Planet X or Niribu is 2.8 AU.
That puts Niribu in the Asteroid Field between Mars and Jupiter.
So far so good, we have 6 orbits, two of missing planets, one of the missing planets left a trail called the asteroid belt. The only debatable point is if a planet in a 10 AU orbit had a slow collision with Saturn in a 9.6 Orbit. Like I said, I don’t plan on proving the missing planets existed in this work. I merely explain where they had to have been and supply a formula that will accurately predict the orbits of planets about to be discovered. When these planets are discovered and they align to my solar model, then the PROOF the missing planets at one time existed will have been given!
Another good reason to think Saturn somehow absorbed another planet, is to try to explain why Saturn and Jupiter are so much larger than the rest of the planets. Absorption due to a slow collision makes perfect sense. I am not the first to say this is a possible way some planets are formed.
Now I will explain the formula for my second set of numbers that locates 6 additional orbits of planets. This set contains three known planets and a theorized orbit for a planet yet to be discovered. It also contains two orbits of planets that no longer exist. One planet is most likely to have collided in the asteroid belt with Planet X or Niribu. I call this missing planet the Planet Y which is short for Yod. The other missing planet I have named Planet Z short for Zeda or Zeta to fans of the channeled work many or discussing. This planet merged or was absorbed into Jupiter.
In an interesting side note, the Zeta’s foretold their planet would be discovered in July 2002. Well it has. Only it no longer exists. The Zeta’s are an entity that is confused their world was destroyed
They are similar to a ghost on a television set. They are a sort of interference, that doesn’t belong in the picture.
Can I prove two planets existed near each other in orbits in the asteroid belt? No. But, when other planets are found that align to orbits I have given in this solar model, these planet will then be taken to have existed for fact!
Can I prove a planet existed near the orbit of Jupiter that was somehow absorbed or merged into Jupiter? No! But, once again as other planets are found that align correctly to my solar model these missing planets will be taken as fact!
This set of numbers is a blend of Titius-Bode, but there is no variable to insert. It is just start here at one number and double, double, double.
This is the only set with no variable in the doubling.
This set contains mostly numbers from Titius-Bodes.
The first number or starting point is 2.4. Why 2.4?
Well since this solar model is based upon AU or a relationship to earths distance to the sun, why not start with 10 percent of an earth day of 24 hours? One-one-thousandth of earths circumference in miles is also 2.4. The ratio of 2 to 4 is .50. A perfect half. Four divided by 2 is two. 2 is the first even number, it is the first number that can be squared. 2^2 is four. 2 is the only even number that is prime, while four is the first number that is not prime. So 2 and 4 belong together for many reasons.
2 to 4 is also a simple explanation of the law of double as well.
So a starting point containing 2 and 4 is a well-designed location to start in my opinion. Just like unity was our starting point in our first set of numbers, this number is our second starting point.
The formula is simple
Start at 2.4 and DOUBLE five times!
2.4 – 4.8 – 9.6 – 19.2 – 38.4 – 76.8
The first location in this sequence is part of the asteroid belt. The fifth number in the sequence is the Kuiper Belt.
Two of our known planets are perfectly aligned in AU to this sequence of numbers, the gas giants Saturn and Neptune are where the third and fourth numbers in this sequence suggest. The fifth number in this sequence is exactly where the Kuiper Belt is located, it is where both Pluto and Quaoar now orbit. In the future Pluto will be considered nothing but a moon of a planet that no longer exists. I call this missing planet Theth, in Hebrew it means Ninth, and since this orbit is now associated with Pluto or the so-called ninth planet, I thought Theth was a most appropriate name. Theth exploded and formed the Kuiper Belt. The recently discovered object temporarily named Quaoar is a Pluto like object only Quaoar has a near perfect circular orbit around the sun around 42.00 AU. The original planet Theth, that no longer exists, was located near 38.40 AU or the heart of the Kuiper Belt beyond Neptune. Pluto’s erratic orbit can now be easily explained by considering that it once orbited planet Theth along with its moon Charon and Quaoar. A collision or a core meltdown of the parent planet to Pluto (Theth) hurled Pluto into its current erratic orbit. Gravity has averaged out the orbit of Pluto to around 36.00 AU, though at times it’s orbit can be within Neptune and beyond the newly discovered Quaoar. Quaoar most likely had a slight change of orbit from near 38.40 AU to around 42.00 AU since it was not directly impacted by a direct blast when the parent planet of Pluto and Quaoar (Theth) was destroyed. So the blast of Theth’s destruction bumped the orbit of Quaoar a little further from the Sun, and it dramatically altered the orbit of Pluto to what we now see. If we average the orbits of Pluto and Quaoar we have the perfect orbit that my theory suggests for Theth, that being 38.40 AU.
This is the first theory that explains properly Pluto’s small size similar to a moon and it’s erratic orbit. It was a moon of Theth and is not a planet. The same thing can be said of Quaoar, it was a moon of the same planet that Pluto was a moon to! The Kuiper Belt is also explained with this theory. It is exactly where it should be if we consider planet Theth once existed at 38.40 AU.
While many small objects have been found in the Kuiper Belt, very few will be spherical planet/moon like objects such as Pluto and Quaoar. The only question is what destroyed the original planet that Pluto and Quaoar once orbited that being planet Theth? Was it a collision? Or was it a core meltdown from a defective core? The idea that the Kuiper Belt is left over debris from early planetary formation is wrong. The Kupier Belt is exactly where a planet should be! The Kupier Belt is estimated to be only one tenth the mass of earth. That is hardly enough material to prove that some celestial quary to make planets was the reason for the Kuiper Belt. A planet was at 38.40 AU as my theory suggests, it was Theth and it exploded and formed the Kuiper Belt. Its moons were left behind, those being Pluto and Quaoar and any other spherical objects found in the Kuiper Belt if any.
This formula predicts an orbit of a planet beyond Theth or the Kupier Belt, Pluto and Quaoar. When one is located in the predicted orbit, then the theory of the other two orbits that are for missing planets will be considered fact. Those are the missing orbits for Planet Y and Z, good old Yod and Zeda.
Here are the numbers for my second set of planet orbits.
2.40 (Planet Y – Yod – Asteroid Belt )
4.80 (Planet Z – Zeda)
38.40 (Planet Theth – Kuiper Belt – Pluto – Quaoar)
76.80 (Planet U1)
Now it is time to give my third set of numbers for planetary orbits.
This set is nothing like the other two sets!
IT IS RADICALLY DIFFERENT!
It is my favorite set of numbers too, since it has two planetary orbit locations that have undiscovered planets that in no way are near anything Titius-Bodes predicts.
This set of numbers also aligns pesty Venus and Neptune. They are the big anomalies in our solar system. I explain why they are where they are in this formula!
Yes, you can say I saved the best part for last!
This set of orbits proves absolute design to this solar system. The factor of the doubling is Pi. The variable is 2/3 or .666. The variable is a negative or minus. The starting points is a classic esoteric number that is a major name in the bible in Gematria, that is ALPHA-OMEGA!
Do you really want to argue proof of DESIGN in my solar system model when the key UNKNOWN PLANETS that are discovered soon will be aligned perfectly to a formula that begins with ALPHA-OMEGA as the starting point?
This is my third planetary orbit formula in my solar model.
= n – .666
where n = (1.332, Pi, Pi^2, Pi^3, 2Pi^3, 3Pi^3)
As you can see, THIS IS A COMPLEX AND INTELLIGENT SEQUENCE OF NUMBERS! There is no way someone can say to me this was a random event. Why start at 1.332? That is double .666 the variable. Why a variable of .666. Does not this whole model of a solar system revolve around three sets of six numbers or three sixes? Now some will say wow EVIL, is not EVIL backwards LIVE?
In gematria, the Greek THEOLOGY of numerology based upon the Greek Alphabet, the number 666 was used for a bad person. Well in reality in ancient Greece 666 was a holy number, since it is used to square a circle!
666 and 888 square a circle. By the way, in Greek gematria Jesus is 888.
Now in GREEK the name ALPHA-OMEGA has a value of 1332. Was the designer of the solar system a GREEK?
The Alpha-Omega is unity or a circle. It is a symbol said to represent GOD, he who was the first and he who shall be the last. Actually a circle has no beginning or an end so 1332 or double the variable of 666 represents unity in gematria. I’m sure there aren’t too many astro-physicists walking around with such esoteric knowledge.
Now 666 is special to me also, since upside down 666 is 999. 999 is also NINES and my birth name was ENNIS or an anagram of NINES. I guess I was destined to reveal this solar model.
Venus and Neptune the two planets that destroy every typical solar model such as Titius-Bodes, etc. are perfectly aligned to this third formula.
Two planet orbits no longer exist, but two unknown planet orbits are theorized by this formula. These planets will validate this solar model in the future.
Another GODLY part of this formula is the fact Pi^3 appears. Pi^3 is 31.006. 31 in Hebrew Kabbalah the equivalent of gematria is Aleph Lamed. Translated as GOD or EL. So GOD’s main name in the Hebrew bible is encoded in the formula as Pi^3.
Is it coincidence or DIVINE DESIGN? I won’t argue the point in this work, but I will in a later analysis of PDF.
In the future when planets are found that align to the theoretical location of orbits I have given, well let’s just say this solar system model will do what Einstein searched his whole life for. It will unite the physical world to physics and theology. It will be PROOF of Solar design to scientists and theologists alike!
These are the orbital numbers produced by my third formula, I called it Pi^3.
The true Perihelion of Venus is .668 our .666 is actually .667, so this formula is aligned to within .001 or the closest orbit of Venus to the Sun. That is not in AU it is in 10^8 miles.
The AU of Venus is considered to be .720.
The Perihelion of Neptune is 30.220, so we are once again within 1 to the third digit for a Perihelion measurement of a planets orbit. No one has ever aligned both Venus and Neptune in a formula within 1 to the third decimal place!
This means this formula creates the Perihelion of orbits. The other two formula creates perfect AU’s. This formula creates Perihelion (10^8 miles). This is once again an argument for DESIGN rather than random chance.
As unknown planets (U2 and U3) are found that align perfectly to this formula, it will validate my solar model as being PROOF of Solar Design to our Solar System!
The second planetary orbit created in this formula is an orbit that once again places a planet in the orbit of the asteroid belt. I doubt all three collided at the same time. The iron asteroids in this orbit make it look like a very fast early collision occurred at the iron core level of two young planets. It is quite possible that one of the planets of this triplet orbit then spun out of control most likely into Jupiter. It could have been any of the three asteroid distance orbit planets in any of the three sets. Which one it was is irrelevant. However, I have decided to name the second planet in this set Juno. Juno is the wife of Jupiter in mythology so when the triple planet orbit was broken by a collision of two planets, Jupiter got his wife!
The third planet I have named Nikkee the Goddess of Victory. For Nikkee is my earthly goddess companion/wife. So Nikkee of course merged with Saturn and El-Sollog.
So there we have it.
Three sets of six planets, the dreaded 666 that is also the basis of a carbon 12 atom, with all the orbits to known planets perfectly aligned.
We have the orbits of planets that collided and created the asteroid belt. We have an explanation as to why some gas planets are so large.
We have LOGICAL starting points in all the sets of numbers.
We have LOGICAL progression of the numbers creating perfect orbits to known planets.
In time the undiscovered planets will be found. They will align to my solar model, and in the future Physics, Theology, Mathematics, Philosophy, Astronomy and Science all begin with a lesson on PDF, the Planet Distance Formula.
The key to any type of PROOF for this solar model is watching to see at what orbits the next planets discovered in our solar system are found to have.
My formula predicts three unknown planets at
62.012 (10^8 Miles)
93.018 (10^8 Miles)
Sollog Immanuel Adonai-Adoni
July 11th 2002
Edited October 8th 2002
February 22nd 2004 Addendum
With the discovery of DW 2004 on February 17th 2004 (ONE DAY before the 74th Anniversary of the Discovery of Pluto – 1 74 or 147), it is now clear that the Kupier Belt is similar to the Asteroid Belt in that it was formed by the collision of at least two planets.
Two of these planets resided at approximately 38.4 and 62.0 (10^8 Miles). The orbits were very elliptical and the orbits crossed each other, which eventually caused a collision and formed the Kupier Belt.
Pluto and Quaoar are moons of the planet at 38.4 (10^8 Miles) that I called Theth above.
DW 2004 is a left over moon from the planet that was originally at 62.0 (10^8 Miles). I called this planet U2 above.
The Kupier Belt confirms that two planets collided, the fact that Pluto and Quaoar remain in orbit near where Theth should have been according to my theory and that a new moon type object similar to both Pluto and Quaoar has been found near where I theorized U2 would be is validation that DW 2004 is the moon of U2 and Pluto and Quaoar are the moons of Theth.
Planets U1 and U3 are still beyond Pluto. The theoretical orbit of U1 is 76 AU and the theoretical orbit of U3 is 93.0 (10^8 Miles)
If the Kupier Belt is found to extend out as far as 93.0 (10^8 Miles) which some have already theorized, then both U1 and U3 have suffered the same fate as U2 and Theth, that being they were destroyed by collision.
The current estimates of the width of the Kupier Belt fit well with the theory that the Kupier Belt may contain the material from 4 destroyed planets.
However, a gas giant similar to Neptune may be found where U1 and U2 are theorized to be located. That would mean U1 and U3 collided and formed a gas giant.
It may still be seen that both U1 and U3 exist as planets if the Kupier Belt does not extend much farther than 62.0 (10^8 Miles)
So in the future the discovery of additional objects similar to Pluto/Quaoar/DW 2004 may be found in the Kupier Belt.
Objects closer to 38.4 (10^8 Miles) are moons of Theth. Objects closer to 62.0 (10^8 Miles) are moons of U2.
If any such Planetoid objects are found where U1 and U3 are theorized to be located, then they are moons of the planets that once resided there.
Only time will tell what remains in the areas at 76.8 AU and 93.0 (10^8 Miles). It will be either moons of planets that were destroyed, a Gas Giant or perhaps two new worlds.
Titius-Bodes Law – Simple Planetary Distance Rule know for a couple of inaccuracies. It is a simple doubling law with a starting point that creates orbital distances to AU by doubling and adding four to a number and then dividing by 10.
1 3 7 – Known in Physics as the “fine-structure constant” of quantum electrodynamics. In Kabbalah 137 is the number of Kabbalah and also the wheel of one.
CREATOR FORMULA – Theorized by me in 1995. It states the circumference ratios of earth or aligned to the orbital rations of planets in our solar system.
PROOF for CREATOR Formula – Theorized in July 2002 by me, it is a simple PROOF showing how the ratios of four inner planets are perfectly aligned to ratios of earth’s circumference.
Titius-Bodes Variance – A formula I created a few days ago to align Titius-Bodes to actual distances to the sun in 10^8 miles instead of AU.
Discovery of Quaoar – The discovery of this object has led me to believe that Pluto and it are nothing but moons of a planet that once orbited at 38.40 AU. In time Pluto will no longer be considered a planet. Pluto and Quaoar are left behind moons of Theth. My Theth Theory fully explains Pluto, Quaoar and the Kuiper Belt.
Discovery of DW 2004 – This discovery confirms my theory that Pluto and Quaoar are moons as is DW 2004 of two planets that collided to form the Kupier Belt.
Visual Aid – The Image Below is not to scale, but it does show how the three sets of planets I have theorized line up. | 0.880478 | 3.675544 |
The Northern Lights are a visible result of physical processes in inner space. By studying the optical signal from the Northern Lights and similar phenomena, we can gain new knowledge about the physics behind them. In the long run such pure research may be of great importance for applications in our future supply of energy and for future space travel.
A dissertation at Umeå University, Sweden, by researcher Urban Brändström at The Swedish Institute of Space Physics, focuses on the construction and operation of a new land-based metering system, ALIS, designed for optic studies of the Northern Lights and other weak light phenomena. ALIS now consists of six unmanned metering stations placed in a net of squares of about 50 km on a side. Each station is equipped with a light-sensitive CCD camera and a filter wheel with narrow-band filters. It is therefore possible to carry out studies of the different “colors” in the phenomenon observed. Since the stations’ fields of vision overlap, it is also possible to glean information about altitude.
ALIS performed the first unequivocal observations of artificial light emissions at high latitudes. They were generated by a powerful radio transmitter at the EISCAT facility in Tromsø, and they were observed simultaneously by several ALIS stations. This made it possible to obtain altitude profiles for the first time. Experiments of this type thus offer exciting potential for enhanced understanding of the physics of inner space.
Rick McGregor | alfa
K-State study reveals asymmetry in spin directions of galaxies
03.06.2020 | Kansas State University
The cascade to criticality
03.06.2020 | ETH Zurich Department of Physics
An analysis of more than 200,000 spiral galaxies has revealed unexpected links between spin directions of galaxies, and the structure formed by these links...
Two prominent X-ray emission lines of highly charged iron have puzzled astrophysicists for decades: their measured and calculated brightness ratios always disagree. This hinders good determinations of plasma temperatures and densities. New, careful high-precision measurements, together with top-level calculations now exclude all hitherto proposed explanations for this discrepancy, and thus deepen the problem.
Hot astrophysical plasmas fill the intergalactic space, and brightly shine in stellar coronae, active galactic nuclei, and supernova remnants. They contain...
In living cells, enzymes drive biochemical metabolic processes enabling reactions to take place efficiently. It is this very ability which allows them to be used as catalysts in biotechnology, for example to create chemical products such as pharmaceutics. Researchers now identified an enzyme that, when illuminated with blue light, becomes catalytically active and initiates a reaction that was previously unknown in enzymatics. The study was published in "Nature Communications".
Enzymes: they are the central drivers for biochemical metabolic processes in every living cell, enabling reactions to take place efficiently. It is this very...
Early detection of tumors is extremely important in treating cancer. A new technique developed by researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from normal tissue. The work is published May 25 in the journal Nature Nanotechnology.
researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from...
Microelectronics as a key technology enables numerous innovations in the field of intelligent medical technology. The Fraunhofer Institute for Biomedical Engineering IBMT coordinates the BMBF cooperative project "I-call" realizing the first electronic system for ultrasound-based, safe and interference-resistant data transmission between implants in the human body.
When microelectronic systems are used for medical applications, they have to meet high requirements in terms of biocompatibility, reliability, energy...
19.05.2020 | Event News
07.04.2020 | Event News
06.04.2020 | Event News
03.06.2020 | Medical Engineering
03.06.2020 | Physics and Astronomy
03.06.2020 | Physics and Astronomy | 0.852742 | 3.625629 |
H.E.S.S. is a system of Imaging Atmospheric Cherenkov Telescopes that investigates cosmic gamma rays in the energy range from 10s of GeV to 10s of TeV. The name H.E.S.S. stands for High Energy Stereoscopic System, and is also intended to pay homage to Victor Hess, who received the Nobel Prize in Physics in 1936 for his discovery of cosmic radiation. The instrument allows scientists to explore gamma-ray sources with intensities at a level of a few thousandths of the flux of the Crab nebula (the brightest steady source of gamma rays in the sky). H.E.S.S. is located in Namibia, near the Gamsberg mountain, an area well known for its excellent optical quality. The first of the four telescopes of Phase I of the H.E.S.S. project went into operation in Summer 2002; all four were operational in December 2003, and were officially inaugurated on September 28, 2004. A much larger fifth telescope – H.E.S.S. II – is operational since July 2012, extending the energy coverage towards lower energies and further improving sensitivity.
The H.E.S.S. observatory is operated by the collaboration of more than 170 scientists, from 32 scientific institutions and 12 different countries: Namibia and South Africa, Germany, France, the UK, Ireland, Austria, Poland, the Czech Republic, Sweden, Armenia, and Australia. To date, the H.E.S.S. Collaboration has published over 100 articles in high-impact scientific journals, including the top-ranked ‘Nature’ and ‘Science’ journals.
In a survey in 2006, H.E.S.S. was ranked the 10th most influential observatory worldwide, joining the ranks with the Hubble Space Telescope or the telescopes of the European Southern Observatory ESO in Chile.
Named HESS II, the giant telescope’s 600-tonne bulk and 28-metre mirror will survey the southern hemisphere, hunting for violent, high-energy cosmic sources such as supermassive black holes, supernovae and pulsars.
Cherenkov telescopes search for signs of very-high-energy gamma rays by watching for Cherenkov radiation – a scatter of charged particles produced from gamma-ray interactions in our atmosphere and captured as faint flashes of blue light. HESS II captures these flashes with a camera around a million times as fast as one you or I might own.
There are currently two other operating Cherenkov systems – MAGIC, in the Canary Islands and VERITAS, in Arizona. The HESS array includes four smaller telescopes, each with a 12-metre mirror. HESS II has an “unprecedented” resolving ability, says the team, enabling it to capture a sharper picture of the skies.
Gamma-ray observations from HESS will be used in combination with data from the Square Kilometre Array (SKA), the world’s largest radio telescope system, expected to begin observing in 2020. Comprising telescopes scattered across South Africa, Australia and New Zealand, the SKA will be sensitive enough to detect the equivalent of an airport radar on a planet 50 light years away. | 0.859291 | 3.81426 |
One of the brightest stars you'll see in the sky these days is Betelgeuse, whose red tones provide a fun skywatching target in February.
This monster star is about 1,000 times the size of our sun, according to NASA, and sits on the shoulder of the famous constellation Orion. The star is variable, meaning that it brightens and dims periodically. Lately, it's been dimming more, leading scientists to speculate that Betelgeuse could be somewhat close to a supernova explosion, in which the star would run out of gas to burn, then blow up.
You can easily find Betelgeuse in the constellation Orion anytime between November and February. RIght now, in New York City, Betelgeuse is rising in daylight, so you'll see it as soon as the sky darkens enough. The star is remaining above the horizon until a few hours before dawn. You can check your local times using SkySafari, a free app for Android or iPhone.
Here's how to track down Betelgeuse: Once you go outside, give your eyes a few minutes to get adjusted to the darkness. Then turn to the southwestern sky in the Northern Hemisphere (the northwestern sky in the Southern Hemisphere) and look for the distinctive star pattern of Orion, centered on the three stars of its belt.
If you imagine Orion as its namesake, "the hunter," Betelgeuse marks the left-hand shoulder. The star is so bright and red, even in light-polluted areas, that you can't miss it. Betelgeuse is easily visible to the eye, and you won't see much more detail using binoculars or a telescope.
The star is so intriguing that the Hubble Space Telescope periodically turns its powerful gaze on Betelgeuse to see what scientists can learn. One particularly intriguing observation found a massive hotspot, the cause of which is still unknown, according to the European Space Agency.
During its current dimming spree, you can track Betelgeuse's activity and submit your observations to the American Association of Variable Star Observers to help the group gather more information on its variability. More details on how to participate are here.
- Night sky, February 2020: What you can see this month [maps]
- Best night sky events of February 2020 (stargazing maps)
- The 10 must-see skywatching events to look for in 2020 | 0.847344 | 3.60766 |
This article may need to be rewritten to comply with Wikipedia's quality standards, as it is inconsistent and not always clear. See Talk. (September 2018)
Weightlessness is the complete or near-complete absence of the sensation of weight. This is also termed zero-g, although the more correct term is "zero g-force". It occurs in the absence of any contact forces upon objects including the human body.
Weight is a measurement of the force on an object at rest in a relatively strong gravitational field (such as on the surface of the Earth). These weight-sensations originate from contact with supporting floors, seats, beds, scales, and the like. A sensation of weight is also produced, even when the gravitational field is zero, when contact forces act upon and overcome a body's inertia by mechanical, non-gravitational forces- such as in a centrifuge, a rotating space station, or within an accelerating vehicle.
When the gravitational field is non-uniform, a body in free fall experiences tidal effects and is not stress-free. Near a black hole, such tidal effects can be very strong. In the case of the Earth, the effects are minor, especially on objects of relatively small dimensions (such as the human body or a spacecraft) and the overall sensation of weightlessness in these cases is preserved. This condition is known as microgravity, and it prevails in orbiting spacecraft.
In Newtonian mechanics the term "weight" is given two distinct interpretations by engineers.
To sum up, we have two notions of weight of which weight1 is dominant. Yet 'weightlessness' is typically exemplified not by absence of weight1 but by the absence of stress associated with weight2. This is the intended sense of weightlessness in what follows below.
A body is stress free, exerts zero weight2, when the only force acting on it is weight1 as when in free fall in a uniform gravitational field. Without subscripts, one ends up with the odd-sounding conclusion that a body is weightless when the only force acting on it is its weight.
The apocryphal apple that fell on Newton's head can be used to illustrate the issues involved. An apple weighs approximately 1 newton (0.22 lbf). This is the weight1 of the apple and is considered to be a constant even while it is falling. During that fall, its weight2 however is zero: ignoring air resistance, the apple is stress free. When it hits Newton, the sensation felt by Newton would depend upon the height from which the apple falls and weight2 of the apple at the moment of impact may be many times greater than 1 N (0.22 lbf). It is this weight2 which distorts the apple. On its way down, the apple in its free fall does not suffer any distortion as the gravitational field is uniform.
Throughout this discussion on using stress as an indicator of weight, any pre-stress which may exist within a body caused by a force exerted on one part by another is not relevant. The only relevant stresses are those generated by external forces applied to the body.
The definition and use of 'weightlessness' is difficult unless it is understood that the sensation of "weight" in everyday terrestrial experience results not from gravitation acting alone (which is not felt), but instead by the mechanical forces that resist gravity. An object in a straight free fall, or in a more complex inertial trajectory of free fall (such as within a reduced gravity aircraft or inside a space station), all experience weightlessness, since they do not experience the mechanical forces that cause the sensation of weight.
As noted above, weightlessness occurs when
For the sake of completeness, a 3rd minor possibility has to be added. This is that a body may be subject to a field which is not gravitational but such that the force on the object is uniformly distributed across the object's mass. An electrically charged body, uniformly charged, in a uniform electric field is a possible example. Electric charge here replaces the usual gravitational charge. Such a body would then be stress free and be classed as weightless. Various types of levitation may fall into this category, at least approximately.
A body in free fall (which by definition entails no aerodynamic forces) near the surface of the earth has an acceleration approximately equal to 9.8 m/s2 (32 ft/s2) with respect to a coordinate frame tied to the earth. If the body is in a freely falling lift and subject to no pushes or pulls from the lift or its contents, the acceleration with respect to the lift would be zero. If on the other hand, the body is subject to forces exerted by other bodies within the lift, it will have an acceleration with respect to the freely falling lift. This acceleration which is not due to gravity is called "proper acceleration". On this approach, weightlessness holds when proper acceleration is zero.
Weightlessness is in contrast with current human experiences in which a non-uniform force is acting, such as:
In cases where an object is not weightless, as in the above examples, a force acts non-uniformly on the object in question. Aero-dynamic lift, drag, and thrust are all non-uniform forces (they are applied at a point or surface, rather than acting on the entire mass of an object), and thus create the phenomenon of weight. This non-uniform force may also be transmitted to an object at the point of contact with a second object, such as the contact between the surface of the Earth and one's feet, or between a parachute harness and one's body.
Tidal forces arise when the gravitational field is not uniform and gravitation gradients exist. Such indeed is the norm and strictly speaking any object of finite size even in free-fall is subject to tidal effects. These are impossible to remove by inertial motion, except at one single nominated point of the body. The Earth is in free fall but the presence of tides indicates that it is in a non-uniform gravitational field. This non-uniformity is more due to the moon than the sun. The total gravitational field due to the sun is much stronger than that of the moon but it has a minor tidal effect compared with that of the moon because of the relative distances involved. Weight1 of the earth is essentially due to the sun's gravity. But its state of stress and deformation, represented by the tides, is more due to non uniformity in the gravitational field of the nearby moon. When the size of a region being considered is small relative to its distance from the gravitating mass the assumption of uniform gravitational field holds to a good approximation. Thus a person is small relative to the radius of Earth and the field for a person at the surface of the earth is approximately uniform. The field is strictly not uniform and is responsible for the phenomenon of microgravity. Objects near a black hole are subject to a highly non-uniform gravitational field.
In all inertial reference frames, while weightlessness is experienced, Newton's first law of motion is obeyed locally within the frame. Inside the frame (for example, inside an orbiting ship or free-falling elevator), unforced objects keep their velocity relative to the frame. Objects not in contact with other objects "float" freely. If the inertial trajectory is influenced by gravity, the reference frame will be an accelerated frame as seen from a position outside the gravitational attraction, and (seen from far away) the objects in the frame (elevator, etc.) will appear to be under the influence of a force (the so-called force of gravity). As noted, objects subject solely to gravity do not feel its effects. Weightlessness can thus be realised for short periods of time in an airplane following a specific elliptic flight path, often mistakenly called a parabolic flight. It is simulated poorly, with many differences, in neutral buoyancy conditions, such as immersion in a tank of water.
Zero-g is an alternative term for weightlessness and holds for instance in a freely falling lift. Zero-g is subtly different from the complete absence of gravity, something which is impossible due to the presence of gravity everywhere in the universe. "Zero-gravity" may also be used to mean effective weightlessness, neglecting tidal effects. Microgravity (or µg) is used to refer to situations that are substantially weightless but where g-force stresses within objects due to tidal effects, as discussed above, are around a millionth of that at the Earth's surface. Accelerometers can only detect g-force i.e. weight2 (= mass × proper acceleration). They cannot detect the acceleration associated with free fall.[a]
Humans experience their own body weight as a result of this supporting force, which results in a normal force applied to a person by the surface of a supporting object, on which the person is standing or sitting. In the absence of this force, a person would be in free-fall, and would experience weightlessness. It is the transmission of this reaction force through the human body, and the resultant compression and tension of the body's tissues, that results in the sensation of weight.
Because of the distribution of mass throughout a person's body, the magnitude of the reaction force varies between a person's feet and head. At any horizontal cross-section of a person's body (as with any column), the size of the compressive force being resisted by the tissues below the cross-section is equal to the weight of the portion of the body above the cross-section. In the pose adopted in the accompanying illustration, the shoulders carry the weight of the outstretched arms and are subject to a considerable torque.
A common conception about spacecraft orbiting the earth is that they are operating in a gravity free environment. Although there is a way of making sense of this within the physics of Einstein's general relativity, within Newtonian physics, this is technically inaccurate .
Spacecraft are held in orbit by the gravity of the planet which they are orbiting. In Newtonian physics, the sensation of weightlessness experienced by astronauts is not the result of there being zero gravitational acceleration (as seen from the Earth), but of there being no g-force that an astronaut can feel because of the free-fall condition, and also there being zero difference between the acceleration of the spacecraft and the acceleration of the astronaut. Space journalist James Oberg explains the phenomenon this way:
The myth that satellites remain in orbit because they have "escaped Earth's gravity" is perpetuated further (and falsely) by almost universal misuse of the word "zero gravity" to describe the free-falling conditions aboard orbiting space vehicles. Of course, this isn't true; gravity still exists in space. It keeps satellites from flying straight off into interstellar emptiness. What's missing is "weight", the resistance of gravitational attraction by an anchored structure or a counterforce. Satellites stay in space because of their tremendous horizontal speed, which allows them--while being unavoidably pulled toward Earth by gravity--to fall "over the horizon." The ground's curved withdrawal along the Earth's round surface offsets the satellites' fall toward the ground. Speed, not position or lack of gravity, keeps satellites in orbit around the earth.
A geostationary satellite is of special interest in this context. Unlike other objects in the sky which rise and set, an object in a geostationary orbit appears motionless in the sky, apparently defying gravity. In fact, it is in a circular equatorial orbit with a period of one day.
To a modern physicist working with Einstein's general theory of relativity, the situation is even more complicated than is suggested above. Einstein's theory suggests that it actually is valid to consider that objects in inertial motion (such as falling in an elevator, or in a parabola in an airplane, or orbiting a planet) can indeed be considered to experience a local loss of the gravitational field in their rest frame. Thus, in the point of view (or frame) of the astronaut or orbiting ship, there actually is nearly-zero proper acceleration (the acceleration felt locally), just as would be the case far out in space, away from any mass. It is thus valid to consider that most of the gravitational field in such situations is actually absent from the point of view of the falling observer, just as the colloquial view suggests (see equivalence principle for a fuller explanation of this point). However, this loss of gravity for the falling or orbiting observer, in Einstein's theory, is due to the falling motion itself, and (again as in Newton's theory) not due to increased distance from the Earth. However, the gravity nevertheless is considered to be absent. In fact, Einstein's realization that a pure gravitational interaction cannot be felt, if all other forces are removed, was the key insight to leading him to the view that the gravitational "force" can in some ways be viewed as non-existent. Rather, objects tend to follow geodesic paths in curved space-time, and this is "explained" as a force, by "Newtonian" observers who assume that space-time is "flat," and thus do not have a reason for curved paths (i.e., the "falling motion" of an object near a gravitational source).
In the theory of general relativity, the only gravity which remains for the observer following a falling path or "inertial" path near a gravitating body, is that which is due to non-uniformities which remain in the gravitational field, even for the falling observer. This non-uniformity, which is a simple tidal effect in Newtonian dynamics, constitutes the "microgravity" which is felt by all spacially-extended objects falling in any natural gravitational field that originates from a compact mass. The reason for these tidal effects is that such a field will have its origin in a centralized place (the compact mass), and thus will diverge, and vary slightly in strength, according to distance from the mass. It will thus vary across the width of the falling or orbiting object. Thus, the term "microgravity," an overly technical term from the Newtonian view, is a valid and descriptive term in the general relativistic (Einsteinian) view.
The term micro-g environment (also µg, often referred to by the term microgravity) is more or less a synonym of weightlessness and zero-G, but indicates that g-forces are not quite zero, just very small.
Airplanes have been used since 1959 to provide a nearly weightless environment in which to train astronauts, conduct research, and film motion pictures. Such aircraft are commonly referred by the nickname "Vomit Comet".
To create a weightless environment, the airplane flies in a six-mile long parabolic arc, first climbing, then entering a powered dive. During the arc, the propulsion and steering of the aircraft are controlled such that the drag (air resistance) on the plane is cancelled out, leaving the plane to behave as it would if it were free-falling in a vacuum. During this period, the plane's occupants experience 22 seconds of weightlessness, before experiencing about 22 seconds of 1.8 g acceleration (nearly twice their normal weight) during the pull-out from the parabola. A typical flight lasts around two hours, during which 30 parabolae are flown.
Versions of such airplanes have been operated by NASA's Reduced Gravity Research Program since 1973, where the unofficial nickname originated. NASA later adopted the official nickname 'Weightless Wonder' for publication. NASA's current Reduced Gravity Aircraft, "Weightless Wonder VI", a McDonnell Douglas C-9, is based at Ellington Field (KEFD), near Lyndon B. Johnson Space Center.
NASA's Microgravity University - Reduced Gravity Flight Opportunities Plan, also known as the Reduced Gravity Student Flight Opportunities Program, allows teams of undergraduates to submit a microgravity experiment proposal. If selected, the teams design and implement their experiment, and students are invited to fly on NASA's Vomit Comet.
The European Space Agency flies parabolic flights on a specially-modified Airbus A310-300 aircraft, in order to perform research in microgravity. As well European ESA, French CNES and German DLR fly campaigns of three flights on consecutive days, each flying about 30 parabolas, for a total of about 10 minutes of weightlessness per flight. These campaigns are currently operated from Bordeaux - Mérignac Airport in France by the company Novespace, a subsidiary of French CNES, while the aircraft is flown by test pilots from DGA Essais en Vol. The first ESA Zero-G flights were in 1984, using a NASA KC-135 aircraft in Houston, Texas. As of May 2010 , the ESA has flown 52 campaigns and also 9 student parabolic flight campaigns.
Novespace created Air Zero G in 2012 to share the experience of weightlessness to 40 public passengers per flight, using the same A310 ZERO-G than for scientific experiences. These flights are sold by Avico, are mainly operated from Bordeaux-Merignac, France, and intend to promote European space research, allowing public passengers to feel weightlessness. Jean-François Clervoy, Chairman of Novespace and ESA astronaut, flies with Air Zero G one-day-astronauts on board A310 Zero-G. After the flight, he explains the quest of space and talks about the 3 space travels he did along his career. The aircraft has also been used for cinema purposes, with Tom Cruise and Annabelle Wallis for the Mummy in 2017.
The Zero Gravity Corporation, founded in 1993 by Peter Diamandis, Byron Lichtenberg, and Ray Cronise, operates a modified Boeing 727 which flies parabolic arcs to create 25-30 seconds of weightlessness. Flights may be purchased for both tourism and research purposes.
Ground-based facilities that produce weightless conditions for research purposes are typically referred to as drop tubes or drop towers.
NASA's Zero Gravity Research Facility, located at the Glenn Research Center in Cleveland, Ohio, is a 145-meter vertical shaft, largely below the ground, with an integral vacuum drop chamber, in which an experiment vehicle can have a free fall for a duration of 5.18 seconds, falling a distance of 132 meters. The experiment vehicle is stopped in approximately 4.5 meters of pellets of expanded polystyrene and experiences a peak deceleration rate of 65g.
Also at NASA Glenn is the 2.2 Second Drop Tower, which has a drop distance of 24.1 meters. Experiments are dropped in a drag shield, in order to reduce the effects of air drag. The entire package is stopped in a 3.3 meter tall air bag, at a peak deceleration rate of approximately 20g. While the Zero Gravity Facility conducts one or two drops per day, the 2.2 Second Drop Tower can conduct up to twelve drops per day.
Humans cannot utilize these gravity shafts, as the deceleration experienced by the drop chamber would likely kill or seriously injure anyone using them; 20g is about the highest deceleration that a fit and healthy human can withstand momentarily without sustaining injury.
Other drop facilities worldwide include:
Conditions similar to some in weightlessness can also be simulated by creating the condition of neutral buoyancy, in which human subjects and equipment are placed in a water environment and weighted or buoyed until they hover in place. NASA uses neutral buoyancy to prepare for extra-vehicular activity (EVA) at its Neutral Buoyancy Laboratory. Neutral buoyancy is also used for EVA research at the University of Maryland's Space Systems Laboratory, which operates the only neutral buoyancy tank at a college or university.
Neutral buoyancy is not identical to weightlessness. Gravity still acts on all objects in a neutral buoyancy tank; thus, astronauts in neutral buoyancy training still feel their full body weight within their spacesuits, although the weight is well-distributed, similar to force on a human body in a water bed, or when simply floating in water. The suit and astronaut together are under no net force, as for any object that is floating, or supported in water, such as a scuba diver at neutral buoyancy. Water also produces drag, which is not present in vacuum.
Long periods of weightlessness occur on spacecraft outside a planet's atmosphere, provided no propulsion is applied and the vehicle is not rotating. Weightlessness does not occur when a spacecraft is firing its engines or when re-entering the atmosphere, even if the resultant acceleration is constant. The thrust provided by the engines acts at the surface of the rocket nozzle rather than acting uniformly on the spacecraft, and is transmitted through the structure of the spacecraft via compressive and tensile forces to the objects or people inside.
Weightlessness in an orbiting spacecraft is physically identical to free-fall, with the difference that gravitational acceleration causes a net change in the direction, rather than the magnitude, of the spacecraft's velocity. This is because the acceleration vector is perpendicular to the velocity vector.
In typical free-fall, the acceleration of gravity acts along the direction of an object's velocity, linearly increasing its speed as it falls toward the Earth, or slowing it down if it is moving away from the Earth. In the case of an orbiting spacecraft, which has a velocity vector largely perpendicular to the force of gravity, gravitational acceleration does not produce a net change in the object's speed, but instead acts centripetally, to constantly "turn" the spacecraft's velocity as it moves around the Earth. Because the acceleration vector turns along with the velocity vector, they remain perpendicular to each other. Without this change in the direction of its velocity vector, the spacecraft would move in a straight line, leaving the Earth altogether.
The net gravitational force due to a spherically symmetrical planet is zero at the center. This is clear because of symmetry, and also from Newton's shell theorem which states that the net gravitational force due to a spherically symmetric shell, e.g., a hollow ball, is zero anywhere inside the hollow space. Thus the material at the center is weightless.
Following the advent of space stations that can be inhabited for long periods, exposure to weightlessness has been demonstrated to have some deleterious effects on human health. Humans are well-adapted to the physical conditions at the surface of the Earth. In response to an extended period of weightlessness, various physiological systems begin to change and atrophy. Though these changes are usually temporary, long term health issues can result.
The most common problem experienced by humans in the initial hours of weightlessness is known as space adaptation syndrome or SAS, commonly referred to as space sickness. Symptoms of SAS include nausea and vomiting, vertigo, headaches, lethargy, and overall malaise. The first case of SAS was reported by cosmonaut Gherman Titov in 1961. Since then, roughly 45% of all people who have flown in space have suffered from this condition. The duration of space sickness varies, but in no case has it lasted for more than 72 hours, after which the body adjusts to the new environment. NASA jokingly measures SAS using the "Garn scale", named for United States Senator Jake Garn, whose SAS during STS-51-D was the worst on record. Accordingly, one "Garn" is equivalent to the most severe possible case of SAS.
The most significant adverse effects of long-term weightlessness are muscle atrophy (see Reduced muscle mass, strength and performance in space for more information) and deterioration of the skeleton, or spaceflight osteopenia. These effects can be minimized through a regimen of exercise, such as cycling for example. Astronauts subject to long periods of weightlessness wear pants with elastic bands attached between waistband and cuffs to compress the leg bones and reduce osteopenia. Other significant effects include fluid redistribution (causing the "moon-face" appearance typical of pictures of astronauts in weightlessness), a slowing of the cardiovascular system as blood flow decreases in response to a lack of gravity, a decreased production of red blood cells, balance disorders, and a weakening of the immune system. Lesser symptoms include loss of body mass, nasal congestion, sleep disturbance, excess flatulence, and puffiness of the face. These effects begin to reverse quickly upon return to the Earth.
In addition, after long space flight missions, astronauts may experience severe eyesight problems. Such eyesight problems may be a major concern for future deep space flight missions, including a manned mission to the planet Mars. Exposure to high levels of radiation may influence the development of atherosclerosis also.
On December 31, 2012, a NASA-supported study reported that manned spaceflight may harm the brains of astronauts and accelerate the onset of Alzheimer's disease. In October 2015, the NASA Office of Inspector General issued a health hazards report related to human spaceflight, including a human mission to Mars.
Russian scientists have observed differences between cockroaches conceived in space and their terrestrial counterparts. The space-conceived cockroaches grew more quickly, and also grew up to be faster and tougher.
Chicken eggs that are put in microgravity two days after fertilization appear not to develop properly, whereas eggs put in microgravity more than a week after fertilization develop normally.
A 2006 Space Shuttle experiment found that Salmonella typhimurium, a bacterium that can cause food poisoning, became more virulent when cultivated in space. On April 29, 2013, scientists in Rensselaer Polytechnic Institute, funded by NASA, reported that, during spaceflight on the International Space Station, microbes seem to adapt to the space environment in ways "not observed on Earth" and in ways that "can lead to increases in growth and virulence".
Weightlessness can cause serious problems on technical instruments, especially those consisting of many mobile parts. Physical processes that depend on the weight of a body (like convection, cooking water or burning candles) act differently in free-fall. Cohesion and advection play a bigger role in space. Everyday work like washing or going to the bathroom are not possible without adaptation. To use toilets in space, like the one on the International Space Station, astronauts have to fasten themselves to the seat. A fan creates suction so that the waste is pushed away. Drinking is aided with a straw or from tubes.
"Jake Garn was sick, was pretty sick. I don't know whether we should tell stories like that. But anyway, Jake Garn, he has made a mark in the Astronaut Corps because he represents the maximum level of space sickness that anyone can ever attain, and so the mark of being totally sick and totally incompetent is one Garn. Most guys will get maybe to a tenth Garn, if that high. And within the Astronaut Corps, he forever will be remembered by that."
One of the nice things about living in space is that exercise is part of your job ... If I don't exercise six days a week for at least a couple of hours a day, my bones will lose significant mass - 1 percent each month ... Our bodies are smart about getting rid of what's not needed, and my body has started to notice that my bones are not needed in zero gravity. Not having to support our weight, we lose muscle as well. | 0.852291 | 3.652439 |
Konstantin Batygin did not set out to solve one of the solar system’s most puzzling mysteries when he went for a run up a hill in Nice, France. Dr. Batygin, a Caltech researcher, best known for his contributions to the search for the solar system’s missing “Planet Nine,” spotted a beer bottle. At a steep, 20 degree grade, he wondered why it wasn’t rolling down the hill.
He realized there was a breeze at his back holding the bottle in place. Then he had a thought that would only pop into the mind of a theoretical astrophysicist: “Oh! This is how Europa formed.”
Europa is one of Jupiter’s four large Galilean moons. And in a paper published Monday in the Astrophysical Journal, Dr. Batygin and a co-author, Alessandro Morbidelli, a planetary scientist at the Côte d’Azur Observatory in France, present a theory explaining how some moons form around gas giants like Jupiter and Saturn, suggesting that millimeter-sized grains of hail produced during the solar system’s formation became trapped around these massive worlds, taking shape one at a time into the potentially habitable moons we know today.
Dr. Batygin and Dr. Morbidelli say earlier theories explain only a part of how the solar system’s many objects formed. The two researchers set out to present the rest of the story with equations explaining how a new planet transitions from being surrounded by its disk of matter, to creating satellite building blocks, all the way to the formation of moons like Europa.
When Dr. Batygin and Dr. Morbidelli ran computer simulations of their proposed theory, they found that they’d accidentally re-created Jupiter’s small innermost moons as well as the four Galilean satellites, much as we see them today.
“I thought I was still dreaming when I saw the results,” Dr. Batygin said.
The equations amount to a recipe for how to make a moon. It starts with a mix of hydrogen and helium gas raining down onto Jupiter from above. Some of the gas gets swept out and away, spreading viscously as it goes into orbit around Jupiter in a process called decretion.
At this point in Jupiter’s formation, the only solid particles that orbited it were smaller than one millimeter across. Because this dust is very small — tiny grains about two parts ice to one part rock — it can couple itself to the gas washing away from Jupiter.
“The disk around Jupiter acts a little bit like a vacuum cleaner, where it sources small dust from the protoplanetary disk,” Dr. Batygin said.
As this material builds up over the course of about a million years, he says, it eventually reaches a mass that approximately matches Io, Europa, Ganymede and Callisto today.
The dust clumps together into a massive carpet of icy asteroids, some of which slow down, growing larger as they consume some of the other objects.
“Once the moon is big enough to ship, it gets on the conveyor belt,” Dr. Batygin said, and eventually moves in closer to Jupiter, parking into its orbit around the planet.
In this model, Io was formed in about 1,000 years and then quickly got ejected from the satellite feeding zone, leaving behind a mess of remaining icy asteroids in wonky orbits. Around 10,000 years later, Europa grows over about the course of a millennium and does the same thing. After a 30,000-year break, Ganymede begins to form, but takes 2,000 years to grow. Callisto, however, begins to form when the material from Jupiter is nearly depleted, so it takes much longer, around eight million years.
The model offers a similar explanation for Saturn and its largest moon, Titan.
Jonathan Lunine, an astronomer at Cornell University who has studied the Galilean satellites’ formation, says the paper “sketches out a scenario more like the formation of the terrestrial planets,” than other theories. But he thinks that “it doesn’t solve head-on the curious fact that Ganymede, Callisto and Titan (Titan being the big moon of Saturn) all have very similar sizes and densities and yet totally different geologic histories.”
Closer study will be needed to fully explain these moons’ history. Luckily, missions planned to Saturn’s moon Titan and Jupiter’s moons Callisto, Europa and Ganymede in the next 20 years will yield more data to test theories like this one. And this research may aid our understanding about whether life is possible around other stars.
“If we’re going to find life, arguably the best place to look are the icy satellites of the giant planets,” Dr. Batygin said. If similar moons are likely to form around other stars’ gas giants, it raises the question of whether “life in the universe is actually pretty common” he said. “I don’t know, of course, but it’s an exciting thing to think about.” | 0.855879 | 3.94941 |
Ten years at Mars: new global views plot the Red Planet's history
3 June 2013New global maps of Mars released on the 10th anniversary of the launch of ESA's Mars Express trace the history of water and volcanic activity on the Red Planet, and identify sites of special interest for the next generation of Mars explorers.
The unique atlas comprises a series of maps showing the distribution of minerals formed in water, by volcanic activity, and by weathering to create the dust that makes Mars red. They create a global context for the dominant geological processes that sculpted the planet we see today.
The maps were built from ten years of data collected by the OMEGA mineralogical mapper on Mars Express, which determines the mineral composition of the martian surface by analysing the spectrum of reflected sunlight.
|Mars mineral maps. Credit: ESA (Click here for further details and larger versions of this video.)|
"The history of Mars is encoded in its minerals," says Alvaro Giménez, ESA’s Director of Science and Robotic Exploration. "These new global views, made possible thanks to the longevity of ESA’s Mars Express mission, are helping us to unlock the secrets of 4.6 billion years of planetary evolution.
"The atlas released today will help to determine future landing sites for the next generation of Mars landers and rovers, and identify sites of special interest for future manned missions, helping to keep Europe at the forefront of planetary exploration."
Each map represents a different chapter in the story of geological evolution on Mars.
Maps showing the distribution of minerals formed in water
|Map showing distribution of hydrated minerals. Credit: ESA/CNES/CNRS/IAS/Université Paris-Sud, Orsay; NASA/JPL/JHUAPL; Background image: NASA MOLA|
The first map shows individual sites of hydrated minerals – 'phyllosilicates' and hydrated salts that form only in the presence of water. These are primarily seen in the most ancient cratered terrain dating back to over four billion years ago, suggesting that Mars sustained surface and subsurface liquid water during its first few hundred million years, potentially providing conditions favourable to early life.
Maps showing the distribution of minerals formed by volcanic activity
The next two maps showing the minerals olivine and pyroxene tell the story of volcanism, with differences in the chemical composition of the solidified lavas yielding clues as to the evolution of the temperature and pressure inside the planet.
|Map showing distribution of olivine (top) and pyroxene (bottom). Credits: ESA/CNES/CNRS/IAS/Université Paris-Sud, Orsay; Background image: NASA MOLA|
Olivine and pyroxene are the two primary minerals in basalt that form when lava solidifies. Basalt characterises the crust of Mars as well as oceanic crust on Earth and the volcanic seas on the Moon.
Some of the most pristine, magnesium-rich olivines exposed on the surface of Mars today are found around impact craters that have excavated samples of very ancient mantle from beneath the crust.
Olivine-rich surfaces are also associated with a global lava-flooding event around 3.7 billion years ago, when magma erupted onto the surface through fractures in the floors of impact craters, similar to the way in which the Moon's large impact basins were flooded with volcanic lava. Only a few traces of this global event remain today, with subsequent geological activity overprinting the signature.
Pyroxenes are particularly widespread in the cratered highlands, pointing to some of the most ancient portions of the planet’s crust. In the smooth northern plains, the pyroxenes reflect the eruption of more evolved lavas compared to the pristine olivines.
Maps showing the distribution of dust created by weathering
Dust obscures much of the underlying rock on Mars, but it is very closely related to ferric oxide, a mineral phase of iron found all over the planet, with greatest abundances in the northern lowlands and the volcanic province of Tharsis.
|Maps showing distribution of (top) ferric oxides, a mineral phase of iron and (bottom) dust, across the surface of Mars, Credits: ESA/CNES/CNRS/IAS/Université Paris-Sud, Orsay; Background image: NASA MOLA|
The Red Planet's dust is thought primarily to result from chemical reactions with the atmosphere, causing the iron-rich rocks to 'rust' slowly over billions of years, giving Mars its distinctive hue.
Weathering and erosion from past glacial activity and impact events, as well as dust storms, winds and freezing and thawing cycles today, contribute to the continued production of fine-grained dust.
"Collectively, these mineral maps provide unique records of the planet's evolution through time. They exhibit the role water and volcanic processes played over the entire planet, spanning geological aeons," says Jean-Pierre Bibring, Principal Investigator for OMEGA.
Maps providing hints for future in-situ exploration
The maps also highlight areas of particular scientific interest that may warrant further in-situ exploration, such as the abundance of hydrated mineral exposures clustered along the boundary between the low northern plains and the ancient cratered highlands.
"Against the flanks of these cliffs, thick ice deposits may have preserved ancient water-altered sites for a longer period of time than in more exposed locations," says Professor Bibring.
In some places, the maps show an overlap between volcanic outcrops and hydrated minerals: here, minerals may have become altered via heating during volcano–ice interactions.
One such location, known as Nili Fossae, is identifiable by the obvious bright red/yellow spot in the olivine map, a mineral easily weathered into clay in the presence of water. If rocks here were altered by hydrothermal activity, then conditions may have once existed there to support life.
"These are very special sites – possibly unique within the entire Solar System – with well preserved records of the environment during the few hundreds of millions of years following planet formation, during which life might have emerged on Earth and possibly at Mars," adds Professor Bibring.
Ten years of discovery
In addition to the tantalising tale of the history of water and volcanism on the surface, Mars Express has also been conducting a wide range of studies of the Red Planet, from the subsurface all the way up to the upper atmosphere and beyond to Mars’ two tiny moons, Phobos and Deimos, providing an
|Poster showing some of the scientific and operational highlights from Mars Express, 2003-2013. Credits: Images of Mars, Phobos & Deimos: ESA/DLR/FU Berlin (G. Neukum)|
Over 95% of the surface has been imaged by the mission's high-resolution camera, with two thirds mapped at a resolution of 20 m per pixel or better, and much of it in stereo, yielding stunning 3D images.
Ground-penetrating radar has added a third dimension to the planet by determining the vertical extent of the polar ice caps. At the south pole, there is enough water locked up in ice to cover the entire planet with a layer of water 11 m deep if melted.
Meanwhile the detection of traces of methane in the atmosphere has led to an intense debate in the scientific community: does it have a volcanic origin, or could it be the result of active biology, as it is on Earth?
Mars Express has also provided the most detailed atlas of its innermost moon Phobos, and in December this year will make its closest pass yet, just 58 km from the centre of the tiny moon.
"The decade-long observations by Mars Express of all aspects of the martian environment are providing us with a truly global perspective on the history of the Red Planet, paving the way for the next generation of Mars exploration missions," says Olivier Witasse, ESA's Mars Express Project Scientist.
"But we still have a lot to look forward to and are planning a number of unique observations with Mars Express, such as coordinating measurements of the atmosphere with NASA's MAVEN spacecraft, watching the very close pass of Comet C/2013 Siding Spring by Mars in October 2014, and monitoring the arrival of ESA's ExoMars Entry, Descent, and Landing Demonstrator module in October 2016."
Notes for Editors
“Global maps of anhydrous minerals at the surface of Mars from OMEGA/MEx,” by A. Ody et al., is published in the Journal of Geophysical Research 117, (2012).
“Global investigation of olivine on Mars: Insights into crust and mantle compositions,” by A. Ody et al., is published in the Journal of Geophysical Research, 118 (2013).
“Hydrous minerals on Mars as seen by the CRISM and OMEGA imaging spectrometers: Updated global view,” by J. Carter et al., is published in the Journal of Geophysical Research 118 (2013).
The new maps are based primarily on data collected by the visible and infrared mineralogical mapping spectrometer, OMEGA (Observatoire pour la Minéralogie, l’Eau, les Glaces et l’Activité). It determines mineral composition from the visible and infrared light reflected from the planet's surface in the wavelength range 0.5–5.2 microns. As light reflected from the surface must pass through the atmosphere before entering the instrument, OMEGA also measures aspects of atmospheric composition. However, the atmosphere is so dense over the 9 km-deep Hellas Basin that detections from the crater floor cannot be made by OMEGA, resulting in the data gap seen on the maps. The vast distance between the surface to Mars Express also impairs measurements over the smaller Argyre basin just to the left of centre in the southern hemisphere.
Seasonal carbon dioxide and water ice frosts occurring in the polar regions restricts observing periods and spatial coverage in these regions.
OMEGA maps the surface composition in 100 m squares. It samples the surface from 4.1 km/pixel down to 350 m/pixel, nadir-pointed. It has achieved 51% coverage at samplings < 500 m/pixel and near total coverage at samplings < 4.1 km/pixel.
The map showing hydrated minerals includes detections made by both ESA’s Mars Express and by NASA’s Mars Reconnaissance Orbiter.
About Mars Express
Mars Express was launched on 2 June 2003 on a Soyuz/Fregat from Baikonur, Kazakhstan. It carries seven scientific instruments: ASPERA (energetic neutral atoms analyser); HRSC (High Resolution Stereo Camera); MaRS (Mars radio sciece experiment); MARSIS (subsurface sounding radar altimeter); OMEGA (visible and infrared mineralogical mapping spectrometer); PFS (Planetary Fourier Spectrometer); and SPICAM (ultraviolet and infrared atmospheric spectrometer). It also transported the Beagle-2 lander to Mars, but contact was lost during landing.
For further information, please contact:
ESA Science and Robotic Exploration Communication Officer
Tel: +31 71 565 6799
Mob: +31 61 594 3 954
Mars Express Project Scientist
Tel: +31 71 565 8015
OMEGA Principal Investigator
Institut d’Astrophysique Spatiale, Université Paris 11 Orsay
Tel: +33 1 69 85 86 86
ESA Media Relations Office
Tel: +33 1 53 69 72 99
(This article was originally published on ESA's Space Science Portal.) | 0.908247 | 3.645614 |
NASA Astronomy Picture of the Day:
The Flame Nebula stands out in this optical image of the dusty, crowded star forming regions toward Orion's belt, a mere 1,400 light-years away. X-ray data from the Chandra Observatory and infrared images from the Spitzer Space Telescope can take you inside the glowing gas and obscuring dust clouds though. Swiping your cursor (or clicking the image) will reveal many stars of the recently formed, embedded cluster NGC 2024, ranging in age from 200,000 years to 1.5 million years young. The X-ray/infrared composite image overlay spans about 15 light-years across the Flame's center. The X-ray/infrared data also indicate that the youngest stars are concentrated near the middle of the Flame Nebula cluster. That's the opposite of the simplest models of star formation for the stellar nursery that predict star formation begins in the denser center of a molecular cloud core. The result requires a more complex model; perhaps star formation continues longer in the center, or older stars are ejected from the center due to subcluster mergers.
Photo by DSS | 0.839847 | 3.089514 |
Markab, Alpha Pegasi (α Peg), is a giant or subgiant star located in the constellation Pegasus. Even though it has the designation Alpha, it is only the third brightest star in the constellation, after Enif and Scheat. Markab has an apparent magnitude of 2.48 and lies at a distance of 133 light years from Earth. Together with the brighter Scheat and Alpheratz and the fainter Algenib, it forms the Great Square of Pegasus, a prominent northern asterism that marks the main body of Pegasus.
Markab is classified either as a giant star of the spectral type B9III or a subgiant of the type A0 IV. The star is running out of the supply of hydrogen at its core, if it has not already, and has expanded to a size of 4.72 solar radii. It will continue to expand and eventually evolve into an orange giant.
Markab has a surface temperature of about 9,765 K and is over 200 times more luminous than the Sun. It is a rapid spinner, with a projected rotational velocity of 125 km/s.
With a mass about three times that of the Sun, Markab is not massive enough to be a supernova candidate. Instead, it will end its life as a massive white dwarf after casting off its outer layers into space to form a planetary nebula.
Markab and Enif, Pegasus’ brightest star, are among the 58 bright stars that have a special status in the field of celestial navigation. Navigational stars are among the brightest and most recognizable stars in the sky. They include 19 first-magnitude stars, 38 second-magnitude stars and Polaris, the North Star. The stars were selected by Her Majesty’s Nautical Almanac Office (HMNAO) and the US Naval Observatory (USNO) for The Nautical Almanac, a yearly publication for use by the UK and US navies, jointly published by HMNAO and USNO since 1958.
Markab is one of the four bright stars that form the Great Square of Pegasus, an asterism that takes up much of the eastern portion of Pegasus constellation. The other three stars that mark the vertices of the Great Square are Algenib (Gamma Pegasi), Scheat (Beta Pegasi), and Alpheratz (Alpha Andromedae). The asterism outlines the body of the celestial winged horse and is very useful in finding a number of other stars and deep sky objects.
The name Markab (pronunciation: /ˈmɑːrkæb/) is derived from the Arabic markab, from a phrase meaning “the saddle of the horse.” It may also be a mistranscription of Mankib, which comes from the phrase Mankib al-Faras, meaning “the shoulder of the horse.”
The name was approved by the International Astronomical Union’s (IAU) Working Group on Star Names (WGSN) on June 30, 2016.
In Arabic astronomy, Markab was also known as Matn al Faras, “the horse’s withers/shoulder.” The 17th century German astronomer Johann Bayer called the star Yed Alpheras, meaning “the forearm/hand of the horse.”
The Chinese know Alpha Pegasi as 室宿一 (Shì Xiù yī), meaning “the First Star of Encampment.” Markab forms the Chinese Encampment mansion with its Great Square neighbour Scheat. Encampment is one of the seven mansions of the Black Tortoise.
Markab is very easy to identify because it is part of the Great Square of Pegasus, a conspicuous pattern visible for most of the year from northern latitudes. Markab marks the southwest vertex of the Great Square, which can be found using the bright stars that form Cassiopeia’s W. A line extended from Segin, Epsilon Cassiopeiae, through Ruchbah, Delta Cassiopeiae, points in the general direction of the asterism.
Markab and its neighbour Scheat can be used to find two interesting stars, Fomalhaut and 51 Pegasi (Helvetios). Nicknamed “the Eye of Sauron” for its large circumstellar debris disk, Fomalhaut (Alpha Piscis Austrini) is the 18th brightest star in the sky. Despite its brightness, it is difficult to identify because it is isolated in a region that does not contain any other exceptionally bright stars. The star can be found by extending a line from Scheat through Markab. It is the brightest star that appears on the imaginary line.
51 Pegasi is notable for being the first Sun-like star discovered to have an orbiting exoplanet. Significantly fainter at magnitude 5.49, the star can be found in the area between Markab and Scheat.
There are several faint galaxies located in the same field of view as Markab. They belong to the NGC 7448 Group, centered on the magnitude 11.4 spiral galaxy NGC 7448, and include NGC 7437, NGC 7454, NGC 7463, and NGC 7465.
Markab is located in the constellation Pegasus. Representing the mythical winged horse, Pegasus is the seventh largest of all 88 constellations, covering an area of 1,121 square degrees. Like other constellations associated with figures from Greek mythology, it is one of the Greek constellations, first listed by the 2nd century CE Greek astronomer Claudius Ptolemy in his Almagest. Pegasus belongs to the Perseus family of constellations, which includes several other constellations associated with the mythical Greek hero: Perseus, Andromeda, Cassiopeia, Cepheus, and Cetus. In mythology, Pegasus sprang from the neck of Medusa after Perseus beheaded her.
The constellation Pegasus is home to many interesting deep sky objects. The best known ones include the Great Pegasus Cluster (Messier 15), one of the brightest and oldest known globular clusters, the unbarred spiral galaxy NGC 7331, the brightest member of the NGC 7331 Group, the compact galaxy group catalogued as Hickson 92 (HCG 92) and also known as Stephan’s Quintet, the spiral galaxies NGC 7479 (Propeller Galaxy), NGC 7742 (the Fried Egg Galaxy) and NGC 7814, and the gravitationally lensed quasar known as Einstein’s Cross.
The best time of year to see the stars and deep sky objects of Pegasus is during the month of October, when the constellation is prominent in the evening sky.
The 10 brightest stars in Pegasus are Enif (Epsilon Peg, mag. 2.399), Scheat (Beta Peg, mag. 2.42), Markab (Alpha Peg, mag. 2.48), Algenib (Gamma Peg, mag. 2.84), Matar (Eta Peg, mag. 2.95), Homam (Zeta Peg, mag. 3.414), Sadalbari (Mu Peg, mag. 3.514), Biham (Theta Peg, mag. 3.52), Iota Pegasi (mag. 3.77), and Lambda Pegasi (mag. 3.93).
Markab – Alpha Pegasi
|Spectral class||A0 IV or B9III|
|U-B colour index||–0.06|
|B-V colour index||–0.04|
|Distance||133 ± 1 light years (40.9 ± 0.3 parsecs)|
|Parallax||24.46 ± 0.19 mas|
|Radial velocity||-2.2 km/s|
|Proper motion||RA: 60.40 ± 0.17 mas/yr|
|Dec.: -41.30 ± 0.16 mas/yr|
|Mass||cca. 3 M☉|
|Radius||4.72 ± 0.14 R☉|
|Temperature||9,765 ± 63 K|
|Metallicity||−0.02 ± 0.10 dex|
|Rotational velocity||125 km/s|
|Surface gravity||3.51 ± 0.03 cgs|
|Right ascension||23h 04m 45.65345s|
|Declination||+15° 12′ 18.9617″|
|Names and designations||Markab, Alpha Pegasi, α Peg, 54 Pegasi, HD 218045, HR 8781, HIP 113963, FK5 871, SAO 108378, BD +14°4926, PPM 142158, GC 32149, GCRV 14477, ALS 16176, AAVSO 2259+14B, IRAS 23022+1456, PLX 5587, 2MASS J23044565+1512191, TYC 1711-2475-1| | 0.87392 | 3.882031 |
Strange bright spots on the dwarf planet Ceres are giant salt pans caused by the evaporation of water from a subsurface ocean, scientists have confirmed.
The new findings, reported in the journal Nature, solve an enigma which has intrigued both scientists and the public ever since the strange spots were first seen by NASA's Dawn spacecraft.
"We were definitely surprised to see the bright spots," said one of the study's authors, Dr Vishnu Reddy of the Planetary Science Institute in Tucson, Arizona.
"These bright spots are consistent with briny water coming up from the sub-surface which sublimates [a process where a solid evaporates into a gas without passing through a liquid phase] leaving behind [salts] on the surface," Dr Reddy said.
"We had some hints that Ceres might have a subsurface ocean but the presence of salts on the surface was a surprise."
The dwarf planet Ceres has a diameter of about 950 kilometres and is the largest object in the main asteroid belt between Mars and Jupiter.
The general surface of Ceres is as dark as fresh asphalt, however it is covered in over 130 bright spots — some as white as ocean ice. Almost all are associated with impact craters.
Using data from Dawn's spectral framing camera, the authors examined the largest of the bright spots on the floor of the giant 90-kilometre-wide, four-kilometre-deep Occator crater, finding hydrated magnesium sulphates.
Dr Reddy and colleagues found the level of hydration decreased with distance from the spot, supporting the idea of an underground source.
"We're still not sure how or why the water is getting exposed onto the surface," Dr Reddy said.
"There is an almost global network of cracks on the surface of these craters and we think that might be a way for water in a subsurface ocean to make its way to the surface and sublimate."
The authors also examined a thin misty haze that regularly forms above the spot during daylight.
They concluded the fog was caused by the condensation of small particles of ice and salt, said lead author Dr Andreas Nathues of the Max Planck Institute in Germany.
"Water ice, salts and recent sublimation phenomena are signs of a geologically active planetary surface," Dr Nathues said.
The researchers said the findings could help us understand how our solar system — and particularly Earth — evolved.
"A significant number of objects in the inner solar system are now known to have water ice or briny water on them, and all these ingredients are needed for life on Earth as we know it," Dr Reddy said.
"So the ingredients for life could have come from all these small bodies and they contributed a lot of material to Earth early in the history of the solar system both in terms of organics and water, so we could be here because of asteroids hitting the Earth."
Ceres a long-distance visitor
Meanwhile, a second study reported in Nature found minerals on the surface of Ceres indicates the dwarf planet may have formed in the outer solar system and migrated inwards to its present orbit.
Scientists led by Dr Maria Cristina De Sanctis of the Istituto Nazionale di Astrofisica in Rome used the Visible-Infrared Mapping Spectrometer aboard the Dawn spacecraft to obtain new spectral data indicating the widespread presence of substances called ammoniated phyllosilicates across the surface of Ceres.
Ammonia ices are found in the cold outer reaches of the solar system. Their incorporation into Ceres' surface during its formation suggests that the dwarf planet formed out there, before migrating into the main asteroid belt. | 0.887478 | 3.982069 |
In the first working week of the new year, it is time to look back and remember the successes of 2019. The past year was remembered by technological breakthroughs and new scientific problems. Let’s take a closer look at the most interesting results.
Black hole portrait
In the spring, the Event Horizon Telescope collaboration introduced the world the first image of a supermassive black hole in the neighboring M87 galaxy. This was an excellent result of gigantic work – for several days, eight radio observatories around the world, including Antarctica, simultaneously watched a black hole. The data were processed on clusters in MIT and MPIfR, and they were delivered on hard drives – it is unrealistic to transfer the volume of the order of petabytes via the Internet from remote observatories (especially from Antarctica). A few more months were spent on image processing and reconstruction. A good story about the details of an experiment can be read, for example, on Elements (one, two) or on N + 1
In the image itself, we see an accretion disk – a heated substance, spinning in a spiral before falling into a black hole. The spot in the center is not the black hole itself, but rather the shadow from it: the light passing near the black hole is bent due to gravitational lensing, so the shadow is several times larger than the event horizon of the black hole.
The accretion disk of this black hole is turned toward us by its plane. If it were located sideways to us (like the rings of Saturn), then we would see something similar to a black hole from Interstellar. Unfortunately, astronomy is an extremely observational science: we have not the slightest chance to influence these grandiose processes or even look at them from a different angle due to the great distance to them.
It remains to add that this image alone does not prove the presence of black holes – we are confident in their existence due to the mass of other results. Its value is more likely in confirming our ideas about what is happening in the nuclei of galaxies. And of course, in creating a huge international collaboration that allows systematic observations with a telescope the size of the Earth. In the near future, the inclusion of new, shorter-wavelength telescopes in the network, and the study of the dynamics of processes around black holes in the nuclei of the M87 and the Milky Way.
Hubble Constant Problems
Our Universe is expanding: the distances between neighboring galaxies are constantly increasing; the rate of this expansion is determined by the Hubble constant. Its accurate measurements are the most important task for cosmology, and at the same time the task is very difficult. Until recently, everything converged at a value of about 70 km / s per megaparsec. Good accuracy was achieved only the year before last: an analysis of the data of the Plank satellite, which measured the anisotropy of the CMB radiation, led to a Hubble constant of 67.4 ± 0.5 km / s / Mpc. The Dark Energy Survey collaboration, which studied fluctuations in the density of matter in the Universe using a network of optical telescopes, got the same result.
But 2019 brought surprises. Several groups that collected long-term statistics on various space objects – quasars, Cepheids, space masers – converged at a value of about 74 km / s / Mpc (blue dots on the graph). In contrast to the results of last year, in all these works, the distance to the existing facilities was measured. The fluctuations of the relict radiation and the density of matter reflect what happened at the dawn of the Universe. As a result, we have a difference of more than four standard deviations between the values for the early and current Universe, which is undoubtedly intriguing and at least gives rise to discussions about new physics.
Here you can find a lot of controversial points: for example, the distances to many of the objects were calibrated using the same standard candles, so they can not be considered independent. The cherry on the cake is a measurement made by supermassive red giants (red dot): it gives a compromise result of 69.8 km / s / Mpc, but ironically, the calibration of distances to these red giants is even less accurate. Now there is a rather active debate in the community on this topic, and the reason for the discrepancy is still unclear. I would like to believe that in the near future the paradox will begin to be resolved.
Something similar happens in the microworld: measurements of the size of a proton (more precisely, its charge radius) give different results. And the discrepancies here are even more significant.
In general, there are two simple ways to measure the radius of a proton:
- Electron bombard a proton: the closer the electron flies to the proton, the more attractive the curvature of its path. Using the scattering pattern, one can reconstruct the radius in which the proton charge is concentrated.
- Spectroscopy of hydrogen. The hydrogen nucleus is the proton, and its size affects the energy levels at which the electron can be. By simultaneously measuring the energy of two levels, you can calculate the radius of the nucleus.
Both methods gave the same result: about 0.875 femtometers. In 2010, the MPQ team proposed replacing the electron in the hydrogen atom with a muon, a heavier elementary particle with similar properties. The heavy muon rotates closer to the proton, so the radius of the proton has a stronger effect on its energy levels. The measurement result was unexpectedly less – 0.841 fm. The measurements were repeated in 2013, the result was the same.
While the whole world was thinking why muon hydrogen behaves in a special way and if there is any new physics here, MPQ decided to repeat the experiment with ordinary hydrogen – and again got a smaller proton radius! A year later, in 2018, spectroscopy of other levels in ordinary hydrogen was repeated in Paris … and the old radius value was obtained! Here, the emphasis of discussions has shifted towards the search for commonplace errors, up to taking into account the difference in height between the two laboratories: accurate spectroscopy is essentially a comparison with the well-known frequency / time standard, and according to the general theory of relativity, time flows in Paris and Munich in slightly different ways. for different distances to the center of the earth.
The past year has pleased me already with two experiments, and even from another continent. First, a group from Toronto repeated the experiment with hydrogen spectroscopy and got the same result as MPQ. And soon it was confirmed by the electron-proton scattering experiment from the American collaboration. In parallel with this, the MPQ group began exactly the same experiment that the French conducted in 2018 – a test for reproducibility unprecedented in modern science! There are already preliminary results, but the authors have not yet disclosed them – they are only intriguing in that they will be interesting. The reason for the discrepancy is still unknown, but apparently everything will become clear in the near future.
In the fall, Nature published an article in which the Google team demonstrated quantum superiority. Their 53-qubit quantum chip Sycamore was able to solve a specific problem in 200 seconds. It would take 10 thousand years to solve it on a classic supercomputer.
The task itself, on which the result was shown, turned out to be quite banal. A quantum computer differs from a normal one in that it can, ahem, perform quantum operations inaccessible to classical computers (thanks, Cap!). Therefore, in the experiment, the quantum chip performed a random set of quantum operations, and a classic computer simulated the same set of actions.
A serious discussion has unfolded around the result. For example, IBM researchers say that an optimized classic algorithm would solve the problem not in thousands of years, but in a couple of days. The issue of error correction is even more acute: quantum memory is so fragile that software error correction does not save here, and well-known correction mechanisms in hardware complicate the architecture of quantum chips by orders of magnitude. And scaling quantum chips from dozens of qubits to at least hundreds is far beyond what is currently achievable. Therefore, the result of Google is very mixed: yes, we have stepped on the threshold of the quantum era, but how far we can go forward – and whether we can at all – remains unknown.
Compressed Light for LIGO
Everyone heard about the recent discovery of gravitational waves and the 2017 Nobel Prize that followed. Now there are three sufficiently sensitive observatories of gravitational waves in the world: two LIGO detectors in the United States and VIRGO in Italy. These are incredibly accurate laser interferometers: to achieve current accuracy, enormous forces were invested in measuring noise of various nature and optimizing them:
Today, the main source of noise is the quantum shot noise of light (lilac curve): it is caused by the fact that the laser emits photons at random times. Such noise can be dealt with using squeezed light — induced correlations in a ray of light that redistribute the noise of the light intensity into the noise of its phase, which is harmless to our purpose. This technique has already been tested on the German GEO600 interferometer, and last year it was finally put into operation on both LIGO and VIRGO. Apparently, this is the first application of compressed light to solve practical problems. Now the sensitivity of the detectors will increase significantly (up to two times in some frequency ranges), and we hope to hear more interesting phenomena from the far corners of the Universe.
And this is also a special result for Habr – for him we must thank Mikhail Shkaff, who is directly involved in this topic and has written many interesting articles about LIGO and not only. Thank you and new successes!
Neutrino mass limit
Neutrinos remain one of the most mysterious elementary particles: they practically do not interact with matter and can easily pass through the Earth through. We know that they have at least some mass from neutrino oscillations: on the way from the Sun to us, part of the neutrino turns into a neutrino of a different type.
Transformation is a dynamic process, which means that time flows in the neutrino reference frame – that is, they fly slower than the speed of light due to their mass.
Measuring this mass is much more difficult. Its lower limit – about 9 meV – we know from neutrino oscillations. The KATRIN project in Karlsruhe, Germany, took up the measurement of the upper limit. The idea was to observe the radioactive decay of tritium into helium-3, an electron and an antineutrino: it is impossible to detect the latter, but you can measure the velocities of the remaining particles and calculate the missing energy. In practice, it is easiest to work with electrons: the highest achievable speeds mean that all the decay energy has gone into the neutrino and the electron. Such cases are infrequent; therefore, the detector should be well optimized for detecting electrons of a certain energy.
For this reason, the KATRIN project took a long time to prepare, but it gave the first result after a month of operation: the upper limit of the neutrino energy was 1.1 eV, which doubled the previous estimate. It is planned that KATRIN will gain statistics for another five years, improving accuracy to 0.2 eV. And more advanced experiments based on the same idea can increase the measurement accuracy to 40 meV.
Instead of a conclusion
In my opinion, the past year turned out to be very social: the achievements that he remembered are due to the joint efforts of many groups, and to new issues – the differences between them. Teamwork in science – from desktop experiments to international collaborations – is becoming increasingly important to achieve meaningful results. I hope that we will make every effort to ensure that our work is even more productive, and that the results of the coming year are no less interesting. | 0.891962 | 3.620959 |
Astronomers have discovered a striking spiral-arm structure in the disc of gas and dust around the young star Elias 2-27. The structure is made up of the matter near the midplane of the disc – the region in which new planets can be born. This means: the spirals are either a result of the presence of young planets or they create the conditions under which new planets form in the first place.
Planets are born in the interior of discs of gas and dust around newborn stars. This basic idea has a long history, but it is only recently that astronomers have been able to observe these discs directly. An early example is the discovery of the silhouettes of these discs in the 1990s with the Hubble space telescope. Astronomers succeeded in obtaining detailed images only very much later, however. For instance, it was 2014 when ALMA helped them detect gaps in protoplanetary discs.
And a group of astronomers headed by the Humboldt Research Fellow Laura Pérez from the Max Planck Institute for Radio Astronomy used this radio telescope – the Atacama Large Millimeter Array in the Chilean Andes, whose 66 dishes make it the biggest in the world – to observe the young star Elias 2-27, which is in the Snake-Holder (Ophiuchus) constellation around 450 light years from Earth. The team discovered the spiral structure mentioned – without which the planets could possibly not form at all.
The reason for this lies in the birthing process: within a disc of matter, the dust particles collide and clump together. Over time, this creates larger and larger objects. Problems arise as soon as the objects grow to more than a few meters. The surrounding gas then causes so much drag as the objects move on their orbit around the star that they migrate inwards on timescales of 1000 years or less, and fall into the central star.
The birthing process is thus interrupted, because a much longer time is needed for such bodies to collect sufficient mass by successive collisions to grow to the size of planets, at which point their size then means that gas drag has relatively little impact. So how is it that larger objects can form at all? Several possible mechanisms have been suggested that would allow the primordial rocks to grow and ultimately reach the size where they mere with the aid of gravity to form full-size planets.
In regions of higher density as occur along the density waves which have just been observed, the planet formation could progress much more rapidly, due to the increased gravitational force in the region concerned as well as the higher probability of collisions.
“The structure we have observed with Elias 2-27 is the first direct indication of spiral density waves in a protoplanetary disc,” says Laura Pérez. “It shows that instabilities can form within the disc, leading to sub-regions with much higher density and thus the formation of further planets.” These instabilities occur not only on the dimensions of planet formation: probably the best-known example is density waves in spiral galaxies that give rise to their distinctive spiral arms.
Conversely, planets which have already formed in the disc can trigger spiral density waves while they orbit the central star. To differentiate between these two roles – spiral arms as the trigger for planet formation on the one hand, or being formed themselves by young planets on the other – a deeper understanding is required, and observations such as the ALMA image just published will make their contribution here.
“After years of being able to measure only the integrated thermal radiation around young stars, we now see them in all their beauty and diversity, in the meantime with a spiral structure as well. This helps us to gain a better understanding of how planets form,” says Thomas Henning, Director at the Max Planck Institute for Astronomy in Heidelberg, who was also involved in the most recent observations.
“Over the past decades, astronomers have found a considerable variety of exoplanets. We can only explain this variety when we understand the early phases of planet formation – and the impressively detailed ALMA images make an important contribution here,” says Hendrik Linz, also a scientist at the Max Planck Institute in Heidelberg.
The two sweeping spiral arms around Elias 2-27 extend to more than ten billion kilometers from the young star – further into space than the Kuiper belt in our Solar System. “The presence of spiral density waves at these extreme distances from the star could explain the existence of exoplanets, which orbit their central stars at a similarly large separation,” says Pérez. The conventional models say that these planets should not be able to form locally in the first place.
The young star Elias 2-27 is part of a much larger star formation region bearing the designation Rho Ophiuchi in the Snake-Holder constellation. Elias 2-27 formed only around one million years ago – very recently compared to the age of our Sun, which goes back around 4.6 billion years. Researchers already knew that this star is surrounded by a disc; according to previous observations with a resolution of between 0.6 and 1.1 arc seconds, it could just as well have been an unstructured disc with cylindrical symmetry, however.
The new ALMA observations with a very high resolution of 0.24 arc seconds show radiation with a wavelength of 1.3 millimeters. This is caused by the presence of dust particles that make up between one and ten percent of the total mass of the disc. Using this radiation, the astronomers were able to track the spiral pattern mentioned over a range spanning from approximately 100 astronomical units (i.e. 100 times the average distance between the Earth and the Sun) to 300 astronomical units from the central star.
As mentioned above, the spiral structure could be caused by a planet which already exists within the disc. ALMA has indeed discovered a narrow band with much less dust, but it is not large enough to accommodate a planet which in turn would be large enough to generate the spiral pattern observed.
On the other hand, the gravity of the disc itself can also cause instabilities which can produce these spiral patterns. Given the total mass of the disc and the form and symmetry of the spiral pattern, the authors also consider this possibility to be highly likely.
“ALMA observations of this type are becoming increasingly frequent and should provide us with more and more images of inhomogeneous sub-structures in protoplanetary discs,” says Karl Menten, Director at the Max Planck Institute for Radio Astronomy and co-author of the article in the Science journal. “We should thus increasingly be able to describe the properties of these structures in more detail and clarify the role they play in planet formation.”
Publication: Laura M. Pérez, et al., “Spiral density waves in a young protoplanetary disk,” Science 30 Sep 2016: Vol. 353, Issue 6307, pp. 1519-1521; DOI: 10.1126/science.aaf8296 | 0.911016 | 4.042892 |
Using data from HARPS-TERRA, the Planet Finder Spectrograph and the UCLES echelle spectrograph, astronomers have discovered a new potentially habitable Super-Earth around the nearby red-dwarf star Gliese 832.
An international team of astronomers, led by Robert A. Wittenmyer from UNSW Australia, report the discovery of a new potentially habitable Super-Earth around the nearby red-dwarf star Gliese 832, sixteen light years away. This star is already known to harbor a cold Jupiter-like planet, Gliese 832 b, discovered on 2009. The new planet, Gliese 832 c, was added to the Habitable Exoplanets Catalog along with a total of 23 objects of interest. The number of planets in the catalog has almost doubled this year alone.
Gliese 832 c has an orbital period of 36 days and a mass at least five times that of Earth’s (≥ 5.4 Earth masses). It receives about the same average energy as Earth does from the Sun. The planet might have Earth-like temperatures, albeit with large seasonal shifts, given a similar terrestrial atmosphere. A denser atmosphere, something expected for Super-Earths, could easily make this planet too hot for life and a “Super-Venus” instead.
The Earth Similarity Index (ESI) of Gliese 832 c (ESI = 0.81) is comparable to Gliese 667C c (ESI = 0.84) and Kepler-62 e (ESI = 0.83). This makes Gliese 832 c one of the top three most Earth-like planets according to the ESI (i.e. with respect to Earth’s stellar flux and mass) and the closest one to Earth of all three, a prime object for follow-up observations. However, other unknowns such as the bulk composition and atmosphere of the planet could make this world quite different to Earth and non-habitable.
So far, the two planets of Gliese 832 are a scaled-down version of our own Solar System, with an inner potentially Earth-like planet and an outer Jupiter-like giant planet. The giant planet may well played a similar dynamical role in the Gliese 832 system to that played by Jupiter in our Solar System. It will be interesting to know if any additional objects in the Gliese 832 system (e.g. planets and dust) follow this familiar Solar System configuration, but this architecture remains rare among the known exoplanet systems.
Publication: Accepted for publication in ApJ
PDF Copy of the Study: GJ 832c: A super-earth in the habitable zone
Images: PHL @ UPR Arecibo, NASA Hubble, Stellarium; PHL @ UPR Arecibo | 0.873985 | 3.898468 |
Amateur Astronomy is the most popular science, for many reasons:
- All the original material of the science is available to anyone who cares to look, unlike almost every other scientific discipline
- A brand new astronomer and an old pro still know approximately the same amount about the Universe: Zero. It sounds discouraging, but it really isn't. Even someone brand new to Astronomy can make valuable contributions to scientific investigation, just like the old pro
- Astronomy is an observational science, unlike almost every other science. You look at things, instead of conducting experiments, so the methods aren't as easy to corrupt as most other sciences. If you try to fake a conclusion, anyone can look at what you looked at, and find you out
- It provides a deep and satisfying connection to our own history. The movement of the heavens have concerned almost every group of ancient humans at least since the invention of agriculture. The star names, constellation names, and the stories about them are thousands of years old. Many of our ancient myths were created to explain the shapes in the sky! (Archaeoastronomy, the study of ancient observatories and astronomical records, is a fascinating discipline, and has accurately dated many of the earliest events in history)
- It's cheap! You can learn the constellations, planets, phases of the moon, and seasons, and follow their changes throughout the year for zero investment. Even very inexpenisve tools like binoculars and a basic star chart open up vast realms of the sky for your curiosity and pleasure
Amateur Astronomers have made, and continue to make, many important contributions to the science
- Most comets and asteroids have been discovered by amateurs
- With the advent of cheap dobsonian reflector telescopes, amateurs are our best defense against an Extinction Level Event. The pros are busy looking through multi-million dollar instruments at obscure stuff, and there are only a few thousand of them. Our best chance of detecting an asteroid or comet on an impact trajectory with Earth (in time to do something about it) are the many thousands of amateurs world-wide looking every night.
- Most of our understanding of meteors and meteor showers come from amateurs. Because thousands of people watch and record their observations of meteors across the globe, we have very detailed information about their behavior
- Amateurs are also the major contributers to our understanding of variable stars and binary stars. These celestial objects change over very long periods, and since there are so many of them out there, there just aren't enough pros to do the job.
- Amateur observations of star occultations have provided very detailed information about the size, shape, rotation period and orbit of asteroids, by combining and analysing everyone's data, as the asteroid's 'shadow' of the occulted star moves across the Earth.
Getting started in Astronomy is easy!
If you are curious, but don't know the first thing about it, start by just watching the major features in the sky
: the moon
, and constellation
s. Pick up an astronomy magazine subscription, or a field-guide, and take a look. The Truth is Out There
If you've had some experience, and want to see more, a pair of binoculars are quite cheap; Typically only costing $US50 or less, they allow you to see far more than you imagine.
If you know you like it, check out Buying your first Telescope, and get one. Very good telescopes can be had for only a modest investment, and with proper care, you can pass them on to your grandchildren
Anyone who would like more details, feel free to /msg me or find my email on my homepage, and ask! | 0.919385 | 3.215382 |
Researchers working off the coast of Mexico have discovered evidence of arsenic-breathing life in oxygen-starved waters. These resilient microbes are a vestige of Earth’s ancient past, but they could also be a sign of things to come under the influence of climate change.
Billions of years ago, when the Earth was still very young, the first organisms to emerge did not have the benefit of abundant oxygen. Instead, these pioneering microbes likely exploited other elements to get their energy, including nitrogen, sulfur, and, perhaps surprisingly, arsenic—a compound typically associated with poison. Eventually, our planet became rich in oxygen owing to the effects of photosynthesizing organisms, which converted carbon dioxide into oxygen.
Plentiful amounts of oxygen made those early microorganisms obsolete—or at least that’s what we thought. New research published this week in Proceedings of the National Academy of Sciences suggests some organisms with an arsenic-based respiratory system are still around, and they’re found pretty much where you’d expect them to be: low-oxygen environments.
More specifically, they live in marine oxygen-deficient zones (ODZs)—a middle layer of tropical ocean where oxygen exists in trace amounts. The traces of these atavistic microbes were discovered by a team led by Jaclyn Saunders, a postdoctoral fellow at the Woods Hole Oceanographic Institution and the Massachusetts Institute of Technology, off the coast of Mexico in the Eastern Tropical South Pacific ODZ. The new research shows that this ancient survival strategy is still in use some low-oxygen, or anoxic, marine ecosystems.
“We’ve known for a long time that there are very low levels of arsenic in the ocean,” Gabrielle Rocap, a co-author of the study and a University of Washington professor of oceanography, said in a press statement. “But the idea that organisms could be using arsenic to make a living—it’s a whole new metabolism for the open ocean.” The creatures that live in ODZs, she said, “have to use other elements that act as an electron acceptor to extract energy from food.”
Given the ongoing effects of climate change, the new finding grimly suggests an expansion of habitat for these microbes, as ODZs are produced by sensitive imbalances between the amount of oxygen available in the atmosphere and the decay of organic matter. More encouragingly, however, the finding also holds implications in the search for extraterrestrial life. Astrobiologists can now include low-oxygen, arsenic-friendly environments in their hunt for microbial alien life.
For the study, Saunders’ team analyzed seawater pulled from the ETSP ODZ. Among the bits and pieces of DNA found floating in the solution were genetic pathways associated with arsenic. As Saunders explained to Gizmodo in an email, the pathways her team identified all appear to be bacterial in nature, as the sequences derived came from a prokaryotic, or single-celled, metagenome (i.e. all the genetic material present in an environmental sample).
“We filtered seawater through a 30-micron mesh first—so we’re only looking at small organisms—and then we passed that seawater through a 0.2 micron filter which captured the microbial cells,” said Saunders. “The DNA from all the organisms captured was then extracted, cut up into little pieces, and sequenced.”
These short sequences were then put together in a “sequence puzzle” to create a long, contiguous stretch of DNA called a contig, she explained. From there, the arsenic-related genes were identified on the contigs assembled from the metagenome sequence data. This form of DNA sequencing “has really accelerated our understanding of environmental communities that aren’t amenable to classical microbiological isolation techniques,” said Saunders.
Two species of microorganism, the researchers suspect, are cycling two forms of arsenic in what is now a newly detected respiratory cycle, where respiration is essentially the transformation of chemical energy into biological energy. Less than 1 percent of the total microbe population found in these waters are capable of breathing arsenic, the researchers estimated. The scientists also speculated that these water-borne microbes might be distantly related to similar microbes found in hot springs and contaminated, arsenic-rich sites on land.
The existence of this cycle, “may be underestimated in the modern ocean” and potentially a “significant contributor to biogeochemical cycles in the anoxic ancient oceans when arsenic concentrations were higher,” the researchers wrote in the study.
In terms of next steps, Saunders is hoping to culture the arsenic-gobbling microbes in her lab so they can be studied further.
“I have also returned to the location where this DNA sample was collected to try to observe microbial cycling of arsenic through coupled chemical and genetic sequencing analyses, “ she said. Indeed, a logical next step is to put together a whole genome to better characterize these microbes and determine how they fit into the larger marine environment.
Saunders agreed that her finding is relevant to the search for extraterrestrial life.
“There are ocean worlds—planetary bodies that have liquid water oceans—in our own solar system,” she told Gizmodo. “Enceladus is a moon of Saturn that has a rocky core, a liquid water ocean, and a thick ice crust on the surface. It is one of the most promising locations for finding life elsewhere in the universe.”
The identification of these arsenic-friendly organisms in the oxygen-poor open ocean water column, she said, expands the limits at which scientists would traditionally search for such microbes.
Finding arsenic-breathing microbes on Enceladus or elsewhere would obviously be a huge deal, but as this new paper makes clear, some of the most alien lifeforms can be found right here on Earth. | 0.840818 | 3.436618 |
Image: NASA/DON DAVIS
Few researchers deny that a giant space rock slammed into the earth 65 million years ago, at the Cretaceous-Tertiary (K-T) boundary. Whether or not that colossal collision wiped out the dinosaursamong the two thirds of the world's species that disappeared at that timehas remained an open question. A report in today's Science says yes: the mass dying was the swift work of an asteroid or lone comet.
Although a single impactor is the most commonly quoted cause of the K-T mass extinction in the popular press, some scientists still argue that intense volcanism in the Deccan Traps of present-day India was the true killer. Either event would have ejected tons of dust and gases into the atmosphere, essentially choking life out of existence, but their influence on climate would have lasted different lengths of time. The effects of an impact would diminish quickly; dust and gas from the Deccan volcanism would have squelched biological productivity for all of the 500,000 years or more that the eruptions occurred.
According to sedimentation rates outlined in the new study, ocean life rebounded within only 10,000 years of the initial die-off. "The Deccan volcanism might have stressed out the environment, but the impactor dealt the final blow," says Sujoy Mukhopadhyay, a geochemist at the California Institute of Technology and lead author of the research paper.
That conclusion points to an extraterrestrial killer, but what type? Mukhopadhyay says he and his colleagues had originally set out to determine whether the impactor was a member of a comet shower, as some workers have suggested. If that were true, then extra amounts of cosmic dust and associated helium-3 (a rare isotope of helium) would have bombarded the planet just before and after the impact. On the contrary, the researchers found nearly steady abundances of helium-3 in rocks spanning the K-T boundary, suggesting the impactor must have been working alone. | 0.834092 | 3.200739 |
The possibility of life on Mars may not be consigned to the distant past. New research suggests our neighboring world could hide enough oxygen in briny liquid water near its surface to support microbial life, opening up a wealth of potentially habitable regions across the entire planet. Although the findings do not directly measure the oxygen content of brines known to exist on the Red Planet, they constitute an important step toward determining where life could exist there today.
Aerobic respiration, which relies on oxygen, is a key component of present-day life on Earth. In this process, cells take in oxygen and break it down to produce energy to drive metabolism. Mars’s very low levels of atmospheric oxygen have led many scientists to dismiss the possibility of aerobic respiration there today, but the new research brings this possibility back into play. The study appears in the October 22 edition of Nature Geoscience.
"Our work is calling for a complete revision for how we think about the potential for life on Mars, and the work oxygen can do, implying that if life ever existed on Mars it might have been breathing oxygen," says lead study author Vlada Stamenkovic, a researcher at NASA's Jet Propulsion Laboratory in California. "We have the potential now to understand the current habitability."
Although Mars is today a freeze-dried desert, it possesses abundant reserves of subsurface water ice, as well as some amount of liquid water in the form of brines. The brines’ high salt content lowers the temperature at which they freeze, allowing them to remain liquid even on Mars’s frigid surface. In their new study, Stamenkovic and his colleagues coupled a model of how oxygen dissolves in brines with a model of the Martian climate. Their results revealed that pools of salty liquid at or just beneath the surface could capture the meager amounts of oxygen from the Red Planet’s atmosphere, creating a reservoir that microbes might metabolically utilize. According to the research, Martian brines today could hold higher concentrations of oxygen than were present even on the early Earth—which prior to about 2.4 billion years ago harbored only trace amounts of the gas in its air.
The study analyzed how slow shifts in Mars’s tilt in relation to the sun (a well-studied phenomenon still unfolding today) would change the planet’s average temperature, examining a slice of time spanning from 20 million years in the past to 10 million years in the future. This analysis showed that associated temperature changes across these lengthy periods of time could allow brines to absorb and retain oxygen from the thin Martian air.
And while the model-based results might seem quite speculative, they do align with otherwise- mysterious in-situ findings on Mars. NASA's Curiosity rover has identified rocks rich in the element manganese, which likely required significant oxygen to form. "Manganese deposition on Earth is really closely associated with life, both indirectly and directly," says Nina Lanza, a planetary geologist at Los Alamos National Research Laboratory in New Mexico. However, that does not mean Martian life created the manganese deposits; instead, it could simply be that Mars possessed much more atmospheric oxygen in the past than it does today—something supported by several other independent lines of evidence.
An oxygen-rich ancient Mars, in turn, would necessitate a thicker atmosphere—possibly thick enough to have allowed oceans of water to accumulate on the surface. That is the Martian history most researchers currently embrace, based on a wealth of observations from multiple missions.
But Stamenkovic says an ocean, an oxygen-rich atmosphere, or a warmer climate may not be required to create the deposits. It is also possible that the brines interacting with the rocks over millions of years could have formed manganese-rich rocks and could still create them today, eliminating the need for Mars to once have had Earth-like oceans and atmosphere. Lanza agrees that the manganese-rich rocks could have formed on an ocean-free Mars, but notes that further study is needed.
Steve Clifford, an expert in Martian hydrology at the Planetary Science Institute in Arizona who was not part of the project, is not ready to count out the role of oceans in forming Mars’s brines. "You need the presence of water to have these brines," he says. Clifford points out that whatever water survives on Mars today—and researchers think there is enough to cover the entire surface with water at least half a kilometer if not a full kilometer deep—requires even more to have existed in earlier times, essentially assuring the Red Planet’s somewhat watery past.
Regardless of how Mars’s brines came to be, their existence and possible oxygenation suggest a potent, heretofore overlooked planetary niche for past and even present-day life. “The question of extant life is something that we might solve if we had the right tools on Mars,” Stamenkovic says. “Looking for liquid water and brines in the Martian subsurface would be the first step; drilling would be another critical step.”
But just because the brines might hold on to oxygen does not necessarily mean they constitute a planet-spanning refuge for any Martian microbes. For one thing, Stamenkovic and his colleagues have not yet modeled the brines’ actual formation or stability over time; instead they simply looked for regions in which the salty liquid could exist, based on measured Martian atmospheric pressures and a range of average annual estimated temperatures. Brines would require saltier conditions to form at the equator, which would cause them to absorb less oxygen and become less suitable habitats—but polar brines would be able to absorb enough oxygen to potentially support a wider variety of life forms, according to the study.
However, according to Edgard Rivera-Valentin, it would be difficult for salts near the surface to absorb water vapor from Mars’s atmosphere to make the brine in the first place—a process known as deliquescence. Rivera-Valentin, a planetary scientist at the Texas-based Lunar and Planetary Institute who was not part of the study, says deliquescence is challenging even at the planet’s poles. There water vapor is more abundant than at the equator, thanks to the presence of ice caps, but it is still scarce in the atmosphere due to freezing temperatures.
Instead, Rivera-Valentin says equatorial brines are more likely to form as subsurface water comes in contact with salt-rich minerals, rather than from salts interacting with atmospheric water vapor. According to Clifford, water-rock interactions throughout the planet are more likely to happen deep beneath the surface, where groundwater can dissolve the rocks around it while remaining isolated from the atmosphere for billions of years. "In the near-surface, it’s a little bit harder to anticipate what the composition of brines would be or how saturated they would be," Clifford says. Rivera-Valentin also expressed concern that the brines might be too salty for life. “The types of brines that would form on Mars would kill it,” he says. “Life as we know it on Earth would not be able to survive these brines—too salty and too cold.”
Woodward Fischer, a geobiologist at the California Institute of Technology and a co-author on the paper, says that to find the salty limit of life, one would have to know something about the energy budget of a cell. “We barely know that in certain very specific instances of laboratory [microbes] on Earth, and we have no idea [about it] on any other planet,” he says. Fischer thinks scientists should avoid overly rigid constraints when it comes to imagining how alien, unearthly life might emerge and evolve.
If in fact briny, biologically friendly oases dot the Red Planet, they paradoxically could be bad news for future life-hunting missions there, rendering wide swaths of the planet potentially habitable—and thus off-limits for in-situ exploration, based on current interpretations of international law. Planetary protection protocols require stringent decontamination methods for spacecraft that land near “special regions” deemed likely to hold the conditions necessary for life—namely, the presence of a usable energy source and of liquid water. These protocols seek to prevent the accidental extinction or contamination of possible Martian life by invading microorganisms from Earth, and are also meant to keep our own planet safe from any Martian bugs that might someday hitch a ride to Earth on future sample-return missions. Presumably, if the bulk of the Martian surface and subsurface were to suddenly be seen as a “special region,” exploration could still occur there via robots somehow completely purged of all potentially contaminating traces of Earthly biology.
Such strict requirements would drive up the already high cost of Martian exploration, but Stamenkovic remains optimistic. “I think there's a sweet spot where we can be curious and we can be explorers and not mess things up,” he says. “We have to go for that.” | 0.853442 | 3.92896 |
Kropotkin, Mars and the Pulse of Asia
Anthropogenic climate change is usually portrayed as a recent discovery, with a genealogy that extends no further backwards than Charles Keeling sampling atmospheric gases from his station near the summit of Mauna Loa in the 1960s, or, at the very most, Svante Arrhenius’s legendary 1896 paper on carbon emissions and the planetary greenhouse. In fact, the deleterious climatic consequences of economic growth, especially the influence of deforestation and plantation agriculture on atmospheric moisture levels, were widely noted, and often exaggerated, from the Enlightenment until the late nineteenth century. The irony of Victorian science, however, was that while human influence on climate, whether as a result of land clearance or industrial pollution, was widely acknowledged, and sometimes envisioned as an approaching doomsday for the big cities (see John Ruskin’s hallucinatory rant, ‘The Storm Cloud of the Nineteenth Century’), few if any major thinkers discerned a pattern of natural climate variability in ancient or modern history. The Lyellian world-view, canonized by Darwin in The Origin of Species, supplanted biblical catastrophism with a vision of slow geological and environmental evolution through deep time. Despite the discovery of the Ice Age(s) by the Swiss geologist Louis Agassiz in the late 1830s, the contemporary scientific bias was against environmental perturbations, whether periodic or progressive, on historical time-scales. Climate change, like evolution, was measured in eons, not centuries.
Oddly, it required the ‘discovery’ of a supposed dying civilization on Mars to finally ignite interest in the idea, first proposed by the anarchist geographer Kropotkin in the late 1870s, that the 14,000 years since the Glacial Maximum constituted an epoch of on-going and catastrophic desiccation of the continental interiors. This theory—we might call it the ‘old climatic interpretation of history’—was highly influential in the early twentieth century, but waned quickly with the advent of dynamic meteorology in the 1940s, with its emphasis on self-adjusting physical equilibrium.footnote1 What many fervently believed to be a key to world history was found and then lost, discrediting its discoverers almost as completely as the eminent astronomers who had seen (and in some cases, claimed to have photographed) canals on the Red Planet. Although the controversy primarily involved German and English-speaking geographers and orientalists, the original thesis—postglacial aridification as the driver of Eurasian history—was formulated inside Tsardom’s école des hautes études: St Petersburg’s notorious Peter-and-Paul Fortress where the young Prince Piotr Kropotkin, along with other celebrated Russian intellectuals, was held as a political prisoner.
Exploration of Siberia
The famed anarchist was also a first-rate natural scientist, physical geographer and explorer. In 1862, he voluntarily exiled himself to eastern Siberia in order to escape the suffocating life of a courtier in an increasingly reactionary court. Offered a commission by Alexander ii in the regiment of his choice, he opted for a newly formed Cossack unit in remote Transbaikalia, where his education, pluck and endurance quickly recommended him to lead a series of expeditions—for the purposes of both science and imperial espionage—into a huge, unexplored tangle of mountain and taiga wildernesses recently annexed by the Empire. Whether measured by physical challenge or scientific achievement, Kropotkin’s explorations of the lower Amur valley and into the heart of Manchuria, followed by a singularly daring reconnaissance of the ‘vast and deserted mountain region between the Lena in northern Siberia and the higher reaches of the Amur near Chita’,footnote2 were comparable to the Great Northern Expeditions of Vitus Bering in the eighteenth century or the contemporary explorations of the Colorado Plateau by John Wesley Powell and Clarence King. After thousands of miles of travel, usually in extreme terrain, Kropotkin was able to show that the orography of northeast Asia was considerably different from that envisioned by Alexander von Humboldt and his followers.footnote3 He was also the first to demonstrate that the plateau was a ‘basic and independent type of the Earth’s relief’ with as wide ‘a distribution as mountain ranges’.footnote4
Kropotkin also encountered a riddle in Siberia that he later tried to solve in Scandinavia. While on his epic trek across the mountainous terrain between the Lena and the upper Amur, his zoologist comrade Poliakov discovered ‘palaeolithic remains in the dried beds of shrunken lakes, and other similar observations gave evidence on the desiccation of Asia’. This accorded with the observations of other explorers in Central Asia—especially the Caspian steppe and Tarim basin—of ruined cities in deserts and dry lakes that had once filled great basins.footnote5 After his return from Siberia, Kropotkin took an assignment from the Russian Geographical Society to survey the glacial moraines and lakes of Sweden and Finland. Agassiz’s ice-age theories were under intense debate in Russian scientific circles, but the physics of ice was little understood. From detailed studies of striated rock surfaces, Kropotkin deduced that the sheer mass of continental ice sheets caused them to flow plastically, almost like a super-viscous fluid—his ‘most important scientific achievement’, according to one historian of science.footnote6 He also became convinced that Eurasian ice sheets had extended southward into the steppe as far as the 50th parallel. If this was indeed the case, it followed that with the recession of the ice, the northern steppe became a vast mosaic of lakes and marshes (he envisioned much of Eurasia once looking like the Pripet Marshes), then gradually dried into grasslands and finally began to turn into desert. Desiccation was a continuing process (causing, not caused by, diminishing rainfall) that Kropotkin believed was observable across the entire Northern Hemisphere.footnote7
An outline of this bold theory was first presented to a meeting of the Geographical Society in March 1874. Shortly after the talk, he was arrested by the dreaded Third Section and charged with being ‘Borodin’, a member of an underground anti-tsarist group, the Circle of Tchaikovsky. Thanks to this ‘chance leisure bestowed on me’, and special permission given by the Tsar (Kropotkin, after all, was still a prince), he was enabled to obtain books and continue his scientific writing in prison, where he completed most of a planned two-volume exposition of his glacial and climatic theories.footnote8
This was the first scientific attempt to make a comprehensive case for natural climate change as a prime-mover of the history of civilization.footnote9 As noted earlier, Enlightenment and early Victorian thought universally assumed that climate was historically stable, stationary in trend, with extreme events as simple outliers of a mean state. In contrast, the impact of human modification of the landscape upon the atmospheric water cycle had been debated since the Greeks. For instance, Theophrastus, Aristotle’s heir at the Lyceum, reportedly believed that the drainage of a lake near Larisa in Thessaly had reduced forest growth and made the climate colder.footnote10 Two thousand years later, the Comtes de Buffon and de Volney, Thomas Jefferson, Alexander von Humboldt, Jean-Baptiste Boussingault and Henri Becquerel (to give just a short list) were citing one example after another of how European colonialism was radically changing local climates through forest clearance and extensive agriculture.footnote11 (‘Buffon’, wrote Clarence Glacken, ‘concluded it was possible for man to regulate or to change the climate radically.’)footnote12 Lacking any longterm climate records that might reveal major natural variations in weather patterns, the philosophes were instead riveted by the innumerable circumstantial reports of declining rainfall in the wake of plantation agriculture on island colonies. In the same vein, Auguste Blanqui’s older brother, the political economist Jerome-Adolphe Blanqui, later cited Malta as an example of a man-made island desert and warned that the heavily logged foothills of the French Alps risked becoming an arid ‘Arabia Petraea’.footnote13 By the 1840s, according to Michael Williams, ‘deforestation and consequent aridity was one of the great “lessons of history” that every literate person knew about.’footnote14
Two of these literate people were Marx and Engels, both of whom were fascinated by the Bavarian botanist Karl Fraas’s cautionary account of the transformation of the eastern Mediterranean climate by land clearance and grazing. Fraas had been a member of the impressive scientific retinue that accompanied the Bavarian Prince Otto when he became King of Greece in 1832.footnote15 Writing to Engels in March 1868, Marx enthused about his book:
He maintains that as a result of cultivation and in proportion to its degree, the ‘damp’ so much beloved by the peasant is lost (hence too plants emigrate from south to north) and eventually the formation of steppes begins. The first effects of cultivation are useful, later devastating owing to deforestation, etc. This man is both a thoroughly learned philologist (he has written books in Greek) and a chemist, agricultural expert, etc. The whole conclusion is that cultivation when it progresses in a primitive way and is not consciously controlled (as a bourgeois of course he does not arrive at this), leaves deserts behind it, Persia, Mesopotamia, etc., Greece. Here again another unconscious socialist tendency!footnote16
Similarly Engels, later referring to deforestation of the Mediterranean in The Dialectics of Nature, warned that after every human ‘victory’, ‘nature takes its revenge’: ‘Each victory, it is true, in the first place brings about the results we expected, but in the second and third places it has quite different, unforeseen effects which only too often cancel the first.’footnote17 But if nature has teeth with which to bite back against human conquest, Engels saw no evidence of natural forces acting as independent agents of change within the span of historical time. As he emphasized in a description of the contemporary German landscape, culture is promethean while nature is at most reactive:
There is devilishly little left of ‘nature’ as it was in Germany at the time when the Germanic peoples immigrated into it. The earth’s surface, climate, vegetation, fauna, and the human beings themselves have infinitely changed, and all this owing to human activity, while the changes of nature in Germany which have occurred in this period of time without human interference are incalculably small.footnote18
In contrast to the seventeenth century, when earthquakes, comets, plagues and arctic winters reinforced a cataclysmic view of nature amongst the great savants like Newton, Halley and Leibniz,footnote19 weather and geology in nineteenth-century Europe seemed as stable from decade to decade as the gold standard. For this reason, at least, Marx and Engels never speculated on the possibility that the natural conditions of production over the past two or three millennia might have been subject to directional evolution or epic fluctuation, or that climate therefore might have its own distinctive history, repeatedly intersecting and over-determining a succession of different social formations. Certainly they believed that nature had a history, but it was enacted on long evolutionary or geological time-scales. Like most scientifically literate people in mid-Victorian England, they accepted Sir Charles Lyell’s uniformitarian view of earth history, upon which Darwin had built his theory of natural selection, even while they satirized the reflection of English Liberal ideology in the concept of geological gradualism.
The long international controversy starting in the late 1830s over Agassiz’s ‘discovery’ of the Great Ice Age did not put this reigning anthropogenic model into question, since geologists were vexed for decades by the problem of Pleistocene chronology: unable to establish the order of succession amongst glacial drifts, or estimate the relative age of the ancient human and megafaunal remains whose discovery was a staple sensation of mid-Victorian times.footnote20 Although ‘glacial research prepared the way for insight into the reality of short-term changes in climate gauged against geological time’, there was no measure of the Ice Age’s temporal distance from modern climate.footnote21 Cleveland Abbe, the greatest American weather scientist of the late nineteenth century, expressed the consensus view of the ‘rational climatology’ school when he wrote in 1889 that ‘great changes have taken place during geological ages perhaps 50,000 years distant’ but ‘no important climatic change has yet been demonstrated since human history began.’footnote22
Desiccation of Asia and Mars
Kropotkin radically challenged this orthodoxy by asserting a continuity of global climatic dynamics between the end of the Ice Age and modern times; far from being stationary as early meteorologists believed, climate had been continuously changing in a unidirectional sense and without human help throughout history. In 1904, on the thirtieth anniversary of his original presentation to Russian geographers, and amidst much public interest in recent expeditions to inner Asia by the Swedish geographer Sven Hedin and the American geologist Raphael Pumpelly, the Royal Geographical Society invited Kropotkin to outline his current views.
In his article, he argued that recent explorations like Hedin’s had fully vindicated his theory of rapid desiccation in the post-glacial era, proving that ‘from year to year the limits of the deserts are extended’. Based on this inexorable trend from ice sheet to lake land and then from grassland to desert, he proposed a startlingly new theory of history.footnote23 East Turkestan and Central Mongolia, he claimed, were once well-watered and ‘advanced in civilization’:
All of this is gone now, and it must have been the rapid desiccation of this region which compelled its inhabitants to rush down to the Jungarian Gate, down to the lowlands of the Balkhash and Obi, and thence, pushing before them the former inhabitants of the lowlands, to produce those great migrations and invasions of Europe which took place during the first centuries of our era.footnote24
Nor was this just a cyclical fluctuation: progressive desiccation, emphasized Kropotkin, ‘is a geological fact’, and the Lacustrine period (the Holocene) must be conceptualized as an epoch of expanding drought. As he had already written five years earlier: ‘And now we are fully in the period of a rapid desiccation, accompanied by the formation of dry prairies and steppes, and man has to find out the means to put a check to that desiccation to which Central Asia already has fallen a victim, and which menaces Southeastern Europe.’footnote25 Only heroic and globally coordinated action—planting millions of trees and digging thousands of artesian wells—could arrest future desertification.footnote26
Kropotkin’s hypothesis of natural, progressive climate change had a differential reception: greeted with more scepticism in continental Europe than in English-speaking countries or amongst scientists working in desert environments. In Russia, where his contributions to physical geography were well known, there had been intense interest, following the great famine of 1891–92, in understanding whether drought on the black-soil steppe, the new frontier of wheat production, was a result of cultivation or an omen of creeping desertification. In the event, the two internationally recognized authorities on the question, Aleksandr Voeikov—a pioneer of modern climatology, and an old colleague of Kropotkin’s from the Geographical Society in the early 1870s—and Vasili Dokuchaev—celebrated as ‘the father of soil science’—found little evidence of either process at work. In their view, the steppe climate had not changed in historical time, although the succession of wet and dry years might be cyclical in nature. Voeikov, like many other contemporary scientists in Europe, was intrigued if not convinced by the ideas about climate variability advanced by the brilliant German glaciologist Eduard Brückner.footnote27
Brückner’s 1890 landmark book Climatic Changes Since 1700 (unfortunately never translated into English) argued the case for multi-decadal climatic fluctuations in historical times.footnote28 In stunningly modern fashion, unequaled in rigour until the work of Emmanuel Le Roy Ladurie and Hubert Lamb, he combined documentary and proxy sources like grape harvest dates, retreating glaciers and accounts of extreme winters with an analysis of the previous century of instrumental data from different stations to arrive at a picture of a quasi-periodic, 35-year cycling between wet/cool and dry/warm years that regulated changes in European harvests, and perhaps world climate as a whole. Brückner, who knew very little about meteorology and nothing about the general circulation of the atmosphere, was extremely disciplined in avoiding the conjectures and anecdotal claims that contaminated the next generation of debate about climate change, and wisely refused to speculate on the causality of what became known as the ‘Brückner cycle’. In countries whose scientific culture was largely German (most of central Europe and also Russia at the turn of the century), Brückner’s cautious model of climate oscillation was preferred to Kropotkin’s climatic catastrophism.footnote29
In the English-speaking world, on the other hand, Kropotkin’s 1904 article—seemingly buttressed by recent scientific research on the fossil great lakes and dry rivers of the American West, the Sahara and Inner Asia—was generally received with great interest. Its most immediate and remarkable impact, however, was extra-terrestrial. Percival Lowell, a wealthy Boston Brahman, had abandoned his career as an orientalist in 1894 to build an observatory in Flagstaff, Arizona where he could study the canali on Mars ‘discovered’ by Giovanni Schiaparelli in 1877 and later ‘confirmed’ by several leading astronomers. Until Lowell, these hallucinatory channels or fissures were believed by most to be natural features of the Red Planet, although the Belfast journalist and science-fiction writer Robert Cromie had already suggested in an 1890 novel that the canals were oases created by an advanced civilization on a dry and dying world.footnote30 Five years later, in his sensational book Mars, Lowell proposed that Cromie’s fiction was observable science: because of their geometry, the canals must be an artificial irrigation system built by intelligent life. Moreover, Martian civilization had obviously put an end to ‘nations’ and warfare in order to build on a planetary scale. But ‘what manner of beings they may be we lack the data even to conceive.’footnote31
Newspaper readers across the globe were electrified, composers wrote Mars marches, and an English journalist named Wells found the plot for a book that continues to fascinate and terrify readers. Lowell quickly acquired implacable scientific foes, such as the co-discoverer of natural selection and acquaintance of Kropotkin, Alfred Russel Wallace; but with the popular press as an ally, he soon convinced public opinion that a Martian civilization was fact, not speculation. He liked to astound audiences with photographs of the ‘canals’, always apologizing for the blurred images.footnote32 But what was the nature and history of this alien civilization? Lowell may have met Kropotkin when the latter gave a series of lectures on evolution at Boston’s Lowell Institute in 1901, but whatever the case may be, the 1904 paper on progressive desiccation struck Lowell like a lightning bolt. Here was a master narrative to explain not only the ‘tragedy of Mars’ but also the fate of the Earth. Lowell argued that because of its smaller size, planetary evolution was accelerated on Mars, thus providing a preview of how the Earth would change in eons to come. ‘On our own world’, he wrote in the 1906 book Mars and Its Canals, ‘we are able only to study our present and our past; in Mars we are able to glimpse, in some sort, our future.’ That future was planetary desiccation as oceans evaporated and dried into land, forest gave way to steppe, and grasslands became deserts. He agreed with Kropotkin about the velocity of aridification: ‘Palestine has desiccated within historic times.’footnote33
Two years later, in popular talks published under the title Mars as Abode of Life, he devoted a lecture to ‘Mars and the Future of Earth’, warning that ‘the cosmic circumstance about them which is most terrible is not that deserts are, but that deserts have begun to be. Not as local, evitable evils only are they to be pictured, but as the general unspeakable death-grip on our world.’ His prime example, not surprisingly, was Central Asia: ‘The Caspian is disappearing before our eyes, as the remains, some distance from its edge, of what once were ports mutely inform us.’ Someday, the only option left to humans in this ‘struggle for existence in their planet’s decrepitude and decay’ would be to emulate the Martians and build canals to bring polar water to their last oases.footnote34 Lowell, a skilled mathematician but a hapless geologist, liked to impress visitors to Arizona with the Petrified Forest as an example of desiccation at work, although the tree fossils dated from the Triassic Period, 225 million years earlier. Likewise he took for granted the evidence for unidirectional and rapid climate change on Earth.
In fact, Kropotkin’s theory, based on landscape impressions and the hypothesis of a Eurasian ice sheet, was a speculative leap far ahead of any data about past climates or their causes. Indeed it was essentially untestable. Theoretical as contrasted to descriptive meteorology, for example, was still in its swaddling clothes. By coincidence, Kropotkin’s paper was published almost simultaneously with an obscure article by a Norwegian scientist named Jacob Bjerknes that laid down the first foundations for a physics of the atmosphere, in the form of a half dozen fundamental equations derived from fluid mechanics and thermodynamics. ‘He [Bjerknes] conceived the atmosphere’, observes a historian of geophysics, ‘from a purely mechanical and physical viewpoint, as an “air-mass circulation engine”, driven by solar radiation and deflected by rotation, expressed in local differences of velocity, density, air pressure, temperature and humidity.’ It would take more than half a century for these conceptual seeds to grow into modern dynamic meteorology; in the meantime, it was impossible to propose a climate model for Kropotkin’s theory.footnote35
Quantitative evidence for understanding past climate was likewise a bare cupboard. Brückner had used instrumental records with impressive skill, but only for the period after the French Revolution. In 1901, the Swedish meteorologist Nils Ekholm, writing in the Quarterly Journal of the Royal Meteorological Society, had soberly surveyed the available pre-instrumental documentary evidence and found that much of it was simply worthless: ‘Almost the only weather phenomenon of which the old chronicles give trustworthy reports are severe winters.’ Comparing Tycho Brahe’s pioneering instrumental weather readings in 1579–82 from an island off the Danish coast with modern measurements from the same location, he found some indications that winters were milder and that Northern European climate in general was more ‘maritime’ than three centuries earlier. But this was the limit of disciplined inference: ‘The character in other respects and the cause of this variation are unknown. We cannot say if the variation is periodical, progressive or accidental, nor how far it extends in space and time.’ Since Ekholm reasonably assumed that insolation had been constant for at least a million years and that the Earth’s orbital variability had had minimal influence over the last millennium of climate, the most likely cause of climate change (based on the famous experiments of his colleague Svante Arrhenius) was a fluctuation in atmospheric carbon dioxide and thereby the greenhouse effect.footnote36
But there was an avid appetite amongst scientists and geographers, as well as the general public, for bolder theories, and as the Royal Society had undoubtedly hoped, Kropotkin’s paper, aside from gifting Lowell’s Mars mania, stimulated a far-reaching debate that lasted until the eve of the First World War. Lord Curzon, the Viceroy of India, even waded into the controversy, siding with the explorers who had seen desertification first hand rather than with ‘untravelled scientists’ who denied climate change.footnote37 One of the eminent travellers and scientists who embraced the evidence for progressive desiccation was Europe’s other red prince, Leone Caetani, whose Annali dell’Islam (10 volumes, 1905–29) became the foundation stone for Islamic studies in the West. A skilled linguist, he had travelled widely in the Muslim world before being drawn into left-wing politics. Although a Papal prince, he became a parliamentary deputy for the anti-clerical Radical Party, and in 1911 joined with the majority faction of the Socialists to oppose the invasion of Libya. After the rise of fascism, he moved to Canada and continued work on the Annali.footnote38 Caetani hypothesized that the originally fertile Arabian Peninsula was the home of all Semite cultures, but aridification and subsequent overpopulation had forced one group after another to migrate; indeed, desiccation was the environmental motor force behind the expansion of Islam. Hugo Winckler, the famed German archaeologist/philologist who had discovered Hattusa, the lost capital of the Hittites, arrived at the same idea independently, and the ‘Winckler–Caetani’ or ‘Semite Wave’ theory subsequently became a touchstone of pan-Arab ideology in the 1920s and 30s.footnote39
The most fervent adherent to the desiccation hypothesis, however, was the Yale geographer Ellsworth Huntington, a former missionary in Turkey and a veteran of the 1903 Pumpelly Expedition to Transcaspia and the 1905 Barrett Expedition to Chinese Turkestan. His observations from the latter mission confirmed those of earlier travellers in Xinjiang and supported Kropotkin’s theory: ‘All the more arid part of Asia, from the Caspian Sea eastward for over 2,500 miles, appears to have been subject to a climatic change whereby it has been growing less and less habitable for the last two or three thousand years.’footnote40 At first Huntington vigorously defended Kropotkin’s ideas to the letter, but in his 1907 book, The Pulse of Asia, he amended the theory in one decisive regard. Considering the menu of possible climate hypotheses—‘uniformity, deforestation [anthropogenic change], progressive change, and pulsatory change’—he now voted for the last. Climate change, Huntington argued, took the form of great, Sun-driven oscillations of centuries-long duration: wet periods followed by mega-droughts.footnote41 Although he attributed the idea to reading Brückner, his cycles were an order of magnitude longer in frequency and had the epic effects ascribed to progressive desiccation by Kropotkin.
Like Lowell, Huntington was a superb publicist. He aggressively sought further evidence for the cyclical thesis in Palestine, Yucatan and the American West, where he worked with tree-ring pioneer Andrew Douglas (Lowell’s former assistant at the observatory) in the ancient California sequoias.footnote42 From each new investigation came an article or book bolstering his claim that societies and civilizations rose and fell with these climatic oscillations. ‘With every throw of the climatic pulse which we have felt in Central Asia, the centre of civilization has moved this way or that. Each throb has sent pain and decay to the lands whose day was done, life and vigour to those whose day was yet to be.’footnote43 (Owen Lattimore, author of the classic 1940 work The Inner Asian Frontiers of China, parodied Huntington’s image of ‘hordes of erratic nomads, ready to start for lost horizons at the joggle of a barometer, in search of suddenly vanishing pastures.’footnote44)
Huntington’s majestic oscillations were an unexpected gift to searchers for ultimate causations in history, and The Pulse of Asia helped inspire Arnold Toynbee’s famous theory of civilizational cycles driven by responses to environmental challenges.footnote45 But Huntington’s sweeping claims made others nervous. Both the Royal Geographical Society and Yale University (which was considering promoting him to a professorship) discreetly canvassed the opinions of major authorities. The explorer Sven Hedin derided the whole idea of desiccation: ‘Men and camels, country and climate—none has undergone any change worth mention.’footnote46 Albrecht Penck, one of the giants of modern physical geography, gently observed of Huntington that ‘sometimes his thoughts run ahead of his facts. He works more with a vital scientific imagination than with a critical faculty.’footnote47
Eduard Brückner in Vienna, whom Huntington acknowledged as one of his masters, was also polite but devastating in his assessment:
He takes his data from historical works without examining it properly. He is not sufficiently aware to what degree he may use data as facts. In particular the archaeological results are by no means definitive enough as he himself explains in his work The Pulse of Asia . . . He has shown several times the desire to fit the facts to his theory. During my visit to Yale Dr Huntington showed me the results of his investigations in respect to the rings of old trees in their relationship to fluctuations of climate. He has collected very interesting material, but again I had the impression that he concluded more from his curves than a cautious man ought to conclude. He claimed in several cases that he saw a parallelism in the curve where I could not see one.footnote48
Huntington did not receive the promotion and left Yale.
Brückner’s critique anticipated Irving Langmuir’s famous definition of ‘pathological science’ as research ‘led astray by subjective effects, wishful thinking or threshold interactions’.footnote49 In addition to the usual sins of confusing coincidence with correlation and correlation with causality, Huntington and his several prominent co-thinkers—especially the Clark University geographer Charles Brooks—were addicted to circular argumentation. ‘Huntington’, Le Roy Ladurie wrote in his Histoire du climat, ‘explained the Mongol migrations by the fluctuations in rainfall and barometric pressure in the arid zones of Central Asia. Brooks carried on the good work by basing a graph of rainfall in Central Asia on the migration of the Mongols!’footnote50 In another instance, Brooks, who followed Huntington in believing that tropical climates could not support advanced civilizations, concluded that the existence of Angkor Wat proved that the climate of Cambodia in 600 ad must have been more temperate.footnote51
As for spectacular ruins in the deserts, the geographer and historian Rhoads Murphey demonstrated in a 1951 article, contra Huntington, that in the case of North Africa there is little evidence of climate change since the Roman period. Instead, he explained the desolate landscapes where wheat fields and Roman towns once flourished as a result of the neglect or destruction of water-storage infrastructures. (Huntington seemed to have forgotten the dependence of desert societies upon groundwater rather than rain.) In a classic example of the kind of ‘natural experiment’ that Jared Diamond would decades later urge historians to adopt, Murphey cited the example of the Aïr Massif in Niger where the French forcibly evicted the rebellious Tuareg population in 1917: ‘As population decreased, wells, gardens and stock were allowed to deteriorate, and within less than a year the area looked exactly like the other areas which have been used as evidence of progressive desiccation.’footnote52
For all this, the Kropotkin/Huntington debate about natural climate change in history might have left a more fruitful legacy if it had stayed within the domain of physical geography. Huntington, however, fused his distinctive ideas about climate cycles with the extreme environmental determinism advocated by the German geographer Friedrich Ratzel and his American disciple Ellen Churchill Semple. They argued that cultural and ethnic characteristics were mechanically and irreversibly imprinted upon human groups by their natural habitats, especially climate. Huntington also became mesmerized by the bizarre ideas of a professor of German in Syracuse named Charles Kullmer who believed that human mental activity, both individual and social, was governed by the electrical potential of barometric depressions. As Huntington’s biographer explains: ‘Kullmer measured the number of nonfiction books taken from libraries and the barometric pressure at such time; “high pressure means more serious books, and low pressure fewer.”’ Huntington, ‘electrified’ by Kullmer’s findings, wrote ‘I have pondered a great deal over the Italian Renaissance; and now I am wondering whether by any chance that was associated with some change in storm frequency.’ Huntington subsequently tested Kullmer’s thesis by having a friend’s children type three dictated stanzas of Spencer’s The Faerie Queene every day for months while their father recorded the barometric pressure. Huntington then compared the pattern of errors: ‘There seems to be a connection between weather and mental ability far closer than we have hitherto suspected. I am at work just now trying to apply this to Japan.’footnote53
But Huntington soon put barometry aside, concluding that it was actually temperature, perhaps in collusion with humidity, that determined human mental acuity and industrial efficiency. This ‘meteorological Taylorism’, as James Fleming calls it, was then subsumed by Huntington’s passion for eugenics and racial engineering.footnote54 While an ailing Kropotkin, who had returned to Russia in 1917 to support the anarchist movement, was racing to finish his magisterial scientific testament, Glacial and Lacustrine Periods,footnote55 Huntington was publishing increasingly bizarre papers on the adaptability of white men to the Australian tropics and the impact of climate on human productivity in Korea. A few years later, he was struggling to understand the effect of overpopulation on Chinese character, decrying the immigration of Puerto Ricans to New York, and pontificating in Harper’s about ‘Temperature and the Fate of Nations’.footnote56 In effect, Huntington, like Ratzel, Semple and many others, was aggrandizing the climatic race theories of Herodotus and Montesquieu—the first convinced that Greece was man’s perfect habitat; the other, France—into an all-encompassing meteorological anthropology.
In the 1910s and 1920s, the heyday of scientific racism (of which Huntington was a fervent proponent), these ideas were easily embraced by mainstream scholarship; by the late 1930s, however, a new generation of academics began to recoil from the dark implications of environmental determinism alloyed with white supremacy and its apotheosis, fascism. As his biographer gingerly observes: ‘Huntington’s insistence on a hierarchy of innate competence, and consistent inquiry into the eugenic cause in the 1930s, was perhaps unfortunate. When he proposed on the eve of World War ii that Caucasians with blond hair and blue eyes were possessed of greater longevity than others, his utterance seemed peculiarly non sequitur.’footnote57 (The Nazis, meanwhile, were integrating desiccationist ideas into their rationale for the removal and mass murder of the populations of Poland and the ussr. The Slavs were simultaneously condemned for failing to drain the post-glacial wetlands east of the Vistula and for allowing them to turn into desert—Versteppung. Only the master race could arrest the great drying.footnote58) Huntington’s wild theories and crude determinism, together with the absence of reliable historical weather data, began to taint the enterprise of climate history for most geographers and historians. In 1937, the physicist Sir Gilbert Walker, who had spent a lifetime searching for structure in weather data, wrote an obituary for climatic determinism, a theory he equated with astrology: ‘I regard the widespread faith in the effective control of weather by periods as based partly on a mistaken handling of plotted data and partly on an instinct that survives in many of us, like the faith in the effect of the Moon on the weather, from the time when our forefathers believed in the control of human affairs by the heavenly bodies with their fixed cycles.’footnote59
In the postwar period, moreover, ‘a new disciplinary consensus’ emerged amongst climatologists: ‘Namely that the global climate system contained overriding equilibrating processes providing resilience against secular climate fluctuations.’footnote60 Meanwhile, the natural archives of deep Eurasia that hid the secrets of its climate history were off-limits: the only Westerners to visit the Tarim Basin during the Cold War were cia agents (Lop Nor was the Chinese nuclear test site). Finally in 2010–11, more than a century after the controversial expeditions of Stein, Heden and Huntington, an interdisciplinary team of Chinese, American, Swiss and Australian researchers spent a field season in the Tarim Basin, modelling relict hydrologies and sampling such potential climate archives as sediments from the now vanished Lake Lop Nor and dead trees interred in sand dunes.
Their results were published at the beginning of this year. Desiccation, it turns out, is a modern phenomenon, not an ancient curse: ‘The Tarim Basin was continuously wetter than today at least as early as ad 1180 until the middle ad 1800s.’ This falls within the parameters, generously construed, of the Little Ice Age, and the researchers attribute the wetting to a southward shift of the boreal westerlies that produced enhanced snowfall in the mountains that feed the Tarim and its sister rivers. It was this ‘greening of the desert’, not its relentless expansion, that was a mainspring of late medieval and early modern history:
We propose that wetting of the interior Asian desert corridor stimulated southward migration of winter rangeland, which was essential in fuelling the horse-driven Mongol conquests across Eurasian deserts. In addition, wetter-than-present Asian deserts may have aided in the spread of pastoralism out of the Mongolian heartland, strengthening cultural and economic affinities among the Mongols and Turkic-speaking groups on the periphery of the steppe.footnote61
Since the late nineteenth century, however, the progressive warming of interior Asia has produced a net drying which the researchers warn may be a prelude to the future northward expansion of the deserts. Meanwhile, other climate scientists have expressed concern that precipitation regimes in western Asia may be radically changing as well. A research group based at Columbia University’s Lamont-Doherty Earth Observatory, which has been studying contemporary and historical megadroughts, recently published a paper warning that the disastrous 2007–10 drought in Syria, the most severe in the instrumental record and a principal catalyst to social unrest, was likely part of ‘a longterm drying trend’ associated with rising greenhouse emissions.footnote62 This uncomfortably accords with an earlier study which predicted that the entire climatological Fertile Crescent, from the Jordan Valley to the Zagros foothills, might disappear by the end of the century: ‘Ancient rain-fed agriculture enabled the civilizations to thrive in the Fertile Crescent region, but this blessing is soon to disappear due to human-induced climate change.’footnote63 The Anthropocene, it seems, may vindicate Kropotkin after all. | 0.859824 | 3.381508 |
Did you know that the immense gravity of a black hole can convert matter into energy more efficiently than the nuclear fusion inside stars does…?
Interestingly, it turns out I was wrong in my previous post. As it happens, black holes can have surrounding chemistry. This image shows an artist’s impression (not mine) of a black hole surrounded by a molecular cloud. X-ray observatories have found that some x-ray ‘colours’ vary drastically with time, while others remain constant. In other words, around some black holes, something is scattering the x-rays before they get to us. Quite a good indication, as it happens, of black hole chemistry, with dust molecular gas and atomised metals (the sort of things that are generally quite good at scattering x-rays). Thus far, this has only been observed in the central supermassive black holes in certain bright galaxies, but logically, there’s no reason why phenomena like this should restrict themselves to large scales.
Recently too, astronomers have discovered the largest black hole in the known universe. At 18 billion solar masses, it weighs in as much as a small galaxy. The mass was calculated thanks to a second black hole in orbit which weighs only around 100 million suns. Not that there’s anything ‘only’ about an object that massive! The two are actually in a decaying orbit too, edging slowly closer. At the rate they’re going, they’re set to merge in about 10,000 years to form one gigamassive black hole! No one knows if there’s an upper size limit to these things either. As far as we know, they could just keep growing indefinitely. Most black holes though, are much smaller. In fact, some scientists believe that rogue black holes might roam the galaxy freely and virtually undetectably. A slightly disconcerting thought, to be honest, especially seeing as the Milky Way is old. Very old. Millions of black holes must have been formed since the Milky Way was young.
But then… Much about these strange beasts is yet unknown. Everything we think we know is still actually a theory, and it’s not like we’ve actually been to any to find out for certain. Maybe someday we’ll know for certain all about black holes. In the meantime, I’m fairly certain our solar system isn’t going to be ripped to atoms by a marauding monster anytime soon. | 0.867573 | 3.428558 |
Schrödinger’s Cat: Explained. Erwin Schrödinger was born in Vienna on August 12, 1887 and was awarded the Nobel Prize in Physics in 1933.
He is best known for his work regarding quantum theory, particularly about his thought experiment involving a cat in order to explain the flawed interpretation of quantum superposition. The Copenhagen Interpretation of quantum mechanics essentially states that an object in a physical system can simultaneously exist in all possible configurations, but observing the system forces the system to collapse and forces the object into just one of those possible states. Schrödinger disagreed with this interpretation. So what does this have to do with cats? Schrödinger wanted people to imagine that a cat, poison, a geiger counter, radioactive material, and a hammer were inside of a sealed container.
Of course, Schrödinger claimed, that was ridiculous. This video from Sixty Symbols does an excellent job at explaining the Shrödinger’s Cat Paradox: Could cold spot in the sky be a bruise from a collision with a parallel universe? Scientists have long tried to explain the origin of a mysterious, large and anomalously cold region of the sky.
In 2015, they came close to figuring it out as a study showed it to be a “supervoid” in which the density of galaxies is much lower than it is in the rest of the universe. However, other studies haven’t managed to replicate the result. 'We Don't Planet' Episode 3: What's Up with Gravitational Lensing? The fundamental description of gravity under general relativity — that the presence of matter and energy deforms the fabric of space-time, and this deformation influences the motion of other objects — leads to a rather unexpected result: a massive object can act like a lens, magnifying and warping the images of background objects.
This prediction was the first major test of general relativity, with Sir Arthur Eddington leading an expedition to measure the small (but detectable) deflection of starlight around our sun, and today this facet of our universe is used as a powerful cosmological probe. Jim Al-Khalili: Is Time Travel Possible? Determinism, Relativity and the Arrow of Time (2011) Fermilab. Better Nuclear Power Through Ping Pong. The lab is deep-space quiet.
A long, narrow hallway hung with fluorescent lights extends to my left. Four or five doors interrupt the flow of drywall. A few of those doors are open, the occupants of the rooms within now out in the hall and staring, ears plugged in anticipation. A technician flips a small lever to activate the vacuum pumps on an 18-foot cannon that is tented in bulletproof polycarbonate. He's dressed casually in dark jeans and a black button-down, an ID card coolly clipped to his pants. The Phenomenon Of Light Generation Through The Crushing Of Materials Is Called? Answer: Triboluminescence The word might sound rather scientific, and maybe a little alien in nature (“triboluminescence” does sound a whole lot like a problem the crew of the Enterprise might run into, after all), but it’s a down-to-Earth phenomenon you may have even experienced yourself.
Triboluminescence is light created when crushing, tearing, or other mechanical action triggers the breakdown of chemical bonds in a material (or when peeling adhesive tapes). A popular classroom demonstration of this phenomenon, for example, is to give students rolls of Wint-O-Green Mint Lifesaver candies, enter a darkened room, and then have the students—much to their delight—throw tons of the candies into their mouths and chomp on them vigorously with their mouths open. Understanding Electricity - Documentary. Entropy, Order and Disorder Energy - Documentary. Heisenberg's uncertainty principle - Documentary. Quantum mechanics - Wikipedia. Solution to Schrödinger's equation for the hydrogen atom at different energy levels.
EINSTEIN AND QUANTUM MECHANICS. No, Scientists Didn't Just Create Negative Mass or Defy the Laws of Physics. Finding faster-than-light particles by weighing them. In a new paper accepted by the journal Astroparticle Physics, Robert Ehrlich, a recently retired physicist from George Mason University, claims that the neutrino is very likely a tachyon or faster-than-light particle.
There have been many such claims, the last being in 2011 when the "OPERA" experiment measured the speed of neutrinos and claimed they travelled a tiny amount faster than light. However, when their speed was measured again the original result was found to be in error – the result of a loose cable no less. Ehrlich's new claim of faster-than-light neutrinos is based on a much more sensitive method than measuring their speed, namely by finding their mass. The result relies on tachyons having an imaginary mass, or a negative mass squared.
Imaginary mass particles have the weird property that they speed up as they lose energy – the value of their imaginary mass being defined by the rate at which this occurs. Skeptics of tachyons often cite conflicts with relativity theory. The LHC Just Discovered A New System of Five Particles. A Unique Find The Large Hadron Collider (LHC), the latest addition to CERN’s accelerator complex, is the most powerful particle accelerator ever built.
It features a 27 kilometer (16 mile) ring made of superconducting magnets and accelerating structures built to boost the energy of particles in the chamber. In the accelerator, two high-energy particle beams are forced to collide from opposite directions at speeds close to the speed of light. The energy densities that are created when these collisions occur cause ordinary matter to melt into its constituent parts—quarks and gluons. The LHC Disproves the Existence of Ghosts and the Paranormal. In Brief.
Alcubierre Warp Drive Time Travel. An Alcubierre Warp Drive stretches spacetime in a wave causing the fabric of space ahead of a spacecraft to contract and the space behind it to expand.
The ship can ride the wave to accelerate to high speeds and time travel. [1611.06985v2] Cosmic Bell Test: Measurement Settings from Milky Way Stars. Nikola Tesla. Tesla's Tower of Power. In 1905, a team of construction workers in the small village of Shoreham, New York labored to erect a truly extraordinary structure. Over a period of several years the men had managed to assemble the framework and wiring for the 187-foot-tall Wardenclyffe Tower, in spite of severe budget shortfalls and a few engineering snags. The project was overseen by its designer, the eccentric-yet-ingenious inventor Nikola Tesla (10 July 1856 – 7 January 1943). Atop his tower was perched a fifty-five ton dome of conductive metals, and beneath it stretched an iron root system that penetrated more than 300 feet into the Earth’s crust. Emdrive - Theory - Principle of Operation. Theory Theory Paper (.pdf) Principle of Operation. Evan Grant: Making sound visible through cymatics.
Physicists Have Modeled the Existence of Newly Discovered Tetraneutrons. In Brief A new study has confirmed previous research on the existence of tetraneurons — a particle with more than two neutrons. The research challenges the current model of particle physics and means we may have to reexamine how we look at nuclear forces like neutron stars. Simulating The Impossible Back in February, physicists from Japan presented evidence that they may have generated tetraneutrons, a particle consisting of four neutrons. But we had no model that revealed how they could possibly exist. Until now. Now, an international team of scientists have used sophisticated supercomputer simulations to show how a tetraneutron could be quasi stable, revealing data that matched with the previous Japanese experiment, according to a new study published in Physical Review Letters.
High-intensity fusion. Pablo Rodriguez Fernandez is hunched over a computer in the control room of MIT’s fusion reactor, gathering data that will inform the design of a new one — a device that could solve the world’s energy problems. He is surrounded by other scientists running simulations and analyzing data. Their work is spread across tables and desks covered in computers and a chaos of wires. The objective: to design a machine that will harness the same energy process that powers the sun and deliver it to the world, carbon free. They are here to make fusion energy a reality.
This is the headquarters of a MIT’s Alcator C-Mod. On this day in mid-September, as Fernandez and his fellow graduate students in the Department of Nuclear Science and Engineering type, calculate, and predict, the machine is operating on the other side of a nearby concrete wall. Despite its apparently casual atmosphere, C-Mod has also established stringent safety standards that have been widely exported across the MIT campus. WMAP- Cosmological Constant or Dark Energy. The Official String Theory Web Site.
A Quantum Teleportation Breakthrough: Physicists Just Smashed Previous Records. In Brief Two separate teams of scientists have successfully conducted the world's first quantum teleportation outside of a laboratory. While the setup of both tests have variations, the conclusion is essentially the same: quantum teleportation is possible.
No Beaming Up, Yet As fascinating as the image it conjures up, quantum teleportation is not the same as teleportation you see in psychic Pokémon, or what you see Scotty doing in Star Trek. Still, quantum teleportation has its own kind of coolness. BBC Four - Order and Disorder. ONExDARKMATTER: Tamara Davis at TEDxBrisbane. ArXiv.org e-Print archive. The Visual Microphone. Science : May the fifth force be with us? Synchronized Ferrofluid Sculptures. This skintight ‘invisibility cloak’ is able to hide any 3-D object — as long as it’s super tiny. Has Stephen Hawking Just Solved a Huge Black-Hole Mystery? Big Crunch. LIGO - Laser Interferometer Gravitational Wave Observatory.
Non-Newtonian Liquid IN SLOW MOTION! System of Transmission of Electrical Energy. SPECIFICATION forming part of Letters Patent No. 645,576, dated March 20, 1900. Application filed September 2, 1897. Serial No. 650,343. (No model.) The Radioactive Boy Scout. There is hardly a boy or a girl alive who is not keenly interested in finding out about things. And that’s exactly what chemistry is: Finding out about things—finding out what things are made of and what changes they undergo. Aperture: Science Time - Schrödinger's Cat. Proof That White Dwarfs Can Reignite and Explode as Supernovae. Einstein's Explanation of Brownian Motion. Watch "TEDxKTH - Gunnar Björk - Teleportation - the Future of Transportation" Video at TEDxTalks. Readings - Bohmian-Mechanics.net. This is part of a correspondence between Sheldon Goldstein and Steven Weinberg on Bohmian Mechanics. It is published here with the kind permission of both.
From: [email protected] To: [email protected] Subject: NYRB Date: Sun, Sep 22 1996, 17:14:44 Dear Professor Weinberg, In your recent response in the NYRB, you ask George Levine, my colleague here at Rutgers, to "suppose that physicists were to announce the discovery that, beneath the apparently quantum mechanical appearance of atoms, there lies a more fundamental substructure of fields and particles that behave according to the rules of plain old classical mechanics. " Longer distance quantum teleportation achieved. Accelerating science.
EUROfusion. ITER - the way to new energy. Fusion: Fusion - a clean future. Little reactors may be best path to nuclear fusion - tech - 05 November 2014. IT ALWAYS seems to be 30 years away. Controlled nuclear fusion seems no closer to being realised now than it was when the idea was put forward in the 1950s. But fusion power stations might be closer than anyone suspected – if we think small. Bigger is better, or so goes the accepted wisdom with nuclear fusion. The massive international experiment ITER takes this to the extreme, employing a doughnut-shaped reaction chamber 20 metres across and up to 1000 staff. The price tag? Now some are advocating that a smaller-scale approach could be swifter and cheaper. Fusion reactors promise cheap, clean energy, leaving behind only small amounts of radioactive waste and with little risk of runaway meltdowns.
It is easier said than done. Seismic Monitor. Kirlian Photography - Building your own equipment. DIY Homemade Kirlian Photographs. Cymatics.org. The Sound of Science. Diffusion Science radio. How do you skim a stone 51 times? Rainwater Harvesting. The European Organization for Nuclear Research. Albert Einstein Online. A fun talk on teleportation. Aether/ZPE - Converting Energy - 04/04/01. Boundary Institute - Home Page. Backstitching Time with Cosmic String, Alaska Science Forum. | 0.85277 | 3.743915 |
It was identified as a gamma-ray burst, resulting from a massive explosion in a distant, young galaxy. Then astronomers realised that this flaring object was much closer to home, in fact it was a gamma-ray source within the Milky Way. Astronomers detected 40 visible-light flashes, only for the source to vanish as quickly as it mysteriously appeared. So what generated this huge firework display for astronomers to originally mistaken it for a gamma-ray burst?
It seems we have an answer, and it has surprised many.
One of the rarest objects ever observed may have sprung to life in our galaxy after a long period of calm. This object is a young neutron star with a magnetic field a billion billion times stronger than the Earth’s, otherwise known as a magnetar…
I’ve been captivated by magnetars ever since I wrote “Pulsars are Exploding Unexpectedly and “Magnetars” Might be to Blame” for the Universe Today back in February. On that occasion, observations of once-periodic pulsars exploding with the intensity of “75,000 Suns,” indicated something rather exotic was happening to our once-regularly spinning neutron stars. And it seems as if it has happened again, only this time within our own galaxy.
Neutron stars are the result of supernovae, an extremely dense lump of neutron-degenerate matter, held together by a balance between an intense gravitational field and the Pauli Exclusion Principal; it is one step before matter is completely overcome by its own gravity, collapsing it into a singularity (or black hole). There could be an intermediate step known as a “quark star,” but this has yet to be confirmed observationally. Not only does the neutron star conserve the angular momentum of its parent star, thereby making it spin hundreds of times per second soon after formation, it also conserves the magnetic field of its parent star. The intense magnetic field channels intense beams of electromagnetic radiation from the neutron stars poles, thereby creating a pulsar.
However, sometimes neutron stars are not as well behaved as pulsars. Sometimes they can evolve into an entirely different creature. Due to a stronger magnetic field, magnetars can be born from neutron stars, magnetic field lines becoming forced together, reconnecting and releasing vast amounts of energy. This is when magnetars become visible to observers, and it seems that the recent magnetar eruption, only 15 000 light-years away (near the constellation of Vulpecula), unleashed a huge amount of magnetic energy, making astronomers mistake it for a gamma-ray burst.
The science behind magnetars is still in its infancy, and this event is the first ever magnetar eruption observed in visible light. This magnetar is known as SWIFT J195509+261406 (as it was identified by NASA’s Swift gamma-ray observatory), but it was initially allocated a gamma-ray burst identifier, GRB 070610.
“We are dealing with an object that has been hibernating for decades before entering a brief period of activity.” -Alberto J. Castro-Tirado, lead author of “Flares from a candidate Galactic magnetar suggest a missing link to dim isolated neutron stars,” Nature.
It is thought that many magnetars populate the Milky Way, but they can only be observed when they erupt sporadically, after remaining dormant for decades. Therefore only a handful have been identified.
It is thought that neutron stars eventually grow out of the “magnetar phase,” gradually losing magnetic energy, retiring into a quieter state. It is hard to prove this theory however, no evolutionary candidate has been observed so far that suggests it was once a magnetar. I don’t think these mysterious objects are about to surrender all their secrets too soon… | 0.87315 | 3.972543 |
Einstein’s Theory ‘Improved’? ... Feb 13, 2006 23:03:56 GMT -6
Post by Chicago Astronomer Joe on Feb 13, 2006 23:03:56 GMT -6
New modern Data Alters E=MC2 ?
Chinese astronomer from the University of St Andrews has fine-tuned Einstein’s groundbreaking theory of gravity, creating a ‘simple’ theory which could solve a dark mystery that has baffled astrophysicists for three-quarters of a century.
A new law for gravity, developed by Dr. Hong Sheng Zhao and his Belgian collaborator Dr. Benoit Famaey of the Free University of Brussels (ULB), aims to prove whether Einstein’s theory was in fact correct and whether the astronomical mystery of Dark Matter actually exists. Their research was published on February 10th in the Astrophysical Journal Letters. Their formula suggests that gravity drops less sharply with distance as in Einstein, and changes subtly from solar systems to galaxies and to the universe.
Theories of the physics of gravity were first developed by Isaac Newton in 1687 and refined by Albert Einstein's general theory of relativity in 1905 to allow light bending. While it is the earliest-known force, gravity is still very much a mystery with theories still unconfirmed by astronomical observations in space.
The ‘problem’ with the golden laws of Newton and Einstein is whilst they work very well on earth, they do not explain the motion of stars in galaxies and the bending of light accurately. In galaxies, stars rotate rapidly about a central point, held in orbit by the gravitational attraction of the matter in the galaxy. However astronomers found that they were moving too quickly to be held by their mutual gravity - so not enough gravity to hold the galaxies together – instead stars should be thrown off in all directions!
The solution to this, proposed by Fritz Zwicky in 1933, was that there was unseen material in the galaxies, making up enough gravity to hold the galaxies together. As this material emits no light astronomers call it ‘Dark Matter’. It is thought to account for up to 90% of matter in the Universe. Not all scientists accept the Dark Matter theory however. A rival solution was proposed by Moti Milgrom in 1983 and backed up by Jacob Bekenstein in 2004. Instead of the existence of unseen material, Milgrom proposed that astronomer’s understanding of gravity was incorrect. He proposed that a boost in the gravity of ordinary matter is the cause of this acceleration.
Milgrom’s theory has been worked on by a number of astronomers since and Dr. Zhao and Dr. Famaey have proposed a new formulation of his work that overcomes many of the problems previous versions have faced.
They have created a formula that allows gravity to change continuously over various distance scales and, most importantly, fits the data for observations of galaxies. To fit galaxy data equally well in the rival Dark Matter paradigm would be as challenging as balancing a ball on a needle, which motivated the two astronomers to look at an alternative gravity idea.
Legend has it that Newton began thinking about gravity when an apple fell on his head, but according to Dr Zhao: ‘It is not obvious how an apple would fall in a galaxy. Mr. Newton’s theory would be off by a large margin; his apple would fly out of the Milky Way. Efforts to restore the apple on a nice orbit around the galaxy have over the years led to two schools of thoughts: Dark Matter versus non-Newtonian gravity. Dark Matter particles come naturally from physics with beautiful symmetries and explain cosmology beautifully; they tend to be everywhere. The real mystery is how to keep them away from some corners of the universe. Also Dark Matter comes hand -–in-hand with Dark Energy. It would be more beautiful if there were one simple answer to all these mysteries.’
Full story here at PhysOrg.com: www.physorg.com/news10813.html
I find it rather hard to believe that Einstein had all the answers with turn of the century data. Theory evolves, adapts and conforms to new solid information...and this is no different. | 0.856316 | 3.483861 |
There have been a number of objects that were once thought to exist by astronomers, but which later ‘vanished’. Here are their stories.
- Vulcan, the intra-Mercurial planet
- Mercury’s Moon
- Neith, the Moon of Venus
- The Earth’s Second Moon
- The Moons of Mars
- The 14th Moon of Jupiter
- Saturn’s Ninth and Tenth Moons
- Six Moons of Uranus
- Planet X
- Nemesis, the Sun’s companion star
Vulcan, the intra-Mercurial planet, 1860-1916, 1971
The French mathematician Urbain Le Verrier, co-predictor with J.C. Adams of the position of Neptune before it was seen, in a lecture at 2 Jan 1860 announced that the problem of observed deviations of the motion of Mercury could be solved by assuming an intra-Mercurial planet, or possibly a second asteroid belt inside Mercury’s orbit. The only possible way to observe this intra-Mercurial planet or asteroids was if/when they transited the Sun, or during total solar eclipses. Prof. Wolf at the Zurich sunspot data center, found a number of suspicious “dots” on the Sun, and another astronomer found some more. A total of two dozen spots seemed to fit the pattern of two intra-Mercurial orbits, one with a period of 26 days and the other of 38 days.
In 1859, Le Verrier received a letter from the amateur astronomer Lescarbault, who reported having seen a round black spot on the Sun on March 26 1859, looking like a planet transiting the Sun. He had seen the spot one hour and a quarter, when it moved a quarter of the solar diameter. Lescarbault estimated the orbital inclination to between 5.3 and 7.3 degrees, its longitude of node about 183 deg, its eccentricity “enormous”, and its transit time across the solar disk 4 hours 30 minutes. Le Verrier investigated this observation, and computed an orbit from it: period 19 days 7 hours, mean distance from Sun 0.1427 a.u., inclination 12# 10′, ascending node at 12# 59′ The diameter was considerably smaller than Mercury’s and its mass was estimated at 1/17 of Mercury’s mass. This was too small to account for the deviations of Mercury’s orbit, but perhaps this was the largest member of that intra-Mercurial asteroid belt? Le Verrier fell in love with the planet, and named it Vulcan.
In 1860 there was a total eclipse of the Sun. Le Verrier mobilized all French and some other astronomers to find Vulcan – nobody did. Wolf’s suspicious ‘sunspots’ now revived Le Verrier’s interest, and just before Le Verrier’s death in 1877 some more ‘evidence’ found its way into print. On April 4 1875, a German astronomer, H. Weber, saw a round spot on the Sun. Le Verrier’s orbit indicated a possible transit at April 3 that year, and Wolf noticed that his 38-day orbit also could have performed a transit at about that time. That ’round dot’ was also photographed at Greenwich and in Madrid.
There was one more flurry after the total solar eclipse at July 29 1878, where two observers claimed to have seen in the vicinity of the Sun small illuminated disks which could only be small planets inside Mercury’s orbit: J.C Watson (professor of astronomy at the Univ. of Michigan) believed he’d found TWO intra-Mercurial planets! Lewis Swift (co-discoverer of Comet Swift-Tuttle, which returned 1992), also saw a ‘star’ he believed to be Vulcan — but at a different position than either of Watson’s two ‘intra-Mercurials’. In addition, neither Watson’s nor Swift’s Vulcans could be reconciled with Le Verrier’s or Lescarbault’s Vulcan.
After this, nobody ever saw Vulcan again, in spite of several searches at different total solar eclipses. And in 1916, Albert Einstein published his General Theory of Relativity, which explained the deviations in the motions of Mercury without the need to invoke an unknown intra-Mercurial planet. In May 1929 Erwin Freundlich, Potsdam, photographed the total solar eclipse in Sumatra, and later carefully examined the plates which showed a profusion of star images. Comparison plates were taken six months later. No unknown object brighter than 9th magnitude was found near the Sun.
But what did these people really see? Lescarbault had no reason to tell a fairy tale, and even Le Verrier believed him. It is possible that Lescarbault happened to see a small asteroid passing very close to the Earth, just inside Earth’s orbit. Such asteroids were unknown at that time, so Lescarbault’s only idea was that he saw an intra-Mercurial planet. Swift and Watson could, during the hurry to obtain observations during totality, have misidentified some stars, believing they had seen Vulcan.
“Vulcan” was briefly revived around 1970-1971, when a few researchers thought they had detected several faint objects close to the Sun during a total solar eclipse. These objects might have been faint comets, and later comets have been observed that later did pass close enough to the Sun to collide with it.
Mercury’s Moon, 1974
Two days before the 29 March 1974 Mariner 10 flyby past Mercury, one instrument began registering bright emissions in the extreme UV that had “no right to be there”. The next day it was gone. Three days later it reappeared, and the “object” appeared to detach itself from Mercury. The astronomers first thought they had seen a star. But they had seen it in two quite different directions, and every astronomer knew that these extreme UV wavelengths couldn’t penetrate very far through the interstellar medium, suggesting that the object must be close. Did Mercury have a moon?
After a hectic Friday, when the “object” had been computed to move at 4 km/s, a speed consistent with that of a moon, JPL managers were called in. They turned the then-dying spacecraft over full time to the UV team, and everyone started worrying about a press conference scheduled for later that Saturday. Should the suspected moon be announced? But the press already knew. Some papers — the bigger, more respectable ones — played it straight; many others ran excited stories about Mercury’s new moon.
And the “moon” itself? It headed straight on out from Mercury, and was eventually identified as a hot star, 31 Crateris. What the original emissions came from, the ones spotted on the approach to the planet, remains a mystery. So ends the story of Mercury’s moon but at the same time a new chapter in astronomy began: extreme UV turned out not to be so completely absorbed by the interstellar medium as formerly believed. Already the Gum nebula has turned out to be a quite strong emitter in the extreme UV, and spreads across 140 degrees of the night sky at 540 angstroms. Astronomers had discovered a new window through which to observe the heavens.
Neith, the Moon of Venus, 1672-1892
In 1672, Giovanni Domenico Cassini, one of the prominent astronomers of the time, noticed a small companion close to Venus. Did Venus have a satellite? Cassini decided not to announce his observation, but 14 years later, in 1686, he saw the object again, and then entered it in his journal. The object was estimated to have about 1/4 the diameter of Venus, and it showed the same phase as Venus. Later, the object was seen by other astronomers as well: by James Short in 1740, Andreas Mayer in 1759, J. L. Lagrange in 1761 (Lagrange announced that the orbital plane of the satellite was perpendicular to the ecliptic). During 1761 the object was seen a total of 18 times by five observers. The observations of Scheuten on June 6 1761 was especially interesting: he saw Venus in transit across the Sun’s disk, accompanied by a smaller dark spot on one side, which followed Venus in its transit. However, Samuel Dunn at Chelsea, England, who also watched that transit, did not see that additional spot. In 1764 there were 8 observations by two observers. Other observers tried to see the satellite but failed to find it.
Now the astronomical world was faced with a controversy: several observers had reported seeing the satellite while several others had failed to find it in spite of determined efforts. In 1766, the director of the Vienna observatory, Father Hell (!), published a treatise where he declared that all observations of the satellite were optical illusions — the image of Venus is so bright that it is reflected in the eye, back into the telescope, creating a secondary image at a smaller scale. Others published treatises declaring that the observations were real. J. H. Lambert of Germany published orbital elements of the satellite in Berliner Astronomischer Jahrbuch 1777: mean distance 66.5 Venus radii, orbital period 11 days 3 hours, inclination to ecliptic 64 degrees. It was hoped that the satellite could be seen during the transit of Venus in front of the Sun June 1 1777 (it is self evident that Lambert made a mistake in calculating these orbital elements: at 66.5 Venus radii, the distance from Venus is about the same as our Moon’s distance from the Earth. This fits very badly with the orbital period of 11 days or only somewhat more than 1/3 of the orbital period of our Moon. The mass of Venus is a little smaller than the mass of the Earth).
In 1768 there was one more observation of the satellite, by Christian Horrebow in Copenhagen. There were also three searches, one made by one of the greatest astronomers of all time, William Herschel — all three of them failed to find any satellite. Quite late in the game, F. Schorr from Germany tried to make a case for the satellite in a book published in 1875.
In 1884, M. Hozeau, former director of the Royal Observatory of Brussels, suggested a different hypothesis. By analysing available observations Hozeau concluded that the Venus moon appeared close to Venus approximately every 2.96 years or 1080 days. Hozeau suggested that it wasn’t a moon of Venus, but a planet of its own, orbiting the sun once every 283 days and thus being in conjunction with Venus once every 1080 days. Hozeau also named it Neith, after the mysterious goddess of Sais, whose veil no mortal raised.
In 1887, three years after the “moon of Venus” had been revived by Hozeau, the Belgian Academy of Sciences published a long paper where each and every reported observation was investigated in detail. Several observations of the satellite were really stars seen in the vicinity of Venus. Roedkier’s observations “checked out” especially well — he had been fooled, in succession, by Chi Orionis, M Tauri, 71 Orionis, and Nu Geminorum! James Short had really seen a star somewhat fainter than 8th magnitude. All observations by Le Verrier and Montaigne could be similarly explained. Lambert’s orbital calculations were demolished. The very last observation, by Horrebow in 1768, could be ascribed to Theta Librae.
After this paper was published, only one more observation was reported, by a man who had earlier made a search for the satellite of Venus but failed to find it: on Aug 13 1892, E. E. Barnard recorded a 7th magnitude object near Venus. There is no star in the position recorded by Barnard, and Barnard’s eyesight was notoriously excellent. We still don’t know what he saw. Was it an asteroid that hadn’t been charted? Or was it a short-lived nova that nobody else happened to see?
The Earth’s Second Moon, 1846-present
In 1846, Frederic Petit, director of the observatory of Toulouse, stated that a second moon of the Earth had been discovered. It had been seen by two observers, Lebon and Dassier, at Toulouse and by a third, Lariviere, at Artenac, during the early evening of March 21 1846. Petit found that the orbit was elliptical, with a period of 2 hours 44 minutes 59 seconds, an apogee at 3570 km above the Earth’s surface and perigee at just 11.4 km (!) above the Earth’s surface. Le Verrier, who was in the audience, grumbled that one needed to take air resistance into account, something nobody could do at that time. Petit became obsessed with this idea of a second moon, and 15 years later announced that he had made calculations about a small moon of Earth which caused some then-unexplained peculiarities in the motion of our main Moon. Astronomers generally ignored this, and the idea would have been forgotten if not a young French writer, Jules Verne, had not read an abstract. In Verne’s novel “From the Earth to the Moon”, Verne lets a small object pass close to the traveller’s space capsule, causing it to travel around the Moon instead of smashing into it:
“It is”, said Barbicane, “a simple meteorite but an enormous one, retained as a satellite by the attraction of the Earth.”
“Is that possible?”, exclaimed Michel Ardan, “the earth has two moons?”
“Yes, my friend, it has two moons, although it is usually believed to have only one. But this second moon is so small and its velocity is so great that the inhabitants of Earth cannot see it. It was by noticing disturbances that a French astronomer, Monsieur Petit, could determine the existence of this second moon and calculated its orbit. According to him a complete revolution around the Earth takes three hours and twenty minutes. . . . “
“Do all astronomers admit the the existence of this satellite?”, asked Nicholl
“No”, replied Barbicane, “but if, like us, they had met it they could no longer doubt it. . . . But this gives us a means of determining our position in space . . . its distance is known and we were, therefore, 7480 km above the surface of the globe where we met it.”
Jules Verne was read by millions of people, but not until 1942 did anybody notice the discrepancies in Verne’s text:
- A satellite 7480 km above the Earth’s surface would have a period of 4 hours 48 minutes, not 3 hours 20 minutes.
- Since it was seen from the window from which the Moon was invisible, while both were approaching, it must be in retrograde motion, which would be worth remarking. Verne doesn’t mention this.
- In any case the satellite would be in eclipse and thus be invisible. The projectile doesn’t leave the Earth’s shadow until much later.
Dr. R.S. Richardson, Mount Wilson Observatory, tried in 1952 to make the figures fit by assuming an eccentric orbit of this moon: perigee 5010 km and apogee 7480 km above Earth’s surface, eccentricity 0.1784.
Nevertheless, Jules Verne made Petit’s second moon known all over the world. Amateur astronomers jumped to the conclusion that here was opportunity for fame — anybody discovering this second moon would have his name inscribed in the annals of science. No major observatory ever checked the problem of the Earth’s second moon, or if they did they kept quiet. German amateurs were chasing what they called Kleinchen (“little bit”) — of course they never found Kleinchen.
W. H. Pickering devoted his attention to the theory of the subject: if the satellite orbited 320 km above the surface and if its diameter was 0.3 meters, with the same reflecting power as the Moon, it should be visible in a 3-inch telescope. A 3 meter satellite would be a unaided-eye object of magnitude 5. Though Pickering did not look for the Petit object, he did carry on a search for a secondary moon — a satellite of our Moon (“On a photographic search for a satellite of the Moon”, Popular Astronomy, 1903). The result was negative and Pickering concluded that any satellite of our Moon must be smaller than about 3 meters.
Pickering’s article on the possibility of a tiny second moon of Earth, “A Meteoritic Satellite”, appeared in Popular Astronomy in 1922 and caused another short flurry among amateur astronomers, since it contained a virtual request: “A 3-5-inch telescope with a low-power eyepiece would be the likeliest mean to find it. It is an opportunity for the amateur.” But again, all searches remained fruitless.
The original idea was that the gravitational field of the second moon should account for the then inexplicable minor deviations of the motion of our big Moon. That meant an object at least several miles large — but if such a large second moon really existed, it would have been seen by the Babylonians. Even if it was too small to show a disk, its comparative nearness would have made it move fast and therefore be conspicuous, as today’s watchers of artificial satellites and even airplanes know. On the other hand, nobody was much interested in moonlets too small to be seen.
There have been other proposals for additional natural satellites of the Earth. In 1898 Dr Georg Waltemath from Hamburg claimed to have discovered not only a second moon but a whole system of midget moons. Waltemath gave orbital elements for one of these moons: distance from Earth 1.03 million km, diameter 700 km, orbital period 119 days, synodic period 177 days. “Sometimes”, says Waltemath, “it shines at night like the Sun” and he thinks this moon was seen in Greenland on 24 October 1881 by Lieut Greely, ten days after the Sun had set for the winter. Public interest was aroused when Waltemath predicted his second moon would pass in front of the Sun on the 2nd, 3rd or 4th of February 1898. On the 4th February, 12 persons at the post office of Greifswald (Herr Postdirektor Ziegel, members of his family, and postal employees) observed the Sun with their unaided eye, without protection of the glare. It is easy to imagine a faintly preposterous scene: an imposing-looking Prussian civil servant pointing skyward through his office window, while he reads Waltemath’s prediction aloud to a knot of respectful subordinates. On being interviewed, these witnesses spoke of a dark object having one fifth the Sun’s apparent diameter, and which took from 1:10 to 2:10 Berlin time to traverse the solar disk. It was soon proven to be a mistake, because during that very hour the Sun was being scrutinized by two experienced astronomers, W. Winkler in Jena and Baron Ivo von Benko from Pola, Austria. They both reported that only a few ordinary sunspots were on the disk. The failure of this and later forecasts did not discourage Waltemath, who continued to issue predictions and ask for verifications. Contemporary astronomers were pretty irritated over and over again having to answer questions from the public like “Oh, by the way, what about all these new moons?”. But astrologers caught on — in 1918 the astrologer Sepharial named this moon Lilith. He considered it to be black enough to be invisible most of the time, being visible only close to opposition or when in transit across the solar disk. Sepharial constructed an ephemeris of Lilith, based on several of Waltemath’s claimed observations. He considered Lilith to have about the same mass as the Moon, apparently happily unaware that any such satellite would, even if invisible, show its existence by perturbing the motion of the Earth. And even to this day, “the dark moon” Lilith is used by some astrologers in their horoscopes.
From time to time other “additional moons” were reported from observers. The German astronomical magazine “Die Sterne” reported that a German amateur astronomer named W. Spill had observed a second moon cross our first moon’s disc on May 24, 1926.
Around 1950, when artificial satellites began to be discussed in earnest, everybody expected them to be just burned-out upper stages of multistage rockets, carrying no radio transmitters but being tracked by radar from the Earth. In such cases a bunch of small nearby natural satellites would have been most annoying, reflecting radar beams meant for the artificial satellites. The method to search for such natural satellites was developed by Clyde Tombaugh: the motion of a satellite at e.g. 5000 km height is computed. Then a camera platform is constructed that scans the sky at precisely that rate. Stars, planets etc will then appear as lines on the photographs taken by this camera, while any satellite at the correct altitude will appear as a dot. If the satellite was at a somewhat different altitude, it would produce a short line.
Observations began in 1953 at the Lowell Observatory and actually invaded virgin territory: with the exception of the Germans searching for “Kleinchen” nobody had ever paid attention to the space between the Moon and the Earth! By the fall of 1954, weekly journals and daily newspapers of high reputation stated that the search had brought its first results: one small natural satellite at 700 km altitude, another one 1000 km out. One general is said to have asked: “Is he sure they’re natural?”. Nobody seems to know how these reports originated — the searches were completely negative. When the first artificial satellites were launched in 1957 and 1958, the cameras tracked those satellites instead.
But strangely enough, this does not mean that the Earth only has one natural satellite. The Earth can have a very near satellite for a short time. Meteoroids passing the Earth and skimming through the upper atmosphere can lose enough velocity to go into a satellite orbit around the Earth. But since they pass the upper atmosphere at each perigee, they will not last long, maybe only one or two, possibly a hundred revolutions (about 150 hours). There are some indications that such “ephemeral satellites” have been seen; it is even possible that Petit’s observers did see one. (see also)
In addition to ephemeral satellites there are two more possibilities. One is that the Moon had a satellite of its own — but despite several searches none has been found (in addition it’s now known that the gravity field of the Moon is uneven or “lumpy” enough for any lunar satellite orbit to be unstable — any lunar satellite will therefore crash into the Moon after a fairly short time, a few years or possibly a decade). The other possibility is that there might be Trojan satellites, i.e. secondary satellites in the lunar orbit, travelling 60 degrees ahead of or behind the Moon.
Such “Trojan satellites” were first reported by the Polish astronomer Kordylewski of Krakow observatory. He started his search in 1951, visually with a good telescope. He was hoping for reasonably large bodies in the lunar orbit, 60 degrees away from the Moon. The search was negative, but in 1956 his compatriot and colleague, Wilkowski, suggested that there may be many tiny bodies, too small to be seen individually but many enough to appear as a cloud of dust particles. In such a case, they would be best visible without a telescope i.e. with the unaided eye! Using a telescope would “magnify it out of existence”. Dr Kordylewski was willing to try. A dark night with clear skies, and the Moon being below the horizon, was required.
In October 1956, Kordylewski saw, for the first time, a fairly bright patch in one of the two positions. It was not small, subtending an angle of 2 degrees (i.e. about 4 times larger than the Moon itself), and was very faint, only about half as bright as the notoriously difficult Gegenschein (counterglow — a bright patch in the zodiacal light, directly opposite to the Sun). In March and April 1961, Kordylewski succeeded in photographing two clouds near the expected positions. They seem to vary in extent, but that may be due to changing illumination. J. Roach detected these cloud satellites in 1975 with the OSO (Orbiting Solar Observatory) 6 spacecraft. In 1990 they were again photographed, this time by the Polish astronomer Winiarski, who found that they were a few degrees in apparent diameter, that they “wandered” up to ten degrees away from the “trojan” point, and that they were somewhat redder than the zodiacal light.
So the century-long search for a second moon of the Earth seems to have succeeded, after all, even though this ‘second moon’ turned out to be entirely different from anything anybody had ever expected. They are very hard to detect and to distinguish from the zodiacal light, in particular the Gegenschein.
But people are still proposing additional natural satellites of the Earth. Between 1966 and 1969 John Bargby, an American scientist, claimed to have observed at least ten small natural satellites of the Earth, visible only in a telescope. Bargby found elliptical orbits for all the objects: eccentricity 0.498, semimajor axis 14065 km, which yields perigee and apogee heights of 680 and 14700 km. Bargby considered them to be fragments of a larger body which broke up in December 1955. He based much of his suggested satellites on supposed perturbations of artificial satellites. Bargby used artificial satellite data from Goddard Satellite Situation Report, unaware that the values in this publication are only approximate and sometimes grossly in error and can therefore not be used for any precise scientific analysis. In addition, from Bargby’s own claimed observations it can be deduced that when at perigee Bargby’s satellites ought to be visible at first magnitude and thus be easily visible to the unaided eye, yet no-one has seen them as such.
In 1997, Paul Wiegert (et al) discovered that the near-Earth asteroid 3753 Cruithne has a very strange orbit and can be considered a companion to Earth, though it certainly does not orbit the Earth directly. 2002 AA29 also has a special relationship with Earth.
The Moons of Mars, 1610, 1643, 1727, 1747, 1750, 1877-present
The first to guess that Mars had moons was Johannes Kepler in 1610. When trying to solve Galileo’s anagram referring to Saturn’s rings, Kepler thought that Galileo had found moons of Mars instead.
In 1643, the Capuchin monk Anton Maria Shyrl claimed to really have seen the moons of Mars. We now know that would be impossible with the telescopes of that time — probably Shyrl got deceived by a star nearby Mars.
In 1727, Jonathan Swift in “Gulliver’s Travels” wrote about two small moons orbiting Mars, known to the Laputian astronomers. Their periods of revolution were 10 and 21.5 hours. These ‘moons’ were in 1750 adopted by Voltaire in his novel “Micromegas”, the story of a giant from Sirius visiting our solar system.
In 1747 a German captain, Kindermann, had claimed to have seen the moon (just one!) of Mars, on 10 July 1744. Kindermann reported the orbital period of this martian moon as 59 hours 50 minutes and 6 seconds (!)
In 1877, Asaph Hall finally discovered Phobos and Deimos, the two small moons of Mars. Their orbital periods are 7 hours 39 minutes and 30 hours 18 minutes, quite close to the periods guessed by Jonathan Swift 150 years earlier!
The 14th Moon of Jupiter, 1975-1980
In 1975, Charles Kowal at Palomar (discoverer of Comet 95 P/Chiron) photographed an object thought to be a new satellite of Jupiter. It was seen several times, but not enough to determine an orbit, then lost. It used to show up as a footnote in texts of the late 70s.
And then in 2000 it was found again by S. S. Sheppard et al!
Saturn’s Ninth and Tenth Moons, 1861, 1905-1960, 1966-1980
In April 1861 Hermann Goldschmidt announced the discovery of a 9th moon of Saturn, which orbited the planet between Titan and Hyperion. He named that moon Chiron (!). However the discovery was never confirmed — nobody else ever saw this satellite “Chiron”. Later, Pickering discovered what’s now considered Saturn’s 9th moon, Phoebe, in 1898. This was the first time a satellite of another planet was discovered by photographical observations. Phoebe is also Saturn’s outermost moon.
In 1905, Pickering though he had discovered a tenth moon, which he named Themis. According to Pickering, it orbited Saturn between the orbits of Titan and Hyperion in a highly inclined orbit: mean distance from Saturn 1,460,000 km, orbital period 20.85 days, eccentricity 0.23, inclination 39 degrees. Themis was never seen again, but nevertheless appeared in almanacs and astronomy books well into the 1950’s and 1960’s.
In 1966, A. Dollfus discovered another new moon of Saturn. It was named Janus, and orbited Saturn just outside its rings. It was so faint and close to the rings that the only chance to see it was when the rings of Saturn were seen from the edge, as happened in 1966. Now Janus was Saturn’s tenth moon.
In 1980, when Saturns rings again were seen edgewise, a flurry of observations discovered a lot of new satellites close to the rings of Saturn. Close to Janus another satellite was discovered, named Epimetheus. Their orbits are very close to each other, and the most interesting aspect of this satellite pair is that they regularly switch orbits with each other! It turned out that the “Janus” discovered in 1966 really were observations of both of these co-orbital satellites. Thus the ‘tenth moon of Saturn’ discovered in 1966 really turned out to be two different moons! The spacecraft Voyager 1 and Voyager 2, which travelled past Saturn shortly afterwards, confirmed this.
Six Moons of Uranus, 1787
In 1787, William Herschel announced the discovery of six satellites of Uranus. Herschel here made a mistake — only two of his six satellites were real (Titania and Oberon, the largest and outermost two satellites), the remaining four were just stars which happened to be nearby (…I think I’ve heard this story before…. 🙂
Planet X, 1841-1992
In 1841, John Couch Adams began investigating the by then quite large residuals in the motion of Uranus. In 1845, Urbain Le Verrier started to investigate them, too. Adams presented two different solutions to the problem, assuming that the deviations were caused by the gravitation from an unknown planet. Adams tried to present his solutions to the Greenwich observatory, but since he was young and unknown, he wasn’t taken seriously. Urbain Le Verrier presented his solution in 1846, but France lacked the necessary resources to locate the planet. Le Verrier then instead turned to the Berlin observatory, where Galle and his assistant d’Arrest found Neptune on the evening of Sept 23, 1846. Nowadays, both Adams and Le Verrier share the credit of having predicted the existence and position of Neptune.
Inspired by this success, Le Verrier attacked the problem of the deviations of Mercury’s orbit, and suggested the existence of an intra-mercurial planet, Vulcan, which later turned out to be non-existent.)
On 30 Sept 1846, one week after the discovery of Neptune, Le Verrier declared that there may be still another unknown planet out there. On October 10, Neptune’s large moon Triton was discovered, which yielded an easy way to determine accurately the mass of Neptune, which turned out to be 2% larger than expected from the perturbations upon Uranus. It seemed as if the deviations in Uranus’ motion really was caused by two planets — in addition the real orbit of Neptune turned out to be significantly different from the orbits predicted by both Adams and Le Verrier.
In 1850 Ferguson was observing the motion of the minor planet Hygeia. One reader of Ferguson’s report was Hind, who checked the reference stars used by Ferguson. Hind was unable to find one of Ferguson’s reference stars. Maury, at the Naval Observatory, was also unable to find that star. During a few years it was believed that this was an observation of yet another planet, but in 1879 another explanation was offered: Ferguson had made a mistake when recording his observation — when that mistake was corrected, another star nicely fit his ‘missing reference star’.
The first serious attempt to find a trans-Neptunian planet was done in 1877 by David Todd. He used a “graphical method”, and despite the inconclusivenesses of the residuals of Uranus, he derived elements for a trans-Neptunian planet: mean distance 52 a.u., period 375 years, magnitude fainter than 13. Its longitude for 1877.84 was given 170 degrees with an uncertainty of 10 degrees. The inclination was 1.40 degrees and the longitude of the ascending node 103 degrees.
In 1879, Camille Flammarion added another hint as to the existence of a planet beyond Neptune: the aphelia of periodic comets tend to cluster around the orbits of major planets. Jupiter has the greatest share of such comets, and Saturn, Uranus and Neptune also have a few each. Flammarion found two comets, 1862 III with a period of 120 years and aphelion at 47.6 a.u., and 1889 II, with a somewhat longer period and aphelion at 49.8 a.u. Flammarion suggested that the hypothetical planet probably moved at 45 a.u.
One year later, in 1880, professor Forbes published a memoir concerning the aphelia of comets and their association with planetary orbits. By about 1900 five comets were known with aphelia outside Neptune’s orbit, and then Forbes suggested one trans-Neptunian moved at a distance of about 100 a.u., and another one at 300 a.u., with periods of 1000 and 5000 years.
During the next five years, several astronomers/mathematicians published their own ideas of what might be found in the outer parts of the solar system. Gaillot at Paris Observatory assumed two trans-Neptunian planets at 45 and 60 a.u. Thomas Jefferson Jackson See predicted three trans-Neptunian planets: “Oceanus” at 41.25 a.u. and period 272 years, “trans-Oceanus” at 56 a.u. and period 420 years, and finally another one at 72 a.u. and period 610 years. Dr Theodor Grigull of Munster, Germany, assumed in 1902 a Uranus-sized planet at 50 a.u. and period 360 years, which he called “Hades”. Grigull based his work mainly on the orbits of comets with aphelia beyond Neptune’s orbit, with a cross check whether the gravitational pull of such a body would produce the observed deviations in Uranus motion. In 1921 Grigull revised the orbital period of “Hades” to 310-330 years, to better fit the observed deviations.
In 1900 Hans-Emil Lau, Copenhagen, published elements of two trans-Neptunian planets at 46.6 and 70.7 a.u. distance, with masses of 9 and 47.2 times the Earth, and a magnitude for the nearer planet around 10-11. The 1900 longitudes of those hypothetical bodies were 274 and 343 degrees, both with the very large uncertainty of 180 degrees.
In 1901, Gabriel Dallet deduced a hypothetical planet at 47 a.u. with a magnitude of 9.5-10.5 and a 1900 longitude of 358 degrees. The same year Theodor Grigull derived a longitude of a trans-Neptunian planet less than 6 degrees away from Dallet’s planet, and later brought the difference down to 2.5 degrees. This planet was supposed to be 50.6 a.u. distant.
In 1904, Thomas Jefferson Jackson See suggested three trans-Neptunian planets, at 42.25, 56 and 72 a.u. The inner planet had a period of 272.2 years and a longitude in 1904 of 200 degrees. A Russian general named Alexander Garnowsky suggested four hypothetical planets but failed to supply any details about them.
The two most carefully worked out predictions for the Trans-Neptune were both of American origin: Pickering’s “A search for a planet beyond Neptune” (Annals Astron. Obs. Harvard Coll, vol LXI part II 1909), and Percival Lowell’s “Memoir on a trans-Neptunian planet” (Lynn, Mass 1915). They were concerned with the same subject but used different approaches and arrived at different results.
Pickering used a graphical analysis and suggested a “Planet O” at 51.9 a.u. with a period of 373.5 years, a mass twice the Earth’s and a magnitude of 11.5-14. Pickering suggested eight other trans-Neptunian planets during the forthcoming 24 years. Pickerings results caused Gaillot to revise the distances of his two trans-Neptunians to 44 and 66 a.u., and he gave them masses of 5 and 24 Earth masses.
All in all, from 1908 to 1932, Pickering proposed seven hypothetical planets — O, P, Q, R, S, T and U. His final elements for O and P define completely different bodies than the original ones, so the total can be set at nine, certainly the record for planetary prognostication. Most of Pickerings predictions are only of passing interest as curiosities. In 1911 Pickering suggested that planet Q had a mass of 20,000 Earths, making it 63 times more massive than Jupiter or about 1/6 the Sun’s mass, close to a star of minimal mass. Pickering said planet Q had a highly elliptical orbit.
In later years only planet P seriously occupied his attention. In 1928 he reduced the distance of P from 123 to 67.7 a.u., and its period from 1400 to 556.6 years. He gave P a mass of 20 Earth masses and a magnitude of 11. In 1931, after the discovery of Pluto, he issued another elliptical orbit for P: distance 75.5 a.u., period 656 years, mass 50 Earth masses, eccentricity 0.265, inclination 37 degrees, close to the values given for the 1911 orbit. His Planet S, proposed in 1928 and given elements in 1931, was put at 48.3 a.u. distance (close to Lowell’s Planet X at 47.5 a.u.), period 336 years, mass 5 Earths, magnitude 15. In 1929 Pickering proposed planet U, distance 5.79 a.u., period 13.93 years, i.e. barely outside Jupiter’s orbit. Its mass was 0.045 Earth masses, eccentricity 0.26. The least of Pickering’s planets is planet T, suggested in 1931: distance 32.8 a.u., period 188 years.
Pickering’s different elements for planet O were:
|1908||51.9||373.5 y||2 earth's||11.5-13.4||105.13|
|1928||35.23||209.2 y||0.5 earth's||12|
Percival Lowell, most well known as a proponent for canals on Mars, built a private observatory in Flagstaff, Arizona. Lowell called his hypothetical planet Planet X, and performed several searches for it, without success. Lowell’s first search for Planet X came to an end in 1909, but in 1913 he started a second search, with a new prediction of Planet X: epoch 1850-01-01, mean long 11.67 deg, perih. long 186, eccentricity 0.228, mean dist 47.5 a.u. long arc node 110.99 deg, inclination 7.30 deg, mass 1/21000 solar masses. Lowell and others searched in vain for this Planet X in 1913-1915. In 1915, Lowell published his theoretical results of Planet X. It is ironical that this very same year, 1915, two faint images of Pluto was recorded at Lowell observatory, although they were never recognized as such until after the discovery of Pluto (1930). Lowell’s failure of finding Planet X was his greatest disappointment in life. He didn’t spend much time looking for Planet X during the last two years of his life. Lowell died in 1916. On the nearly 1000 plates exposed in this second search were 515 asteroids, 700 variable stars and 2 images of Pluto!
The third search for Planet X began in April 1927. No progress was made in 1927-1928. In December 1929 a young farmer’s boy and amateur astronomer, Clyde Tombaugh from Kansas, was hired to do the search. Tombaugh started his work in April 1929. On January 23 and 29, Tombaugh exposed the pair of plates on which he found Pluto when examining them on February 18. By then Tombaugh had examined hundreds of plate pairs and millions of stars. The search for Planet X had come to an end.
Or had it? The new planet, later named Pluto, turned out to be disappointingly small, perhaps only one Earth mass but probably only about 1/10 Earth masses or smaller (in 1979, when Pluto’s satellite Charon was discovered, the mass of the Pluto-Charon pair turned out to be only about 1/400 Earth mass!). Planet X must, if it was causing those perturbations in the orbit of Uranus, be much larger than that! Tombaugh continued his search another 13 years, and examined the sky from the north celestial pole to 50 deg. south declination, down to magnitude 16-17, sometimes even 18. Tombaugh examined some 90 million images of some 30 million stars over more than 30,000 square degrees on the sky. He found one new globular cluster, 5 new open star clusters, one new supercluster of 1800 galaxies and several new small galaxy clusters, one new comet, about 775 new asteroids — but no new planet except Pluto. Tombaugh concluded that no unknown planet brighter than magnitude 16.5 did exist — only a planet in an almost polar orbit and situated near the south celestial pole could have escaped his detection. He could have picked up a Neptune-sized planet at seven times the distance of Pluto, or a Pluto-sized planet out to 60 a.u.
The naming of Pluto is a story by itself. Early suggestions of the name of the new planet were: Atlas, Zymal, Artemis, Perseus, Vulcan, Tantalus, Idana, Cronus. The New York Times suggested Minerva, reporters suggested Osiris, Bacchus, Apollo, Erebus. Lowell’s widow suggested Zeus, but later changed her mind to Constance. Many people suggested the planet be named Lowell. The staff of the Flagstaff observatory, where Pluto was discovered, suggested Cronus, Minerva, and Pluto. A few months later the planet was officially named Pluto. The name Pluto was originally suggested by Venetia Burney, an 11-year-old schoolgirl in Oxford, England.
The very first orbit computed for Pluto yielded an eccentricity of 0.909 and a period of 3000 years! This cast some doubt whether it was a planet or not. However, a few months later, considerably better orbital elements for Pluto were obtained. Below is a comparison of the orbital elements of Lowell’s Planet X, Pickering’s Planet O, and Pluto:
|Lowell's X||Pickering's O||Pluto|
|a (mean dist)||43||55.1||39.5|
|N (long asc node)||(not pred)||100||109.4|
|W (long perihelion)||204.9||280.1||223.4|
|T (perihelion date)||Febr 1991||Jan 2129||Sept 1989|
|u (mean annual motion)||1.2411||0.88||1.451|
|P (period, years)||282||409.1||248|
|T (perihel. date)||1991.2||2129.1||1989.8|
|E (long 1930.0)||102.7||102.6||108.5|
|m (mass, Earth=1)||6.6||2||0.002|
The mass of Pluto was very hard to determine. Several values were given at different times — the matter wasn’t settled until James W. Christy discovered Pluto’s moon Charon in June 1978 — Pluto was then shown to have only 20% of the mass of our Moon! That made Pluto hopelessly inadequate to produce measurable gravitational perturbations on Uranus and Neptune. Pluto could not be Lowell’s Planet X — the planet found was not the planet sought. What seemed to be another triumph of celestial mechanics turned out to be an accident — or rather a result of the intelligence and thoroughness of Clyde Tombaugh’s search.
|The mass of Pluto:|
|Crommelin 1930:||0.11||(Earth masses)|
|1965:||<0.14||(occultation of faint star by Pluto)|
|Christy, 1978:||0.002||(Charon discovered)|
The mass of Pluto:
Another short-lived trans-Neptunian suspect was reported on April 22 1930 by R.M. Stewart in Ottawa, Canada — it was reported from plates taken in 1924. Crommelin computed an orbit (dist 39.82 a.u., asc node 280.49 deg, inclination 49.7 deg!). Tombaugh searched for the “Ottawa object” without finding it. Several other searches were made, but nothing was ever found.
Meanwhile Pickering continued to predict new planets (see above). Others also predicted new planets on theoretical grounds (Lowell himself had already suggested a second trans-Neptunian at about 75 a.u.). In 1946, Francis M. E. Sevin suggested a trans-Plutonian planet at 78 a.u. He first derived this from a curious empirical method where he grouped the planets and the erratic asteroid Hidalgo, into two groups of inner and outer bodies:
He then added the logarithms of the periods of each pair of planets, finding a roughly constant sum of about 7.34. Assuming this sum to be valid for Mercury and the trans-Plutonian too, he arrived at a period of about 677 years for “Transpluto”. Later Sevin worked out a full set of elements for “Transpluto”: dist 77.8 a.u., period 685.8 years, eccentricity 0.3, mass 11.6 Earth masses. His prediction stirred little interest among astronomers.
In 1950, K. Schutte of Munich used data from eight periodic comets to suggest a trans-Plutonian planet at 77 a.u. Four years later, H. H. Kitzinger of Karlsruhe, using the same eight comets, extended and refined the work, finding the supposed planet to be at 65 a.u., with a period of 523.5 years, an orbital inclination of 56 degrees, and an estimated magnitude of 11. In 1957, Kitzinger reworked the problem and arrived at new elements: dist 75.1 a.u., period 650 years, inclination 40 degrees, magnitude around 10. After unsuccessful photographic searches, he re-worked the problem once again in 1959, arriving at a mean dist of 77 a.u., period 675.7 years, inclination 38 degrees, eccentricity 0.07, a planet not unlike Sevin’s “Transpluto” and in some ways similar to Pickering’s final Planet P. No such planet has ever been found, though.
Halley’s Comet has also been used as a “probe” for trans-plutonian planets. In 1942 R. S. Richardson found that an Earth-sized planet at 36.2 a.u., or 1 a.u. beyond Halley’s aphelion, would delay Halley’s perihelion passage so that it agreed better with observations. A planet at 35.3 a.u. of 0.1 Earth masses would have a similar effect. In 1972, Brady predicted a planet at 59.9 a.u., period 464 years, eccentricity 0.07, inclination 120 degrees (i.e. being in a retrograde orbit), magnitude 13-14, size about Saturn’s size. Such a trans-Plutonian planet would reduce the residuals of Halley’s Comet significantly back to the 1456 perihelion passage. This gigantic trans-Plutonian planet was also searched for, but never found.
Tom van Flandern examined the positions of Uranus and Neptune in the 1970s. The calculated orbit of Neptune fit observations only for a few years, and then started to drift away. Uranus orbit fit the observations during one revolution but not during the previous revolution. In 1976 Tom van Flandern became convinced that there was a tenth planet. After the discovery of Charon in 1978 showed the mass of Pluto to be much smaller than expected, van Flandern convinced his USNO colleague Robert S. Harrington of the existence of this tenth planet. They started to collaborate by investigate the Neptunian satellite system. Soon their views diverged. van Flandern thought the tenth planet had formed beyond Neptune’s orbit, while Harrington believed it had formed between the orbits of Uranus and Neptune. van Flandern thought more data was needed, such as an improved mass for Neptune furnished by Voyager 2. Harrington started to search for the planet by brute force — he started in 1979, and by 1987 he had still not found any planet. van Flandern and Harrington suggested that the tenth planet might be near aphelion in a highly elliptical orbit. If the planet is dark, it might be as faint as magnitude 16-17, suggests van Flandern.
In 1987, Whitmire and Matese suggested a tenth planet at 80 a.u. with a period of 700 years and an inclination of perhaps 45 degrees, as an alternative to their “Nemesis” hypothesis. However, according to Eugene M. Shoemaker, this planet could not have caused those meteor showers that Whitmire and Matese suggested (see below).
In 1987, John Anderson at JPL examined the motions of the spacecraft Pioneer 10 and Pioneer 11, to see if any deflection due to unknown gravity forces could be found. None was found — from this Anderson concluded that a tenth planet most likely exists! JPL had excluded observations of Uranus prior to 1910 in their ephemerides, while Anderson had confidence in the earlier observations as well. Anderson concluded that the tenth planet must have a highly elliptical orbit, carrying it far away to be undetectable now but periodically bringing it close enough to leave its disturbing signature on the paths of the outer planets. He suggests a mass of five Earth masses, an orbital period of about 700-1000 years, and a highly inclined orbit. Its perturbations on the outer planets won’t be detected again until 2600. Anderson hoped that the two Voyagers would help to pin down the location of this planet.
Conley Powell, from JPL, also analyzed the planetary motions. He also found that the observations of Uranus suddenly did fit the calculations much better after 1910 than before. Powell suggested a planet with 2.9 Earth masses at 60.8 a.u. from the Sun, a period of 494 years, inclination 8.3 degrees and only a small eccentricity. Powell was intrigued that the period was approximately twice Pluto’s and three times Neptune’s period, suggesting that the planet he thought he saw in the data had an orbit stabilized by mutual resonance with its nearest neighbours despite their vast separation. The solution called for the planet to be in Gemini, and also being brighter than Pluto when it was discovered. A search was performed in 1987 at Lowell Observatory for Powell’s planet — nothing was found. Powell re-examined his solution and revised the elements: 0.87 Earth masses, distance 39.8 a.u., period 251 years, eccentricity 0.26, i.e. an orbit very similar to Pluto’s! Currently, Powell’s new planet should be in Leo, at magnitude 12, however Powell thinks it’s premature to search for it, he needs to examine his data further.
Even if no trans-Plutonian planet ever was found, the interest was focused to the outer parts of the solar system. The erratic asteroid Hidalgo, moving in an orbit between Jupiter and Saturn, has already been mentioned. In 1977-1984 Charles Kowal performed a new systematic search for undiscovered bodies in the solar system, using Palomar Observatory’s 48-inch Schmidt telescope. In October 1987 he found the asteroid 1977 UB, later named Chiron, moving at mean distance 13.7 a.u., period 50.7 years, eccentricity 0.3786, inclination 6.923 deg, diameter about 50 km. During his search, Kowal also found 5 comets and 15 asteroids, including Chiron, the most distant asteroid known when it was discovered. Kowal also recovered 4 lost comets and one lost asteroid. Kowal did not find a tenth planet, and concluded that there was no unknown planet brighter than 20th magnitude within 3 degrees of the ecliptic.
Chiron was first announced as a “tenth planet”, but was immediately designated as an asteroid. But Kowal suspected it may be very comet-like, and later it has even developed a short cometary tail! In 1995 Chiron was also classified as a comet – it is certainly the largest comet we know about.
In 1992 an even more distant asteroid was found: Pholus. Later in 1992 an asteroid outside Pluto’s orbit was found, followed by five additional trans-Plutonian asteroids in 1993 and at least a dozen in 1994!
Meanwhile, the spacecraft Pioneer 10 and 11 and Voyagers 1 and 2 had travelled outside the solar system, and could also be used as “probes” for unknown gravitational forces possibly from unknown planets — nothing has been found. The Voyagers also yielded more accurate masses for the outer planets — when these updated masses were inserted in the numerical integrations of the solar system, the residuals in the positions of the outer planets finally disappeared. It seems like the search for “Planet X” finally has come to an end. There was no “Planet X” (Pluto doesn’t really count), but instead an asteroid belt outside Neptune/Pluto was found! The asteroids outside Jupiter’s orbit that were known in August 1993 are as follows:
|Asteroid||a||e||Incl||Node||Arg perih||Mean an||Per||Name|
In November 1994 these trans-Neptunian asteroids were known:
|1992 QB1||43.9||0.07||2.2||22.8||283||1992||Aug||Jewitt & Luu|
|1993 FW||43.9||0.047||7.7||22.8||286||1993||Mar||Jewitt & Luu|
|1993 RO||39.3||0.198||3.7||23.2||139||1993||Sep||Jewitt & Luu|
|1993 RP||39.3||0.114||2.6||24.5||96||1993||Sep||Jewitt & Luu|
|1993 SB||39.4||0.321||1.9||22.7||188||1993||Sep||Williams et al.|
|1993 SC||39.5||0.185||5.2||21.7||319||1993||Sep||Williams et al.|
|1994 ES2||45.3||0.012||1||24.3||159||1994||Mar||Jewitt & Luu|
|1994 EV3||43.1||0.043||1.6||23.3||267||1994||Mar||Jewitt & Luu|
|1994 GV9||42.2||0||0.1||23.1||264||1994||Apr||Jewitt & Luu|
|1994 JQ1||43.3||0||3.8||22.4||382||1994||May||Irwin et al.|
|1994 JR1||39.4||0.118||3.8||22.9||238||1994||May||Irwin et al.|
|1994 JS||39.4||0.081||14.6||22.4||263||1994||May||Luu & Jewitt|
|1994 JV||39.5||0.125||16.5||22.4||254||1994||May||Jewitt & Luu|
|1994 TB||31.7||0||10.2||21.5||258||1994||Oct||Jewitt & Chen|
|1994 TG||42.3||0||6.8||23||232||1994||Oct||Chen et al.|
|1994 TH||40.9||0||16.1||23||217||1994||Oct||Jewitt et al.|
|1994 VK8||43.5||0||1.4||22.5||273||1994||Nov||Fitzwilliams et al.|
The trans-Neptunian bodies seem to form two groups. One group, composed of Pluto, 1993 SC, 1993 SB and 1993 RO, have eccentric orbits and a 3:2 resonance with Neptune. The second group, including 1992 QB1 and 1993 FW, is slightly further out and in rather low eccentricity.
Nemesis, the Sun’s companion star, 1983-present
Suppose our Sun was not alone but had a companion star. Suppose that this companion star moved in an elliptical orbit, its solar distance varying between 90,000 a.u. (1.4 light years) and 20,000 a.u., with a period of 30 million years. Also suppose this star is dark or at least very faint, and because of that we haven’t noticed it yet.
This would mean that once every 30 million years that hypothetical companion star of the Sun would pass through the Oort cloud (a hypothetical cloud of proto-comets at a great distance from the Sun). During such a passage, the proto-comets in the Oort cloud would be stirred around. Some tens of thousands of years later, here on Earth we would notice a dramatic increase in the the number of comets passing the inner solar system. If the number of comets increases dramatically, so does the risk of the Earth colliding with the nucleus of one of those comets.
When examining the Earth’s geological record, it appears that about once every 30 million years a mass extinction of life on Earth has occurred. The most well-known of those mass extinctions is of course the dinosaur extinction some 65 million years ago. About 25 million years from now it’s time for the next mass extinction, according to this hypothesis.
This hypothetical “death companion” of the Sun was suggested in 1985 by Daniel P. Whitmire and John J. Matese, Univ of Southern Louisiana. It has even received a name: Nemesis. One awkward fact of the Nemesis hypothesis is that there is no evidence whatever of a companion star of the Sun. It need not be very bright or very massive, a star much smaller and dimmer than the Sun would suffice, even a brown or a black dwarf (a planet-like body insufficiently massive to start “burning hydrogen” like a star). It is possible that this star already exists in one of the catalogues of dim stars without anyone having noted something peculiar, namely the enormous apparent motion of that star against the background of more distant stars (i.e. its parallax). If it should be found, few will doubt that it is the primary cause of periodic mass extinctions on Earth.
But this is also a notion of mythical power. If an anthropologist of a previous generation had heard such a story from his informants, the resulting scholarly tome would doubtless use words like ‘primitive’ or ‘pre-scientific’. Consider this story:
There is another Sun in the sky, a Demon Sun we cannot see. Long ago, even before great grandmother’s time, the Demon Sun attacked our Sun. Comets fell, and a terrible winter overtook the Earth. Almost all life was destroyed. The Demon Sun has attacked many times before. It will attack again.
This is why some scientists thought this Nemesis theory was a joke when they first heard of it — an invisible Sun attacking the Earth with comets sounds like delusion or myth. It deserves an additional dollop of skepticism for that reason: we are always in danger of deceiving ourselves. But even if the theory is speculative, it’s serious and respectable, because its main idea is testable: you find the star and examine its properties.
However, since the examination of the entire sky in the far IR by IRAS with no “Nemesis” found, the existence of “Nemesis” is not very likely.
Willy Ley: “Watcher’s of the skies”, The Viking Press NY,1963,1966,1969
William Graves Hoyt: “Planet X and Pluto”, The University of Arizona Press 1980, ISBN 0-8165-0684-1, 0-8165-0664-7 pbk.
Carl Sagan, Ann Druyan: “Comet”, Michael Joseph Ltd, 1985, ISBN 0-7181-2631-9
Mark Littman: “Planets Beyond – discovering the outer solar system”, John Wiley 1988, ISBN 0-471-61128-X
Tom van Flandern: “Dark Matter, Missing Planets & New Comets. Paradoxes resolved, origins illuminated”, North Atlantic Books 1993, ISBN 1-55643-155-4
Joseph Ashbrook: “The many moons of Dr Waltemath”, Sky and Telescope, Vol 28, Oct 1964, p 218, also on page 97-99 of “The Astronomical Scrapbook” by Joseph Ashbrook, SKy Publ. Corp. 1984, ISBN 0-933346-24-7
Delphine Jay: “The Lilith Ephemeris”, American Federation of Astrologers 1983, ISBN 0-86690-255-4
William R. Corliss: “Mysterious Universe: A handbook of astronomical anomalies”, Sourcebook Project 1979, ISBN 0-915554-05-4, p 45-71 “The intramercurial planet”, p 82-84 “Mercury’s moon that wasn’t”, p 136-143 “Neith, the lost satellite of Venus”, p 146-157 “Other moons of the Earth”, p 423-427 “The Moons of Mars”, p 464 “A ring around Jupiter?”, p 500-526 “Enigmatic objects”
Richard Baum & William Sheehan: “In Search of Planet Vulcan” Plenum Press, New York, 1997 ISBN 0-306-45567-6 , QB605.2.B38 | 0.891609 | 3.75743 |
Most of Earth’s continents are located in the northern hemisphere. This may be mere coincidence, or it may have an explanation similar to that of the lunar south pole anomaly.
If there is a current going through the solar system from south to north, then there is a predominance of massive particles striking the south pole relative to the north pole.
This has the effect of carving out deeper craters on the south pole of our moon. Similarly, it will have the effect of softening up the crust on Earth’s south pole more than the north pole. This would then lead to more expansion south of the equator than north of it.
300 million years of planetary expansion as seen from the south pole
From measurements, we know that very few particles coming in through the polar auroras actually hit the surface of our planet. Most particles return to space, so the difference in crustal massaging going on at the two poles is likely to be subtle.
However, even small differences can yield profoundly different outcomes over time. | 0.840445 | 3.095228 |
Astronomers are back in the dark about what dark matter might be, after new observations showed the mysterious substance may not be interacting with forces other than gravity after all. Dr. Andrew Robertson of Durham University presented the new results to the European Week of Astronomy and Space Science in Liverpool.
Three years ago, a Durham-led international team of researchers thought they had made a breakthrough in ultimately identifying what dark matter is.
Observations using the Hubble Space Telescope appeared to show that a galaxy in the Abell 3827 cluster — approximately 1.3 billion light years from Earth — had become separated from the dark matter surrounding it.
Such an offset is predicted during collisions if dark matter interacts with forces other than gravity, potentially providing clues about what the substance might be.
The chance orientation at which the Abell 3827 cluster is seen from Earth makes it possible to conduct highly sensitive measurements of its dark matter.
However, the same group of astronomers now say that new data from more recent observations shows that dark matter in the Abell 3827 cluster has not separated from its galaxy after all. The measurement is consistent with dark matter feeling only the force of gravity.
Lead author Dr Richard Massey, in the Centre for Extragalactic Astronomy at Durham University, said:
“The search for dark matter is frustrating, but that’s science. When data improves, the conclusions can change.
“Meanwhile, the hunt goes on for dark matter to reveal its nature.
“So long as dark matter doesn’t interact with the Universe around it, we are having a hard time working out what it is.”
The Universe is composed of approximately 27 per cent dark matter, with the remainder largely consisting of the equally mysterious dark energy. Normal matter, such as planets and stars, contributes a relatively small 5 per cent of the Universe.
There is believed to be about five times more dark matter than all the other particles understood by science, but nobody knows what it is.
However, dark matter is an essential factor in how the Universe looks today, as without the constraining effect of its extra gravity, galaxies like our Milky Way would fling themselves apart as they spin.
The video below is a supercomputer simulation of a collision between two galaxy clusters, similar to the real object known as the “Bullet Cluster,” and showing the same effects tested for in Abell 3827. All galaxy clusters contain stars (orange), hydrogen gas (shown as red) and invisible dark matter (shown as blue).
Individual stars, and individual galaxies are so far apart from each other that they whizz straight past each other. The diffuse gas slows down and becomes separated from the galaxies, due to the forces between ordinary particles that act as friction.
If dark matter feels only the force of gravity, it should stay in the same place as the stars, but if it feels other forces, its trajectory through this giant particle collider would be changed.
In this latest study, the researchers used the Atacama Large Millimetre Array (ALMA) in Chile, South America, to view the Abell 3827 cluster.
ALMA picked up on the distorted infra-red light from an unrelated background galaxy, revealing the location of the otherwise invisible dark matter that remained unidentified in their previous study.
Research co-author Professor Liliya Williams, of the University of Minnesota, said:
“We got a higher resolution view of the distant galaxy using ALMA than from even the Hubble Space Telescope.
“The true position of the dark matter became clearer than in our previous observations.”
While the new results show dark matter staying with its galaxy, the researchers said it did not necessarily mean that dark matter does not interact. Dark matter might just interact very little, or this particular galaxy might be moving directly towards us, so we would not expect to see its dark matter displaced sideways, the team added.
Several new theories of non-standard dark matter have been invented over the past two years and many have been simulated at Durham University using high-powered supercomputers.
Robertson, who is a co-author of the work, and based at Durham University’s Institute for Computational Cosmology, added:
“Different properties of dark matter do leave tell-tale signs.
“We will keep looking for nature to have done the experiment we need, and for us to see it from the right angle.
“One especially interesting test is that dark matter interactions make clumps of dark matter more spherical. That’s the next thing we’re going to look for.”
The video below is a supercomputer simulation of a collision between two galaxy clusters, if dark matter didn’t exist. The resulting distribution of stars and gas disagrees with what is observed in the real Universe, which provides compelling evidence that dark matter is present in the real Universe.
To measure the dark matter in hundreds of galaxy clusters and continue this investigation, Durham University has just finished helping to build the new SuperBIT telescope, which gets a clear view by rising above the Earth’s atmosphere under a giant helium balloon.
Provided by: University of Chicago Medicine [Note: Materials may be edited for content and length.]
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Since the 1995 confirmation of exoplanet 51 Pegasi b, the word exoplanet—a planet orbiting another star—has become a part of the vernacular. And thanks to technologies like the 2009-launched Kepler spacecraft, we’ve continued to discover around 4,000 exoplanets “hundreds or thousands of light years away” in just “one small patch of the Milky Way near the constellation Cygnus.”
The Transiting Exoplanet Survey Satellite (TESS) will discover thousands of exoplanets in orbit around the brightest stars in the sky. In a two-year survey of the solar neighborhood, TESS will monitor more than 200,000 stars for temporary drops in brightness caused by planetary transits. This first-ever spaceborne all-sky transit survey will identify planets ranging from Earth-sized to gas giants, around a wide range of stellar types and orbital distances. No ground-based survey can achieve this feat.
Learn more about the endeavor with The New York Times‘ Out There video above: How NASA’s TESS Spacecraft Will Hunt Exoplanets.
Related reading: NASA’s Exoplanets 101, EarthSky’s What is an exoplanet?, and Ars Technica’s Number of potentially habitable planets in our galaxy: Tens of billions.Related watching on this site: How to Find a Living Planet and How do we know what stars are made of? | 0.901939 | 3.072435 |
Two Americans who discovered the first binary pulsar, an exotic astronomical ‘beacon’, have won this year’s Nobel Prize for Physics. But the finding is not merely a notable first, it also provided a means of detecting the gravity waves predicted by Einstein’s general theory of relativity.
The two winners, Joseph Taylor and Russell Hulse, found the pulsar in 1974, when Taylor was working at the University of Massachusetts in Amherst and Hulse was a postgraduate student. Both now work at Princeton University, New Jersey, but while Taylor has continued to pursue pulsars, Hulse has abandoned astronomy for plasma physics.
Taylor said last week that the award came as ‘a surprise’. Hulse said he thought he was dreaming when he heard his name on early morning radio. Then the phone began to ring. Hulse knew Taylor’s work was highly regarded but had ‘no idea’ that he might share in a Nobel prize.
Pulsars are dense stars that rotate at great speed. As they turn, they emit beams of radio waves that sweep round like the beam of a lighthouse, appearing as pulses to Earthbound astronomers. In a binary system, the pulsar has an equally massive companion in a close orbit which cannot be seen, but is revealed by the way it tugs on the pulsar.
When Taylor joined the staff at Amherst in 1969, he helped to build the Five College Radio Astronomy Observatory. One of his first projects was a systematic search for pulsars. The team found 40 new pulsars, but the binary, which was called PSR1913+16, was ‘by far the most interesting’, Hulse wrote in his thesis.
The two astronomers decided it was a binary pulsar when they detected regular changes in the interval between the radio pulses it emitted. On average, the pulsar rotates once every 0.05903 seconds. But the interval between pulses varies in a regular way because the pulsar is orbiting another body. When the pulsar is moving towards us in its orbit, the pulses are squashed together; when it is moving away, they are stretched out. Hulse and Taylor calculated that the pulsar orbited another star every 8 hours.
The dynamics of the system show that both bodies are neutron stars – collapsed stars made up entirely of neutrons – and are about 10 kilometres across. The stars, each about 1.4 times as massive as the Sun, are separated by only a few times the distance between the Earth and Moon.
General relativity predicts that objects being accelerated in a strong gravitational field will emit gravitational radiation. Imagine a weightlifter’s barbell sitting in a dish of mercury and spinning rapidly. It will make waves. The binary pulsar should emit those waves, draining the system of energy. This in turn should reduce the distance between the two stars, knocking about 75 microseconds a year off the 8-hour orbital period.
After four years of painstaking observations, Taylor confirmed that the orbit’s period was growing shorter. Over 18 years of refining his measurements, he has arrived at a value that lies within 0.3 per cent of that predicted by general relativity. Physicists regard these results as confirming the existence of gravitational radiation.
Taylor, now a professor of physics at Princeton, receives high praise from colleagues. ‘The work is a masterpiece, unbelievably sophisticated and careful . . . a textbook example of science at its best,’ says radio astronomer Frank Drake of the University of California at Santa Cruz.
Although Hulse and Taylor both work at Princeton, they rarely see each other. Hulse left astronomy in 1977 and moved to Princeton’s Plasma Physics Laboratory. He is now principal research physicist at the laboratory, where he models how plasmas – very hot ionised gases – behave when constrained by strong magnet fields. He is little known among astronomers, but Fred Byron, dean of natural sciences and mathematics at the University of Massachusetts, calls him ‘very, very talented . . . one of the best graduate students we ever had’. | 0.859058 | 3.895185 |
There are many things we still don’t know about the Moon, the closest neighbor and moon to the pale blue planet we live on. One of them is the formations called Moon Vortex. Let’s take a closer look at this.
Despite our constantly evolving technology, we are still in the ‘crawling’ stage of space exploration. Although we learn new things about planets and space every day, there is a lot we don’t know. One of the many things we don’t know about is the Moon, the planet’s moon.
On the surface of the moon, there are formations called lunar swirl. These formations; colored stones and dust spirals carry for miles. There are many questions about where and when these vortices occur. According to Space.com, these may be caused by internal magnetic fields or the effects of meteor collisions. Some experts say that the magnetic fields of these vortices may serve as a kind of natural shield because they deflect solar winds and cosmic rays.
How do Moon Vortices Occur?
Experts who do research on the subject have different opinions about how these strange whirlpools have formed. The consensus view is that you have to go to the surface of the Moon to fully understand what is happening.
Ble I would love to see a tool that can learn how much solar wind is coming to the moon’s surface and investigate its effects, Johns said David Blewett, a planet earth scientist at Johns Hopkins University. What is the origin of these magnetic anomalies? The moon does not have a spherical magnetic field but has magnetized crustal rocks. ”
It is not possible to find out if the Moon vortices reflect solar wind and cosmic radiation enough to be really useful until a vehicle reaches the surface of the Moon and makes measurements there.
David Blewett told Space.com that these areas are not likely to be very effective. Blewett said that the area under the umbrella would remain dry, but the area around the umbrella would get wet with both rain and drops flowing from the umbrella. | 0.852623 | 3.159916 |
If skies are clear between midnight and the first glimmer of dawn this weekend, you may get to see some celestial fireworks from the Lyrid meteor shower. While it may not be the richest of the annual shooting star displays, the Lyrids can deliver a few fireballs and a portion of these medium-speed meteors can leave glowing trains.
Cometary particles strewn along the orbit of long-period Comet C/1861 G1 (Thatcher) are the genesis of the Lyrid meteors. Those meteoroids entering the Earth’s atmosphere do so at velocities up to 30 miles (48 kilometres) per second, hence it’s not surprising that the streak of light marking their heated demise can be so impressive.
Active from 14–30 April, the International Meteor Organisation predicts the peak of this year’s shower to occur around 18h UT (7pm BST) on Sunday 22 April, which would favour East Africa, the Middle East, India, China, Southeast Asia and Australia. However, the time of the peak is variable from year to year, so the maximum could lie between 10h and 21h UT (11am to 10pm BST).
Even if the predicted peak of the Lyrids occurs in daylight for Western Europe (including the UK), observers looking in the eastern sky after midnight this weekend can expect around a dozen meteors per hour under favourable conditions – particularly if you start your vigil after the waxing Moon sets. (The 5-day-old lunar crescent sets around 1:40am BST on Saturday 21 April for the centre of the UK, and an hour later Sunday morning.)
It follows that the best views are reserved for those dedicated souls prepared to observe in the small hours between moonset and the first light of dawn around 4am BST in the UK when the radiant of the Lyrids is high in the southeast.
As is typical of most meteor showers, fainter Lyrids are the most plentiful, so your chances of observing some are greatly improved if you can find a safe, rural location well away from artificial lights and take 20 minutes or more to ensure that your eyes are fully dark adapted. | 0.841921 | 3.2393 |
One of the all the more intriguing cosmology stories that turned out at the last part of 2019 was the odd conduct of the close by star known as Betelgeuse. It sits somewhere close to 520 and 650 light-years from Earth, and that is very close all in all, making its conduct specifically noteworthy to us here on Earth.
Months prior, researchers made us aware of the way that Betelgeuse is getting dimmer. This gigantic star is right now a red supergiant, and the way that it had all the earmarks of being diminishing alluded to various potential results, including a potential breakdown and supernova blast.
Presently, with a few additional long stretches of perceptions added to their repertoire, analysts have found that Betelgeuse isn’t simply diminishing, it’s darkening in an exceptionally peculiar way.
High-goals pictures caught by the Very Large Telescope uncover that Betelgeuse is without a doubt diminishing however just piece of it is really changing in brilliance. Look at it:
“The red supergiant star Betelgeuse, in the constellation of Orion, has been undergoing unprecedented dimming,” the European Southern Observatory composes. “This stunning image of the star’s surface, taken with the SPHERE instrument on ESO’s Very Large Telescope late last year, is among the first observations to come out of an observing campaign aimed at understanding why the star is becoming fainter. When compared with the image taken in January 2019, it shows how much the star has faded and how its apparent shape has changed.”
Since just piece of the star is changing in splendor, its shape has all the earmarks of being adjusted, giving it an oval appearance rather than an increasingly uniform round shape. Things being what they are, what’s the arrangement?
As Plait brings up, it’s not possible for anyone to state for sure, in any event not yet, yet one chance is that the supergiant star’s surface has been recolored with an especially huge sunspot. Our own star gets sunspots every now and then, yet they’re generally very little.
On a star like Betelgeuse, things are a ton extraordinary, and the violent attractive powers at work may have delivered an especially monstrous sunspot that is really making the whole star show up less splendid.
The chances that Betelgeuse is getting ready to blow its stop despite everything show up exceptionally thin, and it’s profoundly far-fetched people’re going to observe the supergiant go full supernova at any point in the near future. In any case, until anybody can decisively clarify what’s new with the star, researchers will keep an especially close eye on it. | 0.86964 | 3.740027 |
The recent meteor explosion over Chelyabinsk brought to the forefront a topic that has worried astronomers for years, namely that an impactor from space could cause widespread human fatalities. Indeed, the thousand+ injured recently in Russia was a wake-up call. Should humanity be worried about impactors? “Hell yes!” replied astronomer Neil deGrasse Tyson to CNN’s F. Zakharia .
The geological and biological records attest to the fact that some impactors have played a major role in altering the evolution of life on Earth, particularly when the underlying terrestrial material at the impact site contains large amounts of carbonates and sulphates. The dating of certain large impact craters (50 km and greater) found on Earth have matched events such as the extinction of the Dinosaurs (Hildebrand 1993, however see also G. Keller’s alternative hypothesis). Ironically, one could argue that humanity owes its emergence in part to the impactor that killed the Dinosaurs.
Only rather recently did scientists begin to widely acknowledge that sizable impactors from space strike Earth.
“It was extremely important in that first intellectual step to recognize that, yes, indeed, very large objects do fall out of the sky and make holes in the ground,” said Eugene Shoemaker. Shoemaker was a co-discoverer of Shoemaker-Levy 9, which was a fragmented comet that hit Jupiter in 1994 (see video below).
Hildebrand 1993 likewise noted that, “the hypothesis that catastrophic impacts cause mass extinctions has been unpopular with many geologists … some geologists still regard the existence of ~140 known impact craters on the Earth as unproven despite compelling evidence to the contrary.”
Beyond the asteroid that struck Mexico 65 million years ago and helped end the reign of the dinosaurs, there are numerous lesser-known terrestrial impactors that also appear destructive given their size. For example, at least three sizable impactors struck Earth ~35 million years ago, one of which left a 90 km crater in Siberia (Popigai). At least two large impactors occurred near the Jurassic-Cretaceous boundary (Morokweng and Mjolnir), and the latter may have been the catalyst for a tsunami that dwarfed the recent event in Japan (see also the simulation for the tsunami generated by the Chicxulub impactor below).
Glimsdal et al. 2007 note, “it is clear that both the geological consequences and the tsunami of an impact of a large asteroid are orders off magnitude larger than those of even the largest earthquakes recorded.”
However, in the CNN interview Neil deGrasse Tyson remarked that we’ll presumably identify the larger impactors ahead of time, giving humanity the opportunity to enact a plan to (hopefully) deal with the matter. Yet he added that often we’re unable to identify smaller objects in advance, and that is problematic. The meteor that exploded over the Urals a few weeks ago is an example.
In recent human history the Tunguska event, and the asteroid that recently exploded over Chelyabinsk, are reminders of the havoc that even smaller-sized objects can cause. The Tunguska event is presumed to be a meteor that exploded in 1908 over a remote forested area in Siberia, and was sufficiently powerful to topple millions of trees (see image below). Had the event occurred over a city it may have caused numerous fatalities.
Mark Boslough, a scientist who studied Tunguska noted, “That such a small object can do this kind of destruction suggests that smaller asteroids are something to consider … such collisions are not as improbable as we believed. We should be making more efforts at detecting the smaller ones than we have till now.”
Neil deGrasse Tyson hinted that humanity was rather lucky that the recent Russian fireball exploded about 20 miles up in the atmosphere, as its energy content was about 30 times larger than the Hiroshima explosion. It should be noted that the potential negative outcome from smaller impactors increases in concert with an increasing human population.
So how often do large bodies strike Earth, and is the next catastrophic impactor eminent? Do such events happen on a periodic basis? Scientists have been debating those questions and no consensus has emerged. Certain researchers advocate that large impactors (leaving craters greater than 35 km) strike Earth with a period of approximately 26-35 million years.
The putative periodicity (i.e., the Shiva hypothesis) is often linked to the Sun’s vertical oscillations through the plane of the Milky Way as it revolves around the Galaxy, although that scenario is likewise debated (as is many of the assertions put forth in this article). The Sun’s motion through the denser part of the Galactic plane is believed to trigger a comet shower from the Oort Cloud. The Oort Cloud is theorized to be a halo of loosely-bound comets that encompasses the periphery of the Solar System. Essentially, there exists a main belt of asteroids between Mars and Jupiter, a belt of comets and icy bodies located beyond Neptune called the Kuiper belt, and then the Oort Cloud. A lower-mass companion to the Sun was likewise considered as a perturbing source of Oort Cloud comets (“The Nemesis Affair” by D. Raup).
The aforementioned theory pertains principally to periodic comets showers, however, what mechanism can explain how asteroids exit their otherwise benign orbits in the belt and enter the inner solar system as Earth-crossers? One potential (stochastic) scenario is that asteroids are ejected from the belt via interactions with the planets through orbital resonances. Evidence for that scenario is present in the image below, which shows that regions in the belt coincident with certain resonances are nearly depleted of asteroids. A similar trend is seen in the distribution of icy bodies in the Kuiper belt, where Neptune (rather than say Mars or Jupiter) may be the principal scattering body. Note that even asteroids/comets not initially near a resonance can migrate into one by various means (e.g., the Yarkovsky effect).
Indeed, if an asteroid in the belt were to breakup (e.g., collision) near a resonance, it would send numerous projectiles streaming into the inner solar system. That may help partly explain the potential presence of asteroid showers (e.g., the Boltysh and Chicxulub craters both date to near 65 million years ago). In 2007, a team argued that the asteroid which helped end the reign of the Dinosaurs 65 million years ago entered an Earth-crossing orbit via resonances. Furthermore, they noted that asteroid 298 Baptistina is a fragment of that Dinosaur exterminator, and it can be viewed in the present orbiting ~2 AU from the Sun. The team’s specific assertions are being debated, however perhaps more importantly: the underlying transport mechanism that delivers asteroids from the belt into Earth-crossing orbits appears well-supported by the evidence.
Thus it appears that the terrestrial impact record may be tied to periodic and random phenomena, and comet/asteroid showers can stem from both. However, reconstructing that terrestrial impact record is rather difficult as Earth is geologically active (by comparison to the present Moon where craters from the past are typically well preserved). Thus smaller and older impactors are undersampled. The impact record is also incomplete since a sizable fraction of impactors strike the ocean. Nevertheless, an estimated frequency curve for terrestrial impacts as deduced by Rampino and Haggerty 1996 is reproduced below. Note that there is considerable uncertainty in such determinations, and the y-axis in the figure highlights the “Typical Impact Interval”.
In sum, as noted by Eugene Shoemaker, large objects do indeed fall out of the sky and cause damage. It is unclear when in the near or distant future humanity will be forced to rise to the challenge and counter an incoming larger impactor, or again deal with the consequences of a smaller impactor that went undetected and caused human injuries (the estimated probabilities aren’t reassuring given their uncertainty and what’s in jeopardy). Humanity’s technological progress and scientific research must continue unabated (and even accelerated), thereby affording us the tools to better tackle the described situation when it arises.
Is discussion of this topic fear mongering and alarmist in nature? The answer should be obvious given the fireball explosion that happened recently over the Ural mountains, the Tunguska event, and past impactors. Given the stakes excessive vigilance is warranted.
Fareed Zakharia’s discussion with Neil deGrasse Tyson is below.
The interested reader desiring additional information will find the following pertinent: the Earth Impact Database, Hildebrand 1993, Rampino and Haggerty 1996, Stothers et al. 2006, Glimsdal et al. 2007, Bottke et al. 2007, Jetsu 2011, G. Keller’s discussion concerning the end of the Dinosaurs, “T. rex and the Crater of Doom” by W. Alvarez, “The Nemesis Affair” by D. Raup, “Collision Earth! The Threat from Outer Space” by P. Grego. **Note that there is a diverse spectrum of opinions on nearly all the topics discussed here, and our understanding is constantly evolving. There is much research to be done. | 0.870971 | 3.79043 |
The hunt for exoplanets has been heating up in recent years. Since it began its mission in 2009, over four thousand exoplanet candidates have been discovered by the Kepler mission, several hundred of which have been confirmed to be “Earth-like” (i.e. terrestrial). And of these, some 216 planets have been shown to be both terrestrial and located within their parent star’s habitable zone (aka. “Goldilocks zone”).
But in what may prove to be the most exciting find to date, the German weekly Der Spiegel announced recently that astronomers have discovered an Earth-like planet orbiting Proxima Centauri, just 4.25 light-years away. Yes, in what is an apparent trifecta, this newly-discovered exoplanet is Earth-like, orbits within its sun’s habitable zone, and is within our reach. But is this too good to be true?
For over a century, astronomers have known about Proxima Centauri and believed that it is likely to be part of a trinary star system (along with Alpha Centauri A and B). Located just 0.237 ± 0.011 light years from the binary pair, this low-mass red dwarf star is also 0.12 light years (~7590 AUs) closer to Earth, making it the closest star system to our own.
In the past, the Kepler mission has revealed several Earth-like exoplanets that were deemed to be likely habitable. And recently, an international team of researchers narrowed the number of potentially-habitable exoplanets in the Kepler catalog down to the 20 that are most likely to support life. However, in just about all cases, these planets are hundreds (if not thousands) of light years away from Earth.
Knowing that there is a habitable planet that a mission from Earth could reach within our own lifetimes is nothing short of amazing! But of course, there is reason to be cautiously optimistic. Citing anonymous sources, the magazine stated:
“The still nameless planet is believed to be Earth-like and orbits at a distance to Proxima Centauri that could allow it to have liquid water on its surface — an important requirement for the emergence of life. Never before have scientists discovered a second Earth that is so close by.”
In addition, they claim that the discovery was made by the European Southern Observatory (ESO) using the La Silla Observatory‘s reflecting telescope. Coincidentally, it was this same observatory that announced the discovery of Alpha Centauri Bb back in 2012, which was also declared to be “the closest exoplanet to Earth”. Unfortunately, subsequent analysis cast doubt on its existence, claiming it was a spurious artifact of the data analysis.
However, according to Der Spiegel’s unnamed source – whom they claim was involved with the La Silla team that made the find – this latest discovery is the real deal, and was the result of intensive work. “Finding small celestial bodies is a lot of hard work,” the source was quoted as saying. “We were moving at the technically feasible limit of measurement.”
The article goes on to state that the European Southern Observatory (ESO) will be announcing the finding at the end of August. But according to numerous sources, in response to a request for comment by AFP, ESO spokesman Richard Hook refused to confirm or deny the discovery of an exoplanet around Proxima Centauri. “We are not making any comment,” he is reported as saying.
What’s more, the folks at Project Starshot are certainly excited by the news. As part of Breakthrough Initiatives – a program founded by Russian billionaire Yuri Milner to search for intelligent life (with backing from Stephen Hawking and Mark Zuckerberg) – Starshot intends to send a laser-sail driven-nanocraft to Alpha Centauri in the coming years.
This craft, they claim, will be able to reach speeds of up to 20% the speed of light. At this speed, it will able to traverse the 4.37 light years that lie between Earth and Alpha Centauri in just 20 years. But with the possible discovery of an Earth-like planet orbiting Proxima Centauri, which lies even closer, they may want to rethink that objective.
As Professor Phillip Lubin – a professor at the University of California, Santa Barbara, the brains behind Project Starshot, and a key advisor to NASA’s DEEP-IN program – told Universe Today via email:
“The discovery of possible planet around Proxima Centauri is very exciting. It makes the case of visiting nearby stellar systems even more compelling, though we know there are many exoplanets around other nearby stars and it is very likely that the Alpha Centauri system will also have planets.”
Naturally, there is the desire (especially amongst exoplanet enthusiasts) to interpret the ESO’s refusal to comment either way as a sort of tacit confirmation. And knowing that industry professionals are excited it about it does lend an air of legitimacy. But of course, assuming anything at this point would be premature.
If the statements made by the unnamed source, and quoted by Der Speigel, are to be taken at face value, then confirmation (or denial) will be coming shortly. In the meantime, we’ll all just need to be patient. Still, you have to admit, it’s an exciting prospect: an Earth-like planet that’s actually within reach! And with a mission that could make it there within our own lifetimes. This is the stuff good science fiction is made of, you know.
Further Reading: Der Speigel | 0.833283 | 3.809369 |
China has released 11.25 million spectra of celestial objects acquired by the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) to astronomers worldwide, according to National Astronomical Observatories of Chinese Academy of Sciences (NAOC) Friday.
As the world's largest spectral survey telescope, LAMOST marks the world's first spectral survey project to obtain more than 10 million spectra.
Spectra are key for astronomers to read celestial bodies' chemical compositions, densities, atmospheres and magnetism.
Among the released spectra, there are 9.37 million high-quality spectra, which is twice the total number of other astronomic surveys internationally. There are also 6.36 million stellar spectra, creating the largest stellar parameter catalog in the world.
Finished in 2008, LAMOST began regular surveys in 2012. The telescope is located in NAOC's Xinglong Observatory, in north China's Hebei Province.
The telescope can observe about 4,000 celestial bodies at one time. It can also help calculate the age of more than a million stars, providing basic data to study the evolution of our galaxy.
According to Zhao Yongheng, a researcher from the NAOC, LAMOST's latest spectra data is the world's most complete astronomical data set with the largest survey volume, the highest sampling density and the largest number of samples. It provides a reference for the formation and evolution of the Milky Way as well as other galaxies.
More than 100 institutes and universities from the U.S., Germany, Belgium, Denmark and other countries and regions around the world are using this data to carry out research on the evolution of the Milky Way, stellar physics and special celestial body search.
NAOC has set up an online platform for the spectra data release, allowing users to download it for free.
With LAMOST, Chinese astronomers have reported a series of new findings. They have discovered the most lithium-rich giant star ever known. They also discovered more than 10,000 metal-poor star candidates, which may help shed light on the early universe and the emergence of the first stars and galaxies(Xinhua).
Address: 20A Datun Road, Chaoyang District, Beijing, China code: 100012
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A split-second burst of energy that erupted in deep space is giving astronomers important new clues about a mysterious class of astrophysical phenomena.
Only a handful of these rapid, millisecond-duration events, known as "fast radio bursts" (FRBs), had been detected previously, all of them by a single instrument — the Parkes Observatory in Australia. As a result, some astronomers have speculated that FRBs have local origins.
"Our result is important because it eliminates any doubt that these radio bursts are truly of cosmic origin," study co-author Victoria Kaspi, of McGill University in Montreal, Canada, said in a statement. "The radio waves show every sign of having come from far outside our galaxy — a really exciting prospect."
Kaspi is principal investigator of the Pulsar ALFA (PALFA) survey, a search for pulsars — fast-spinning, super-dense objects that emit beams of light (which appear to pulse at a regular interval, because they can be observed only when the pulsar is pointed at Earth). The research team, led by Laura Spitler of the Max Planck Institute in Germany, discovered the new FRB in the PALFA data.
The newly observed burst is the first of its kind discovered by a telescope other than Parkes, researchers said.
"The brightness and duration of this event, and the inferred rate at which these bursts occur, are all consistent with the properties of the bursts previously detected by the Parkes telescope in Australia," said Spitler, who was completing her PhD at Cornell University when the research began.
The short lifetime of FRBs makes it tough to study them; only seven events, including the newest burst, have been recorded since their 2007 discovery. But the new study should help researchers get a better grip on FRBs.
Their presumed extragalactic origins mean that fast radio bursts could provide unprecedented opportunities to study the intergalactic medium — the dust and gas between galaxies — according to the research paper, which was published in the Astrophysical Journal.
By extrapolating how much of the sky was studied and for how long, scientists have calculated that FRBs probably occur roughly 10,000 times a day. Based on this occurrence rate, PALFA is expected to find two to three more FRBs in the coming years.
The source of fast radio bursts remains a mystery that astrophysicists are eager to solve. A number of exotic possibilities include evaporating primordial black holes, merging or collapsing neutron stars and superconducting cosmic strings. Flares from magnetically active neutron stars, known as magnetars, could also be responsible for the events, researchers said.
Extremely bright flashes from pulsars outside the galaxy are another possibility. The research team suggested that FRBs could be pulses that repeat over even longer timescales than anticipated. If this is the case, longer observation times would be required to spot them.
"We cannot be certain that the bursts are non-repeating," the team wrote in the paper. "Detecting an astrophysical counterpart will be an important step in determining whether we expect repeated events."
Copyright SPACE.com, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed. | 0.895755 | 4.091111 |
Top: Two-dimensional GMOS spectrum of the strong emission line observed in the radio galaxy TGSS J1530+1049. The size of the emission region is a bit less than one arcsec. Bottom: One-dimensional profile of the observed emission line. The asymmetry indicates that the line is Lyman-α at redshift of z = 5.72, making TGSS J1530+1049 the most distant radio galaxy known to date.
Using the Gemini North telescope in Hawai`i, an international team of astronomers from Brazil, Italy, the Netherlands, and the UK has discovered the most distant radio galaxy to date, at 12.5 billion light years, when the Universe was just 7% of its current age.
The team used spectroscopic data from the Gemini Multi-Object Spectrograph (GMOS-N) to measure a redshift of z = 5.72 for the radio galaxy identified as TGSS J1530+1049. This is the largest redshift of any known radio galaxy. The redshift of a galaxy tells astronomers its distance because galaxies at greater distances move away from us at higher speeds, and this motion causes the galaxy's light to shift farther into the red. Because light has a finite speed and takes time to reach us, more distant galaxies are also seen at earlier times in the history of the Universe.
The study was led by graduate students Aayush Saxena (Leiden Observatory, Netherlands) and Murilo Marinello (Observatório Nacional, Brazil), and the observations were obtained through Brazil's participation in Gemini. "In the Gemini spectrum of TGSS J1530+1049, we found a single emission line of hydrogen, known as the Lyman alpha. The observed shift of this line allowed us to estimate the galaxy's distance," explains Marinello.
The relatively small size of the radio emission region in TGSS J1530+1049 indicates that it is quite young, as expected at such early times. Thus, the galaxy is still in the process of assembling. The radio emission in this kind of galaxy is powered by a supermassive black hole that is sucking in material from the surrounding environment. This discovery of the most distant radio galaxy confirms that black holes can grow to enormous masses very quickly in the early Universe.
The measured redshift of TGSS J1530+1049 places it near the end of the Epoch of Reionization, when the majority of the neutral hydrogen in the Universe was ionized by high-energy photons from young stars and other sources of radiation. "The Epoch of Reionization is very important in cosmology, but it is still not well understood," said Roderik Overzier, also of Brazil's Observatorio Nacional, and the Principal Investigator of the Gemini program. "Distant radio galaxies can be used as tools to find out more about this period."
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Supernovae are spectacular, extremely bright explosions in the universe. They are considered some of the brightest explosions in the universe. However, scientists discovered a more spectacular type known as the superluminous supernovae, which is known to shine a hundred times brighter compared to regular supernova. On August 22, 2016, astronomers caught a glimpse of the farthest supernova, its light traveling over 10 billion years in order to reach our planet.
They named this event DES16C2nm and it was very exciting to the scientists considering that they only are able to see it with a telescope since the universe is expanding as it is, such that the light from the explosion is being stretched into wavelengths that are visible from Earth. The light coming from superluminous supernovae, the farthest supernova confirmed, can help us learn more about the universe, and what else is happening in the distant galaxies.
“The more distant supernovae we see, the more information we get on those stars.” one of the study’s authors, Charlotte Angus from the University of Southampton in the United Kingdom, told Gizmodo.
The scientists managed to spot DES16C2nm thanks to the data from the sky-surveying instrument in Chile. It was scheduled for followup observations to try to detect its light spectrum, which came from observations at the Magellan Clay Telescope, the Keck II telescope, the Very Large Telescope and other observatories around the world.
The discovered superluminous supernovae in regular conditions release mostly ultraviolet light, that is hard to spot on Earth’s surface, because our atmosphere absorbs those wavelengths, Angus told Gizmodo. Fortunately, as the universe is constantly expanding, the light from the farthest supernova stretched into optical wavelengths that are accessible for astronomers to see.
It appeared that DES16C2nm lacked hydrogen, which indicates that it must have come from a supermassive, fully-evolved object. For comparison, a lighter or a less-evolved star would contain far more hydrogen.
According to the astronomers, this object is of vast importance for the future of astronomy. The superluminous supernovae appear to be more frequently seen the more distant astronomers are able to see through their telescopes, the paper recently published in The Astrophysical Journal suggests.
If that’s true, researchers need to learn everything that they can about those distant events. According to the scientists, the Large Synoptic Survey Telescope, Euclid, and the Wide-field Infrared Survey Telescope may be able to spot more distant superluminous supernovae in the future.
The observed superluminous supernova is the farthest supernova which was spectroscopically confirmed. That means that the astronomers analyzed its light spectrum in order to confirm its identity. However, it’s not the only most distant candidate. Back in 2012, researchers saw two others and measured the lights distances which were both further than that of DES16C2nm, although they didn’t spectroscopically confirm their identities.
Undoubtedly, more astronomical events in the distant universe are just waiting to be discovered as more high-tech optics emerge. Although DES16C2nm could be the farthest supernova confirmed spectroscopically, there is no doubt that more of such events are just around the corner. | 0.868059 | 4.019579 |
March 28, 2012
Are the bright crater rims and striations on Vesta the mark of discharge “vents”?
Are asteroids and comets close cousins in the Solar System’s family? Comets are usually called “dirty snowballs” in the scientific press, although missions like Giotto and Deep Impact observed them to be blackened, cratered, and fractured. There are no ice fields on Halley’s comet, and there is no reflective crust. In fact, when the Giotto spacecraft flew by Halley’s comet, mission specialists called it the blackest object they had ever seen. Highly energetic plumes blasted out from its dark, dense nucleus.
Deep Impact’s investigation of Comet Tempel 1 revealed an object that looked more like an asteroid than a chunk of loosely conglomerated dirty ice. There were large craters, scattered boulders, and cliffs, with no indication that a dirty snowball was slowly disintegrating. There was OH in the comet’s vicinity, which was interpreted as having come from broken-up water molecules on the comet nucleus, but there was so little ice on the surface that its origin was open to speculation.
In 2001, Deep Space 1 encountered comet Borrelly. To the astonishment of the mission team, it was a hot, dry desert-like body, not a cold chunk of ice. This conforms to the Electric Universe model of comets as planetary debris, born in catastrophic planetary electrical encounters.
When comets move through the radial electric field of the Solar System as they orbit the Sun, electrical stress on the nucleus causes them to emit visible plasma glow-mode discharges. In an Electric Universe, comets are electrically active, solid bodies.
Comets form plasma sheaths, called “comas,” often more than a million kilometers in diameter: it is not the passive sublimation of ice that creates them, they are formed around electrodes in a low-pressure-gas electric discharge. Plasma sheaths are regions of strong electric fields, which are capable of generating ultraviolet light and X-rays. Comet Hyakutake was a good example of that phenomenon. The cometary discharge also tends to concentrate into ”hot spots” on the comet nucleus, and ”cathode jets” emanate from those spots.
A previous Picture of the Day article discussed “Centaur objects” that revolve around the Sun near the asteroid belt. Centaurs exhibit characteristics of both comets and asteroids. 2060 Chiron, for example, displays a coma whenever it reaches perihelion, although it does not grow a tail. A coma was seen around 174P Echeclus in 2005, so it is also classified as a “cometary asteroid.” Many Centaurs are now known to behave like comets, except that they are so far from the Sun that its radiant heat cannot sublimate ice.
As has been written in past Pictures of the Day about Vesta, topographic data indicates an object that has undergone a catastrophic resurfacing. Punctures, gouges, and fractures dominate its terrain. On an asteroid 500 kilometers in diameter are craters 50 kilometers wide, with a 375 kilometer “impact basin” in the southern polar region.
The latest images from the Dawn spacecraft show several areas where bright material seems to have vented from Vesta’s surface. Since discharges and arcs form the comet phenomena, and exposing asteroids to intense electric fields can elicit plasma ejections, perhaps the areas on Vesta are where electrical connections were once made between it and its parent or other bodies in the solar system. | 0.887679 | 4.031421 |
Two different theories were published on the origin of Ceres' white spots showing there's much more scientists don't know about our solar system.
The dwarf planet was discovered last year and since then, scientists have been baffled by Ceres’ bright, white spots located on one of its large craters.
The first conclusion was that they were large deposits of salt and after further analysis, published in a recent study, scientists have come up with a new theory. The Occator Crater is where the white spots are at their brightest and its here that huge concentrations of sodium carbonate – a substance usually found in household cleaning products here on Earth – which is formed in underwater hydrothermal vents and sodium carbonate being responsible for the bright, white spots.
The carbonate-rich planet would be one of the highest concentrated of carbon ever discovered which doesn’t coincide with the theory that material was deposited on the planet through asteroid collisions millions of years ago. A second study theorizes that the planet is much drier than first thought which poses the question of how the carbonate formed if there wasn’t sufficient water.
It could be that the interior of Ceres is much warmer than previously thought and could mean water was present underneath the surface with the salts being remnants of minerals once dissolved.
“The minerals we have found at the Occator central bright area require alteration by water. Carbonates support the idea that Ceres had interior hydrothermal activity, which pushed these materials to the surface within Occator,” stated Maria Cristina De Sanctis, investigator on the Dawn spacecraft.
The mystery could be the key to the origin of water in our solar system and its role and ability to retain itself.
“Understanding water on Ceres—how much it has, how it attained and retained it, whether it formed in the asteroid belt or further out—has really important implications for the formation of the solar system overall,” Michael Bland of the US Geological Survey said. “I think Ceres is a great target for Dawn and future missions, as a way to bridge the inner and outer solar system.” | 0.84879 | 3.638396 |
NASA Selects Instrument Team to Build Next-Gen Planet Hunter
NASA has selected a team to build a new, cutting-edge instrument that will detect planets outside our solar system, known as exoplanets, by measuring the miniscule “wobbling” of stars. The instrument will be the centerpiece of a new partnership with the National Science Foundation (NSF) called the NASA-NSF Exoplanet Observational Research program, or NN-EXPLORE.
The instrument, named NEID (pronounced “nee-id”), which is short for NN-EXPLORE Exoplanet Investigations with Doppler Spectroscopy, will measure the tiny back-and-forth wobble of a star caused by the gravitational tug of a planet in orbit around it. The wobble tells scientists there is a planet orbiting the star, and the size of the wobble indicates how massive the planet is.
The highly precise instrument, to be built by a Pennsylvania State University research group led by Dr. Suvrath Mahadevan, will be completed in 2019 and installed on the 3.5-meter WIYN telescope at the Kitt Peak National Observatory in Arizona.
Using NEID as a facility observatory instrument, astronomers will be able to search out and study new planets and planetary systems, as well as follow-up the discoveries of NASA’s planet-hunting missions Kepler/K2 and the in-development Transiting Exoplanet Survey Satellite (TESS). NEID will also help identify promising targets for future observations with the James Webb Space Telescope and the Wide-Field Infrared Survey Telescope.
“The NEID instrument is a critical part of NASA’s partnership with NSF; this state-of-art precision instrument will enable the community to search for new worlds using the WIYN Telescope,” said Paul Hertz, NASA Astrophysics Division Director in Headquarters, Washington. “We look forward to many new discoveries that can then be further explored using NASA’s space telescopes.”
NEID was one of two concepts for an extreme precision Doppler spectrometer that were selected for a detailed six-month study by NASA in June 2015.
The name NEID is derived from a word meaning “to discover/visualize” in the native language of the Tohono O’odham, on whose land Kitt Peak National Observatory is located. | 0.887812 | 3.164189 |
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Karbonmonoksid (CO) er en giftig gass for oss mennesker, men ute i verdensrommet er det derimot knyttet til liv -- i form av stjernedannelse. Jeg heter Marie og tar en doktorgrad i astrofysikk. Dette er det jeg forsker på.
Jeg heter Renate, og jeg tar en mastergrad i astrofysikk ved universitetet i Oslo.
The finite speed of light enables us to look back in time as we peer out in the universe. This enables us to study how galaxies were formed and how they evolved throughout the history of the universe. However, it is difficult to study distant galaxies in detail: Each galaxy only covers a few pixels, even in the best images from the Hubble Space Telescope, and they are so faint that they are only barely detected even with our largest telescopes. Nature has provided us with a tool to overcome these obstacles: Light rays from distant galaxies are deflected in the gravitational field of a massive object, such as a cluster of galaxies, which acts as a lens. This phenomenon is known as gravitational lensing. If the distant galaxy and the lens are almost perfectly aligned along our line of sight, the light will be focused towards us and the distant source will be magnified. This enables us to see objects and study phenomena which would otherwise be unobservable. | 0.855986 | 3.339672 |
The Event Horizon Telescope --a planet-scale array of eight ground-based radio telescopes forged through international collaboration-was designed to capture images of a black hole. On April 10, in coordinated news conferences across the globe, researchers reveal that they have succeeded, unveiling the first direct visual evidence of a supermassive black hole and its shadow.
This breakthrough was announced April 10 in a series of six papers published in a special issue of The Astrophysical Journal Letters. The image reveals the black hole at the center of Messier 87, a massive galaxy in the nearby Virgo galaxy cluster. This black hole sits 55 million light-years from Earth and has a mass 6.5 billion times that of the sun.
The EHT links telescopes around the globe, including the University of Chicago-run South Pole Telescope , to form an unprecedented Earth-sized "virtual telescope" with unprecedented sensitivity and resolution. The EHT is the result of years of international collaboration, and offers scientists a new way to study the most extreme objects in the universe predicted by Einstein’s theory of general relativity.
This artist’s impression depicts superheated material swirling around the black hole at the heart of the galaxy M87.
"We have taken the first picture of a black hole-a one-way door out of our universe," said EHT project director Sheperd S. Doeleman of the Center for Astrophysics Harvard & Smithsonian. "This is an extraordinary scientific feat accomplished by a team of more than 200 researchers."
Black holes are extraordinary cosmic objects with enormous masses but extremely compact sizes. The presence of these objects affects their environment in extreme ways, warping spacetime and super-heating any surrounding material.
"If immersed in a bright region, like a disc of glowing gas, we expect a black hole to create a dark region similar to a shadow-something predicted by Einstein’s general relativity that we’ve never seen before," explained chair of the EHT Science Council Heino Falcke of Radboud University in the Netherlands. "This shadow, caused by the gravitational bending and capture of light by the event horizon, reveals a lot about the nature of these fascinating objects and has allowed us to measure the enormous mass of M87’s black hole."
Multiple calibration and imaging methods have revealed a ring-like structure with a dark central region-the black hole’s shadow-that persisted over multiple independent EHT observations.
The EHT observations use a technique called very-long-baseline interferometry, which synchronizes eight telescope facilities around the world and exploits the rotation of our planet to form one huge, Earth-size telescope observing at a wavelength of 1.3mm. This technique allows the EHT to achieve an angular resolution of 20 micro-arcseconds-enough to read a newspaper in New York from a sidewalk café in Paris.
One of these telescopes was the South Pole Telescope, one of the most sensitive instruments in the world built to search for the oldest light in the universe. Operated by an international collaboration led by the University of Chicago, the South Pole Telescope helped calibrate the data from all telescopes and is key to expanding the EHT’s reach around the globe.
"The South Pole Telescope’s location at the southernmost point of the Earth makes it an important component of the global EHT network," said Prof. John Carlstrom, who directs the telescope. "Although M87 is not visible from the South Pole, it is a crucial player in observing other black holes, such as the massive one at the center of our own galaxy."
Creating the EHT was a formidable challenge which required upgrading and connecting a worldwide network of eight pre-existing telescopes deployed at a variety of challenging high-altitude sites. These locations included volcanoes in Hawaii and Mexico, mountains in Arizona and the Spanish Sierra Nevada, the Chilean Atacama Desert, and Antarctica.
Besides the South Pole Telescope, the other contributing telescopes were ALMA , APEX , the IRAM 30-meter telescope , the James Clerk Maxwell Telescope , the Large Millimeter Telescope Alfonso Serrano , the Submillimeter Array , and the Submillimeter Telescope. Petabytes of raw data from the telescopes were combined by highly specialized supercomputers hosted by the Max Planck Institute for Radio Astronomy and MIT Haystack Observatory.
"Once we were sure we had imaged the shadow, we could compare our observations to extensive computer models that include the physics of warped space, superheated matter and strong magnetic fields. Many of the features of the observed image match our theoretical understanding surprisingly well," said Paul T.P. Ho , EHT board member and director of the East Asian Observatory. "This makes us confident about the interpretation of our observations, including our estimation of the black hole’s mass."
The construction of the EHT and the observations represent the culmination of decades of observational, technical and theoretical work. Thirteen partner institutions worked together to create the EHT, using both pre-existing infrastructure and support from a variety of agencies. Key funding was provided by the National Science Foundation, the EU’s European Research Council and funding agencies in East Asia.
"We have achieved something presumed to be impossible just a generation ago," concluded Doeleman. "Breakthroughs in technology, connections between the world’s best radio observatories, and innovative algorithms all came together to open an entirely new window on black holes and the event horizon."
The South Pole Telescope collaboration is led by the University of Chicago, and includes research groups at over a dozen institutions-including the UChicago-affiliated Argonne and Fermi national laboratories. Specialized EHT instrumentation was provided by the University of Arizona. The participation of the South Pole Telescope in the EHT is funded primarily by the National Science Foundation.
Meet a UChicagoan
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Data and politics
Student who nearly beat FiveThirtyEight’s election prediction meets Nate Silver
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"[Student] feedback is a million times better than a book review."
--Asst Prof. Ling Ma, AB’05, on her book Severance
Nobel laureates launch new economic policy series
Tea Time Concert: Ellie Kirk, harp
In first, scientists demonstrate ’one-way street’ for energy flow
Law School Alum
Lori Lightfoot, JD’89, elected mayor of Chicago
Free public lecture series to explore symmetry in the universe
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Harris Public Policy
New study downplays politicians’ impact on economy and crime
"The outcome of any serious research can only be to make two questions grow where only one grew before."
Big Brains Podcast
Tiny creatures, big discoveries with Nipam Patel | 0.843798 | 3.938411 |
Our sun is one star among 50 billion in the galaxy. Our galaxy is only one among 50 billion in the universe. With a vastness this incomprehensible, it is easy to feel like we are mere specks of sand on an endless shore. But our sun is special. Though roughly 150 million kilometers separate us, we could not be more connected. Literally, everything you see comes from the sun. The words you are reading now are really photons that left the sun about 8 minutes ago only to bounce off this page and into your eyes. We owe our very existence to our sun. It provides just enough heat to keep our fragile bodies from freezing to ice or burning to a crisp. Every bite of food we eat we owe to the sun, whose energy is converted into plants that provide sustenance for everything up the food chain.
We have understood the sun's importance for millennia. The earliest humans, awestruck by its blazing splendor, left drawings of the sun on cave walls. Nearly every civilization, no matter where it sprang up on the planet, has revered the sun. Myths about the sun were the basis of the earliest deities of ancient Sumerian, Hindu, Egyptian, Chinese, and Meso-American cultures. Before Apollo, the ancient Greeks worshiped the sun-god Helios. Before Zeus, the ancient Romans worshiped Sol.
Throughout our history, the sun has been central to humanity's quest for meaning in the universe. But our history has been a brief moment in our sun's 4.5 billion year life. Only recently, through advances in science and technology, have we begun to understand our sun - where it came from, how it functions, how it affects our lives and how it eventually will destroy our planet.
Our Sun is a comprehensive, easy-to-understand guide to everything we know about our closest star. Illustrated with stunning pictures from NASA's newly-launched Solar Dynamics Observatory, Our Sun will reveal the science behind the sun, trace its impact on human history, and reveal its growing importance to our future way of life.
Christopher Cooper is an acknowledged expert on energy and environmental policy. He holds a JD in energy law from Vermont Law School and a master's degree in communication from the University of Miami. Former Senior Fellow at the Institute for Energy and the Environment, Cooper has traveled the globe analyzing the most effective methods of harnessing the sun's energy—from solar towers in South Korea to massive photovoltaic arrays in Mongolia's Gobi Desert. He writes about the history of science and technology, with an emphasis on the adoption of electricity innovations. Among his other books are The Governance of Energy Megaprojects and Our Sun: Biography of a Star.
Christopher Cooper is an expert in energy policy and is a Senior Research Fellow at Vermont Law School's Institute for Energy & the Environment. He has traveled the globe analyzing the most effective methods of harnessing the sun's energy -- from solar towers in South Korea to massive photovoltaic arrays in Mongolia's Gobi Desert. He has written extensively on solar power and the effects of solar activity on electrical systems, including designing a comprehensive plan to protect the North American electricity grid from impending solar storms. His work is published widely in academic journals and trade press from Energy Policy to The Electricity Journal. In 2005, he founded the New York-based Network for New Energy Choices, a non-profit organization devoted to expanding distributed generation and consumer choice in electricity markets. He graduated from Wake Forest University, where he studied politics and ancient religions, holds a master's degree in communication theory from the University of Miami, and earned a J.D. with a certificate in energy law from Vermont Law School (America's top-ranked energy & environmental law program, according to U.S. News & World Report). | 0.81738 | 3.200436 |
Planet-forming disks of material typically orbit around the equators of stars, but now scientists have discovered such rings can go dramatically awry and encircle the poles of stars instead.
The new study suggests that worlds could exist with polar orbits around pairs of stars, potentially leading to seasons extraordinarily different than Earth’s.
Stars are born within clouds of gas and dust. The gravitational pull of each star draws such material into spiraling orbits around it. Although clumps of this cloud start off moving in random directions at random speeds, as the cloud collapses, the clumps collide and merge. The result over time is a flattened disk called a protoplanetary disk that usually spins in the same direction as its star and surrounds the star’s equator. The planets that emerge from such a disk also typically orbit around the star’s equator, as is the case with the worlds of our solar system. [Secrets of Planet Birth Revealed in Amazing ALMA Radio Telescope Images]
Prior work found that nearly all young stars are initially surrounded by protoplanetary disks. In the case of protoplanetary disks around single stars, at least a third go on to form planets, said lead study author Grant Kennedy, an astronomer at the University of Warwick in England.
However, computer simulations have previously suggested that after protoplanetary disks have formed, any extra material they collect can knock them off-kilter. This could explain why astronomers have detected exoplanets with relatively crooked orbits around stars.
Kennedy and his colleagues focused on so-called circumbinary planets, which orbit around binary stars. Scientists had suspected that planets around binary stars could become misaligned—instead of orbiting the stars in the same plane in which the stars orbit one another, these worlds could orbit around their poles instead.
Now, Kennedy and his colleagues have detected the first example of a misaligned circumbinary protoplanetary disk. “It’s one of those examples that nature manages to be more creative than we expect,” Kennedy told Space.com.
The scientists focused on the quadruple-star system HD 98800, located about 146 light-years from Earth. “If planets were born here, there would be four suns in the sky,” study co-author Daniel Price of Monash University in Australia said in a statement.
Using the Atacama Large Millimeter/submillimeter Array (ALMA), a huge radio observatory in Chile, the astronomers captured high-resolution images of the protoplanetary disk around two of the four stars. This ring is about the same diameter as the solar system’s asteroid belt. (The other two stars lie outside the disk; the two pairs of stars orbit each other.)
Previous research confirmed the way in which these binary stars orbited one another. The new study revealed the protoplanetary disk around these stars essentially orbited around their poles, like a Ferris wheel with a carousel at its center.
“I wasn’t actually expecting these data to reveal a polar configuration,” Kennedy said. “Based on previous results, I had made all these predictions of complicated warped structures, but they turned out to be completely wrong. The end result is much simpler and more compelling.”
These new findings suggest that circumbinary planets in polar configurations may prove more common than often assumed, Kennedy said. “The disks exist, so why shouldn’t the planets?” he said.
If a planet ever developed from the newfound protoplanetary disk, the scientists noted that from the surface of this world, the disk would resemble a thick band rising almost straight up from the horizon. The pair of stars the planet orbited would appear to move in and out of the plane of the disk, giving items on the world’s surfaces two shadows at times. [The Most Fascinating Exoplanets Discovered in 2018]
Such a planet might also experience unusual seasons, Kennedy said. “For Earth, the seasons happen because of the tilt of the Earth’s axis,” he explained. This leads the amount of daylight each hemisphere gets each day to grow or shrink over the course of the year, and this influences how warm or cold they are, he said.
With any planet that might evolve in HD 98800, axial tilt is not the only potential factor underlying seasonal variations. “The stars will also change their height in the sky as they orbit each other,” Kennedy said. Depending on the season, “sometimes there would be two suns during the day, sometimes one.”
The scientists detailed their findings online today (Jan. 14) in the journal Nature Astronomy.
Copyright 2018 Space.com, a Future company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed. | 0.882946 | 3.894589 |
Blue supergiant stars are unique, in the sense that they are amongst the most luminous stars, and yet short-lived. These stars can transform into red supergiant stars before eventually exploding during the supernova event.
Blue supergiant stars are amongst the largest and brightest stars in the world. They are characterized by high temperatures ranging from 20,000 – 50,000 kelvin (35,540.3 – 89,540.3 °F). These bright and hot stars are roughly the size of 20 solar masses. However, their size can vary a lot.
A blue supergiant star can be as big as 1,000 solar masses. So, Here are few interesting facts about blue supergiant stars:
Blue supergiant stars are known for the fast stellar winds which blow on their surfaces. However, these winds, although fast, occur sparsely
These stars have short lifespans in comparison to most stars; which is why they are found in cosmic structures such as spiral galaxies and open clusters. These structures are younger in comparison to other cosmic structures
Blue supergiant stars are of rare occurrence in comparison to other kinds of stars. However, the luminosity of these stars makes them easily visible | 0.852505 | 3.287892 |
Indeed. WTF did I just watch? He’s going to prove gravity is an effect and not a force? Waves? Ripples? He’s gone full Mel Gibson.
Gravity isn't a force.In Newton’s view, all objects — from his not-so-apocryphal apple to planets and stars — exert a force that attracts other objects. That universal law of gravitation worked pretty well for predicting the motion of planets as well as objects on Earth — and it's still used, for example, when making the calculations for a rocket launch.
But Newton's view of gravity didn't work for some things, like Mercury’s peculiar orbit around the sun. The orbits of planets shift over time, and Mercury’s orbit shifted faster than Newton predicted.
Einstein offered a different view of gravity, one that made sense of Mercury. Instead of exerting an attractive force, he reasoned that each object curves the fabric of space and time around them, forming a sort of well that other objects — and even beams of light — fall into. Think of the sun as a bowling ball on a mattress. It creates a depression that draws the planets close.
This new model solved the Mercury problem. It showed that the sun so curves space that it distorts the orbits of nearby bodies, including Mercury. In Einstein’s view, Mercury might look like a marble forever circling the bottom of a drain.
Einstein’s theory has been confirmed by more than a century of experiments, starting with one involving a 1919 solar eclipse in which the path of light from distant stars was shifted by the sun’s intense gravitation — by just the amount Einstein had predicted.
But Ghez and her colleagues wanted to subject Einstein to a more rigorous test. So they watched what happened when light from the star S0-2 passed Sagittarius A*, which is four million times more massive than the sun.
For the new research, Lu, Ghez and their collaborators used a trio of giant telescopes in Hawaii to watch as a bluish star named S0-2 made its closest approach to Sagittarius A* in its 16-year orbit around the black hole.
If Einstein was right, the black hole would warp space and time in a way that extended the wavelength of light from S0-2. In short, the waves would stretch out as the intense gravity from the black hole drained their energy, causing the starlight's color to shift from blue to red. If the star continued to glow blue, it would give credence to Newton's model of gravity, which doesn't account for the curvature of space and time. If it turned a different color, it would have hinted at some other model of gravity altogether.
Just as Einstein would have predicted, the star glowed red.
Nope. Still sounds insane. I mean, even if you don't unpack all of the obvious woo and just look at the idea of him quitting acting to teach people that he's discovered 100 year old settled physics (gravity isn't a force....though it's still referred to as one colloquially, but definitely not scientifically), that's fucking crazy.rewatch it with einsteins model of gravity in mind and suddenly he doesnt sound so insane. | 0.819479 | 3.897352 |
HD 149026 is a yellow subgiant star approximately 257 light-years away in the constellation of Hercules. The star is thought to be much more massive, larger, and brighter than the Sun. As of 2005[update], an extrasolar planet has been confirmed to be orbiting the star. The name of this star comes from its identifier in the Henry Draper Catalog.
The star is thought to be much more massive, larger, and brighter than the Sun. The higher mass of the star causes that despite considerably younger age (2.0 Ga) it is already much more evolved than the Sun. The internal fusion of hydrogen in the core of the star is coming to an end and it is beginning to evolve towards red gianthood. HD 149026 is about 260 light-years distant, which means the star is not visible to the unaided eye. However, it should be an easy target to binoculars or a small telescope.
The star is over twice as enriched with chemical elements heavier than hydrogen and helium as the Sun. Because of this and the fact that the star is relatively bright, a group of astronomers in N2K Consortium began to study the star. The star's anomalous composition as measured may be surface pollution only, from the intake of heavy-element planetisimals.
In 2005 they discovered an unusual extrasolar planet orbiting the star. The planet, designated HD 149026 b, was detected transiting the star allowing its diameter to be measured. It was found to be smaller than other known transiting planets, meaning the planet is unusually dense for a closely-orbiting giant planet. The temperature of the giant planet is calculated to be 3,700°F (2,040° C), generating so much infrared heat that it glows. Scientists believe the planet absorbs nearly all the sunlight and radiates it into space as heat.
* 51 Pegasi
1. ^ a b c d e f g h i "SIMBAD query result: HIP 80838 -- Star". SIMBAD. Centre de Données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD+149026. Retrieved 2009-05-20.
* "N2K Information For Star HD149026". San Francisco State University. N2K Consortium. http://tauceti.sfsu.edu/n2k/hd149026/index.html. Retrieved 2008-06-22.
* Naeye, Robert (2005-07-07). "Amateur Detects New Transiting Exoplanet". Sky & Telescope. http://www.skyandtelescope.com/news/3310446.html?page=1&c=y. Retrieved 2008-06-22.
* Naeye, Robert (2005-07-08). "One Big Ball of Rock". Sky & Telescope. http://www.skyandtelescope.com/news/3310426.html?page=1&c=y. Retrieved 2008-06-22. | 0.819618 | 3.744832 |
Gibbous ♊ Gemini
Moon phase on 10 January 2082 Saturday is Waxing Gibbous, 10 days young Moon is in Taurus.Share this page: twitter facebook linkedin
Previous main lunar phase is the First Quarter before 3 days on 7 January 2082 at 04:45.
Moon rises in the afternoon and sets after midnight to early morning. It is visible to the southeast in early evening and it is up for most of the night.
Lunar disc appears visually 7.3% narrower than solar disc. Moon and Sun apparent angular diameters are ∠1814" and ∠1951".
Next Full Moon is the Wolf Moon of January 2082 after 4 days on 14 January 2082 at 18:11.
There is medium ocean tide on this date. Sun and Moon gravitational forces are not aligned, but meet at very acute angle, so their combined tidal force is moderate.
The Moon is 10 days young. Earth's natural satellite is moving from the first to the middle part of current synodic month. This is lunation 1014 of Meeus index or 1967 from Brown series.
Length of current 1014 lunation is 29 days, 16 hours and 18 minutes. It is 1 hour and 44 minutes shorter than next lunation 1015 length.
Length of current synodic month is 3 hours and 34 minutes longer than the mean length of synodic month, but it is still 3 hours and 29 minutes shorter, compared to 21st century longest.
This New Moon true anomaly is ∠84.8°. At beginning of next synodic month true anomaly will be ∠122.6°. The length of upcoming synodic months will keep increasing since the true anomaly gets closer to the value of New Moon at point of apogee (∠180°).
4 days after point of apogee on 5 January 2082 at 22:19 in ♓ Pisces. The lunar orbit is getting closer, while the Moon is moving inward the Earth. It will keep this direction for the next 7 days, until it get to the point of next perigee on 17 January 2082 at 16:31 in ♌ Leo.
Moon is 395 064 km (245 481 mi) away from Earth on this date. Moon moves closer next 7 days until perigee, when Earth-Moon distance will reach 365 690 km (227 229 mi).
6 days after its ascending node on 3 January 2082 at 19:51 in ♓ Pisces, the Moon is following the northern part of its orbit for the next 7 days, until it will cross the ecliptic from North to South in descending node on 17 January 2082 at 15:31 in ♌ Leo.
6 days after beginning of current draconic month in ♓ Pisces, the Moon is moving from the beginning to the first part of it.
12 days after previous South standstill on 29 December 2081 at 05:56 in ♐ Sagittarius, when Moon has reached southern declination of ∠-28.138°. Next 2 days the lunar orbit moves northward to face North declination of ∠28.182° in the next northern standstill on 12 January 2082 at 16:51 in ♊ Gemini.
After 4 days on 14 January 2082 at 18:11 in ♋ Cancer, the Moon will be in Full Moon geocentric opposition with the Sun and this alignment forms next Sun-Earth-Moon syzygy. | 0.83659 | 3.220548 |
Astronomers around the globe have still not managed to explain how a distant star in the universe, commonly referred to as Tabby’s star, or KIC 8462852, dims unnaturally and totally randomly. No known astronomical phenomenon can explain why the star decreases in brightness, which has led many experts to speculate whether it is possible that a massive alien megastructure encompasses the star.
Tabby’s star, also referred to as KIC 8462852 has created an unprecedented buzz in the scientific community since 2015 when a team of astronomers discovered that the light of this star often decreased by up to 20% because a large object was allegedly orbiting it.
Now, a new diminution of the brightness has been detected that has led scientists to speculate once again, whether an alien super civilization has created a massive megastructure that is absorbing energy from its star?
ALERT: @tsboyajian star is dipping. This is not a drill. Astro tweeps on telescopes in the next 48 hours: spectra please! wrote Jason Wright Associate professor of astronomy and astrophysics at Penn State University.
The tweet sent to Tabetha Boyajian, the astronomer whose nickname the star owes, woke the astronomic community that immediately set to take advantage of this new opportunity to measure the light of Tabby’s star in a new effort to unveil the mysterious cause behind the dimming brightness of the star.
Tabetha Boyajian responded #TabbysStar is dipping! OBSERVE!! Calling out NASAs’ Kepler, and Hubble observatories among others, adding that the brightness has declined by 2% and it seems to be “just the beginning”.
What causes the enigmatic dimming at Tabby’s Star remains one of the greatest astronomical enigmas of our time.
When astronomers noticed the dimming around the star for the first time, it created great confusion. Tabetha Boyajian, a postdoc at Yale, told The Atlantic: “We’d never seen anything like this star. It was really weird. We thought it might be bad data or movement on the spacecraft, but everything checked out.”
Jason Wright, who recently tweeted about the star’s odd dimming phenomenon says that these structures, or better said mega-structures, could be the product of a highly advanced alien civilization.
As noted by space.com “Scientists have hypothesized that the changes could be due to a swarm of comets passing in front of the star, that they’re the result of strong magnetic activity, or that it’s some massive structure built by aliens. But no leading hypothesis has emerged, so scientists have been eager to capture a highly detailed picture of the light coming from the star during one of these dimming periods.”
Several theories have been put forth trying to explain why the star dims unnaturally.
One such theory has aliens involved, as presented recently by an—Professor Zaza Osmanov—astronomer at the Free University of Tbilisi (Georgia), who assures that if we are looking at an alien megastructure which is causing the star to dim, then our current technology will allow us to identify such megastructures using infrared telescopes.
According to Professor Zaza Osmanov, we could really have found evidence of such alien megastructures and we can even verify the claims using current technology.
Professor Osmanov made headlines in 2016 when he published a study saying that the alien megastructures are more likely to be shaped like thin discs rather than ‘spherical shells.’
In the new scientific paper—published on arXiv—Osmanov writes ‘We have argued that by monitoring the nearby zone of the solar system approximately 64 pulsars are expected to be located inside it.’ | 0.898155 | 3.314797 |
Wraithlike NGC 6369 is a faint apparition in night skies popularly known as the Little Ghost Nebula. It was discovered by 18th century astronomer Sir William Herschel as he used a telescope to explore the medicinal constellation Ophiucus. Herschel historically classified the round and planet-shaped nebula as a Planetary Nebula. But planetary nebulae in general are not at all related to planets. Instead they are gaseous shrouds created at the end of a sun-like star’s life, the dying star’s outer layers expanding into space while its core shrinks to become a white dwarf. The transformed white dwarf star, seen near the center, radiates strongly at ultraviolet wavelengths and powers the expanding nebula’s glow. Surprisingly complex details and structures of NGC 6369 are revealed in this tantalizing image composed from Hubble Space Telescope data. The nebula’s main round structure is about a light-year across and the glow from ionized oxygen, hydrogen, and nitrogen atoms are colored blue, green, and red respectively. Over 2,000 light-years away, the Little Ghost Nebula offers a glimpse of the fate of our Sun, which could produce its own planetary nebula about 5 billion years from now. | 0.825027 | 3.392809 |
JWST's Science Focus
JWST will provide cutting edge observations that will delve into the mysteries of the first objects to form in the early universe, the assembly of galaxies, the birth of stars and planetary systems, planetary systems and the origins of life, and much more.
The End of the Dark Ages: First Light and Reionization
Theory and observation have given us a simple picture of the early universe. As the universe expanded and cooled, some hydrogen molecules were formed, and these in turn enabled the formation of the first individual stars. The first stars formed in those regions that were the most dense.
According to theory and the Wilkinson Microwave Anisotropy Probe (WMAP), the universe has expanded by a factor of 20 since that time, the mean density was 8000 times greater than it is now, and the age was about 180 million years. Also according to theory, these first stars were 30 to 1000 times as massive as the Sun and millions of times as bright and burned for only a few million years before meeting a violent end. Each one would produce either a (superluminous) pair-instability supernova or collapse directly to a black hole. The supernovae would enrich the surrounding gas with the chemical elements produced in their interiors, and future generations of stars would all contain these heavier elements (“metals”). The black holes would start to swallow gas and other stars to become mini-quasars, growing and merging to become the huge black holes now found at the centers of nearly all galaxies. The distinction is important because only the supernovae return heavy elements to the gas. The supernovae and the mini-quasars, if beamed, should be observable by the JWST. Both might also be sources of gamma ray bursts and gravity wave bursts that could be discovered by other observatories and then observed in followup by JWST. In addition to the supernovae of the first light stars, JWST will also be able to detect the first galaxies and star clusters.
The JWST First Light theme science goal is to find and understand these predicted first light objects. To find them, the JWST must provide exceptional imaging capabilities in the near IR band. To verify that the high-z galaxies are indeed made of primordial stars and do not contain older stellar populations, mid-infrared observations are required. An observational approach to identify these objects has been described in the JWST SWG First Light white paper.
Assembly of Galaxies
Galaxies are the visible building blocks of the universe. Theory and observation also give us a preferred picture of the assembly of galaxies. It seems that small objects formed first, and then were drawn together to form larger ones. This process is still occurring today, as the Milky Way merges with some of its dwarf companions, and as the Andromeda Nebula heads toward the Milky Way for a future collision. Galaxies have been observed back to times within one billion years after the Big Bang.
Despite all the work done to date, many questions are still open. We do not really know how galaxies are formed, what controls their shapes, what makes them form stars, how the chemical elements are generated and redistributed through the galaxies, whether the central black holes exert great influence over the galaxies, or what are the global effects of violent events as small and large parts join together in collisions.
The JWST Assembly of Galaxies theme goal is to observe galaxies back to their earliest precursors (z > 10) so that we can understand their growth and their morphological and metallicity evolution. The JWST must provide imaging and spectroscopy over the 0.6 to 27 µm band to meet this objective.
Birth of Stars and Protoplanetary Systems
While stars are a classic topic of astronomy, only in recent times have we begun to understand them with detailed observations and computer simulations. A hundred years ago we did not know that they are powered by nuclear fusion, and 50 years ago we did not know that stars are continually being formed. We still do not know the details of how they are formed from clouds of gas and dust, or why most stars form in groups, or how planets form with them. We also do not know the details of how they evolve and liberate the “metals” back into space for recycling into new generations of stars and planets. In many cases these old stars have major effects on the formation of new ones.
Observations show that most stars are formed in multiple star systems and that many have planets. However, there is little agreement about how this occurs, and the discovery of large numbers of massive planets in very close orbits around their stars was very surprising. We also know that planets are common around late-type stars (cooler and less massive than the Sun), and that debris disks might signal their presence.
The JWST Birth of Stars and Protoplanetary Systems theme goal is to unravel the birth and early evolution of stars, from infall on to dust-enshrouded protostars, to the genesis of planetary systems. JWST is uniquely primed to solve these mysteries given the combination of its high resolution observing modes, imaging, spectroscopy, and coronographic capabilities, and superb near and mid-IR sensitivity.
Planetary Systems and the Origins of Life
Understanding the origin of the Earth and its ability to support life is a key objective for all of astronomy and is central to the JWST science program. Key parts of the story include understanding the formation of small objects and how they combine to form large ones, learning how they reach their present orbits, learning how the large planets affect the others in systems like ours, and learning about the chemical and physical history of the small and large objects that formed the Earth and delivered the necessary chemical precursors for life. The cool objects and dust in the outer Solar System are evidence of conditions in the early Solar System, and are directly comparable to cool objects and dust observed around other stars.
The JWST Planetary Systems and Origins of Life theme goal is to determine the physical and chemical properties of planetary systems, and investigate the potential for the origins of life in those systems. JWST must provide near and mid IR imaging and spectroscopy to observe exoplanets.
JWST's planetary exploration theme also includes a rich solar system science case with imaging and spectroscopic characterization of Mars and the outer planets, Kuiper belt objects, dwarf planets, icy moons, and comets. | 0.906402 | 4.129804 |
Supermassive black hole
A supermassive black hole (SMBH or sometimes SBH) is the largest type of black hole, containing a mass of the order of hundreds of thousands to billions of times the mass of the Sun (M☉). Black holes are a class of astronomical object that have undergone gravitational collapse, leaving behind spheroidal regions of space from which nothing can escape, not even light. Observational evidence indicates that nearly all large galaxies contain a supermassive black hole, located at the galaxy's center. In the case of the Milky Way, the supermassive black hole corresponds to the location of Sagittarius A* at the Galactic Core. Accretion of interstellar gas onto supermassive black holes is the process responsible for powering quasars and other types of active galactic nuclei.
Supermassive black holes have properties that distinguish them from lower-mass classifications. First, the average density of a SMBH (defined as the mass of the black hole divided by the volume within its Schwarzschild radius) can be less than the density of water in the case of some SMBHs. This is because the Schwarzschild radius is directly proportional to its mass. Since the volume of a spherical object (such as the event horizon of a non-rotating black hole) is directly proportional to the cube of the radius, the density of a black hole is inversely proportional to the square of the mass, and thus higher mass black holes have lower average density. In addition, the tidal forces in the vicinity of the event horizon are significantly weaker for supermassive black holes. The tidal force on a body at the event horizon is likewise inversely proportional to the square of the mass: a person on the surface of the Earth and one at the event horizon of a 10 million M☉ black hole experience about the same tidal force between their head and feet. Unlike with stellar mass black holes, one would not experience significant tidal force until very deep into the black hole.
History of researchEdit
The story of how supermassive black holes were found began with the investigation by Maarten Schmidt of the radio source 3C 273 in 1963. Initially this was thought to be a star, but the spectrum proved puzzling. It was determined to be hydrogen emission lines that had been red shifted, indicating the object was moving away from the Earth. Hubble's law showed that the object was located several billion light-years away, and thus must be emitting the energy equivalent of hundreds of galaxies. The rate of light variations of the source, dubbed a quasi-stellar object, or quasar, suggested the emitting region had a diameter of one parsec or less. Four such sources had been identified by 1964.
In 1963, Fred Hoyle and W. A. Fowler proposed the existence of hydrogen burning supermassive stars (SMS) as an explanation for the compact dimensions and high energy output of quasars. These would have a mass of about 105 – 109 M☉. However, Richard Feynman noted stars above a certain critical mass are dynamically unstable and would collapse into a black hole, at least if they were non-rotating. Fowler then proposed that these supermassive stars would undergo a series of collapse and explosion oscillations, thereby explaining the energy output pattern. Appenzeller and Fricke (1972) built models of this behavior, but found that the resulting star would still undergo collapse, concluding that a non-rotating 0.75×106 M☉ SMS "cannot escape collapse to a black hole by burning its hydrogen through the CNO cycle".
Edwin E. Salpeter and Yakov B. Zel'dovich made the proposal in 1964 that matter falling onto a massive compact object would explain the properties of quasars. It would require a mass of around 108 M☉ to match the output of these objects. Donald Lynden-Bell noted in 1969 that the infalling gas would form a flat disk that spirals into the central "Schwarzschild throat". He noted that the relatively low output of nearby galactic cores implied these were old, inactive quasars. Meanwhile, in 1967, Martin Ryle and Malcolm Longair suggested that nearly all sources of extra-galactic radio emission could be explained by a model in which particles are ejected from galaxies at relativistic velocities; meaning they are moving near the speed of light. Martin Ryle, Malcolm Longair, and Peter Scheuer then proposed in 1973 that the compact central nucleus could be the original energy source for these relativistic jets.
Arthur M. Wolfe and Geoffrey Burbidge noted in 1970 that the large velocity dispersion of the stars in the nuclear region of elliptical galaxies could only be explained by a large mass concentration at the nucleus; larger than could be explained by ordinary stars. They showed that the behavior could be explained by a massive black hole with up to 1010 M☉, or a large number of smaller black holes with masses below 103 M☉. Dynamical evidence for a massive dark object was found at the core of the active elliptical galaxy Messier 87 in 1978, initially estimated at 5×109 M☉. Discovery of similar behavior in other galaxies soon followed, including the Andromeda Galaxy in 1984 and the Sombrero Galaxy in 1988.
Donald Lynden-Bell and Martin Rees hypothesized in 1971 that the center of the Milky Way galaxy would contain a massive black hole. Sagittarius A* was discovered and named on February 13 and 15, 1974, by astronomers Bruce Balick and Robert Brown using the Green Bank Interferometer of the National Radio Astronomy Observatory. They discovered a radio source that emits synchrotron radiation; it was found to be dense and immobile because of its gravitation. This was, therefore, the first indication that a supermassive black hole exists in the center of the Milky Way.
The Hubble Space Telescope, launched in 1990, provided the resolution needed to perform more refined observations of galactic nuclei. In 1994 the Faint Object Spectrograph on the Hubble was used to observe Messier 87, finding that ionized gas was orbiting the central part of the nucleus at a velocity of ±500 km/s. The data indicated a concentrated mass of (2.4±0.7)×109 M☉ lay within a 0.25″ span, providing strong evidence of a supermassive black hole. Using the Very Long Baseline Array to observe Messier 106, Miyoshi et al. (1995) were able to demonstrate that the emission from an H2O maser in this galaxy came from a gaseous disk in the nucleus that orbited a concentrated mass of 3.6×107 M☉, which was constrained to a radius of 0.13 parsecs. They noted that a swarm of solar mass black holes within a radius this small would not survive for long without undergoing collisions, making a supermassive black hole the sole viable candidate.
In February 2020, astronomers reported that a cavity in the Ophiuchus Supercluster, originating from a supermassive black hole, is a result of the largest known explosion in the Universe since the Big Bang.
The origin of supermassive black holes remains an open field of research. Astrophysicists agree that once a black hole is in place in the center of a galaxy, it can grow by accretion of matter and by merging with other black holes. There are, however, several hypotheses for the formation mechanisms and initial masses of the progenitors, or "seeds", of supermassive black holes.
One hypothesis is that the seeds are black holes of tens or perhaps hundreds of solar masses that are left behind by the explosions of massive stars and grow by accretion of matter. Another model hypothesizes that before the first stars, large gas clouds could collapse into a "quasi-star", which would in turn collapse into a black hole of around 20 M☉. These stars may have also been formed by dark matter halos drawing in enormous amounts of gas by gravity, which would then produce supermassive stars with tens of thousands of solar masses. The "quasi-star" becomes unstable to radial perturbations because of electron-positron pair production in its core and could collapse directly into a black hole without a supernova explosion (which would eject most of its mass, preventing the black hole from growing as fast). Given sufficient mass nearby, the black hole could accrete to become an intermediate-mass black hole and possibly a SMBH if the accretion rate persists.
Another model involves a dense stellar cluster undergoing core-collapse as the negative heat capacity of the system drives the velocity dispersion in the core to relativistic speeds. Finally, primordial black holes could have been produced directly from external pressure in the first moments after the Big Bang. These primordial black holes would then have more time than any of the above models to accrete, allowing them sufficient time to reach supermassive sizes. Formation of black holes from the deaths of the first stars has been extensively studied and corroborated by observations. The other models for black hole formation listed above are theoretical.
The difficulty in forming a supermassive black hole resides in the need for enough matter to be in a small enough volume. This matter needs to have very little angular momentum in order for this to happen. Normally, the process of accretion involves transporting a large initial endowment of angular momentum outwards, and this appears to be the limiting factor in black hole growth. This is a major component of the theory of accretion disks. Gas accretion is the most efficient and also the most conspicuous way in which black holes grow. The majority of the mass growth of supermassive black holes is thought to occur through episodes of rapid gas accretion, which are observable as active galactic nuclei or quasars. Observations reveal that quasars were much more frequent when the Universe was younger, indicating that supermassive black holes formed and grew early. A major constraining factor for theories of supermassive black hole formation is the observation of distant luminous quasars, which indicate that supermassive black holes of billions of solar masses had already formed when the Universe was less than one billion years old. This suggests that supermassive black holes arose very early in the Universe, inside the first massive galaxies.
A vacancy exists in the observed mass distribution of black holes. Black holes that spawn from dying stars have masses 5–80 M☉. The minimal supermassive black hole is approximately a hundred thousand solar masses. Mass scales between these ranges are dubbed intermediate-mass black holes. Such a gap suggests a different formation process. However, some models suggest that ultraluminous X-ray sources (ULXs) may be black holes from this missing group.
There is, however, an upper limit to how large supermassive black holes can grow. So-called ultramassive black holes (UMBHs), which are at least ten times the size of most supermassive black holes, at 10 billion solar masses or more, appear to have a theoretical upper limit of around 50 billion solar masses, as anything above this slows growth down to a crawl (the slowdown tends to start around 10 billion solar masses) and causes the unstable accretion disk surrounding the black hole to coalesce into stars that orbit it.
A small minority of sources argue that distant supermassive black holes whose large size is hard to explain so soon after the Big Bang, such as ULAS J1342+0928, may be evidence that our universe is the result of a Big Bounce, instead of a Big Bang, with these supermassive black holes being formed before the Big Bounce.
Activity and galactic evolutionEdit
Gravitation from supermassive black holes in the center of many galaxies is thought to power active objects such as Seyfert galaxies and quasars. An active galactic nucleus (AGN) is now considered to be a galactic core hosting a massive black hole that is accreting matter and displays a sufficiently strong luminosity. The nuclear region of the Milky Way, for example, lacks sufficient luminosity to satisfy this condition. The unified model of AGN is the concept that the large range of observed properties of the AGN taxonomy can be explained using just a small number of physical parameters. For the initial model, these values consisted of the angle of the accretion disk's torus to the line of sight and the luminosity of the source. AGN can be divided into two main groups: a radiative mode AGN in which most of the output is in the form of electromagnetic radiation through an optically thick accretion disk, and a jet mode in which relativistic jets emerge perpendicular to the disk.
Some of the best evidence for the presence of black holes is provided by the Doppler effect whereby light from nearby orbiting matter is red-shifted when receding and blue-shifted when advancing. For matter very close to a black hole the orbital speed must be comparable with the speed of light, so receding matter will appear very faint compared with advancing matter, which means that systems with intrinsically symmetric discs and rings will acquire a highly asymmetric visual appearance. This effect has been allowed for in modern computer generated images such as the example presented here, based on a plausible model for the supermassive black hole in Sgr A* at the centre of our own galaxy. However the resolution provided by presently available telescope technology is still insufficient to confirm such predictions directly.
What already has been observed directly in many systems are the lower non-relativistic velocities of matter orbiting further out from what are presumed to be black holes. Direct Doppler measures of water masers surrounding the nuclei of nearby galaxies have revealed a very fast Keplerian motion, only possible with a high concentration of matter in the center. Currently, the only known objects that can pack enough matter in such a small space are black holes, or things that will evolve into black holes within astrophysically short timescales. For active galaxies farther away, the width of broad spectral lines can be used to probe the gas orbiting near the event horizon. The technique of reverberation mapping uses variability of these lines to measure the mass and perhaps the spin of the black hole that powers active galaxies.
In the Milky WayEdit
- The star S2 follows an elliptical orbit with a period of 15.2 years and a pericenter (closest distance) of 17 light-hours (1.8×1013 m or 120 AU) from the center of the central object.
- From the motion of star S2, the object's mass can be estimated as 4.1 million M☉, or about 8.2×1036 kg.
- The radius of the central object must be less than 17 light-hours, because otherwise S2 would collide with it. Observations of the star S14 indicate that the radius is no more than 6.25 light-hours, about the diameter of Uranus' orbit.
- No known astronomical object other than a black hole can contain 4.1 million M☉ in this volume of space.
Infrared observations of bright flare activity near Sagittarius A* show orbital motion of plasma with a period of 45±15 min at a separation of six to ten times the gravitational radius of the candidate SMBH. This emission is consistent with a circularized orbit of a polarized "hot spot" on an accretion disk in a strong magnetic field. The radiating matter is orbiting at 30% of the speed of light just outside the innermost stable circular orbit.
On January 5, 2015, NASA reported observing an X-ray flare 400 times brighter than usual, a record-breaker, from Sagittarius A*. The unusual event may have been caused by the breaking apart of an asteroid falling into the black hole or by the entanglement of magnetic field lines within gas flowing into Sagittarius A*, according to astronomers.
Outside the Milky WayEdit
Unambiguous dynamical evidence for supermassive black holes exists only in a handful of galaxies; these include the Milky Way, the Local Group galaxies M31 and M32, and a few galaxies beyond the Local Group, e.g. NGC 4395. In these galaxies, the mean square (or rms) velocities of the stars or gas rises proportionally to 1/r near the center, indicating a central point mass. In all other galaxies observed to date, the rms velocities are flat, or even falling, toward the center, making it impossible to state with certainty that a supermassive black hole is present. Nevertheless, it is commonly accepted that the center of nearly every galaxy contains a supermassive black hole. The reason for this assumption is the M-sigma relation, a tight (low scatter) relation between the mass of the hole in the 10 or so galaxies with secure detections, and the velocity dispersion of the stars in the bulges of those galaxies. This correlation, although based on just a handful of galaxies, suggests to many astronomers a strong connection between the formation of the black hole and the galaxy itself.
The nearby Andromeda Galaxy, 2.5 million light-years away, contains a (1.1–2.3)×108 (110–230 million) M☉ central black hole, significantly larger than the Milky Way's. The largest supermassive black hole in the Milky Way's vicinity appears to be that of M87, at a mass of (6.4±0.5)×109 (c. 6.4 billion) M☉ at a distance of 53.5 million light-years. The supergiant elliptical galaxy NGC 4889, at a distance of 336 million light-years away in the Coma Berenices constellation, contains a black hole measured to be 2.1×1010 (21 billion) M☉.
Masses of black holes in quasars can be estimated via indirect methods that are subject to substantial uncertainty. The quasar TON 618 is an example of an object with an extremely large black hole, estimated at 6.6×1010 (66 billion) M☉. Its redshift is 2.219. Other examples of quasars with large estimated black hole masses are the hyperluminous quasar APM 08279+5255, with an estimated mass of 2.3×1010 (23 billion) M☉, and the quasar S5 0014+81, with a mass of 4.0×1010 (40 billion) M☉, or 10,000 times the mass of the black hole at the Milky Way Galactic Center.
Some galaxies, such as the galaxy 4C +37.11, appear to have two supermassive black holes at their centers, forming a binary system. If they collided, the event would create strong gravitational waves. Binary supermassive black holes are believed to be a common consequence of galactic mergers. The binary pair in OJ 287, 3.5 billion light-years away, contains the most massive black hole in a pair, with a mass estimated at 18 billion M☉. In 2011, a super-massive black hole was discovered in the dwarf galaxy Henize 2-10, which has no bulge. The precise implications for this discovery on black hole formation are unknown, but may indicate that black holes formed before bulges.
On March 28, 2011, a supermassive black hole was seen tearing a mid-size star apart. That is the only likely explanation of the observations that day of sudden X-ray radiation and the follow-up broad-band observations. The source was previously an inactive galactic nucleus, and from study of the outburst the galactic nucleus is estimated to be a SMBH with mass of the order of a million solar masses. This rare event is assumed to be a relativistic outflow (material being emitted in a jet at a significant fraction of the speed of light) from a star tidally disrupted by the SMBH. A significant fraction of a solar mass of material is expected to have accreted onto the SMBH. Subsequent long-term observation will allow this assumption to be confirmed if the emission from the jet decays at the expected rate for mass accretion onto a SMBH.
In 2012, astronomers reported an unusually large mass of approximately 17 billion M☉ for the black hole in the compact, lenticular galaxy NGC 1277, which lies 220 million light-years away in the constellation Perseus. The putative black hole has approximately 59 percent of the mass of the bulge of this lenticular galaxy (14 percent of the total stellar mass of the galaxy). Another study reached a very different conclusion: this black hole is not particularly overmassive, estimated at between 2 and 5 billion M☉ with 5 billion M☉ being the most likely value. On February 28, 2013 astronomers reported on the use of the NuSTAR satellite to accurately measure the spin of a supermassive black hole for the first time, in NGC 1365, reporting that the event horizon was spinning at almost the speed of light.
In September 2014, data from different X-ray telescopes has shown that the extremely small, dense, ultracompact dwarf galaxy M60-UCD1 hosts a 20 million solar mass black hole at its center, accounting for more than 10% of the total mass of the galaxy. The discovery is quite surprising, since the black hole is five times more massive than the Milky Way's black hole despite the galaxy being less than five-thousandths the mass of the Milky Way.
Some galaxies, however, lack any supermassive black holes in their centers. Although most galaxies with no supermassive black holes are very small, dwarf galaxies, one discovery remains mysterious: The supergiant elliptical cD galaxy A2261-BCG has not been found to contain an active supermassive black hole, despite the galaxy being one of the largest galaxies known; ten times the size and one thousand times the mass of the Milky Way. Since a supermassive black hole will only be visible while it is accreting, a supermassive black hole can be nearly invisible, except in its effects on stellar orbits.
In December 2017, astronomers reported the detection of the most distant quasar currently known, ULAS J1342+0928, containing the most distant supermassive black hole, at a reported redshift of z = 7.54, surpassing the redshift of 7 for the previously known most distant quasar ULAS J1120+0641.
Hawking radiation is black-body radiation that is predicted to be released by black holes, due to quantum effects near the event horizon. This radiation reduces the mass and energy of black holes, causing them to shrink and ultimately vanish. If black holes evaporate via Hawking radiation, a supermassive black hole with a mass of 1011 (100 billion) M☉ will evaporate in around 2×10100 years. Some monster black holes in the universe are predicted to continue to grow up to perhaps 1014 M☉ during the collapse of superclusters of galaxies. Even these would evaporate over a timescale of up to 10106 years.
- Black holes in fiction
- Central massive object
- Galactic Center – Rotational center of the Milky Way galaxy
- Galactic Center GeV Excess – Unexplained gamma-ray radiation in center of Milky Way galaxy
- General relativity – Einstein's theory of gravitation as curved spacetime
- Hypercompact stellar system
- List of most massive black holes – Wikipedia list article
- Spin-flip – A sudden change of spin axis caused by merging with another black hole
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This new theory that accepts that the Universe is going through periodic expansions and contractions is called "Big Bounce"
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Authors: Sarah Blunt, Eric L. Nielsen, Robert J. De Rosa, et al.
Leading Author’s Institution: Department of Physics, Brown University, Providence, RI 02912, USA
Status: Accepted for publication in ApJ [open access]
Discoveries of exoplanets happen quite often these days, so much so that the discovery alone is not enough to satisfy collective scientific curiosity. Discovery with direct imaging, in particular, does not usually reveal much about the planet, other than its existence. However, unlike the transit method and radial velocity measurements, direct imaging allows us to observe exoplanets with very long periods, which is an under-sampled population in the list of currently known exoplanets. Still, this double-edged method of measurement cannot give us full orbital parameters of the planetary system. This population of exoplanets cannot be easily observed by any other method but direct imaging, so the question arises—how can we find the orbital properties of this planetary system with the measurements we have?
The authors of this paper use a new rejection sampling method to quickly find the orbits of these exoplanets, called Orbits for the Impatient (OFTI) . This method generates random orbital fits from astrometric measurements, then scales and rotates the orbits, and then reject orbits too unlikely. A visualization of this process is shown in Figure 1.
This method uses astrometric observations and their uncertainties with prior probability density functions to produce posterior probability density functions of generated orbits. The main process of a rejection sampling method goes like this: the code generates random sets of orbital parameters, calculates a probability for each value, then rejects values with lower probabilities. The rejection process in OFTI is determined by comparing the generated probability to a selected number in (0,1). If the generated probability is greater than the random variable, then the orbit is accepted. This process repeats until any desired numbers of orbits have been selected.
Usually, algorithms such as Metropolis-Hastings MCMC are used for orbital fitting problems. However, this method takes far less time than an MCMC approach. The OFTI trials are independent, so the fitting and rejection-sampling can be done several times without incurring a bias in fitting. Running OFTI for several successive trials gives an unbiased estimate of the orbit up to 100 times faster than traditional Metropolis-Hasting MCMC fitting.
You may wonder how this method manages to run quickly without compromising the accuracy of its results. The answer to this musing is, of course, clever computational and statistical techniques tricks. OFTI uses vectorized arrays rather then iterative loops when possible and is specifically designed to run multiple trials in parallel. Since there is an associated error with the astrometric measurements that OFTI uses to generate orbits, it first calculates the minimum χ 2 value of all orbits tested during an initial run. Then it subtracts the minimum χ 2 value from all other generated χ 2. This way, orbits with an artificially high χ 2 are not unfairly flat-out rejected. OFTI also confines the inclination and mass based on prior measurements, then uses the maximum, minimum an standard deviation of the array to change the range of values for these parameters, which prevents the generation of obviously unlikely orbits.
In this paper, the authors use this fitting method to find orbital parameters for 10 directly imaged exoplanets and other objects, including brown-dwarfs and low-mass stars. The objects have at least two measured epochs of astrometry each; however in these cases, the orbit has not yet been measured because the measurements only cover a short range of the objects’s orbit, but using OFTI they successfully solved for the orbit of all of the aforementioned sub-stellar objects. The fitting for one of these objects,GJ 504 b, the current coldest imaged exoplanet, is shown in Figure 2.
The most obvious application of this new process is long-period exoplanets, but the authors also solve for the orbits of a variety of other systems, including trinary stars and brown dwarf systems. OFTI is also very useful in planning follow-up observations of targets. This method is incredibly useful to not only planetary scientists but also to all kinds of stellar specialists. Impatient scientists can now use this method to achieve quick and accurate results, which are, quite frankly, the best kind of results. | 0.878274 | 3.888044 |
Astronomers have discovered a new population of foreign asteroids that have been quietly orbiting the Sun on the outskirts of our Solar System.
These 19 space rocks have been right under our noses the entire time, almost since the Solar System formed some 4.5 billion years ago. But they were hidden amongst all the other objects part of a group known as the Centaurs, according to a research paper published in the Monthly Notices of the Royal Astronomical Society on Thursday.
Centaurs describe small bodies, mostly with unstable orbits, that orbit the Sun faraway, near the outer planets. They can be difficult to detect due to their small sizes; scientists estimate that there may be somewhere between 44,000 to more than 10,000,000 of these objects. A tiny proportion of asteroids in the group, however, are unlike all the others.
"We examined 17 multiple-opposition high-inclination Centaurs and the two polar trans-neptunian objects 2008 KV42 and (471325) 2011 KT19," the paper's abstract read. "The statistical distributions show that their orbits were nearly polar 4.5 Gyr in the past, and were located in the scattered disc and inner Oort cloud regions."
In short, these 19 asteroids have very odd orbits. When traced back in time they would have been circling the Sun at inclinations of nearly 90 degrees compared to the flat disk that the planets formed in.
The explanation for their existence is that they must have been captured from another nearby star when the Sun was forming, the researchers from the Observatoire de la Côte d'Azur, France, and São Paulo State University, Brazil, suggested.
If you want to take social distancing to the next level, and go to the Moon, take this: A complete lunar geology mapREAD MORE
“The close proximity of the stars meant that they felt each others’ gravity much more strongly in those early days than they do today,” said Fathi Namouni, lead author of the study. “This enabled asteroids to be pulled from one star system to another.”
The researchers built simulations of the incomers' orbits by taking into account their properties described in existing datasets. Their sizes range from 10km (6.3 miles) to 300km (186 miles across) in diameter.
“The discovery of a whole population of asteroids of interstellar origin is an important step in understanding the physical and chemical similarities and differences between Solar System-born and interstellar asteroids,” said co-author Maria Morais.
“This population will give us clues about the Sun’s early birth cluster, how interstellar asteroid capture occurred, and the role that interstellar matter had in chemically enriching the Solar System and shaping its evolution.”
An asteroid heading to Earth looks like it's, erm, wearing a mask
Here’s another asteroid oddity to marvel at: Astronomers at the Arecibo Observatory in Puerto Rico operated by the University of Central Florida are tracking asteroid 1998 OR2 approaching Earth.
A doppler radar scan of the asteroid on April 17 showed the outer edge of the object looks rounded, with a dimple in the center. In these times of coronavirus concern, someone thought it looked a bit like a mask and put out a press release.
“The small-scale topographic features such as hills and ridges on one end of asteroid 1998 OR2 are fascinating scientifically,” said Anne Virkki, head of Planetary Radar at the observatory. “But since we are all thinking about COVID-19 these features make it look like 1998 OR2 remembered to wear a mask.”
Don’t worry, the asteroid will also be abiding by social distancing rules and will come no closer than 16 times the distance between the Earth and the Moon on April 29, then head off around the Sun again. ® | 0.900316 | 3.880858 |
The extension of astronomical study beyond the solar system is the observation of the stars, which constitute the major population of our Milky Way galaxy and the other galaxies. Ancient civilizations sometimes thought of the stars as small lights hanging from a celestial dome or as holes in the dome through which the fires of hell could be seen. The Greek astronomers alluded to the stars as suns, and the Arabic astronomers were aware of this possibility as well, but it was not until the time of Copernicus that stars were definitely established as bright, distant objects. In the following years it was determined that stars are balls of hot, glowing gases. However, men did not learn the source of stellar energy until recent decades.
Distance and Brightness Measurement
The ability to measure immense distances is essential to the study of stars. Astronomers have had to develop new techniques and adopt new units of measurement. Thus stellar distances are usually expressed in light-years or parsecs. A light-year is the distance that light travels in one year, moving at approximately 186,000 miles, or 300,000 kilometers, per second. One parsec is equivalent to 3.26 light-years.
Measurement of distances to nearby stars is relatively straightforward, the method employed being similar to that of the surveyor. The radius of the earth’s orbit is used as a baseline and also as a distance unit called the astronomical unit. The position of a nearby star is observed in relation to the background of more distant stars. The star is again observed from the opposite point of the earth’s orbit, and its relative position is seen to have changed. This is called parallax, and the angle subtended by the astronomical unit at the distance of the star is called the parallactic angle.
If the star’s apparent brightness is measured, the astronomer can then compute the actual brightness of the star. For convenience, 10 parsecs is used as the standard distance for expressing actual brightness. That is, the brightness of the star as it would appear at a distance of 10 parsecs from the earth is considered to be its actual brightness, or absolute magnitude.
Magnitude. In expressing stellar brightness, astronomers reduce their measurements to a convenient power relation that has its origins in the response of the eye to light. This response is measured in magnitudes and is related to the intensity of the stimulus on a logarithmic scale. The term magnitude has been used to express stellar brightness since the days of the ancient Greek astronomers, who thought that a star’s brightness depends simply on its size or magnitude. (It is now known that other factors are involved as well.)
The Hertzsprung-Russell Diagram. If the absolute magnitudes of a large number of stars are determined and plotted against the temperatures of these stars, a diagram known as the Hertzsprung-Russell (H-R) diagram results. This type of diagram is fundamental to astronomy because it reveals that there is a systematic organization to the physical properties of the stars.
The H-R diagram is of immediate interest here, however, because it is also of importance in the measurement of stellar distances. The astrometric technique used for measuring distances to nearby stars cannot be used for greater distances because the parallactic angle simply becomes too small to measure. However, if an astronomer can identify where a distant star would lie on an H-R diagram, he then knows its absolute brightness and can determine its distance. Since an astronomer can measure very feeble light sources, this photometric method is a powerful method indeed.
The Period-Luminosity Relation and Hubble’s Law. Nature has provided two other methods of establishing stellar distances. One method involves true variable stars—pulsating stars with a periodic change in brightness that is related to their changes in size. The period of pulsation of any gaseous sphere is related in a simple way to the density of the sphere. Basically, the more dense a star is, the shorter is its period of pulsation. Also, the more dense a star is, the smaller it is, and hence the smaller is its surface area. Other things being equal, therefore, the denser a star is, the fainter is its absolute magnitude.
Astronomers have established a period-brightness, or period-luminosity (P-L relation), for pulsating stars. All that they need to do to use the P-L relation is to measure the period of pulsation of a star. They then know the star’s absolute magnitude and can compute its distance. Pulsating stars are very easily recognized even in other nearby galaxies, and the distances to these galaxies can therefore be measured.
The other method of measuring distances pertains to the galaxies themselves. When galaxies are far enough away, they all appear to be moving away from us. The speed of their recession seems to follow a simple law called Hubble’s law (after Edwin Hubble), which states that the speed is proportional to the distances of the galaxies. Using this law, astronomers can measure the great distances of the universe.
Stellar Masses and Composition
Distances do not tell astronomers how stars are born, evolve, and die, however. To obtain such information they must also be able to measure the mass and determine the composition of stars.
Mass is a difficult property to measure, because it is necessary to weigh a star against something. That “something” can only be another star, and for this reason astronomers study binaries (double-star systems in which two stars revolve around one another). From such studies it has been deduced that there is a fundamental relation between a star’s mass and its luminosity—the so-called mass-luminosity relation. This relation holds true for most stars but there are exceptions, notably those stars known as white dwarfs. To increase knowledge about stellar masses a considerable amount of work must be done over the coming years.
The problem of composition is even more perplexing. A spectrogram of a star reveals only those elements contained in the star’s atmosphere, mainly the lower chromosphere. From such information an astronomer has to infer the composition of the main body of the star. All of the available evidence leads to the conclusion that, in general, stars are composed of 70 percent hydrogen, 28 percent helium, and 2 percent heavier elements by weight. Different stellar models can be set up and studied on a computer by varying these percentages. In this way an astronomer can look at stellar evolution in theory and then test the theory by observation.
Classification of Stars
Spectrographs are also used in the classification of stars. That is, the spectral classification of a star is determined by the presence or absence of certain lines in its spectrum and by the strength and shape of those lines. Since the appearance of the lines depends primarily upon the brightness and temperature of the star, it is possible to simplify the identification of stars to the point where an astronomer need only look at the spectrum of a star to do this.
The basic classification system in general use today is the Morgan-Keenan system, referred to as the MK Classification. It is essentially an excellent extension and refinement of an earlier Harvard Classification. In the MK system, stars are assigned the letters O, B, A, F, G, K, or M, in order of decreasing temperature. Each letter type is further subdivided into 10 classes, 0 through 9, again in order of decreasing temperature. There are also certain types of stars that do not fit into the general system and are instead assigned special letters. Thus carbon, or C, stars are similar to the cool M stars in temperature but have quite different spectra.
Stars of the same spectral type and lying at about the same distance from the earth are often quite different in brightness. Since the stars must have the same surface temperature, this can only mean that they have different surface areas—that is, they are different in size. This in turn leads to the concept of luminosity classes and the fact that there are dwarf stars, giant stars, and even supergiant stars. In the MK Classification these types are indicated by additional numerals, ranging from 0 for the most luminous supergiants to VI for subdwarfs. For example, the sun is a type G2V star; a G2III star would be a giant with the same temperature as the sun.
Giant stars are objects of great interest in modern astronomy. These huge stars are very tenuous. In fact, their density is so low that it is possible for matter to escape from them, and this has been observed to occur. Intensive studies of this mechanism of loss of mass, with subsequent enrichment of the interstellar medium, are currently under way.
Another area of interest to modern astronomers is the study of stellar evolution. It is thought that there is an evolutionary order to the types of stars, and that the life history of a star like the sun can be described in the following way.
The star begins as a cloud of dust and gas in the interstellar medium. Somehow, perhaps because of magnetic fields, the cloud exceeds a certain density and begins to collapse inwards. Pressure in the protostar’s center causes it to glow. In order to reach a stable configuration, convective currents carry heat to the surface of the protostar, which rapidly contracts until it is one of the main sequence of stars on the H-R diagram and is generating its energy by nuclear fusion. This process takes about a million years. The star then remains stable for billions of years until a large portion of its core is converted to helium by nuclear reactions. At this point the star expands because of increased internal temperatures and becomes a giant, until continuing reactions cause the core to collapse slowly again. The star continues to contract until it becomes a white dwarf. The dying star takes billions of years to cool off and become a black dwarf, a burned-out sun.
For stars a little less massive than the sun the evolutionary process may take much longer, whereas stars much less massive may proceed directly towards becoming black dwarfs in only a few million years. On the other hand, events in stars much more massive than the sun are more drastic and proceed at a much faster rate. In such stars it is thought that the collapse of the core after the giant stage occurs in a catastrophic way, producing what is known as a nova—an exploding star. If the star is very massive, it may become a supernova. After the explosion a white dwarf remains, with a great amount of ejected material being returned to the interstellar medium. In this process the content of the interstellar medium is altered, and the next stars formed from it will be quite different.
Studies of such evolutionary concepts have only begun. Testing the results of these studies requires a combination of observational efforts covering the entire electromagnetic spectrum. One area of study that may be very useful is that of binary systems in which the stars are quite close to one another. Spectroscopic evidence indicates that such stars are constantly exchanging mass—that is, one star is gaining mass at the expense of the other. In some close binaries the stars are both losing mass, which is streaming away from the system in a great pinwheel pattern. In all such systems the stars are evolving faster than they ordinarily would and provide interesting subjects for evolutionary studies. | 0.894555 | 4.041357 |
Living on Mars
Children of Mars
| ||Automatic translation|| ||Category: probes and satellites|
Updated February 01, 2014
|The journey to Mars is a dream for humans much more ambitious than the trip to the Moon made in the 1970s (Apollo programs). What are the obstacles to us in 2014, to send men to Mars and especially go back healthy on our planet?|
In reality, the obstacles are numerous but the main current brakes are technological, financial and human order. To overcome these obstacles and gain all the necessary technology, it might take many decades. From Mars and return to Earth, is a mission impossible for the 2020s, as the pitfalls are many. As for live, simulations as Mars 500 show the enormous human and technical complexity of an such mission. Since the 1960s, scientists studying the planet Mars through the many space missions past and present (Mars Global Surveyor, Mars Pathfinder, Mars Odyssey, Mars Express, Mars Exploration Rover, Mars Reconnaissance Orbiter, Phoenix, Mars Science Laboratory). Their probes and robots show to us, regularly hostile environment of Mars and scientists now have a pretty good idea of the history of its water, its climate, its basement, potential dangers to the surface of Mars, possible landing sites for human and living conditions for a manned mission.
| ||But it is not enough to live on Mars. Prior it will take to reach Mars, make a number of intermediate missions to gradually acquire the necessary technologies to children of Mars. |
In addition, the necessary budget is huge, a global collaboration of government and nongovernmental organizations is essential. Just the trip would cost $ 10 billion.
To go to Mars must be in good health, and that is why the main preoccupation of scientists is to preserve the health of men and women traveling in weightlessness. Already in the 1970s, with the Soviet Soyuz 9, had tested long stays in space. After only 18 days, the bones and muscles of astronauts had atrophied (muscle loss 30%).
Since then, in space stations, astronauts do a series of exercises several hours a day to maintain their muscle mass, but the mass loss remains high (15% muscle loss every 300 days). But this is not the most worrying to health. The stress caused by long journeys is huge and psychological equilibrium is disrupted by this isolation. The choice of men and women who will go, will be extremely selective because they will hold several years.
Image: The thin atmosphere of Mars contains carbon dioxide and nitrogen. The pressure is 0.6 kPa on Earth while it is 101 KPa. The gravity on Mars is 0.376 g while on Earth it is 1 g. The sun's rays are harmful and as children of the moon, it will protect from the sun. Under these conditions a pressurized suit is mandatory. The environment of Mars is particularly hostile, there is no oxygen, and the temperature reached -60 ° C on average. Credit astronoo
The journey to Mars
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To minimize the cost of travel, the mission should last at least 15 years because the most favorable alignments between Earth and Mars (shortest distance) occur only very rarely.
The shortest distance between two bodies is when Mars is in opposition, that is to say when the Earth comes between Mars and the Sun. These oppositions are held approximately every 780 days (26 months), but given the relative eccentricity of the orbits of Mars and Earth, the shortest distance between the Earth and Mars (55 million kilometers) does not return all 26 months. it will be necessary to wait the concordance between the perihelion of Mars and the opposition of the two planets, or 7 oppositions, i.e. 15 years.
In these favorable conditions, astronauts traveling 6 months to go and less than four months for the return, in the best conditions. Astronauts will be confined in a cramped box and the psychological aspect of this confinement is difficult to manage, all human beings are not capable, moreover very little will support. It will make a drastic selection of the candidates.
Live for months in complete autonomy in a capsule requires to take oxygen, water and food needed to travel. For a journey of nine months, the mass of oxygen, water and food needed is huge. Each day, a man consumes about 1 kg of food, 1 kg of oxygen and 3 kg of water. To optimize the load, so it will recycle water and waste and carry a mini terrestrial ecosystem that allows the survival of the crew during this long journey. For oxygen it will take the CO2 discharged and produce oxygen through photosynthesis of plants. For water, it will be necessary to recycle the urine. For food, it will be necessary to recycle organic waste and grow vegetables in the waste. In addition it must be ensured that no pathogen invades the capsule. The psychological balance between men and women will be strongly put to the test. Although astronauts will be confined in a cramped box, facing to their confinement, the outward journey remains the easiest part of the mission.
Upon arrival on the Martian soil, candidates must be autonomous and mostly stay healthy and this task is much more complex than it seems. The Martian atmosphere is hostile, the light is low, the solar radiations are harmful, there is no oxygen, there is no liquid water and the temperature reached average -60 ° C and can drop to -130 ° C. On the desert surface of Mars, nothing grows, it will be necessary to find water, produce energy, oxygen, water and food in mini heated greenhouses. To build this, it will require a lot of materials, absent on Mars. It will not be possible to carry the materials needed to build a power plant, a boiler, a water reservoir, a unit of wastewater treatment, a radio room, a laboratory, a workshop, offices, rooms, sports halls, a kitchen, a restaurant, a library, etc. As for the return to Earth, it is the most obscure part of the mission. We have to wait a giant technological leap forward to consider.
nota: MELiSSA (Micro-Ecological Life Support System Alternative) is a project whose objective is the study of an ecosystem of micro-organisms and plants. This tool allows to better understand the behavior of artificial ecosystems and the development of technology for a future regenerative life support system for manned space missions of long duration, for example a lunar base or a mission to Mars. The driving force of MELISSA is recovering the food , water and oxygen from wastes (faeces, urea), carbon dioxide and minerals. Based on the principle of "aquatic" ecosystem, MELISSA has 5 compartments colonized respectively by thermophilic anoxygenic bacteria, photohererotrophic bacteria, nitrifying bacteria, photosynthetic bacteria, higher plants, and the crew. Hazardous waste and air pollutants are processed using the natural function of plants that in their turn provide food and contribute to the purification of water and oxygen to revitalize the air.
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Image: since 1997, the French-Italian Concordia base in Antarctica, located at an altitude of 3233 meters, is one of three research stations in the Antarctic continent. The other two are the U.S. Amundsen-Scott base and the Russian Vostok base. During the 9 months of winter, Concordia hosts in especially difficult circumstances, fifteen people in total autonomy, in the coldest region of the world. On the foreground image, polygonal buildings placed on six hydraulic cylinders to compensate variations in levels of frozen ground and in the background the entire power station (central, boiler, water tank, radio, laboratory, bedrooms, kitchen, restaurant, library, ...).
While these scientists are on Earth, all they need unless oxygen need assistance terrestrial. To supply the people of Concordia, land and air transport used are huge. Approximately 350 tons of supplies arrive by three land convoys organized during the summer season. The isolation for a long time a small group of human beings is ideal for define type portraits for an exploration of Mars.
The roadmap for Mars mission
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Mission ISECG has identified a set of tasks required in the lunar vicinity and on the surface of the Moon, before considering a manned mission to Mars, for the years 2030.
Ten space agencies met in Kyoto August 30, 2011 under the ISECG (International Space Exploration Coordination Group) to discuss the development of a common roadmap for coordinated space exploration internationally. Before sending men to Mars, it will return to the Moon and send humans to an asteroid. Each of these objectives will allow space agencies to gradually acquire the necessary technologies to reach Mars. Roadmap to prepare for a possible manned mission to Mars, highlights efforts to achieve financial and technological leaps to cross by global governmental and non-governmental organizations. Sustainable exploration, affordable and productive of the surface of Mars by humans is a very long term goal. The global roadmap for the exploration of Mars, creates a framework for the coordination of preparatory activities. This global roadmap Mars exploration is linked to a set of priorities and goals of preliminary respect and there are not that technological objectives. Of course we need to develop exploration technologies and the infrastructure needed to live and work beyond low Earth orbit.
But we must also engage the public, to interactive manner, as in a common space exploration cause. Human missions beyond low Earth orbit are possible with a coordinated international participation because the pitfalls are considerable. It will take a lot of expertise to enhance safety, expand human presence beyond low-Earth orbit to continually increase the number of people on each destination, extending the duration of manned missions in self-sufficiency, reduce the risk of space environment on human health and the technological equipment and finally to highlight the benefits to the whole of humanity.
nota: Agencies involved in the development of a common roadmap for coordinated space exploration are: ASI (Italy), CNES (France), CSA (Canada), DLR (Germany), ESA (European Space Agency), JAXA (Japan), KARI (Republic of Korea), NASA (United States), Roscosmos (Russia), UKSA (UK).
Image: The roadmap idealistic to prepare a possible manned mission to Mars, highlights the financial efforts to achieve. The roadmap should allow to achieve this objective covers a period of 25 years and describes an sequence of of intermediaries robotic and human necessary. | 0.835132 | 3.085457 |
|The Scientific Objectives
listed in the Introduction are designed to produce a much more detailed
picture of the
heliosphere and what it looks like. They will specifically
produce answers on the shape of the termination shock and on the thickness
of both the inner and outer heliosheaths.
The Scientific Objectives lead to a group of Observing Objectives. These are a detailed description of what phenomena will be measured at what distances from the Sun, and where the measurements are most important.
Refer to the horizontal bars on page 6 for identification of the Observing Objectives and where the observations will be concentrated. (follow links below to details on the phenomena)
Heliosheath Solar Wind Plasma
| Solar wind plasma expands
more-or-less freely until it meets the local interstellar medium (LISM).
On the simplest level, the interaction is stagnation point flow
between two fluids flowing towards each other. In the example shown here,
there is a spherical source (the Sun) of outflow and a planar flow from
the right. Both flows come to a halt (in the solar frame of reference)
at the stagnation point. As the flows approach the stagnation
point, they are turned. The LISM flow dominates so it forces the solar
wind to turn and eventually flow in the same direction as the LISM flow,
down the heliotail. The surface that divides the two flows is the
Solar wind flow is initially supersonic. Therefore, it will generally have to be slowed before it can be turned to flow down the heliotail. Solar wind flow normally will slow abruptly at the termination shock, with supersonic flow inside the termination shock and subsonic flow outside the termination shock - in the inner heliosheath. The termination shock is thought to be at ~100 AU.
The direction of solar north (solar rotation) is indicated here by v. However, the ideal situation shown here is axisymmetric about the axis in the LISM upstream direction.
As solar wind plasma passes through the termination shock it is heated back to coronal temperatures of ~one million degrees. It is also compressed by a factor of <~ four, although the density is so small at 100 AU that the compression still leaves a very sparse plasma of less than one particle per cubic centimeter (0.1 - 0.3 per cubic centimeter).
The flow speed just inside the termination shock is 400-750 km/s and 100-200 km/s just beyond the termination shock. This decreases as the flow is turned and the flow speed in heliotail is ~25 km/s.
If the LISM flow speed is faster than the sound and Alfven speeds then there will also be a bow shock out in front of the stagnation point. In this case, there will also be an outer heliosheath between the heliopause and the bow shock.
Interplanetary Magnetic Field (click on title to go to detailed discussion)
| The interplanetary magnetic field (IMF)
is drawn into a Archimedian spirals as it is carried away from the
Sun by the solar wind. This happens because the footpoints of the field
remain attached to the Sun, which is rotating once every 25.5 days. Since
it takes on the order of one year for the solar wind to reach the termination
shock, 10-20 complete spirals are formed over this distance. These
spirals are shown in Figure OO.02 for three magnetic field lines at
solar latitudes of 6, 45, and 84 degrees north (green, orange, and red,
At the termination shock the IMF is amplified in exactly the same way the solar wind plasma is compressed. Beyond the termination shock the IMF is further amplified as the solar wind in the inner heliosheath is slowed and turned. The field amplification is shown here by the more tightly spiraled magnetic field in the inner heliosheath.
Figure OO.02 is highly idealized because it neglects several
phenomena which might otherwise mask or even obliterate the perfect spirals
illustrated here. These phenomena include, but are not limited to, footpoint
wandering at the Sun due to convective motions in the photosphere and
fluctuations introduced in the corona, solar wind, and at the termination
The heliospheric magnetic field is of little dynamical importance throughout most of the heliosphere. But, because of the amplification in the inner heliosheath, it is possible for the field to become strong enough to affect the flow near the stagnation point between the solar wind outflow and the incoming interstellar plasma flow, at the front of the heliopause in the upstream direction. This is called the Cranfill effect.
Even inside the termination shock, the IMF is not ever smooth. Fluctuations in direction occur on all time scales down to far less than one second. At times longer than a day, the fluctuations are primarily due to changes in the dominant polarity at the Sun and are discussed below in relation to reconnection. At shorter time scales, the fluctuations are due to:
Field Direction Fluctuations
The IMF in the vicinity of the stagnation point changes polarity at least twice every solar rotation period of 25.5 days, and also fluctuates in direction due to the entrained MHD turbulence in the inner heliosheath. At the same time, the magnetic field is being amplified by "pile-up" as it is carried towards the stagnation point in the upstream direction. Therefore, near the stagnation point the plasma beta (ratio of internal energy density to magnetic field energy density) is much less than one.
Therefore, reconnection probably occurs first on the heliopause in the vicinity of the stagnation point in the upstream direction. One of the principle reasons for sending The Interstellar Probe in this direction is to have it pass through this reconnection region.
A low beta plasma in the inner heliosheath is pressed against what is probably either a low beta or O beta interstellar plasma in the outer heliosheath. The polarity being favorable for reconnection. The magnetic fields should be generally oppositely directed across the heliopause at the stagnation point for reconnection to take place. This is satisfied during roughly half of any given 25 day interval since the magnetic field near the equator always alternates polarity over 25 days due to solar rotation and fluctuates continuously in direction.
In the anomalous component of cosmic rays, fluxes of helium, nitrogen, oxygen, neon, protons, and carbon are observed to be enhanced in a region of the energy spectrum ranging from a kinetic energy of 20 MeV to ~300 MeV. The radial intensity gradient of these particles is positive out to the maximum distance reached by current spacecraft, indicating that this component is not of solar origin, an that it probably originates in the outer solar system. It is likely that anomalous cosmic rays are particles in the solar wind that are accelerated at the termination shock. The particles in the solar wind are not, however, ambient solar wind plasma. instead, the particles are initially neutral interstellar atoms that have streamed into the heliosphere as a consequence of its motion through the LISM. They have become ionized and picked up by the solar wind and then carried with the IMF back out to the termination shock. There they are accelerated to the observed energies. It was predicted that the particles would be predominantly in a charge state of +1 if the hypothesis for their origin were correct and this has recently been confirmed.
Anomalous Cosmic Rays
Interstellar neutral gas flows relatively unimpeded into the heliosphere, although it possibly experiences filtration at the heliospheric boundaries. Neutral interstellar hydrogen is especially susceptible to the effects of filtration, being decelerated and heated in passing from the LISM into the heliosphere. Atoms flowing into the supersonic solar wind inside the termination shock can undergo either photoionization or charge exchange ionization and the new ions almost instantaneously respond to the electromagnetic fields in the solar wind. The newly born ions immediately gyrate about the IMF, after which they experience scattering and isotropization by either ambient or self-generated low-frequency electromagnetic fluctuations in the solar wind plasma. Since the newly born ions are eventually isotropized, their mean bulk velocity is now that of the solar wind i.e., they convect with the solar wind flow, and are then said to be picked up by the solar wind. The isotropized pickup ions form a distinct population of energetic ions (~1 KeV) in the solar wind whose origin is the interstellar medium and which serves as the seed population for anomalous cosmic rays.
Neutral Hydrogen UV Glow
Neutral Hydrogen UV Glow
There are at at least 70,000 trans-Neptunian objects in the outer solar system with diameters larger than 100 km in the radial zone extending outwards from the orbit of Neptune (at 30 AU) to 50 AU. There may be many more bodies beyond 50 Au, but these are presently beyond the limits of detection. Observations show that the trans-Neptunians are mostly confined within a few degrees of the ecliptic, leading to the realization that they occupy a ring or belt surrounding the Sun. This ring is generally referred to as the Kuiper Belt.
Kuiper Belt Dust
Energetic neutral atoms
Energetic Neutral Atoms
Pileup (H, Ions, Dust, Interstellar Magnetic Field)
Large Interstellar Dust Grains
|Dust grains in the diffuse inerstellar medium have been believed to be smaller than 0.5 microns until larger ones have been discovered by the dust detectors on-board the interplanetary spacecraft Ulysses and Galileo. Since large grains are much less abundant than small interstellar dust grains, they do not contribute much to the extinction of starlight and are thus hard to observe spectroscopically. Therefore, in-situ measurements are needed to measure the flux and/or composition of the large-grain component in interstellar space. Despite their low spatial concentration, large interstellar grains carry a large fraction of the total dust mass in the local interstellar medium, and potentially distribute large amounts of refratory/organic substances over large spatial scales.|
|Large intersellar grains penetrate the heliopause unperturbed due to their large inertia. They move in good approximation on hyperbolic trajectories through the heliosphere. The bending of the grain's trajectories towards the Sun causes their spatial density to be enhanced in a regeion downstream of the Sun. This region is called the gravitational focus and is shaped like a parabola. The picture on the right shows the calculated spatial distribution of large interstellar grains in a 20AU x 20AU plane around the Sun. The grains enter the plane from the right and move to the left. The gravitational focus is clearly visible on the right hand side of the picture.||
|This is what a interstellar dust particle might look like. Many such dust grains are collected in the upper atmosphere by aircraft flying at high altitudes. Most of these grains are believed to be interplanetary dust grains (IDPs), but grains have been found inside the IDPs that show non-solar isotopic composition. Top candidates for interstellar grains are GEMS (glass with embedded metals and sulfides) that consist mainly of amorphous silicate, which is also believed to be the major constituent of interstellar dust grains. GEMS are typically some tenths of a micron to some micron in size, and are therefore larger than "classical interstellar grains". A collection of IDPs is kept at the Astromaterial Collection Facility at the NASA Johnson Space Center.|
Small Interstellar Dust Grains
|Extinction of starlight in the EUV indicates that solid particles in interstellar space can be as small as large mono-molecules. A good fit to the spectroscopic data is achieved when considering polycyclic aromatic hydrocarbon (PAH) molecules. The largest grains that are evident from extinction measurements have diameter of about 0.5 microns. This size range can be considered as "classical" interstellar grains, because their existence was known long before the in-situ measurements of interstellar grains in the Solar System. Fits to the extinction curve indicate that the grain size distribution drops very steep to large masses, that is, small interstellar grains are much more abundant than large ones. If this is true, why haven't they been discovered in early in-situ measurements (e.g. with the instruments on-board the Pioneer 8 and 9 spacecraft)? After the obvious non-detection of interstellar dust by Pionner, it was argued that the grains develop a electrostatic charge in the plasma and radiation environment of interplanetary space, and that this charge couples them to the solar wind, which transports them out of the Solar System. This interpretation is consistent with the mass distribution of interstellar grains that have been detected in-situ by Ulyssess and Galileo.|
|Modeling the motion of small interstellar dust particles through the heliopause has shown that the solar wind magnetic field is capable of inhibiting small grains from entering the inner Solar System. The figure on the right shows the spatial distribuion of 0.1 micron grains that enter the Solar System from the right with a velocity of 26 km/s. The panel covers an area of 80AU x 80AU. The actual distribution depends on the phase of the solar cycle, since the magnetic field polarity in the solar wind changes with the cycle. As a result of the deceleration of the grains, a region of increased spatial density forms upstream of the Sun. The spatial density inside 5AU is strongly reduced during the whole 22-year solar cycle.||
|Recently, it was argued, that grains in the size range below 0.05 microns can interact strongly with the compressed magnetic field in the heliopause region, effectively diverting them around the heliosphere. Unfortunately, such small grains are out of the sensitivity range of todays in-situ dust detectors. Outside the heliosphere interstellar grains of sizes of a few tens of a nanometer should be present abundantly, as indicated by the extinction data. One very interesting quantity to measure in interstellar space is the velocity dispersion of these small grains, since the dispersion indicates the amount of disturbance that the local cloud has experienced in the past.|
Return to Introduction
Go to Mission Technology | 0.818105 | 3.932562 |
19 relations: Apparent magnitude, Bright Star Catalogue, Constellation, Cygnus (constellation), Durchmusterung, Earth, Epoch (astronomy), Flamsteed designation, Henry Draper Catalogue, Hipparcos, Kelvin, Light-year, Parsec, Smithsonian Astrophysical Observatory Star Catalog, Star, Stellar classification, Stellar parallax, Subgiant, Sun.
The apparent magnitude of a celestial object is a number that is a measure of its brightness as seen by an observer on Earth.
The Bright Star Catalogue, also known as the Yale Catalogue of Bright Stars or Yale Bright Star Catalogue, is a star catalogue that lists all stars of stellar magnitude 6.5 or brighter, which is roughly every star visible to the naked eye from Earth.
A constellation is a group of stars that are considered to form imaginary outlines or meaningful patterns on the celestial sphere, typically representing animals, mythological people or gods, mythological creatures, or manufactured devices.
Cygnus is a northern constellation lying on the plane of the Milky Way, deriving its name from the Latinized Greek word for swan.
In astronomy, Durchmusterung or Bonner Durchmusterung (BD), is the comprehensive astrometric star catalogue of the whole sky, compiled by the Bonn Observatory (Germany) from 1859 to 1903.
Earth is the third planet from the Sun and the only astronomical object known to harbor life.
In astronomy, an epoch is a moment in time used as a reference point for some time-varying astronomical quantity, such as the celestial coordinates or elliptical orbital elements of a celestial body, because these are subject to perturbations and vary with time.
A Flamsteed designation is a combination of a number and constellation name that uniquely identifies most naked eye stars in the modern constellations visible from southern England.
The Henry Draper Catalogue (HD) is an astronomical star catalogue published between 1918 and 1924, giving spectroscopic classifications for 225,300 stars; it was later expanded by the Henry Draper Extension (HDE), published between 1925 and 1936, which gave classifications for 46,850 more stars, and by the Henry Draper Extension Charts (HDEC), published from 1937 to 1949 in the form of charts, which gave classifications for 86,933 more stars.
Hipparcos was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993.
The Kelvin scale is an absolute thermodynamic temperature scale using as its null point absolute zero, the temperature at which all thermal motion ceases in the classical description of thermodynamics.
The light-year is a unit of length used to express astronomical distances and measures about 9.5 trillion kilometres or 5.9 trillion miles.
The parsec (symbol: pc) is a unit of length used to measure large distances to astronomical objects outside the Solar System.
The Smithsonian Astrophysical Observatory Star Catalog is an astrometric star catalogue.
A star is type of astronomical object consisting of a luminous spheroid of plasma held together by its own gravity.
In astronomy, stellar classification is the classification of stars based on their spectral characteristics.
Stellar parallax is the apparent shift of position of any nearby star (or other object) against the background of distant objects.
A subgiant is a star that is brighter than a normal main-sequence star of the same spectral class, but not as bright as true giant stars.
The Sun is the star at the center of the Solar System. | 0.900417 | 3.725669 |
By Sara Seager, Massachusetts Institute of Technology (MIT)
Somewhere out there, a living, breathing world peacefully orbits its star. Inhabiting the world is a dynamic ecosystem full of thriving bacteria. The life itself has no consciousness or intelligence, but the planet as a whole is an active world, connected through cycles of geophysics, chemistry, and biology in a landscape with liquid water oceans, continents, mountains and volcanoes. We imagine there could be millions or even billions of such planets in our Galaxy. Is Proxima Centauri lucky enough to host such a planet?
To find out whether or not a planet has life, it is not enough to know that the planet is rocky and if the planet orbits in the host star’s habitable zone. We must be able to investigate the planet’s atmosphere. For Proxima Cenaturi, as in most cases, we will need a to use a different telescope than one used to discover the planet (see post by Ignas Snellan). More specifically we want to observe the planet atmosphere to first assess the greenhouse power of the atmosphere to estimate whether or not the surface temperature is suitable for life. Next we want to determine if there are gases that indicate the planet is habitable. Most challenging but most exciting, we want to know if the exoplanet atmosphere contains gases that might indicate if the planet is possibly inhabited.
By habitable I mean a planet with surface liquid water oceans, since all life as we know it needs liquid water. But, since oceans are hard to identify from afar, we will look for water vapor as an indicator of water oceans. By possibly inhabited I mean the identification of signs of life by way of biosignature gases—gases that are produced by life and can accumulate in an exoplanet atmosphere to be detectable from afar. Even if we are lucky enough to detect a biosignature gas on a rocky planet orbiting Proxima Centauri, we will not know if the suspect gases are produced by tiny microbes, enormous animals, or intelligent humanoids. We also will not know if the life producing the gases is carbon based or something more exotic. We focus on what life does—life metabolizes and produces byproduct gases, not on what life is.
Oxygen is our most compelling biosignature gas. Oxygen fills Earth’s atmosphere to 20% by volume. But, without plants or photosynthetic bacteria, Earth’s atmosphere would have virtually no oxygen. Oxygen, and its photochemical byproduct ozone, have strong spectral features at a range of wavelengths, accessible with future ground- and space-based telescopes that might be able to study atmospheres of any planets discovered orbiting Proxima Centauri. If we detect oxygen, astronomers and the public alike will be absolutely ecstatic. But does an oxygen detection mean we have found alien life? No. Unfortunately the attribution of oxygen—or any gas—to life is an in depth, complicated, and somewhat subjective process. The reason is that there are many ways oxygen can be produced, and accumulate, in an exoplanet atmosphere that has nothing to do with life. We must be able to rule out all other possibilities of oxygen generation by non-biological processes. Even then, we will only be able to claim a strong suggestion of life detection not a robust detection.
A flurry of recent activity has detailed a number of different oxygen-producing scenarios that are not related to life. Most of the scenarios have to do with a lack of oxygen “sinks”. If oxygen is not destroyed, then even small quantities of oxygen can accumulate over a large amount of time. One of the more compelling oxygen false positive scenarios is related to the ultraviolet (UV) radiation of exoplanet host stars. The UV radiation splits apart molecules in the planet atmosphere, setting off a chain of chemical reactions that produce byproducts that can destroy oxygen. A major player, OH, is nicknamed the “garbage eater of the atmosphere” because of its power to destroy oxygen and other gases. M dwarf stars typically have a high far-ultraviolet radiation flux (< 200 nm) and a lower near-ultraviolet radiation flux (200-300 nm) compared to our Sun. Any exoplanet orbiting an M star will therefore be subject to different photochemistry than Earth’s atmosphere. Specifically, the chains of reactions that produces OH are weaker, owing to strong far-ultraviolet radiation. With a much smaller amount of OH compared to Earth’s atmosphere, abiotic oxygen can accumulate. To identify this false positive scenario we would need to be able to measure Proxima Cenaturi’s far-UV and near-UV radiation. Other oxygen false-positive scenarios include planets with a carbon dioxide-dominated atmosphere but little volcanic emission, an M star that took a very long time to reach a stable hydrogen burning phase, a planet undergoing a transient ocean evaporation from a runaway greenhouse effect, and more. If we are so lucky to find oxygen on Proxima Centauri, we will have a lot of further observations and atmosphere modeling work to do to understand if the oxygen can be attributed to life or if it might be a false positive.
Beyond oxygen, astronomers also consider a wide range of other biosignature gases, including methane, nitrous oxide, dimethyl sulfide, and others. Despite a growing list and detailed studies, I worry that the list of gases may be too limited, or that the types of planets modeled—usually small deviations from an Earth twin—are not broad enough to anticipate the range of what planet types are out there. If Proxima Cenaturi has a rocky planet in its habitable zone, we should do all we can to make sure we don’t miss a sign of life, just because we were too constrained in our thinking.
Life on Earth produces literally thousands of gases. Most are produced in too small quantities to accumulate to any reasonable level in Earth’s atmosphere. In addition, most are produced for highly organism-specific reasons—such as stress and signaling—that appear to be whims of evolution. Some molecules could be produced in larger quantities on another planet and/or accumulate in an exoEarth atmosphere to high levels, depending on the exoEarth ecology and surface and atmosphere chemistry. In other words, there is a possibility that any gas might be a biosignature gas, if it is present in very high quantities in an exoplanet atmosphere and can’t otherwise be explained away.
Motivated by this reasoning, my team spent a few years constructing and curating a list of all molecules that exist in gas form in a planet atmosphere with a similar temperature and pressure to Earth’s. We both combinatorically constructed lists and also exhaustively searched the literature and found about 14,000 molecules. About 2500 of these are hydrocarbons. We plan to work through this list in classes of molecules to understand their atmospheric and surface chemistry, photochemistry, and spectral properties. From this we can select both promising chemical candidates, and promising ways to search the spectrum that could capture the most diverse range of such candidates.
Does this sound like a lot of work for a library of gases even though the study of atmospheres of any planets found to orbit Proxima Cenaturi and others lie a decade or more in the future? It is. But it will take a long time to fully prepare so we don’t miss out on a biosignature gas detection.
Despite an exhuberant realization that the search for and detection of biosignature gases is within reach, there is a long road ahead. Nonetheless the coming decades are opportune for extensive progress in finding and characterizing other Earths, and full of hope for biosignature gas detection. I remain as hopeful as ever as I plan to devote the rest of my career to the search for life on exoplanets.
About the Author
Sara Seager is an astrophysicist and planetary scientist at MIT. Her science research focuses on theory, computation, and data analysis of exoplanets. Her research has introduced many new ideas to the field of exoplanet characterization, including work that led to the first detection of an exoplanet atmosphere. Professor Seager also works in space instrumentation and space missions for exoplanets, including CubeSats, as a co-I on the MIT-led TESS, a NASA Explorer Mission to be launched in 2017, and chaired the NASA Science and Technology Definition Team for a “Probe-class” Starshade and telescope system for direct imaging discovery and characterization of Earth analogs. Professor Seager was elected to the National Academy of Sciences in 2015, is a 2013 MacArthur Fellow, and in 2012 was named in Time Magazine’s 25 Most Influential in Space. | 0.813237 | 3.837292 |
Astronomers discover supermassive black hole in an ultracompact dwarf galaxy
A team of scientists from the Faculty of Physics and Sternberg State Astronomical Institute, MSU, leading an international collaboration with members from Europe, Chile, the U.S. and Australia discovered a supermassive black hole in the center of the Fornax galaxy. The results of the research were published in Monthly Notices of the Royal Astronomical Society journal.
Fornax UCD3 is a part of a Fornax galaxy cluster and belongs to a very rare and unusual class of galaxies, ultracompact dwarfs. The mass of such dwarf galaxies reaches several dozen millions of solar masses, and the radius does not typically exceed 300 light years. This ratio between mass and size makes UCDs the densest stellar systems in the universe.
"We have discovered a supermassive black hole in the center of Fornax UCD3. The black hole mass is 3.5 million that of the sun, similar to the central black hole in our own Milky Way," explained Anton Afanasiev, the first author of the article, a student of the department of the Faculty of Physics, MSU.
In the course of the study, the scientists used the data collected with SINFONI, an infrared integral field spectrograph installed at one of the 8.2 meter VLT telescopes in Chile operated by the European Southern Observatory. Having analyzed the observed spectra, the authors derived the dependence between stellar velocity dispersion and radius in Fornax UCD3. Velocity dispersion quantifies the average variation between the individual stellar line-of-sight velocity and the mean velocity of the entire stellar population. In the presence of a massive body such as a black hole, the stars are influenced by its gravity and accelerate in different directions. Due to that, their average speed does not grow, but the dispersion increases considerably. This is the very effect that was observed in this galaxy—the velocity dispersion in its center is so high that it can only be explained by the presence of a massive central black hole.
After that, the scientists compared the dependence of velocity and dispersion with dynamic models based on different assumptions of black hole mass. They found that the model suggesting the mass of the black hole being equal to 3.5 million solar masses agreed with the observations best. They also considered the possibility that no black hole was present there at all, but that hypothesis was excluded with the statistical significance of (99.7 percent).
The black hole discovered by the authors is the fourth ever to be found in UCDs and corresponds to 4 percent of the total galaxy mass. In average galaxies, this ratio is considerably lower (about 0.3 percent). Though there are few known examples, the existence of massive black holes in UCDs is a strong argument for the tidal origin of such galaxies. According to this hypothesis, an average-sized galaxy passed a bigger and more massive one at a certain stage of its evolution, and as a result of the influence of tidal forces, lost the majority of its stars. The remaining compact nucleus has become what we know as an ultracompact dwarf.
"To be able to say with complete assurance that this hypothesis is correct, we need to discover more supermassive black holes in UCDs. This is one of the prospects of this work.
Moreover, a similar methodology may be applied to more massive and less dense compact elliptical galaxies. In one of our next works, we will study the population of central black holes in objects of this kind," concluded the scientist. | 0.814215 | 4.008914 |
Quasars. When I was young I, along with millions of other kids, looked up at the sky in wonder, and wanted to know more about the universe in which our tiny planet resides. I learned about the solar system, about our galaxy, about stars an nebulae, and even about black holes. But the one thing which captured my imagination was the Quasar. Moving fantastically fast, astonishingly bright, and a long way from the Earth, the mystery of the Quasar was a thing of wonder to me.
More is known now about these illusive objects. Originally known as 'Quasi-steller Objects', Chinese-born US astrophysicist Hong-Yee Chiu shortened the name to the more manageable Quasar. Discovered in the late 1950's using radio telescopes, the first Quasars were thought to be stars. They were later discovered to something very different.
Current thought has it that Quasars have what are called 'Supermassive Black Holes' at their centres. The energy that escapes from the Quasars is generated beyond the event horizon, and is thus able to be expelled. Quasars are small, smaller than the orbit of Neptune, as they are able to shift luminosity levels quickly.
When, in 1963, Maarten Schmidt studied the spectrum of 3C 273 (the first Quasar to be discovered, which can be seen in Virgo) he saw that the spectral lines did not fit with any know substances. The reson for this, discovered some time later, was that there was a large red shift in the spectrum. The substances were actually Hydrogen. This red-shift, as described in the Doppler effect, that the object being observed is moving away from the observer. Given the size of the red shift, it was concluded that these objects must be moving very fast. In fact, 3C 273 was later shown to be over 2,000 milllion light years away, and moving at almost 48,000 km/s.
There are many types of Quasar known to scientists now, the two shown in the picture above fr example, and even double quasars have been seen. There aren't any Quasars near us, which, given what's inside them is probably a good thing! Hopefully more will be known about them, as they could hold clues to the nature of the early universe. | 0.829255 | 3.55401 |
When Italian astronomer Galileo Galilei first spotted four moons of Jupiter through a telescope, he realised that not everything goes around the Earth, as was the prevailing theory in 1610.The presumed origin of the Galilean moons was in a swirling circumplanetary disc of gas and dust around the newborn Jupiter.But direct evidence of circumplanetary discs made of gas and dust eluded astronomers, despite an intensive search. Until now.We detected the first evidence for one of these discs in the form of an infrared glow around a baby planet called PDS 70 b, the details published in two papers this week.Trump Confuses, Says NASA Should Not Talk About Going to the MoonIt Was Not Easy to FindThe discovery required one of the largest telescopes on Earth (the creatively named Very Large Telescope in Chile), a sophisticated spectrograph (SINFONI) to acquire images at different wavelengths in the infrared, and new image-processing algorithms developed specifically for the dataset we gathered.The newborn planet orbits a star called PDS 70, which is young and relatively close to us (a trifling 369 light years away) in what is known as the Upper Centaurus-Lupus star-forming region of the Milky Way.The star is just a baby itself, less than 10 million years old. In stellar terms PDS 70 is barely out of nappies (our Sun is 4.6 billion years old).Apart from its youth and proximity, the main reason we chose to study PDS 70 is that previous observations showed a large hole or gap in the disc of gas and dust surrounding the star.This hole, covering an area almost the size of our Solar System, hints at the presence of planets orbiting the star, which are responsible for carving away the disc material.The new images we gathered show that the gap is not entirely empty.They reveal arcs and spirals of dusty material, and a bright blob, which had first been detected and interpreted as a baby planet in two studies published last year.And it’s a whopper planet - about 10 times heavier than Jupiter.In the InfraredWhat is new in our analysis is that we probed infrared light from the planet at longer wavelength than previous studies. We were able to show for the first time that the planet’s infrared colours cannot be explained by its atmosphere alone.Instead, the measured infrared excess suggests the presence of a circumplanetary disc, just like the one imagined as the birthplace of Jupiter’s four Galilean moons – Io, Europa, Ganymede and Callisto.Decades ago, the same argument was used as evidence for the presence of protoplanetary discs, the dusty discs of gas around baby stars that are the birthplaces of planets themselves.Now we can use the same techniques but on a smaller scale to see the birthplace of moons.The tricky part is that spotting planets with a telescope is like staring into car headlights and trying to spot a firefly. We first had to model and subtract the bright glare of the star, to spot the feeble glow of the planet.In our processed image (above) we carefully deleted the starlight (we show the location with an asterisk), revealing both the planet and faint structures in the disc surrounding the star.Possible MoonsThe discovery of the four largest moons of Jupiter four centuries ago gave astronomers a first hint that giant planets must form surrounded by a circumplanetary disc.Plenty of work has been done since to try to understand their properties, but we finally have direct confirmation that they exist. It’s the culmination of a long search.It’s also exciting. Our work shows that theoretical models of giant planet formation were not too far off. There is now the possibility that moons could be forming right now in the circumplanetary disc around PDS 70 b.It’s hoped the new algorithm we developed can now be used to attempt to extract faint signals from other complex datasets of planets forming in other star systems.It blows the mind to think we might see other planets and even moons in the process of formation, using the biggest telescope in the world. It’s just another reminder of how small and insignificant we really are.(This is an opinion piece and the views expressed above are the author’s own. The Quint neither endorses nor is responsible for the same. This article was originally published on The Conversation. Read the original article here).NASA’s Planet-Hunting Probe Spots Earth-Sized Planet We'll get through this! Meanwhile, here's all you need to know about the Coronavirus outbreak to keep yourself safe, informed, and updated. The Quint is now available on Telegram & WhatsApp too, Click here to join. | 0.805329 | 4.000391 |
Telescope for NASA's WFIRST mission advances to new phase of development
On schedule to launch in the mid-2020s, NASA's Wide Field Infrared Survey Telescope (WFIRST) mission will help uncover some of the biggest mysteries in the cosmos. The state-of-the-art telescope on the WFIRST spacecraft will play a significant role in this, providing the largest picture of the universe ever seen with the same depth and precision as the Hubble Space Telescope.
The telescope for WFIRST has successfully passed its preliminary design review, a major milestone for the mission. This means the telescope has met the performance, schedule, and budget requirements to advance to the next stage of development, where the team will finalize its design.
"It is an honor to work with such a dedicated and talented development team. Each individual has helped ensure the telescope is technically sound, safe, and capable of carrying out compelling science," said Scott Smith, WFIRST telescope manager at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "It's exciting to picture our new telescope out in space, exploring the universe, and we look forward to pushing the boundaries of human knowledge."
WFIRST is leveraging existing hardware that was transferred to NASA, and the development is much further along at this point than it would be if the telescope had originated with WFIRST. While many of the inherited components are being modified or reconfigured to function as part of the final design, the telescope is already at a very advanced stage of design.
WFIRST is a high-precision survey mission that will advance our understanding of fundamental physics. WFIRST is similar to other space telescopes, like Spitzer and the James Webb Space Telescope, in that it will detect infrared light, which is invisible to human eyes. Earth's atmosphere absorbs infrared light, which presents challenges for observatories on the ground. WFIRST has the advantage of flying in space, above the atmosphere.
The WFIRST telescope will collect and focus light using a primary mirror that is 2.4 meters in diameter. While it's the same size as the Hubble Space Telescope's main mirror, it is only one-fourth the weight, showcasing an impressive improvement in telescope technology.
The mirror gathers light and sends it on to a pair of science instruments. The spacecraft's giant camera, the Wide Field Instrument (WFI), will enable astronomers to map the presence of mysterious dark matter, which is known only through its gravitational effects on normal matter. The WFI will also help scientists investigate the equally mysterious "dark energy," which causes the universe's expansion to accelerate. Whatever its nature, dark energy may hold the key to understanding the fate of the cosmos.
In addition, the WFI will survey our own galaxy to further our understanding of what planets orbit other stars, using the telescope's ability to sense both smaller planets and more distant planets than any survey before (planets orbiting stars beyond our Sun are called "exoplanets"). This survey will help determine whether our solar system is common, unusual, or nearly unique in the galaxy. The WFI will have the same resolution as Hubble, yet has a field of view that is 100 times greater, combining excellent image quality with the power to conduct large surveys that would take Hubble hundreds of years to complete.
WFIRST's Coronagraph Instrument (CGI) will directly image exoplanets by blocking out the light of their host stars. To date, astronomers have directly imaged only a small fraction of exoplanets, so WFIRST's advanced techniques will expand our inventory and enable us to learn more about them. Results from the CGI will provide the first opportunity to observe and characterize exoplanets similar to those in our solar system, located between three and 10 times Earth's distance from the Sun, or from about midway to Jupiter to about the distance of Saturn in our solar system. Studying the physical properties of exoplanets that are more similar to Earth will take us a step closer to discovering habitable planets.
"The science enabled by our telescope is extraordinary," said Goddard's Jeff Kruk, the WFIRST project scientist. "We are asking, 'what is the fate of the universe?' by looking at how the expansion of the universe is accelerating, and we are asking, 'are we alone?' by looking for exoplanets in neighboring planetary systems."
"WFIRST will set out to address lofty questions and it is amazing to see our team come together with a robust technical solution to explore them," said Smith. "I am grateful for all of our partners across the country that have contributed to mature this development, and I look forward to our future investigations in space with NASA's next flagship mission."
The team at Harris Corporation in Rochester, New York, the prime contractor for the telescope, is making significant strides in modifying the preexisting hardware for the spacecraft.
"Both mirrors are actively being shaped to the unique optical requirements of the telescope," said Bill Gattle, president of Space Systems for L3Harris Technologies (Harris Corporation merged with L3 Technologies in July). "We're very excited to be contributing to this world-class observatory and the groundbreaking science it will deliver." | 0.854142 | 3.530015 |
Astronomers have used NASA’s Chandra X-ray Observatory and other telescopes to show that a recently discovered galaxy is undergoing an extraordinary boom of stellar construction. The galaxy is 12.7 billion light years from Earth, seen at a critical stage in the evolution of galaxies about a billion years after the Big Bang.
After astronomers discovered the galaxy, known as SPT 0346-52, with the National Science Foundation’s South Pole Telescope (SPT), they observed it with several space and other ground-based telescopes. Data from the Atacama Large Millimeter/submillimeter Array (ALMA) previously revealed extremely bright infrared emission, suggesting that the galaxy is undergoing a tremendous burst of star birth.
However, an alternative explanation remained: Was much of the infrared emission instead caused by a rapidly growing supermassive black hole at the galaxy’s centre? Gas falling towards the black hole would become much hotter and brighter, causing surrounding dust and gas to glow in infrared light. To explore this possibility, researchers used NASA’s Chandra X-ray Observatory and CSIRO’s Australia Telescope Compact Array, a radio telescope.
No X-rays or radio waves were detected, so astronomers were able to rule out a black hole being responsible for most of the bright infrared light.
“We now know that this galaxy doesn’t have a gorging black hole, but instead is shining brightly with the light from newborn stars,” says Jingzhe Ma of the University of Florida in Gainesville, Florida, who led the new research. “This gives us information about how galaxies and the stars within them evolve during some of the earliest times in the universe.”
Stars are forming at a rate of about 4,500 times the mass of the Sun every year in SPT0346-52, one of the highest rates seen in a galaxy. This is in contrast to a galaxy like the Milky Way that only forms about one solar mass of new stars per year.
“Astronomers call galaxies with lots of star formation ‘starburst’ galaxies,” says Anthony Gonzalez, also of the University of Florida. “That term doesn’t seem to do this galaxy justice, so we are calling it a ‘hyper-starburst’ galaxy.”
The high rate of star formation implies that a large reservoir of cool gas in the galaxy is being converted into stars with unusually high efficiency.
Astronomers hope that by studying more galaxies like SPT0346-52 they will learn more about the formation and growth of massive galaxies and the supermassive black holes at their centres.
“For decades, astronomers have known that supermassive black holes and the stars in their host galaxies grow together,” says Joaquin Vieira of the University of Illinois at Urbana-Champaign. “Exactly why they do this is still a mystery. SPT0346-52 is interesting because we have observed an incredible burst of stars forming, and yet found no evidence for a growing supermassive black hole. We would really like to study this galaxy in greater detail and understand what triggered the star formation and how that affects the growth of the black hole.”
SPT0346-52 is part of a population of strong gravitationally-lensed galaxies discovered with the SPT. SPT0346-52 appears about six times brighter than it would without gravitational lensing, which enables astronomers to see more details than would otherwise be possible. | 0.808425 | 4.060095 |
Asteroid 44 Nysa will be well placed, lying in the constellation Cetus, well above the horizon for much of the night.
Regardless of your location on the Earth, 44 Nysa will reach its highest point in the sky around midnight local time.
From Cambridge, it will be visible between 20:01 and 05:11. It will become accessible around 20:01, when it rises to an altitude of 21° above your eastern horizon. It will reach its highest point in the sky at 00:38, 56° above your southern horizon. It will become inaccessible around 05:11 when it sinks below 22° above your western horizon.
The geometry of the alignment
This optimal positioning occurs when it makes its closest approach to the point in the sky directly opposite to the Sun – an event termed opposition. Since the Sun reaches its greatest distance below the horizon at midnight, the point opposite to it is highest in the sky at the same time.
At around the same time that 44 Nysa passes opposition, it also makes its closest approach to the Earth – termed its perigee – making it appear at its brightest in the night sky. This happens because when 44 Nysa lies opposite to the Sun in the night sky, the solar system is lined up so that 44 Nysa, the Earth and the Sun lie in a straight line with the Earth in the middle, on the same side of the Sun as 44 Nysa.
On this occasion, 44 Nysa will pass within 1.287 AU of us, reaching a peak brightness of magnitude 9.5. Nonetheless, even at its brightest, 44 Nysa is a faint object beyond the reach of the naked eye; binoculars or a telescope of moderate aperture are needed.
Finding 44 Nysa
The chart below indicates the path of 44 Nysa across the sky around the time of opposition.
The position of 44 Nysa at the moment of opposition will be as follows:
|Asteroid 44 Nysa||02h43m20s||+08°56'||Cetus||9.5|
The coordinates above are given in J2000.0.
|The sky on 03 November 2017|
15 days old
All times shown in EDT.
The circumstances of this event were computed from orbital elements made available by Ted Bowell of the Lowell Observatory. The conversion to geocentric coordinates was performed using the position of the Earth recorded in the DE405 ephemeris published by the Jet Propulsion Laboratory (JPL).
The star chart above shows the positions and magnitudes of stars as they appear in the Tycho catalogue. The data was reduced by the author and plotted using PyXPlot. A gnomonic projection of the sky has been used; celestial coordinates are indicated in the J2000.0 coordinate system. | 0.892483 | 3.787132 |
In the family of dwarf planets of the solar system, Ceres can be called a kind of outcast or a loner. In addition, the classification took away from her the title of “largest” and now we have the smallest dwarf planet in the system.
We are looking for a missing planet
Ceres color review captured by Dawn in 2015
In 1772 the most popular was the Bode law (the Titius-Bode rule). It was a peculiar formula that roughly indicated the distances at which the solar planets should be located (average orbital radius). The discovery of Uranus in 1781 was in good agreement with the rule, which meant that the object was hiding between Mars and Jupiter.
Several groups were organized for the search, but the lucky astronomer from Italy Giuseppe Piazzi, who in 1801 found Ceres separately and quite by accident (initially looking for a star). True Piazzi thought that in front of him a comet. But to determine the true status was still far away.
Ceres and other major asteroids
The status of Ceres has been controversial for a long time. And this is not surprising, because the new data expanded the understanding of not only the solar system, but also the nature of its objects. The first in favor of planetary status was Johann Bode. He sincerely believed that this was a world not previously found, which, according to the formula, must live in this location.
Ceres received the corresponding designation in the catalog and almost 50 years it was treated as another planet. But let's not forget that the object is in the asteroid belt. Soon, scientists began to notice other objects. We decided to change the status again, but now to asteroid type. Instead of a tiny planet, Ceres was the largest asteroid. But this is not the end. Discussion of nature Pluto touched many objects, whose type had to be reconsidered. This also affected Ceres, who became the dwarf planet. It is interesting that even in the International Space Union they continue to get confused and write that for such objects sometimes they use double designation. Therefore, we can say that we face the largest asteroid and the smallest dwarf planet in the solar system at the same time.
Lonely dwarf resident
Internal structure of Ceres
Ceres performs one rotation around the Sun for 4.6 years with an average distance of 2.77 a. e. If you settled in this world, the duration of the day was only 9 hours and 4 minutes. Despite the confusion in status, Ceres remains the largest space body in the asteroid belt.
In size it covers 975 x 909 km, and in terms of massiveness it takes up only 1.3% of the moon (but is perceived as massive in the asteroid belt). Interestingly, these worlds are still completely alone, that is, there are no objects of this type nearby. The remaining known dwarf planets are located behind Neptune.
High-quality near shots and a detailed description of the dwarf planet was obtained in 2015 thanks to the NASA Dawn mission.
Interesting Facts about Ceres:
- The average surface temperature index ranges from -106 ° C to -33 ° C.
- Became the first dwarf planet to which the spaceship has called.
- The ice mantle is capable of containing about 200 million km 3 water (more fresh water than on Earth).
- There are suspicions of the presence of active cryovolcanoes emitting vaporous jets.
- There is an opinion about the presence of a weak atmosphere with water vapor.
- Bright white spots were found in one of the craters. Ice or salt is suspected as a material.
- It is possible that we have a surviving protoplanet, which managed to survive during the formation and active collisions 4.57 billion years ago.
Photos of Ceres
Crater Hau on Ceres
Dawn managed to capture this image of the large crater Gau located on Ceres. Hau was a goddess in Germany who was sacrificed at the time of gathering rye. The center of the crater formation is full. The diameter covers 84 km, and the resolution is 140 m per pixel. The image was received on August 18, 2015 at a distance of 1,470 km. Dawn is responsible for the mission of the Jet Propulsion Laboratory. Part of a more global Discovery project.
This photo of Ceres in high resolution shows the crater Djuling with a depth of 2.5 km. On the left, there is a small mountain with a height of 1 km. Many formations hint at the flow of material and the presence of ice stocks under the surface layer. At the top of the mountain a slight depression is noticeable, the origin of which is not yet known. Perhaps the whole thing in a landslide. The apparatus succeeded in capturing this view on August 25, 2016 at an altitude of 385 km (36 degrees south. Sh. And 167 degrees e.). Juling is a spirit in the culture of Malaysia. Dawn is responsible for the mission of the Jet Propulsion Laboratory. Part of a more global Discovery project.
Kupalo Crater on Ceres
A Kupalo Ceres crater is displayed on the image obtained by the NASA Dawn unit. This is one of the most young crater formations on the dwarf planet. It is endowed with bright material centered on the rim and walls that can be layered. Stripes at the bottom could form due to melting after impact and debris accumulation. Extends a width of 26 km and is located in the southern middle latitudes. The name is given in honor of the god of vegetation and harvest from the Slavs. Dawn is responsible for the mission of the Jet Propulsion Laboratory. Part of a more global Discovery project. Craters Takel and Kozobi
Dawn succeeded in capturing Takel and Kozobi craters located on Ceres. The first is a young formation associated with bright material (left), and the second is a clear trail of impact (below the center). Dawn is responsible for the mission of the Jet Propulsion Laboratory. Part of a more global Discovery project.
Occator in false color
The Occater snapshot in false color demonstrates the difference in surface composition. Red corresponds to the wave range of 0.97 micrometers (IR), green - 0.75 (red), blue - 0.44 (blue). The crater extends over 90 km. Researchers use a false color to see differences in surface materials. Usually, the blue color on Ceres indicates 130 bright spots and hints at the presence of salts. The device performed a review at a distance of 4,400 km. Dawn is responsible for the mission of the Jet Propulsion Laboratory. Part of a more global Discovery project.
Occator on Ceres Limbus
This image shows the edge of the dwarf planet Ceres with the territory of the northern hemisphere. The majestic crater Occator is striking the eye. It stretches for 92 km and deepens for 4 km. This is the clearest evidence of recent geological activity. The analysis shows that the internal material is represented by salt. It remained after the fine liquid passed through the freezing, and then sublimated (from ice to vapor). The image was obtained by the device Dawn on October 17 at a distance of 1,480 km. The resolution is 140 m per pixel. Dawn is responsible for the mission of the Jet Propulsion Laboratory. Part of a more global Discovery project.
This image was obtained by the Dawn device on April 14-15 at an altitude of 22000 km, displaying the northern section under sunlight. On April 23, the mechanism entered the circular orbital path. The bright feature is called “spot 5” - these are two bright spots located close to each other. The image scale is 2.1 km per pixel, and the angle of the Sun-Ceres apparatus is 91 degrees. Dawn is responsible for the mission of the Jet Propulsion Laboratory. Acts as part of a more global Discovery program. Northern Hemisphere Ceres
On June 6, 2015, Dawn managed to fix craters on the north side of the dwarf planet Ceres. This is one of the first frames from the second orbital passage at an altitude of 4400 km with a resolution of 410 m per pixel. Dawn is responsible for the mission of the Jet Propulsion Laboratory. Part of a more global Discovery project.
Ceres in color
The image shows Ceres in color that is perceived by the human eye. The survey was created in the German Aerospace Center (Berlin), combining frames from Dawn, obtained in 2015 using red, green and blue spectral filters. For the mission of Dawn responsible NASA Jet Propulsion Laboratory. The project is part of the Discovery program, where responsibility is placed on UCLA.
Southern Hemisphere Ceres
On June 6, 2015, Dawn's mission managed to capture this large crater in the southern hemisphere of the dwarf planet Ceres. It can be noted a huge number of different formations created by shock events. The device is located at an altitude of 4400 km, and the resolution - 410 m per pixel. Dawn is responsible for the mission of the Jet Propulsion Laboratory. Part of a more global Discovery project.
Bright spots on the second cartographic orbit of Ceres
On June 6, 2015, Dawn was able to capture the two brightest spots of Ceres. Made at an altitude of 4400 km, where the resolution reaches 410 m per pixel. Scientists are still trying to understand the nature of these spots. There is an assumption that the composition contains salt and ice. Dawn is responsible for the mission of the Jet Propulsion Laboratory. Part of a more global Discovery project.
The Brightest Spots and Crater Occator
The crater Occator is 92 km in diameter and has a depth of 4 km. Inside it is the brightest area in Ceres. A close-up from the Dawn vehicle shows the dome in the smooth center of the crater. Linear formations and fractures stretch upward and diverge laterally. Also around are visible faults, moving to more striking areas. The frame is made of two images created at a shorter exposure. It allows you to reveal the details of bright objects. The photos were taken by a LAMO camera at an altitude of 385 km above Ceres. Dawn is responsible for the mission of the Jet Propulsion Laboratory. Part of a more global Discovery project.
Due to the presence of the atmosphere and traces of water activity, there are suspicions that there once could be life on Ceres. However, scientists do not undertake to unwind this idea and concentrate more on Mars or Europe. However, Ceres is still considered as a possible colony.
An idea is already being developed to form a base in its orbit. But the colonists will have difficulty without the usual amount of sunlight and the absence of a magnetic field. But the dwarf planet will provide us with a decent supply of air and hydrogen, which can be used in the manufacture of rocket fuel. | 0.870001 | 3.665309 |
If the sun looks a little larger than usual today, you're not seeing things. Jan. 2 marks the time when the Earth is at perihelion, the point in its orbit at which it is closest to the sun.
During perihelion, the Earth is exactly 91,402,560 miles (147,098,161 kilometers) from the sun. In actuality, you most likely can't see any difference between the apparent size of the sun today and its appearance at aphelion (when the Earth will be farthest from the star). The difference is only 3.4%, too small to be detected with the naked eye.
On average, the Earth is about 93 million miles (150 million km) from the sun. It will be farthest from the sun on July 5, when the Earth reaches aphelion, a point 94,508,960 miles (152,097,427 km) from the sun. The closest and farthest differences from the sun are very similar because the Earth's orbit is very close to being circular. In fact, as planetary orbits go, ours is close to perfect.
The Eccentric Earth
Only Venus and Neptune have more circular orbits than the Earth. On the other hand, if you look at the diagram of the orbits of the four inner planets accompanying this story, you may easily see that Mercury and Mars have orbits which are seriously eccentric.
Astronomers use the term "eccentric" in its original mathematical sense, meaning "away from the center." A perfect circle has an eccentricity of 0. A straight line would have an eccentricity of 1. Everything else in between is an oval of some kind.
Here's a look at the innermost planets of the solar system in order of increasing eccentricity:
Looking at the diagram, the orbits of Earth and Venus look almost perfectly circular, while that of Mars is slightly closer to the sun towards the bottom. Mercury's orbit is very much closer to the sun on the right. If you look closely, there is a little tick mark on the orbits to indicate where perihelion lies. Don't confuse this mark with the little wedges which denote the orbital nodes, the points where the orbits cross the plane of the ecliptic. The Earth appears right next to the tick mark on its orbit marking perihelion in the image.
Closer to the Sun
So what is the difference for the inhabitants of Earth when our planet is at perihelion instead of aphelion? The Earth is slightly warmer than it would be otherwise, about 4 degrees Fahrenheit (2.3 degrees Celsius).
This perihelion effect is very minor compared to the effects of the tilt of our planet's axis. During December in the Northern Hemisphere, the North Pole is tilted away from the sun so that we receive less sunlight every day.
At the same time, the South Pole is tilted towards the sun, so the Southern Hemisphere receives more sun and experiences summer. In June, the situation is reversed and we have summer in the northern hemisphere and winter in the southern hemisphere.
The only effect of perihelion is that the winters in the Northern Hemisphere are very slightly milder than the winters in the southern hemisphere at the equivalent latitudes. Not as many people live as close to the South Pole as do close to the North Pole, so humanity isn't affected much.
So enjoy that "big" January sun, and look forward to the longer days to come as Earth moves around its orbit to the point where we really receive more sun and spring arrives.
Image courtesy of Science and Analysis Laboratory, NASA-Johnson Space Center
- Astronomers turn back time to solve Einstein ring mystery
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- Pulsar caught binging on star before brilliant x-ray blast
This article originally published at Space.com here | 0.848188 | 3.787034 |
In the search for the hypothetical Planet Nine, scientists may have uncovered another explanation for the patterns in the orbits of Kuiper Belt objects.
The Earth and the Moon were long thought to be virtually identical in composition. Now we know they are not.
Earth currently has a second moon - but it won't stay long.
Why isn't there an endless variety of planets in the universe? An astrophysicist explains why planets only come in two flavors.
Saturn's largest moon has been fully mapped for the first time.
Astronomers have found 20 new moons around Saturn, and will keep finding more as technology improves.
A giant exomoon hundreds of times the size of Earth is revealing secrets about how giant planets like Jupiter and Saturn formed. They might also help astronomers find planets where life may thrive.
Kepler-452b is sometimes called 'Earth 2.0', but there's a lot we still don't know about it.
Most people think that many millions of years ago, Saturn didn't have rings at all. Instead, it had a big moon moving around it. Eventually, the moon burst and broke into pieces.
This hot, acidic neighbor with its surface veiled in thick clouds hasn't benefited from the attention showered on Mars and the Moon. But Venus may offer insights into the fate of the Earth.
A 100-metre-wide asteroid passed just 70,000km from Earth on Thursday, and we had little warning it was about to happen. What threat is posed by asteroids and how do we find them?
Yes, the Sun absolutely spins. In fact, everything in the universe spins. Some things spin faster than the Sun, some are slower and some things spin 'backwards'.
The new era of space exploration is characterized by an emphasis on diversity and international cooperation. But there's a lot of work to do before there's gender equality in STEM fields and at NASA.
When you look at the squiggly lines on Joy Division's famous album cover, you're seeing a record of lightning in outer space.
Whether anything could live in Europa's subsurface ocean depends on what kind of salt it contains. Now scientists have found out.
The dwarf planet Pluto is heading away from the Sun and that's having a devastating impact on its atmosphere.
Exoplanet discovery can help us work out how the Earth will end its days.
There's a mysterious lack of small bodies beyond Neptune, but a 'snowman-shaped' object may help explain why.
A body at least twice as massive as the Earth smashing into Uranus could have made it lopsided, shows research.
Naming features on other worlds is a trickier issue than you might think. | 0.82269 | 3.095058 |
Martian dust storms, which occur during the summer season in the planet’s southern hemisphere, can get pretty intense. Over the course of the past few weeks, a global dust storm has engulfed Mars and forced the Opportunity rover to suspend operations. Given that this storm is much like the one that took place back in 2007, which also raged for weeks, there have been concerns over how this development could affect rover operations.
Meanwhile the Curiosity rover managed to snap pictures of the thickening haze caused by the storm. Though Curiosity is on the other side of the planet from where Opportunity is currently located, atmospheric dust has been gradually increasing over it. But unlike Opportunity, which runs on solar power, Curiosity will remain unaffected by the global storm thanks to its nuclear-powered battery, and is therefore in a good position to study it.
As already noted, Martian storms occur during summer in the southern hemisphere, when sunlight warms dust particles and lifts them higher into the atmosphere, creating more wind. The resulting wind kicks up yet more dust, creating a feedback loop that NASA scientists are still trying to understand. Since the southern polar region is pointed towards the Sun in the summer, carbon dioxide frozen in the polar cap evaporates.
This has the effect of thickening the atmosphere and increasing the surface pressure, which enhances the process by helping suspend dust particles in the air. In some cases, the dust clouds can reach up to 60 km (40 mi) or more in elevation. Though they are common and can begin suddenly, Martian dust storms typically stay contained to a local area and last only about a weeks.
By contrast, the current storm has lasted for several weeks and is currently covering an area that would span North America and Russia combined. While smaller than the storm that took place back in 2007, this storm has intensified to the point where it created a perpetual state of night over the rover’s location in Perseverance Valley and led to a level of atmospheric opacity that is much worse than the 2007 storm.
When dust storms occur, scientists measure them based on their opacity level (tau) to determine how much sunlight they will prevent from reaching the surface. Whereas the 2007 storm had a tau level of about 5.5, this most recent storm reached an estimated tau of 10.8 earlier this month over the Perseverance Valley – where Opportunity is located.
The intensity of the storm also led Bruce Canton, deputy principal investigator of the Mars Color Imager (MARCI) camera onboard NASA’s Mars Reconnaissance Orbiter (MRO), to declare that the storm has officially become a “planet-encircling” (or “global”) dust event. Above the Gale Crater, where Curiosity is located, the tau reading is now above 8.0 – the highest ever recorded by the mission.
While the storm has some worried about the fate of Opportunity, which is Mars’ oldest active rover (having remained in operation for over 14 years), it is also an chance to address one of the greatest questions scientists have about Mars. For example, why do some storms span the entire planet and last for months while others are confined to small areas and and last only a week?
While scientists don’t currently know what the answer is, Curiosity and a fleet of six scientific spacecraft in orbit of Mars are hoping this most recent storm will help them find out. These spacecraft include NASA’s Mars Reconnaissance Orbiter (MRO), 2001 Mars Odyssey and Mars Atmosphere and Volatile EvolutioN (MAVEN) missions, India’s Mars Orbiter Mission (MOM) and the ESA’s Mars Express and ExoMars Trace Gas Orbiter.
The animation (shown above) consists of a series of daily photos captures by Curiosity’s Mast Camera (Mastcam), which show the sky getting hazier over time. While taking these pictures, Curiosity was facing the crater rim, about 30 km (18.6) away from where it stands inside the crater. This sun-obstructing wall of haze is about six to eight times thicker than normal for this time of season.
Nevertheless, Curiosity’s engineers – which are based at NASA’s Jet Propulsion Laboratory in Pasadena, California – have studied how the growing dust storm could affect the rover’s instruments and concluded that it poses little risk. Ironically enough, the largest impact will be on the rover’s cameras, which require extra exposure time due to the low lighting conditions.
As Jim Watzin, the director of NASA’s Mars Exploration Program at the agency’s headquarters in Washington, explained in a NASA press release earlier this month:
“This is the ideal storm for Mars science. We have a historic number of spacecraft operating at the Red Planet. Each offers a unique look at how dust storms form and behave – knowledge that will be essential for future robotic and human missions.”
However, all dust events, regardless of size, help to shape the Martian surface. As such, studying their physics is critical to understanding the Martian climate, both past and present. As Rich Zurek, the chief scientist for the Mars Program Office at NASA’s Jet Propulsion Laboratory, indicated:
“Each observation of these large storms brings us closer to being able to model these events – and maybe, someday, being able to forecast them. That would be like forecasting El Niño events on Earth, or the severity of upcoming hurricane seasons.”
The ability to understand the causes and dynamics of Martian dust storms would not only lead to a better understand of how weather works on other planets, it would also be of immense importance if and and when humans begin traveling to the Red Planet on a regular basis. For instance, if SpaceX really does intend to bring tourists to Mars in the future, said tourists will want to avoid booking during “storm season”.
And if humans should choose to someday make Mars their home, they will need to know when planet-spanning dust storms are coming, especially since their habitats will likely be relying on wind and solar power. In the meantime, NASA and other space agencies will continue to monitor this storm and the Opportunity rover is expected to come through (fingers crossed!) unscathed!
Further Reading: NASA | 0.829875 | 3.835987 |
Newfound Earth-Like Exoplanet Could Support Life
An international team of astronomers has just discovered a planet that is considered to be one of three exoplanets that are most similar to Earth. Approximately five times larger than our home planet, it has been called another "mega-Earth." Robert Wittenmyer et al found this planet after observing small changes in the gravity of its host star, Gliese.
The planet, dubbed Gliese 832c, was found in Gliese's habitable zone, or the area in which the distance from the star yields temperatures that will allow for the existence of liquid water. If we should ever be interested in colonizing this planet, it is extremely close from a cosmic standpoint; it is only 16 light-years away from Earth. (The farthest point in our galaxy, the Milky Way, is 100,000 light-years away.)
According to the Earth Similarity Index (ESI), a formula commonly used by astronomers to determine an exoplanet's similarity to Earth, Gliese 832c is approximately as Earth-like as Gliese 667Cc and Kepler-62e. Where a clone planet of Earth has an ESI of 1, Gliese 832c has an ESI of .81. Abel Mendez Torres, director of the Planetary Habitability Laboratory at the University of Puerto Rico wrote, "This makes Gliese 832c one of the top three most Earth-like planets according to the ESI (i.e., with respect to Earth's stellar flux and mass) and the closest one to Earth of all three - a prime object for follow-up observations."
Gliese 832c has become the 24th planet in the Habitable Exoplanets Catalog, a compilation from the University of Puerto Rico which details the planets that may be able to support alien life or even human colonies. | 0.890167 | 3.102504 |
The discrepancy between how fast the universe seems to be expanding and how fast we expect it to expand is one of cosmology’s most stubbornly persistent anomalies.
Cosmologists base their expectation of the expansion rate—a rate known as the Hubble constant—on measurements of radiation emitted shortly after the Big Bang. This radiation reveals the precise ingredients of the early universe. Cosmologists plug the ingredients into their model of cosmic evolution and run the model forward to see how quickly space should be expanding today.
Yet the prediction falls short: When cosmologists observe astronomical objects such as pulsating stars and exploding supernovas, they see a universe that’s expanding faster, with a larger Hubble constant.
The discrepancy, known as the Hubble tension, has persisted even as all the measurements have grown more precise. Some astrophysicists continue to debate whether the tension might be nothing more than a measurement error. But if the discrepancy is real, it means something is missing from cosmologists’ model of the universe.
Recently, theorists have been busy imagining new cosmic ingredients that, when added to the standard model, would rev up the universe’s expected expansion rate, making it match observations.
“Discovering anomalies is the fundamental way that science makes progress,” said Avi Loeb, a cosmologist at Harvard University and one of dozens of researchers who have proposed solutions to the Hubble tension.
These are some of the top ideas for what could be speeding up cosmic expansion.
The standard model of cosmology incorporates all the familiar forms of matter and radiation and their interactions. It also includes the invisible substances known as dark energy and dark matter, which together make up some 96 percent of the cosmos. Because so little is known about these dark ingredients, they are perhaps the obvious place to begin tampering with the standard model. “That’s what you have at your disposal to change the expansion rate of the universe,” Loeb said.
The standard model assumes that dark matter consists of slow-moving particles that don’t interact with light. But what if we also assume that dark matter is not made of just a single substance? Since many different kinds of visible particles exist—quarks, electrons and so on—there might be multiple dark particles as well.
In a paper published last summer in Physical Review D, Loeb and two collaborators considered a form of dark matter that decays into a lighter particle and a massless particle known as a dark photon. As more and more dark matter decayed over time, they reasoned, its gravitational pull would have lessened, and thus the expansion of the universe would have sped up, relieving the Hubble tension.
But making small changes like this to the standard cosmological model can have unwanted knock-on effects. “It’s very easy to come up with all kinds of slight modifications,” said Marc Kamionkowski, a theoretical physicist at Johns Hopkins University—but it’s hard to do so, he said, without ruining the model’s perfect fit with a wealth of other astronomical observations.
By varying the decay rate and the amount of dark matter that is lost in each decay, Loeb and colleagues selected a model of decaying dark matter that they say still agrees with other astronomical observations. “If you add this ingredient to the standard model of cosmology, everything holds together,” Loeb said.
Yet he remains dissatisfied with the decaying dark matter idea, in part because it introduces two new uncertain quantities into the equations.
“In this case, you add two free parameters in order to resolve one discrepancy—and I’m uneasy about that,” he said, comparing decaying dark matter to the epicycles in Ptolemy’s Earth-centric model of the universe. “I would rather have two discrepancies explained by one parameter.”
Ever since the surprise discovery in 1998 that the expansion of the universe is accelerating, cosmologists have included a repulsive dark energy in their model of cosmic evolution. But its nature remains a mystery. The simplest possibility is that dark energy is the “cosmological constant”—the energy of space itself, with a constant density everywhere. But what if the amount of dark energy in the universe isn’t constant? | 0.83383 | 4.154021 |
Pictish Symbols: Z-Rods and V-Rods – of Celestial / Astronomical Importance?
The Z-Rods and V-Rods: Part 1.
Perhaps the most puzzling aspect of Pictish symbols are that they are often accompanied by the so-called z-rods or v-rods. This apparent embellishment lends another layer of complexity in attempts to understand the meaning being conveyed by the symbols. These have been seen in the past as being reminiscent of forks of lightning, or perhaps as broken arrows or spears. It has been suggested that these therefore might be symbols representing the death of a warrior. However, if we are starting to try to view Pictish symbols in terms of astronomical, calendrical, or astrological events, could the z-rod’s form and function also be explained in these terms?
There is variation in the form that the rods take, but these fall within a quite narrow range of possibilities. For example, the rods are usually not entirely symmetrical, but typically have a ‘tipped’ end and a ‘trailing’ end. Sometimes the tip of the rod takes on a spear or arrow-head appearance, or sometimes the tip appears to be more organic in form, perhaps reminiscent of parts of a plant. The trailing edge of the rods often appear to be plant like, or end in a bulb like structure, or can appear to be resemble a fish tail or perhaps even arrow flights. Simple embellishments often decorate the shafts of the rods, and these again have an organic quality to them, perhaps even reminiscent of tongues of fire. The z-rods, when they appear with the double disc, tend to start below the left hand disc, run parallel with the axis of the symbol, cross backwards over the axis, and then continue above the right hand disc, again in parallel with the axis, therefore taking a form similar to a letter ‘z’ when seen in a mirror (see figure below, 2nd row from top right hand side). However, in a handful of cases, the rods appear to be in the opposite orientation therefore actually resembling a ‘z’. This phenomenon occurs with other symbols and we will explore its significance later.
The z-rods found bisecting the double discs tend to show relatively small terminal decorations in relation to their length. This is in contrast to the other type of rods found associated with Pictish symbols; the ‘v-rods’. (See crescent and V-rod illustration above, top left). Typically v-rods, which usually are found only with the crescent Moon symbol (there is one example of a ‘v’ rod with an arch), have terminals that are relatively large and have shorter rods. With this difference between the two types of rod in mind, it is probably worth considering the possibility that the v-rod may represent an arrow, and in the context of the night sky, perhaps we should view this not as any common arrow but rather a ‘celestial’ arrow, with further information embedded in the image to convey additional information. Similarly, the z-rod of the double disc symbol may represent not an arrow, but a spear with its longer rod and smaller terminals, and if they too are associated with possible astrological symbolism then again we may want to consider the possibility that these spears have a celestial or supernatural aspect.
There are however problems with the identification of the z-rod with a spear, not least the ‘z’ shape of the rod, but also the fact that a spear usually has only one obvious ‘terminal’; the spearhead. However in the National Museum of Scotland, in Edinburgh, there are spears from the Pictish period that have a metal addition to the ‘trailing’ edge. This addition was well described by the Roman writer, Dio Cassius (prior to AD 229) who made the following observations on the tribes in northern Scotland, ‘For arms they have a shield and a short spear, with a bronze apple attached to the end of the spear-shaft, so that when it is shaken it may clash and terrify the enemy.’ This type of spear is also depicted on a Pictish stone from Collessie in Fife.
You can find an image here: http://www.mathstat.strath.ac.uk/outreach/pictish/database.php?image=184
The so-called ‘Collessie man’ is a naked warrior carrying a spear, at the trailing end of the spear can clearly be seen the sort of ‘apple’ described by Dio Cassius. The apple may have other functions other than generating an intimidatory din. One suggestion, in the book Celtic Warriors (Tim Newark , Blandford Press, 1986), is that the apple was to aid the balance of the spear in flight. Is it also possible that this type of spear was suitable for use with a sling, therefore increasing its penetrative ability and range. Could the trailing terminal shown on many of the z-rods actually represent these apples?
If the tip of the rod represented a spearhead, then we would also have to come up with an explanation for the almost organic feel to the shape. However, it turns out that there were a myriad of designs for both arrow and spear heads. These variations may have reflected cultural differences or differences in the favoured material, or perhaps more importantly they may have reflected differences in the use each type of spear or arrow head was put. Spearheads may have been designed to penetrate different types of protective clothing, or armour, to be easily removed, or to be difficult to remove, and a host of other reasons. Spearheads that have been found in the British Isles, could be from spears but also from javelins, thrusting spears, lances or pikes. Two main types of spearhead seem to be common in Britain and Ireland in the first millennium AD. The first type is the ‘shouldered’ spearhead, which was apparently typically Germanic, although it seems to have also been quite common in Ireland. The most common type in Britain was the ‘leaf-shaped’ spear head. Could the leaf shaped spearhead explain the almost organic feel to the leading edge of so many rods? The ‘Collessie man’s’ spear sports a small leaf shaped spearhead, very reminiscent of the rod.
In the book I suggest for a variety of reasons, why the double disc symbol might represent the constellation Leo, the Sun’s ‘house’ or at least part of that constellation (probably the alpha star Regulus).
In the time period we’re interested in, the first millennium, the Irish festival of Lughnasa, named after Lugh, a god of light or the Sun and the Irish equivalent of the Welsh ‘Lleu’, occurred when the Sun rose with Leo’s alpha star, Regulus, with both star and constellation having very strong associations with the Sun. In the context of this Celtic god, the appearance of the z-rodded spear associated with some of the double discs throws up a fascinating possibility. If we further examine the mythology surrounding this god of light, and in particular the Irish version, Lugh, we find that the object most closely associated with this character is in fact a spear. His is no ordinary spear. This weapon almost has a life of its own, seeking out its intended target, rather like a modern homing missile; even Lugh has trouble calming its blood thirsty tendencies. The weapon comes to the fore when Lugh slays the monstrous Fomorian king, Balor, by throwing the spear at his single malevolent eye. This spear has another aspect; it is alive with flame, as would befit a weapon associated with the Sun god. To keep the spear from doing harm when it is not being used, Lugh keeps the weapon in a bucket of water, only removing it when he intends to use it. Such a fiery spear should remind us of a Sun beam or the Sun’s rays, and we should therefore see the spear in itself as a solar motif. Does the z-rod also encompass this idea? Is the z-rod , and in the context of the Pictish symbols, perhaps enhancing the meaning of the individual symbols it is associated with? But what of the fire aspect of Lugh’s weapon? If the z-rod is to be viewed as a solar symbol then is it possible that it is in some way related to Lugh’s spear or at least a Pictish equivalent? In order to answer this, we need to turn to the many of the depictions of the rod. Emanating from the shaft of many of the rods are small curly decorations or florials. Is it possible that these decorations actually represent flames, perhaps mirroring the Irish mythological notion of Lugh’s fiery ‘Sun’ spear? It is certainly a tantalising possibility and would fit with solar symbolism.
If some of the symbolism hints at parallels between the Pictish rods and the Irish Sun god’s weapon, this still doesn’t explain the reason why the rod is bent into a ‘z’ shape nor does it tell us if the rod is conveying some further information. Let us for a moment consider the relationship between the double disc and the z- rod. In the majority of cases the apple-shaped termination of our potential spear is found below and to the left of the double disc, we can then follow the shaft as it travels from left to right until it doubles back, crossing the axis between the two solar discs, before once again continuing on its original left to right path. It therefore describes a ‘backward’ ‘z’. The left to right orientation of these rods fits well with the notion of solar symbolism, in that the Sun’s daily path from east to west is in effect (to an observer) a movement from left to right. This however does not explain why the rod crosses diagonally backwards across the axis of the double disc. However, as well as a suggestion of the Sun’s daily course from east to west, the z-rod could also be explained in terms of the path of other bodies in the solar system. If we turn back to the ancient science of astronomy, one of the first phenomena that the earliest astronomers must have noticed concerned the behaviour of a small collection of celestial bodies that followed the Sun’s path through the sky. To early observers, these bodies generally stayed close to the ecliptic, but had the curious habit of occasionally coming to a halt and wandering away from their original path. This behaviour, which was in contrast to the ‘fixed’ stars, partly gave rise to their Greek name ‘planetese’ and originally meant wanderer. This word of course gave rise to our own word ‘planet’.
This peculiar ‘wandering’ behaviour is technically called retrograde motion, and is a function of our observing planets orbiting the Sun from a planet (Earth) that is also moving around the Sun. This combination of the two orbits gives us the illusion every now and again that the planets slow in their path in the night sky, appear to standstill, and then for short time move backwards, before once again returning to their original direction. This retrograde motion, which is most obvious in the motion of Mercury, Venus, and Mars, when traced out appears to take the form of either a loop or can actually approximate to a ‘z’ shape or to a mirrored ‘z’. It is therefore possible that the z- rod as well as conveying solar imagery linked to the mythology of a Sun god, conveys the notion of the ecliptic or even relates to information on the motion of a particular celestial body. The two mirror image versions of the z-rod, could therefore be attributed simply to artistic variation but also might relate to the artist depicting two different circumstances. So for example, the ‘z’ version of the z-rod and its mirrored counterpart may simply reflect two possible forms of retrograde motion, which can trace out z shape or a mirrored version of this. The planets Jupiter and Saturn also display apparent retrograde motion, with considerable backwards movement, but with little vertical motion away from their path. This apparent backwards motion of all the planets is not a rare occurrence, nor viewed as unimportant, but is used sometimes in both western and eastern astrological predictions, where it is regarded as having a profound influence. The two visible giant outer planets spend about a third of their time in apparent retrograde, Mars about twenty percent of its time, Mercury about ten percent and Venus about seven percent. The Picts would have certainly known, if they were observing the nightly motion of the planets, about the existence of this phenomenon.
In the case of the ‘notched rectangle’ z-rods (see image above, bootom row, left hand side), seven show the rod traversing the symbol from the bottom left hand corner to the top right hand side of the symbols, in other words it diagonally ‘ascends” from left to right (forming a mirrored ‘N’). In the other two other rodded examples, the rods are drawn in the opposite orientation, in effect a mirror image of the other seven, with the rod traversing the symbol from the top left to the bottom right (a descending rod). Rotating the symbol through ninety degrees reveals that these z-rods take the same two forms as the those found with the double disc – the mirrored ‘N’ is simply a ‘z’ rotated, and likewise the more common mirrored ‘N’ is a mirrored ‘z’ rotated. If we also take cognisance of the leading tip of these rods, and the direction they point, the mirrored ‘z’ or ‘N’ rods of the double disc and notched rectangle may actually be indicating rotational direction, rather like a Catherine wheel. The vast majority of the mirrored z- rods of the double discs point to the right indicating perhaps clockwise rotation, likewise the mirrored ‘N’ of the notched rectangles points perhaps also indicating clockwise movement. Even if the tip of the rod pointed to the left it would still indicate a clockwise direction. The less common rodded double discs have rods that describe a true ‘z’ shape. These rods tend to have their tip on the lower arm of the ‘z’, pointing to the right, suggesting anti-clockwise movement, likewise the two ‘N’ shaped rods of the notched rectangle.
This potential mirroring of the symbol is given further credence if one examines the internal circles or notches on the vertical sides of the notched rectangles that frequently occur. Seven of the rodded symbols, plus the unrodded symbol, have circles or notches. In the case of the mirrored ‘N’ or z-rods (clockwise), the left hand notch or circle appears above the rod, and the right hand notch or circle appears below the rod. In the example from Arndilly,
(image can be found here: http://www.mathstat.strath.ac.uk/outreach/pictish/database.php?image=15
with its rod presenting as an ‘N’ (anticlockwise), its left hand circle is below the rod and the right hand circle above the rod – in other words the circles could support the notion that the Arndilly rectangular notched symbol is a deliberate mirror image. This would also parallel the situation with the double discs, where there also appear to be mirrored symbols. The mirroring of not only the rod but key internal features would seem to suggest that the mirroring may well be deliberate and constitute a further level of complexity in terms of the symbols message. This would also apply to the rodded double disc.
Within the main group of snake symbols (above image, top row, right hand side), whether rodded or non-rodded, there appear also to be left facing and right facing forms. Within these two groups the rods themselves, as in the case of the other z-rodded symbols, can be ‘clockwise’ or ‘anti-clockwise’. The largest group is the left hand facing snake, with the majority of examples of these being rodded clockwise. The left handed snakes also make up the majority of non-rodded examples. Meigle 1 and the St Vigeans 2 stones show examples of left hand anti-clockwise rodded snakes. The Aberlemno 1 stone has an example of a non-rodded right handed snake, whilst the right facing snake on the Newton House stone has an anti-clockwise rod. It is possible that these variations in handedness and rod orientation convey some particular information; vital to the interpretation of the pairing.
Within the context of religion and in particular eastern religion (notably Vedic), motion to the right or clockwise motion is seen as auspicious and male, representing the daily motion of the Sun, stars and planets. Left handed or anti-clockwise motion is seen as inauspicious and female. It could therefore be the case that the two forms of the z-rods are communicating information as to whether the timing of the event commemorated by the stone is auspicious or inauspicious. Interestingly, the number of clockwise rods far outnumbers the anti-clockwise rods. It is even possible that the clockwise form is linked to males in some way and the anti-clockwise to females.
Part 2, next week
Posted on April 3, 2013, in Pictish History and tagged Archaeoastronomy, Archaeology, Astrology, Astronomy, Capricorn, Celtic, Celtic Religion, Druid, Druids, Ecliptic, History, Leo, Lleu, Lugh, mysteries, Pictish, pictish stones, pictish symbols, Picts, Retrograde, Scotland, Scottish, Scottish history, Solar, Vedic. Bookmark the permalink. 6 Comments. | 0.858947 | 3.376476 |
It’s been there all along. For years, scientists suspected our moon was a dry expanse, void of water — until now.
Planetary scientists from Brown University reported Monday that water exists across the lunar landscape in rocks called pyroclastics, and that those rocks originated from beneath the surface in the moon’s mantle. The findings, detailed in Nature Geoscience, challenge scientist’s understanding of how the moon formed.
“Almost all examined pyroclastics show enhanced water features, supporting that the lunar mantle is ‘wet’ at a global scale,” Shuai Li, a planetary scientist and the study’s lead author, said via email.
Scientists have been looking for water on celestial bodies beyond Earth as far afield as the dwarf planet, Pluto. But they’ve looked close to home, too. Pyroclastics — glass-like volcanic sediments captured during Apollo missions to the moon and brought back to Earth — contained trace amounts of water and even harbored as much H2O as some rocks on Earth do.
Li wondered if water existed elsewhere on the moon, so he turned to the Moon Mineralogy Mapper, or M3. That’s a special instrument aboard India’s Chandrayaan-1 spacecraft, which captures near-infrared light bouncing off the moon’s surface. Different chemicals on the moon’s exterior interact with the light, producing characteristic reflections — “signatures” — that reveal the compounds’ identities.
Eight years ago, researchers used M3 to spot signs of water at the lunar poles, but doing the same for the rest of the moon is complicated.
The problem is that daytime temperatures on the moon’s surface — reaching upwards of 260 degrees Fahrenheit — can distort or obscure light measurements made by M3. So, Li developed a new model to analyze M3’s data that accounts for this lunar heat. He then mapped where water might be across the moon’s terrain, and estimated how much existed in those places.
He found scant evidence for water on the surface of the moon near the equator with one notable exception: glass-like pyroclastic deposits.
These pyroclastic rocks were made by volcanic eruptions, triggered when a Mars-sized meteorite violently collided with Earth around 4.5 billion years ago and formed the moon. These lunar eruptions continued up until 1 billion years ago, and Li’s results suggest water became embedded in the moon’s molten mantle during this period or soon after. The water is now chemically trapped inside the leftover volcanic rocks, and not sloshing around as a liquid.
But, the water could have come from other sources after the volcanoes ceased. Solar wind could have generated the water by reacting with oxygen on the lunar surface. Or, water-rich meteorites and comets could have crashed into the moon.
Li wanted to clarify the moon water’s origin. So, when he ran his model, he used a conservative threshold for all the water signatures that were possibly made by solar wind and then focused on sites with readings above this threshold. Many pyroclastic deposits detected in the study had three to four times more than this background limit. Meanwhile, the water signatures were not located near craters or other geologic formations suggestive of meteorite and comet impacts, ruling out the idea that the water was left behind by foreign objects.
Similar to how lava disperses after a volcanic eruption, pyroclastic deposits with more water were spread out across a greater land area, further indicating the water originally came from the moon’s mantle and erupted out of now dormant volcanoes.
“The distribution of these water-rich deposits is the key thing,” Ralph Milliken, a planetary scientist and senior author of the study, said in a statement. “They’re spread across the surface, which tells us that the water found in the Apollo samples isn’t a one-off.”
“Lunar pyroclastics seem to be universally water-rich, which suggests the same may be true of the mantle,” Milliken said.
Yet Li and Milliken’s study leaves some questions unanswered, namely what is the source of water in the lunar interior. Was it brought by an asteroid or comet while the moon was still solidifying and covered in shifting pyroclastic flows? Or, did the lunar water somehow survive the heat generated during the moon’s formation and these early volcanic eruptions?
Regardless of its origins, the study authors said, the vast reservoir of water in the pyroclastic deposits may provide an untapped water resource for astronauts during future lunar explorations. | 0.831279 | 3.962107 |
A new and incredibly detailed image of the Lagoon Nebula — a giant planet-forming cloud of gas and dust located over 4000 light years away from Earth — has been captured by Chile’s VLT Survey Telescope (VST) at the European Southern Observatory’s (ESO) Paranal Observatory.
The Lagoon Nebula is home to young stellar clusters and is creating a number of intensely bright, young stars — rustling up considerable interest within the astronomical community.
ESO’s Paranal Observatory, which houses the powerful VST, has proudly released a zoomable, online version of the 16,000-pixel-wide image, allowing viewers to explore the finer details of the nebula. This latest images follows other successes from the VST has including detailed images of the Swan Nebula and the Omega Centauri star cluster.
“The Lagoon Nebula is a huge star formation region, one of only two that is visible with the naked eye. Stars are being born in clumps in the nebula, it’s a stellar nursery,” James Jenkins, an astronomer at the Universidad de Chile, told This is Chile. “At its longest point the width of the Nebula is nearly 70,000 times larger than that of our entire solar system.”
Astrologists in Chile are studying the nature of dark energy, searching for brilliant quasars in the early Universe, probing structures in the Milky Way and looking for hidden objects in deep space — all part of three surveys in which the VST is being used.
History shows that surveys of this nature often unearth the unexpected and many surprises have been discovered that have been vital for the progress of astronomical research.
Data reaching as far back to 2010, previously hidden in ESO’s archive, is now being made available to the public — initiating further discoveries from astronomers. New results include the findings of novel star clusters, the most detailed map yet of the Milky Way, a very deep view of the infrared sky and some of the most distant quasars ever discovered.
ESO’s public surveys are set to continue for many years, providing the public and astronomers alike with valuable information regarding discoveries of the universe. Several sophisticated telescopes are operated from Chile’s Atacama Desert region, — home to some of the clearest skies in the world.
As a result many scientists and astronomers gravitate towards Chile. Aside from the Atacama, ESO facilities are also operated at La Silla, in the Coquimbo region. | 0.817154 | 3.610904 |
Justin Greenhalgh - Talk to Newbury Astronomical Society, 3rd November 2017
Isaac Newton regarded gravity as “instantaneous action at a distance”. In his Special Theory of Relativity, Einstein showed that nothing can exceed the speed of light, so instantaneous action is impossible. In the General Theory of Relativity, gravity is explained as a distortion of space and time, and accelerating masses would generate waves of distortion travelling through space at the speed of light. Einstein himself did not believe gravitational waves (GW) existed.
Potential sources of GW are: the coalescence of compact binary objects (paired neutron stars and black holes) orbiting one another at high speeds; asymmetric stellar collapses; pulsars; low-mass X-ray binary stars and instabilities in neutron stars. The first two generate pulsed GW with characteristic waveforms, whereas the others emit continuous waves. When a GW passes, space is alternately stretched and squashed in two directions at right angles to the direction of travel of the wave. The great distances to detectable sources mean the distortion (strain) would be less than one part in 1022: the earth-moon distance would change by less than the size of an atom. Precision laser interferometers that measure the separation of suspended massive mirrors are used to detect the
change of length due to a GW. There are detectors in the USA: LIGO (Laser Interferometric Gravitational-wave Observatory); in Europe (GEO and Virgo) and in Japan (KAGRA). Future detectors are planned in India and Australia.
LIGO consists of two interferometers, in Washington State and Louisiana, each with two arms of 4 km length. The European systems are smaller, typically less than 1 km. Using two widely-spaced detectors allows signals from local events to be rejected, and gives some directional sensitivity. Noise of various kinds (ocean waves, traffic, rabbits, earthquakes, logging) is the main problem for GW detection, so isolating the detectors from noise requires very sophisticated engineering. The first version of LIGO could measure strains down to a few times 10-23, which in theory meant that only the strongest GW sources could be detected. An upgrade of 10x in sensitivity (and 1000x in the observable volume of space) was funded at a cost of $200 million. The mirror suspension systems,
seismic isolation and feedback controls were all upgraded using techniques developed on the European detectors, and the sensitivity increased to 8x10-24.
On the 14th September 2015, both LIGO stations detected signals consistent with the coalescence of two black holes. Modelling showed their masses were 36 and 29 solar masses, and they were orbiting each other 75 times per second at speeds up to 0.6 of light speed when they merged. The pair emitted the energy equivalent of 3 solar masses in GW radiation in the final 0.2 seconds of their interaction. The event occurred 1.4 billion years ago. The detection occurred during routine testing for noise sources, not on an actual observing run; the announcement of the detection was made only after exhaustive analysis to ensure it was not a false event.
The result, in the centenary year of the publication of the General Theory of Relativity, confirmed the existence of GW, as predicted by that theory, and demonstrated that they can be detected. It also confirmed that black holes with masses of a few tens of solar masses exist. Since the first detection there have been four others of merging black hole pairs, and one of merging neutron stars which was also detected optically and in gamma rays. The coincidence of these detections confirmed that GW do indeed travel at the speed of light.
The future of GW astronomy includes bringing more detectors online, increasing their sensitivityusing optical noise reduction techniques (“squeezed” light), and putting laser interferometers into space (LISA). It will open up an entirely new window on the Universe.
Notes and summary by Chris Hooker. | 0.873847 | 3.858718 |
The Hubble Space Telescope has succeeded in imaging an especially bright quasar from the dawn of the universe. As astronomers report in a paper, J043947.08+163415.7 is 12.8 billion light-years away. That also means that we can see 12.8 billion years into the past. When the light that is reaching us today was emitted from the quasar, the universe was still in its epoch of reionization.
Thus, by discovering this quasar, astronomers have the chance of observing the cosmos as a child. The quasar is approximately as bright as eleven billion Suns. Possibly 10,000 new stars are created in it every year (for comparison: the Milky Way produces approximately one star per year). However, that still wouldn’t make it bright enough for the Hubble to see the quasar. To discover it, an additional cosmic magnifying glass was needed in the form of another, much closer galaxy, whose gravitational forces focused the light from J043947.08+163415.7 like a kind of lens, so that the quasar appears 50 times brighter than it would otherwise. | 0.858799 | 3.297463 |
Mars with the plume circled, right, and zoomed in views of the region at left. Credit: Grupo Ciencias Planetarias (GCP) - UPV/EHU
This article was originally published on The Conversation.
Enormous cloud-like plumes reaching 160 miles above the surface of Mars have left scientists baffled. This is way beyond Mars’ normal weather, reaching into the exosphere where the atmosphere merges with interplanetary space. None of the conventional explanations for such clouds make sense – neither water or carbon dioxide ice nor dust storms nor auroral light emissions usually hit such heights. These “mystery clouds” came as a surprise, in particular when considering they were first spotted by a string of amateur astronomers in 2012. After all, an international fleet of five orbiters and two rovers is currently operating on and around Mars, and one may be excused thinking the red planet has little left to hide and its exploration has become routine. A survey of images from the Hubble Space Telescope and amateur astronomers revealed massive clouds had been seen on Mars before, but none as prominent as the 2012 observations. So what caused these clouds? An international team of scientists led by Agustin Sánchez-Lavega has now published an investigation in the journal
Perhaps these clouds could be aurorae – similar to the northern lights (aurora borealis) here on Earth, or their southern counterpart aurora australis. These displays happen when the Earth’s magnetic field channels charged particles emitted by the Sun towards the poles, where they interact with the atmosphere and emit light. Mars does not have a global magnetic field, only pockets of magnetization. The mystery clouds were spotted over one of these so-called magnetic anomalies, and auroral lights have been observed there previously. However, to explain the 2012 observations, an aurora would have had to be 1,000 times brighter than the northern lights. This would require an increased flow of charged particles from the sun, but its activity was not unusually high during the time.
Storms and Smashes
Could dust be the culprit? A volcanic eruption or an asteroid impact were among the earliest theories about these clouds’ origin. New eruptions on Mars are plausible, though we’re yet to observe any active volcanoes on the planet. The youngest lava flows reported are a few million to tens of million years old, which is recent in geological terms. Mars’ thin atmosphere offers little protection against asteroids, and its surface is pockmarked with impact craters. Cameras on board NASA’s Mars Reconnaissance Orbiter have documented the appearance of hundreds of new craters in the nine years since the spacecraft arrived at Mars. However, both theories were quickly discarded because they were inconsistent with the behavior of the clouds. Continued observations showed that they disappeared during the Martian daytime, were not visible in the evening, and reappeared each morning for at least ten consecutive days. This also rules out dust storms, which frequently engulf large areas of the planet’s surface. Furthermore, the wavelength profile of the light reflected by the mystery clouds is a poor match for Martian dust particles.
Not Cold Enough for Ice
That leaves water or carbon dioxide ice particles, which fit the wavelength profile of the reflected light. Both water and carbon dioxide molecules also occur naturally in the atmosphere at these heights. However, to form these clouds both substances would need to condense into ice particles. This would require the atmospheric temperature at these heights to drop suddenly by up to 100˚C. We’ve no idea what would cause such a drop, and we’re yet to spot such a massive, localized cold snap. Sánchez-Lavega and colleagues thus declare that their “explanations defy our current understanding of Mars’ upper atmosphere” and their investigation only partially lifts the shroud surrounding these mysterious clouds.
Other Martian Mysteries
High altitude clouds are not the only Martian mysteries keeping researchers on their toes. One question driving the exploration of the red planet is whether there has ever been life on Mars. Latest results by NASA’s Curiosity rover reaffirm that the planet provided habitable conditions in its past. Water is the most important prerequisite for life. One explanation for the ongoing formation of gullies and related features, for example, is liquid water at or near the Martian surface even during the currently prevailing extreme dry and cold conditions. And while there are many possible explanations for the enigmatic whiffs of methane observed on Mars, one of the most exciting is the production by microorganisms living just below the surface. Part of the fascination of Mars exploration is that it is very much about understanding our own origins and future. As the example of the mystery cloud observations shows, everybody has a chance to participate in unraveling the red planet’s mysteries. | 0.854147 | 3.906711 |
We gaze into the interstellar depths of the Milky Way through uncountable stars.
In this telescopic scene we look toward the Scutum Starcloud, and next spiral arm in from ours as we gaze toward the core of the Galaxy.
The field is packed with stars, seemingly crowded together in interstellar space. In fact, light years of empty space separate the stars, even in crowded regions of the Milky Way like this.
Two dense clusters of stars stand out like islands in the sea of stars. At lower right is Messier 26, an open cluster made of a few dozen stars. Our young Sun probably belonged to a similar family of stars billions of years ago. M26 lies 5,200 light years away.
At upper left is a condensed spot of light, made of hundreds of thousands of density packed stars in the globular cluster known only as NGC 6712. Though much larger and denser than M26, NGC 6712 appears as a tiny spot because of its remoteness – 23,000 light years away, a good part of the distance toward the centre of the Galaxy.
Look carefully (and it may not be visible on screen) and you might see a small green smudge to the left of NGC 6712. That’s a “planetary nebula” called IC 1295. It’s the blown off atmosphere of an aging Sun-like star. It’s what our Sun will become billions of years from now.
At top is a vivid orange-red star, S Scuti, a giant pulsating star nearing the end of its life.
A truly interstellar scene.
– Alan, November 9, 2014 / © 2014 Alan Dyer | 0.840545 | 3.401035 |
Ever wonder why coffee-table books on astronomy never show pictures of stars as sharply defined spheres like the Sun? After all, a moderate-sized telescope receives about a trillion photons (particles of light) per minute from a nearby star, easily enough to form a well-defined image.
Two phenomena prevent such an image from being obtained. First, if the telescope in question is ground-based, the photons that reach it are scattered slightly by turbulence in the Earth’s atmosphere, which blurs the image. This problem can be overcome by placing the telescope above the atmosphere. This was one of the prime motivations for building the Hubble Space Telescope, but even this ingenious creation falls foul of the second phenomenon.
According to the laws of quantum theory, for every photon recorded by a telescope there is a tiny but irreducible uncertainty in its arrival direction. Given Earth’s remoteness from the stars, this tiny angular uncertainty translates into a large spatial uncertainty back at the star of origin. This means that, at best, stars appear as hazy blobs, even when viewed with the Hubble, and that the light from any planets orbiting a star is lost in the glare of the hazy blob.
With these problems in mind, astronomers are developing special techniques for resolving stars and for detecting planets orbiting them (known as extrasolar planets), especially small, habitable planets like Earth.
The first detection of an extrasolar planet took place in 1995. It was achieved by two Swiss astronomers who observed perturbations to the motion of a star due to a giant Jupiter-sized planet orbiting nearby. Since then nearly 200 Jupiter-sized planets have been found in this way, as well as seven smaller planets comparable in size to Neptune. The presence of some of these planets has been confirmed by the dimming effect they cause when they pass in front of their parent stars. But such means of detection, especially when employed terrestrially, cannot reveal planets as small as Earth.
Enter the MOA project. This is a Japanese–New Zealand enterprise that uses the gravitational bending of light, as implied by Einstein’s General Theory of Relativity, to detect extrasolar planets. The technical term for this bending effect is gravitational microlensing, and the acronym MOA stands for Microlensing Observations in Astrophysics. Gravitational microlensing provides the most sensitive means presently devised for detecting extrasolar planets, and the only means of detecting planets as small as Earth orbiting normal stars like the Sun.
Earth-like extrasolar planets are, of course, the prime goal in the search for life beyond our solar system. For a planet to be habitable, it is generally believed it needs to be of sufficient size to retain an atmosphere; to have a rocky surface (not gaseous like Jupiter) to permit life to evolve on the surface; to be at a distance from its parent star that allows liquid water (not ice or steam) to be present on its surface; to have a parent star sufficiently long-lived that there has been time for life to evolve; to have a neighbouring giant planet to attract, and absorb the impact of, large asteroids that might otherwise hit it; and, possibly, to have a large moon to stabilise its spin axis. These, at any rate, are thought to be the likely requirements for life as we know it. Other types of life in different habitats might also be possible.
The study of extrasolar planets is not driven merely by the search for extra-terrestrial life, however. Indeed, one of the lessons learned since 1995 is that there is a wide diversity of types of planetary system. By observing the full range, astroscientists will understand better the physical processes involved in planetary formation and evolution.
That light was bent by gravitational fields was dramatically confirmed by the British astrophysicist Arthur Stanley Eddington and others in 1919. During a solar eclipse, stars close in the sky to the Sun, and therefore normally lost or hard to see in its glare, were clearly visible, and careful measurements showed their apparent positions changed in accordance with Einstein’s General Theory of Relativity. A contemporary re-evaluation of Eddington’s data reveals a less conclusive result, but more accurate measurements since then have put Einstein’s gravitation bending of light beyond doubt.
Einstein further considered the bending of light by stars other than the Sun in a short paper in 1936. He pointed out that if two stars, as viewed from the Earth, were lined up one behind the other, light from the more distant one would be bent by the gravitational field of the nearer one. As a result, the more distant star, rather than being hidden from view, or occulted, would appear as a ring of light surrounding the nearer star. Einstein referred to this effect as the “lens-like action of the gravitational field” of the nearer star, because the image, although magnified, would also be distorted. But incorrectly he predicted the effect would never be observed, because—and here he may have been influenced by the 1919 observations which could be made only when there was an eclipse, because of the Sun’s proximity to the Earth—the ring would be lost in the blinding glare of the nearer star.
In the 1960s, the idea was resurrected by Sjur Refsdal in Norway and Sydney Liebes in the US. Both men estimated that magnifications as high as 1000 could occur, and, in contrast to Einstein, held that distant faint stars and clusters of stars could act as gravitational lenses. In reality, background star, lens and Earth are rarely in the perfect alignment necessary to create a perfect Einstein ring, and because rays that pass closest to the lensing mass are bent more than rays passing further away, the ideal Einstein ring is generally reduced to two magnified blob-like images on opposite sides of the lensing star, as shown on page 81 (top panel). The two images are so close together that only their summed brightness is recorded by a telescope. As the lens star glides across the line of sight, the summed brightness displays a symmetrical increase and decrease. Planets orbiting the lens star act like smaller gravitational lenses to transitorily enhance or diminish the brightness of the observed star. Happily, the lensing zone is about the size of our solar system, and the probability for orbiting planets to cause an observable effect is quite high, especially if the lens star passes almost directly in front of the background star, and if intense observations are made during the approximately 24-hour period when this happens.
It is difficult to demonstrate gravitational microlensing directly because the bending is only slight and the Einstein ring is too small to be resolved. Artificial enlargement of the effect using plastic lenses milled to mimic the gravitational field can help. Both Liebes and Refsdal made such lenses, shaped like the bases of wine glasses, and the MOA group recently made two more. Simulated stars have been observed through these lenses under a variety of conditions.
Astronomers in New Zealand are ideally situated to observe gravitational microlensing. The densest star field in the sky—the centre of the Milky Way Galaxy, located in the constellation Sagittarius—passes almost directly overhead during the country’s long winter nights, delivering optimum conditions for microlensing. On any winter’s evening, several microlensing events are observable. A Polish–US group known as OGLE (the Optical Gravitational Lensing Experiment) made the first observation of microlensing in this region of the sky in 1993.
Other favoured sites for microlensing are the Large and Small Magellanic Clouds (two dwarf galaxies that orbit the Milky Way Galaxy). A US Australian group and a French group, known respectively as the MACHO (MAssive Compact Halo Objects) Project and EROS (Expérience pour la Recherche d’Objets Sombres), reported the first searches in these galaxies in 1993. They sought evidence of dark astrophysical bodies (rogue planets, dead stars, black holes, or brown dwarves—stellar bodies, with a mass lying below the thermonuclear ignition limit) in the Milky Way acting as gravitational lenses of stars in the more distant Magellanic Clouds. They were prompted to do so by the high speeds of stars in the outskirts of the Milky Way. These stars seemed to require the presence of a large amount of dark matter to confine them in the gravitational field of the Milky Way. After five years, however, the two groups reported that only a small fraction of dark matter could be in the form of MACHOs.
The Early searches for micro-lensing events by OGLE, the MACHO Project and EROS were conducted from observatories in Australia and Chile.
It was soon realised that New Zealand, too, was a location from which valuable observations could be made, serving as a hedge against cloudy weather at critical times in Australia and enjoying a large time differential with Chile.
At the time, Japan and New Zealand were collaborating on the observation of cosmic rays from a supernova that had been spotted in the Large Magellanic Cloud in 1987, and had established a good rapport for innovative research in astrophysics. In addition, New Zealand received an offer of support from the MACHO Project, which was led by Charles Alcock, formerly a student of the University of Auckland and today director of the Harvard-Smithsonian Centre for Astrophysics. John Hearnshaw, director of the University of Canterbury’s Mt John observatory, was quick to appreciate the scientific potential and offered observing time on one of the Mt John telescopes.
The rounded shape of Mt John makes for a smooth airflow over it and thus good astronomical “seeing”. To the west, the Southern Alps attract most of the precipitation that comes off the Tasman Sea, leaving Mt John relatively dry. Two of New Zealand’s foremost opticians, Norman Rumsey and the late Gary Nankivell, offered their expertise to widen the field of view of the telescope, and astronomers at Perth Observatory, Western Australia, offered to help computerise it.
Thus it came about that New Zealand and Japan commenced a gravitational-microlensing project at Mt John. The name “Microlensing Observations in Astrophysics” was proposed by Japan, and New Zealand readily accepted it. More importantly, the main aim of the project was agreed upon: to search for dark matter and extrasolar planets as revealed by gravitational-microlensing. Observations began in 1995.
The years 1995 to 2000 were a learning period for the MOA project, as they were for others in the same business. In retrospect, it will probably become clear that we are still in a learning phase. One of the first skills we had to develop was the analysis of images containing millions of overlapping stars. Techniques were also required for modelling complex microlensing events using clusters of computers. And observations were made every fine night, about 60 per cent of night-time hours.
Perhaps the main lesson learned by MOA in the early years was the advantage of observing microlensing events involving high magnifications, of the order of 100 or more. Rutherford learned a similar lesson almost a hundred years ago. In his classic experiment of 1910, he fired alpha particles (ionised helium atoms) at a sheet of gold foil. Most of the particles, as expected, passed straight through, but some were deflected, having struck something very small and dense at the heart of atoms in the foil. The effect was comparable to gravitational microlensing. The obvious difference is that in Rutherford’s experiment particles were deflected away from the centre of an atom, while microlensing entails photons being attracted by gravity. However, inserting a simple minus sign into the mathematics takes care of this. The important point is that in both situations the most useful information is obtained when the projectile originates directly behind the obstacle. In Rutherford’s case it led to his discovery of the atomic nucleus. For the MOA project and others of its kind, such an alignment yields the largest magnifications in gravitational microlensing.
The gravitational-microlensing event MOA-2002-BLG-33 provides an illustration of what can be achieved when magnification is high. As its name records, this was the 33rd microlensing event observed by the MOA group in the central bulge of the Milky Way during 2002. It reached a peak magnification in excess of 500. The lens for the event was a binary star; that is, a pair of stars orbiting each other about a common centre of mass. Such stars are common, and they form beautiful lenses.
An illustration on the preceding page shows the kite-shaped magnification pattern produced by the binary lens of MOA-2002-BLG-33, and also the star that was magnified. This magnification pattern is typical of the complicated bending of light that occurs with lenses containing more than one component. The star passed horizontally through the kite, taking 15.6 hours. Intense observations made during these hours enabled the characteristics of the star to be measured without the high degree of uncertainty explained above, as if Sherlock Holmes had passed a large magnifying glass over it. By making measurements through different coloured filters, it was possible to form a colour image. The angular resolution of this image is probably the finest yet achieved in any situation and by any means. It corresponds to the resolution needed for this article to be legible from Earth if it was placed on the Moon. The MOA group was assisted in this work by observatories in Chile, South Africa, Israel and Arizona, as well as by the Hubble Space Telescope.
MOA-2003-BLG-53 was another highlight for the MOA project. This was the first microlensing event in which irrefutable evidence of an extra-solar planet was obtained. The planet found in this event is quite similar to Jupiter. It’s mass is double that of Jupiter, and it orbits a star two thirds the mass of the sun in an orbit slightly larger than that of Jupiters’. This star-planet system is some 19,000 light years away, about three quarters the distance to the centre of the Milky Way. The planet was found by the MOA group and by the OGLE group observing from Chile. The combined data from Mt John and Chile are shown overleaf, plus an image of the event obtained by the Hubble Space Telescope in 2006. This shows that in three years since microlensing occurred, the lens and background stars diverged sufficiently for the Hubble to just resolve them, through their different colours. In the future, similar follow-up observations will be made routinely as they enable host stars of planets found by micro-lensing to be classified.
An event found by OGLE in 2005 provided a good example of the power of gravitational microlensing at high magnification. This was OGLE-2005 BLG-169, which reached a magnification in excess of 700. Measurements of the intensity of the magnified star as its light passed through the lens showed that the lens consisted of a small cool star, or red dwarf, that was orbited by a planet, comparable in size to Neptune, at a distance about four times that of the Earth from the Sun. The estimated temperature of the planet was about –200°C. It was possible to determine that it had no gas-giant companions similar to Jupiter, suggesting that it was itself free of gas. The painting on the opening spread of this article is an artist’s rendering of this planet.
In 2002, Yasushi Muraki, professor of physics at Nagoya University and one of New Zealand’s long-standing collaborators from Japan, was awarded a Japanese government research grant to build a new, larger telescope at the Mt John observatory for the MOA project. This was welcome news, as the telescope the MOA project had been using since its inception was significantly smaller than those used by other microlensing groups. The telescope was funded for the purpose of searching for both dark matter and planets in the Milky Way.
Andrew Rakich, a protégé of Nor‑man Rumsey working at the time for Industrial Research Ltd in Wellington, was selected to design the telescope, and Nishimura Optical Company of Kyoto was commissioned to build it. Eco-tourism and education company Earth & Sky, of Lake Tekapo, offered to supply the control room. A design promising 15 times the light-gathering power of the telescope used to date was agreed on, and construction began in 2003. The telescope was fully assembled in Kyoto, then disassembled, shipped to New Zealand, and reassembled in 2004.
While the telescope was under construction, a large electronic camera incorporating a charge-coupled device, or CCD, was designed and built at the University of Nagoya under the direction of Takashi Sako. The camera is the heart of the telescope—all data are recorded by it. Modern CCD cameras have transformed astronomy through their high (almost 100 per cent) light-detection efficiency and their compatibility with powerful computers. They enable millions of stars to be monitored simultaneously. High accuracy is achieved by operating at low temperatures, around –90°C, in a vacuum. The construction of these large, specialist cameras is as complicated as the construction of the telescopes themselves.
An opening ceremony for the new MOA telescope was held on December 1, 2004. Among the 150 guests and dignitaries who attended were Masaki Saito, Japan’s ambassador to New Zealand, Professor Shinichi Hirano, the president of Nagoya University, and Yuji Nishimura, CEO of Nishimura Optical Company. Whetu Tirikatene-Sullivan, wife of MOA team member Denis Sullivan, blessed the telescope and thanked the Japanese government for providing the funding for it.
In 2005 exhaustive commissioning tests were carried out, culminating in the somewhat serendipitous discovery, in association with other micro-lensing groups, of the most Earth-like extrasolar planet yet found. This was an icy planet, similar to OGLE-2005 BLG-169, but slightly smaller.
The future appears bright for the MOA project, and indeed for the microlensing community in general. The ability to detect extrasolar planets as small as Earth means that the abundance of such planets can be measured. From there it should not be a difficult step to estimating the abundance of habitable planets in the universe—an exciting prospect.
To achieve this goal, the MOA project and OGLE will continue their surveys of the Galactic bulge and the Magellanic Clouds for microlensing events. The most promising of these, in particular those with the highest magnifications, will be selected for especially close scrutiny by networks of “follow-up” telescopes.
Two such networks have already been in operation for some years: PLANET/Robonet (PLANET = Probing Lensing Anomalies NET-work) and MicroFUN (Microlensing Follow-Up Network). They have telescopes in Australia, South Africa, Israel, Hawaii, the US, Chile and New Zealand. The Neptune-like extrasolar planets mentioned above were found in collaboration with these groups and OGLE. Of special note here are important observations made of the peaks of high-magnification events from the Stardome and Farm Cove observatories in Auckland using the smallest telescopes in the microlensing community.
More recently, astronomers from Taiwan, China, Japan, India, Thailand, Namibia, Cuba, Venezuela and Argentina have expressed interest in observing future events. Gravitational microlensing is in a growth phase!
Looking further to the future, Antarctica offers exciting prospects. Australian and French astronomers have recently found that the atmospheric conditions at high points on the Antarctic plateau are the best for astronomy on the planet. Images of Scott battling blizzards do not reflect typical plateau weather. Dry, stable conditions are the norm—every astronomer’s dream. The scintillation, or twinkling, of stars is less by a factor of three than at the best sites in Chile and Hawaii. A large French–Italian station has been operating successfully at one of the high points, Dome C, since 2005, and last year a Chinese group reached the highest point on the plateau, Dome A. A telescope at either of these locations would be ideally placed to monitor gravitational microlensing events continuously.
Another possibility is to add further telescopes to the battery that already exists at mid-southern latitudes. Andrew Gould of the US, one of the pioneers of the observational era of gravitational microlensing, has proposed the construction of two further telescopes similar to the MOA one, to be located in South Africa and Chile. And David Bennett, another pioneer of observational microlensing from the US, has proposed the construction of a space telescope dedicated to gravitational microlensing. This could be used to make an accurate census of all types of planet in the Milky Way Galaxy.
The hunt for Earth-like planets is spurred both by scientific curiosity and by competition among various groups using different techniques. Gravitational microlensing is not the only game in town. A US space mission named Kepler will shortly commence a search for Earth-like planets orbiting nearby stars using the “transit” technique, which involves detecting where light from a star is dimmed by planets orbiting it. Kepler will be most sensitive to hot planets orbiting quite close to their parent stars. Gravitational microlensing, on the other hand, is most sensitive to cold planets orbiting further out. The combined results will provide valuable crosschecks, and yield unbiased information on warm Earth-sized planets in the so-called habitable zone. | 0.899757 | 4.008835 |
Moon ♑ Capricorn
Moon phase on 11 June 2006 Sunday is Full Moon, 14 days old Moon is in Sagittarius.Share this page: twitter facebook linkedin
Moon rises at sunset and sets at sunrise. It is visible all night and it is high in the sky around midnight.
Moon is passing about ∠17° of ♐ Sagittarius tropical zodiac sector.
Lunar disc appears visually 0.9% narrower than solar disc. Moon and Sun apparent angular diameters are ∠1873" and ∠1890".
The Full Moon this days is the Strawberry of June 2006.
There is high Full Moon ocean tide on this date. Combined Sun and Moon gravitational tidal force working on Earth is strong, because of the Sun-Earth-Moon syzygy alignment.
The Moon is 14 days old. Earth's natural satellite is moving through the middle part of current synodic month. This is lunation 79 of Meeus index or 1032 from Brown series.
Length of current 79 lunation is 29 days, 10 hours and 40 minutes. It is 1 hour and 46 minutes shorter than next lunation 80 length.
Length of current synodic month is 2 hours and 4 minutes shorter than the mean length of synodic month, but it is still 4 hours and 5 minutes longer, compared to 21st century shortest.
This New Moon true anomaly is ∠64.2°. At beginning of next synodic month true anomaly will be ∠97.5°. The length of upcoming synodic months will keep increasing since the true anomaly gets closer to the value of New Moon at point of apogee (∠180°).
7 days after point of apogee on 4 June 2006 at 01:41 in ♍ Virgo. The lunar orbit is getting closer, while the Moon is moving inward the Earth. It will keep this direction for the next 5 days, until it get to the point of next perigee on 16 June 2006 at 17:07 in ♒ Aquarius.
Moon is 382 614 km (237 745 mi) away from Earth on this date. Moon moves closer next 5 days until perigee, when Earth-Moon distance will reach 368 926 km (229 240 mi).
5 days after its descending node on 5 June 2006 at 12:10 in ♎ Libra, the Moon is following the southern part of its orbit for the next 7 days, until it will cross the ecliptic from South to North in ascending node on 18 June 2006 at 19:11 in ♓ Pisces.
19 days after beginning of current draconic month in ♓ Pisces, the Moon is moving from the second to the final part of it.
13 days after previous North standstill on 29 May 2006 at 01:13 in ♋ Cancer, when Moon has reached northern declination of ∠28.490°. Next day the lunar orbit moves southward to face South declination of ∠-28.452° in the next southern standstill on 12 June 2006 at 10:30 in ♑ Capricorn.
The Moon is in Full Moon geocentric opposition with the Sun on this date and this alignment forms Sun-Earth-Moon syzygy. | 0.860247 | 3.074682 |
Plate Tectonics Could be Essential for Life
Plate tectonics have changed the surface of the Earth, but could they be key to life on this planet and others?
Image credit: USGS
Plate tectonics is the process of continents on the Earth drifting and colliding, rock grinding and scraping, mountain ranges being formed, and earthquakes tearing land apart. It makes our world dynamic and ever-changing. But should it factor into our search for life elsewhere in the universe?
Tilman Spohn believes so. As director of the German Space Research Centre Institute of Planetary Research, and chairman of ESA’s scientific advisory committee, he studies worlds beyond our Earth. When looking into the relationship between habitability and plate tectonics, some fascinating possibilities emerged.
Knowing where to look
It is thought that the best places to search for life in the Universe are on planets situated in “habitable zones” around other stars. These are orbital paths where the temperature is suitable for liquid water; not so close to the star that it boils away, and not so far that it freezes. Spohn believes that this view may be outdated. He elaborates, “you could have habitats outside those, for instance in the oceans beneath ice covers on the Galilean satellites, like Europa. But not every icy satellite would be habitable. Take Ganymede, where the ocean is trapped between two layers of ice. You are missing a fresh supply of nutrition and energy.”
So planets and moons that lie beyond habitable zones could host life, so long as the habitat, such as an ocean, is not isolated. It needs access to the key ingredients of life, including hydrogen, oxygen, nitrogen, phosphorous and sulphur. These elements support the basic chemistry of life as we know it, and the material, Spohn argues, must be regularly replenished. Nature’s method of achieving this on the Earth appears to be plate tectonics.
Plate tectonics – essential for life?
Prof. Tilman Spohn presented his ideas at Europlanet’s recent Planetary Science Congress, held in Germany.
Image credit: Lee Pullen
It is an idea growing in popularity among planetary scientists. Says Spohn, “plate tectonics replenishes the nutrition that primitive life could live on. Imagine a top surface that is depleted of the nutrition needed for bacterial life. It needs to be replenished, and plate tectonics is a method of achieving this.”
Spohn found that the further he delved into the issue, the more important plate tectonics seemed to be for life. For example, it is believed that life developed by moving from the ocean to the kind of strong and stable rock formations that are the result of tectonic action. Plate tectonics is also involved in the generation of a magnetic field by convection of Earth’s partially molten core. This magnetic field protects life on Earth by deflecting the solar wind. Not only would an unimpeded solar wind erode our planet’s atmosphere, but it also carries highly energetic particles that could damage DNA.
Another factor is the recycling of carbon, which is needed to stabilize the temperature here on Earth. Spohn explains, “plate tectonics is known to recycle carbon that is washed out of the atmosphere and digested by bacteria in the soil into the interior of the planet from where it can be outcast through volcanic activity. Now, if you have a planet without plate tectonics, you may have parts of this cycle, but it is broken because you do not have the recycling link.”
It has also been speculated that the lack of tectonic action on Venus contributed to its runaway greenhouse effect, which resulted in the immense temperatures it has today.
All this evidence adds up to paint a convincing picture of many lifeforms only surviving on worlds where plate tectonics are active. For astrobiologists, there is another interesting element to this story. Many within the planetary science community believe that to have plate tectonics, the near-surface rock must be weakened. The molecule most effective at doing this is H2O — water.
New technology is being used to obtain images of planets around other stars. One day we may be able to detect signs of plate tectonics on these distant worlds.
Image credit: Gemini Observatory
So worlds with plate tectonics are likely to have water as well, which means they feature two ingredients theoretically necessary for life. This presents an exciting option: searching for plate tectonics on distant worlds as a sign of life. Spohn agrees that this is a possibility, but remains level-headed. “It’s an interesting idea, but is just speculation at the moment,” he explains. “As a biosignature it would be very difficult to detect, especially with current technology”.
The problem is how challenging it is to spot plate tectonics from orbit even on our own Earth. The jig-saw puzzle shape of continents along with the presence of mountain belts provides indirect evidence. Mid-oceanic ridges are more convincing, but these are covered with water and not visible from space. To see features on an extrasolar planet would require a probe in orbit, and this is far beyond our technological ability. Even if we were able to achieve this, the evidence would still be indirect. Currently there is no conclusive way of remotely determining tectonic action on a planet.
So perhaps using these markers as an indication of life on other worlds is a step too far; but as our technology becomes ever more complex it could become a possibility in the future. Imagine detecting an Earth-sized planet with an atmosphere, water, organic materials, and plate tectonics. It would unquestionably raise hopes for finding life in the universe. | 0.898007 | 3.226091 |
Our galaxy may be awash in homeless planets, wandering through space instead of orbiting a star.
In fact, there may be 100,000 times more “nomad planets” in the Milky Way than stars, according to a new study by researchers at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), a joint institute of Stanford University and the SLAC National Accelerator Laboratory.
If observations confirm the estimate, this new class of celestial objects will affect current theories of planet formation and could change our understanding of the origin and abundance of life.
“If any of these nomad planets are big enough to have a thick atmosphere, they could have trapped enough heat for bacterial life to exist,” said Louis Strigari, leader of the team that reported the result in a paper submitted to the Monthly Notices of the Royal Astronomical Society. Although nomad planets don’t bask in the warmth of a star, they may generate heat through internal radioactive decay and tectonic activity.
Searches over the past two decades have identified more than 500 planets outside our solar system, almost all of which orbit stars. Last year, researchers detected about a dozen nomad planets, using a technique called gravitational microlensing, which looks for stars whose light is momentarily refocused by the gravity of passing planets.
The research produced evidence that roughly two nomads exist for every typical, so-called main-sequence star in our galaxy. The new study estimates that nomads may be up to 50,000 times more common than that.
To arrive at what Strigari himself called “an astronomical number,” the KIPAC team took into account the known gravitational pull of the Milky Way galaxy, the amount of matter available to make such objects and how that matter might divvy itself up into objects ranging from the size of Pluto to larger than Jupiter. Not an easy task, considering no one is quite sure how these bodies form. According to Strigari, some were probably ejected from solar systems, but research indicates that not all of them could have formed in that fashion.
“To paraphrase Dorothy from The Wizard of Oz, if correct, this extrapolation implies that we are not in Kansas anymore, and in fact we never were in Kansas,” said Alan Boss of the Carnegie Institution for Science, author of The Crowded Universe: The Search for Living Planets, who was not involved in the research. “The universe is riddled with unseen planetary-mass objects that we are just now able to detect.”
A good count, especially of the smaller objects, will have to wait for the next generation of big survey telescopes, especially the space-based Wide-Field Infrared Survey Telescope and the ground-based Large Synoptic Survey Telescope, both set to begin operation in the early 2020s.
A confirmation of the estimate could lend credence to another possibility mentioned in the paper – that as nomad planets roam their starry pastures, collisions could scatter their microbial flocks to seed life elsewhere.
“Few areas of science have excited as much popular and professional interest in recent times as the prevalence of life in the universe,” said co-author and KIPAC Director Roger Blandford. “What is wonderful is that we can now start to address this question quantitatively by seeking more of these erstwhile planets and asteroids wandering through interstellar space, and then speculate about hitchhiking bugs.”
Additional authors included KIPAC member Matteo Barnabè and affiliate KIPAC member Philip Marshall of Oxford University. The research was supported by NASA, the National Science Foundation and the Royal Astronomical Society.
Andy Freeberg is media relations manager at SLAC National Accelerator Laboratory. | 0.923856 | 3.922272 |
Astronomers find rhythms at the heart of pulsating stars
A global team of astronomers including Keele University’s Dr Barry Smalley have detected a ‘heartbeat’ among distant young stars which will help scientists understand more about the Sun and the workings of stars.
Using data from NASA’s Transiting Exoplanet Survey Satellite (TESS), a space telescope mainly used to detect planets around distant stars, the international team have for the first time identified a rhythm of activity among a class of stellar objects that had until now puzzled scientists.
The stars in question are known as delta Scuti stars, named after a star in the constellation Scutum. They are around 1.5 to 2.5 times larger than our Sun, and although scientists have previously identified many pulsations when studying this class of stars, they have not been able to determine any specific patterns or rhythms.
But in the past few decades, astronomers have been able to detect the internal oscillations of stars using a branch of science known as asteroseismology. This method reveals their structure, by studying stellar pulsations using careful and precise measurements of changes in light output.
This will allow scientists to understand the workings of distant stars, but can also help us understand how our own Sun produces sunspots, flares and deep structural movements, and using this approach the researchers found 60 delta Scuti stars whose pulsations had a rhythm that made sense.
Their findings have been published in Nature and Dr Smalley said that identifying patterns like this can reveal significant details about the interiors of stars.
Dr Smalley said: “The precision of the measurements from TESS has allowed us to reduce the background noise. We can now clearly hear the ‘song’ being played by the stars. The regular patterns of frequencies found in this study are an important contribution to our understating of the interior of the stars.”
Picture credit: produced by Dr Chris Boshuizen (https://twitter.com/DrChrispyMusic), with assistance from Dr Simon Murphy and Prof. Tim Bedding (University of Sydney). | 0.847794 | 3.432941 |
Of the many ways Earth is polluted, light pollution may be the least talked about. Defined as excessive or obtrusive artificial light, light pollution has consequences. It can wash out starlight in the night sky, interfere with astronomical research, disrupt ecosystems, have adverse health effects, and waste energy.
Take a moment to watch this short film that shows how the view of the cosmos gets better in less light-polluted areas.
I would also argue that light pollution causes many students to develop misconceptions. These misconceptions arise because we often fail to provide children with the time and opportunity to simply observe the night sky. After all, if you live in a metropolitan area, it does take some planning and a little driving to get out of the city.
How many young children today realize that during the course of a year, our view of the night sky changes from month to month? Some constellations are always in the sky, while others appear and disappear over different regions. How many children – or adults for that matter – can explain the rotation and revolution of our nearest celestial neighbor, our moon?
If you would like to learn more about common misconceptions in science, read my my five-part series.
The Night Sky Each Month
Early in our homeschool journey I read the works of Charlotte Mason. Her words, particularly in regards to the natural world resonated with me, “We are all meant to be naturalists, each in his own degree, and it is inexcusable to live in a world so full of the marvels of plant and animal life and to care for none of these things.”
With her words in mind, I have always tried to provide my children with ample time in the outdoors and to develop their observational skills. I also love living books that guide them on their discoveries. One of my favorite for astronomy is The Night Sky Month by Month. This book, written by Will Gater and Giles Sparrow, shows the sky as it is seen around the world in both the northern and southern hemispheres. It is the perfect guide for amateur astronomers – the illustrated pictures and monthly sky guides will help you recognize patterns and track changes in the each hemisphere.
Another great story that will delight younger readers is The Moon Over Star which puts the historic moon landing into historical perspective through the eyes of a child.
Astronomical Events for Spring 2019
Charlotte Mason and I would encourage you to get outside and observe the night sky year round. Encourage your child to begin documenting his or her observations by keeping a moon journal. Sketch the appearance of the moon each night and note the location it is visible in they sky. To get you started, here are a few key events this spring.
March Equinox ~ The March equinox occurs on March 20th whereupon the Sun will shine directly on the equator and there will be nearly equal amounts of day and night throughout the world. This is also the first day of spring (vernal equinox) in the Northern Hemisphere and the first day of fall (autumnal equinox) in the Southern Hemisphere.
Worm Moon ~ This full moon phase occurs on March 21st and was known by early Native American tribes as the Full Worm Moon because this was the time of year when the ground would begin to soften and the earthworms would reappear. This is also the last of three super moons for 2019. The Moon will be at its closest approach to the Earth and may look slightly larger and brighter than usual.
Mercury at Greatest Western Elongation ~ The planet Mercury reaches greatest western elongation of 27.7 degrees from the Sun on April 11th. This is the best time to view Mercury since it will be at its highest point above the horizon in the morning sky. Look for the planet low in the eastern sky just before sunrise.
Fish Moon ~ The Moon will be located on the opposite side of the Earth as the Sun and its face will be will be fully illuminated. Early Native American tribes called this full moon the Full Pink Moon because it marked the appearance of wild ground phlox, which is one of the first spring flowers. Many coastal tribes called it the Full Fish Moon because this was the time that the shad swam upstream to spawn.
Lyrids Meteor Shower ~ The Lyrids is an average shower, usually producing about 20 meteors per hour at its peak. It is produced by dust particles left behind by comet C/1861 G1 Thatcher, which was discovered in 1861. The shower runs annually from April 16-25. These meteors can sometimes produce bright dust trails that last for several seconds. Meteors will radiate from the constellation Lyra, but can appear anywhere in the sky.
You might also be interested in my earlier post, Autumn Astronomy Activities for Middle School
Eta Aquarids Meteor Shower ~ The Eta Aquarids is capable of producing up to 60 meteors per hour at its peak in the Southern Hemisphere and about 30 meteors per hour in the Northern Hemisphere. It is produced by dust particles left behind by comet Halley, which has been known and observed since ancient times. The shower runs annually from April 19 to May 28. Meteors will radiate from the constellation Aquarius, but can appear anywhere in the sky.
Blue Moon ~ This full moon will appear on May 18th and was known by early Native American tribes as the Full Flower Moon because this was the time of year when spring flowers appeared in abundance. There are normally only three full moons in each season; a fourth full moon occurs only happens once every 2.7 years, giving rise to the term, “once in a blue moon.”
Nature Book Club
Welcome to the Nature Book Club Monthly Link Up. Devoted to connecting children to nature, the monthly link up will begin on the 20th day of each month. We welcome your nature book and activity related links. Read on for more details.
The Nature Book Club is brought to you by these nature loving bloggers which are your co-hosts. Are you following them? If you don’t want to miss anything, be sure to follow each one.
Here are the co-hosts, their choices of books, and activities for February 2019:
Stargazing with Children by Thaleia at Something 2 Offer
The Rocket That Flew To Mars Online Book Club by Dachelle at Hide The Chocolate
Along Came Galileo Telescope Craft by Emily at TableLifeBlog
If You Decide to Go to the Moon Phases Activity by Karyn at Teach Beside Me
The Night Sky Events for Spring 2019 by Eva Varga at EvaVarga
Follow the Drinking Gourd Free Unit Study Resources by Jenny at Faith & Good Works
Choose an engaging nature book, do a craft or activity, and add your post to our monthly link up.
The link up party goes live at 9:00 a.m. EST on the 20th of each month and stays open until 11:59 p.m. EST on the last day of the month. Hurry to add your links!
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So we are seeing exactly half of the moon illuminated and half in shadow. Once you understand those four key moon phases, the phases between should be fairly easy to visualize, as the illuminated portion gradually transitions between them. An easy way to remember and understand those "between" lunar phase names is by breaking out and defining 4 words: crescent, gibbous, waxing, and waning.
The word crescent refers to the phases where the moon is less than half illuminated. The word gibbous refers to phases where the moon is more than half illuminated. Waxing essentially means "growing" or expanding in illumination, and waning means "shrinking" or decreasing in illumination. Thus you can simply combine the two words to create the phase name, as follows: After the new moon, the sunlit portion is increasing, but less than half, so it is waxing crescent.
After the first quarter, the sunlit portion is still increasing, but now it is more than half, so it is waxing gibbous. After the full moon maximum illumination , the light continually decreases. So the waning gibbous phase occurs next.
Following the third quarter is the waning crescent , which wanes until the light is completely gone -- a new moon. The Moon's Orbit You may have personally observed that the moon goes through a complete moon phases cycle in about one month.source
The Meaning of Each Moon Cycle
That's true, but it's not exactly one month. The time required for the moon to move to the same position same phase as seen by an observer on earth is called the synodic period or lunation and it is If you were to view the moon cycling the earth from outside our solar system the viewpoint of the stars , the time required is This figure is called the sidereal period or orbital period.
Why is the synodic period different from the sidereal period? The short answer is because on earth, we are viewing the moon from a moving platform: during the moon cycle, the earth has moved approximately one month along its year-long orbit around the sun, altering our angle of view with respect to the moon, and thus altering the phase.
The earth's orbital direction is such that it lengthens the period for earthbound observers. Although the synodic and sidereal periods can be used in certain calculations, the moon phase can't be precisely calculated by simple division of days because the moon's motion orbital speed and position is affected and perturbed by various forces of different strengths. From there, it fades into a Waning Crescent Moon.
Finally, the Moon disappears completely from view into another New Moon phase, only to reemerge and repeat this cycle over and over. Moon phases are the same all over the world. The same percentage and area of the Moon are illuminated no matter where on Earth you are. However, the Moon is rotated in different ways depending on the time, the date, your location, and the Moon's position in the sky. Therefore, the illuminated part of a Waning Gibbous Moon can appear on the left, the right, the top, or the bottom.
Sun enters Scorpio
There is no symbol for the Waxing Gibbous Moon in calendars as it is an intermediate Moon phase. These symbols reflect the Moon's appearance in the Northern Hemisphere, which can be confusing for people in the Southern Hemisphere, where the opposite side may be illuminated.
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The Moon illustration on our Moon phase pages changes as time passes, and indicates more accurately, although not perfectly, which part of the Moon is illuminated in more than locations worldwide. Times for Waning Gibbous can vary by time zone. Dates are based on the local time in New York. Change location.
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The cycles of the Moon or each Moon cycle are a great astrological transit for us to utilize on a day to day basis. The Moon moves very quickly through zodiac signs and through each cycle. Each of these impact us in different ways so it is good to understand how it works for you. To better understand how each these can affect you in everyday life, lets touch on how you can use the Moon calendar to jot down some notes on how it impacts you personally and why.
There are two basic principles to understand about the cycles of the Moon.
When it is waxing, it is the time to build. When it is waning, it is a time to withdraw. Each is covered below to give you an idea of how to integrate it into your everyday life - it will start to become easier and easier as you use it more.
Lunar phase - Wikipedia
Pretty soon you will get a good idea on how to make the most of each cycle in your day-to-day activities. Good time to have an awareness of new is coming into your life and what their needs and expectations are of you.
This is considered a lower energy time. A time for the completion of old tasks and activities and the preparation for new ones. Everything is considered to be in a lull at this time, life energy, emotions and physiological activity. It is often thought not the best time to start new projects - but it may represent the end of a cycle with a new project or job coming up.
So in essence the ending of something in preparation for the beginning of something new. A positive time to get things done. Thoughts are best focused on the creation and starting of things. Easiest to think of it from a farming perspective. Waxing is a time for planting and growing. Waxing means to slowly increase and the intensity increases at this point just before the Full Moon Cycle. Listening skills tend to be less evident - as people get more engaged and focused during this time. | 0.828564 | 3.791389 |
Has Voyager 1 left the solar system? It depends on who you ask. If you ask NASA, the space agency will say that Voyager 1 “has not yet left the solar system or reached interstellar space.” However, if you ask researcher Marc Swisdak and plasma physicists James F. Drake and Merav Opher, they will say that Voyager 1 left the solar system last summer.
“It’s a somewhat controversial view, but we think Voyager has finally left the solar system, and is truly beginning its travels through the Milky Way,” says Swisdak, a lead author of the study and a University of Maryland research scientist.
Swisdak and his colleagues have created a model of the outer edge of the solar system that concurs with recent observations. Their model reveals that Voyager 1 actually passed into interstellar space last summer, a result directly opposing recent papers by NASA indicating that the probe was still in the heliopause transition zone.
Last summer, NASA reported that Voyager 1 recorded “multiple crossing of a boundary unlike anything previously observed.” According to the space agency, the probe recorded consecutive dips in, and later recovery of, solar particle counts. The dips in solar particle counts were consistent with abrupt increases in galactic electrons and protons. Within a month, solar particle counts ceased, and only galactic particle counts endured. However, the probe detected no change in the direction of the magnetic field.
Many scientists believe that Voyager 1 has passed into a “heliosheath depletion region,” but that the probe is still within the boundaries of the heliosphere.
Swisdak and colleagues think there is an entirely different explanation for the probe’s observations.
According to the researchers, magnetic reconnection is essential to grasping NASA’s data. They contend that the heliosphere is both porous to certain particles and layered with intricate magnetic structure. Magnetic reconnection creates an intricate set of nest magnetic “islands.” Interstellar plasma can access the heliosphere along reconnected field lines, and galactic cosmic rays and solar particles mix furiously.
The researchers point out that drops in solar particle counts and swells in galactic particle counts can take place across “slopes” in the magnetic field, while the magnetic field direction itself remains unaltered. Thus, Swisdak and his colleagues argue that Voyager 1 actually traversed the heliopause on July 27, 2012.
Of course, their model is not the only model trying to interpret NASA’s unusual data.
“Other models envision the interstellar magnetic field draped around our solar bubble and predict that the direction of the interstellar magnetic field is different from the solar magnetic field inside,” says Ed Stone, Voyager project scientist. “By that interpretation, Voyager 1 would still be inside our solar bubble.”
Despite NASA’s disagreement with the study’s findings, the space agency acknowledges the importance of taking these results seriously.
“The fine-scale magnetic connection model will become part of the discussion among scientists as they try to reconcile what may be happening on a fine scale with what happens on a larger scale,” says Stone.
The results are discussed in greater detail in The Astrophysical Journal Letters. | 0.859894 | 3.724395 |
Table of Cotents
Introduction to Star
You must have seen a number of stars in the sky at clear night. Have you ever tried to count them?
But, have you ever thought that from where these stars come from?
How do they appear to us although they are thousands of light years away?
Some are even millions and billions of light years away form us.
There are trillions of stars in our universe. Our nearest star is alpha centauri after sun. The collecion of a large number of stars forms a galaxy and collection of many galaxies forms the whole universe.
Well let’s see, how these stars are formed ,how do they die and how the life cycle of a star is completed.
A star has a life span of billions of years. So, it is not possible for one to observe its complete life from its birth to death. However, by observing different stars, their ages and their other characters, scientists have given an acceptable model for the life cycle of a star form its birth to its death.
Firstly, let’s look upon the formation of a star.
Formation of a star
There are a lot of cloud clusters and dust particles present in the space. These matters start to come close to each other and attract each other.. Slowly they form a large mass of cloud and dust. It is called Nebula.
Nebula has extremely low temperature and mainly consists of hydrogen. Their mass is usually more than an average star mass. They are opaque to visible light and don’t reflect light at all. So they must be detected by the IR and UV-rays. The nebula begins to contract by the action of its own internal gravitational force. It becomes more denser and denser. This process continues for million of years depending upon the size of nebulae.
he temperature of the nebula starts to rise slowly and becomes highly packed. As a result, formation of protostar takes place. Protostar has relatively high density and temperature. When its temperature reaches to certain limit, nuclear binding energy of its constituent particle breaks and nuclear fusion reaction initiates. After the initiation of the nuclear reaction, large quantity of heat energy is produced. This results in the birth of a star.
A Living Star
After the birth of a star, the star starts its life of a billion of years. The life of a star depends upon the amount of matter it is composed of. Small stars have low temperature and use up their fuel slowly while large stars use up their fuel in vast amount and have very high temperature. Colour of a star also changes constantly along with the life cycle of a star. It changes as:
Finally, the fuel of the stars become almost finished and the star starts its journey towards death.
Final Stage of a star
After the red-phase of a star, there comes possibility of formation of two types of stars, red supergiant star and red giant star. It depends upon the mass of the star.
1. Star having the mass less than five times the mass of our sun
Formation of Red Giant Star
If the star has the mass less than five times the mass of our sun, the star starts to contract. The star becomes dense. But some of the remnants hydrogen in the outer parts of star starts of fuse and produce large quantity of heat energy. Due to this, the star enlarges. This star of this stage is called red giant star.
Formation of Planetary Nebula
After the hydrogen of the star is completely used up, upper layers will expand and eject the materials to its surrounding while its core starts to shrink. This process continues until the pressure becomes equal to the central electron cloud. It results in the formation of a nebula called as planetary nebula.
If the mass of the star is more than the five times the mass of our sun, the star expands enormously and changes into red supergiant.
The red supergiant cannot balance its inner and outer pressure and hence it explodes. This explosion of red supergiant star is called supernova.
After supernova, either neutron star or a black hole is formed.
For small remnant of supernova:
Formation of Neutron Star
If the remaining mass is relatively less, it starts forming the neutron star. The remaining hydrogen of the mass is converted into the helium. Its mass is large enough to convert helium into carbon and carbon into other elements like silicon, iron, etc. The core becomes so dense that even electrons cannot remain in the orbit. The electron then combines with the protons forming neutrons. Then the star becomes a ball of neutrons, which is called neutron star.
The neutron star has only neutrons as its constituents. So, it has a very large mass and small volume. Typically, a neutron star weighs about 5-10 solar masses and a radius of 10-20 KM. Its escape velocity also becomes very high ( about 108 m/s ).
For large remnant of supernova:
Formation of Black Hole
If the remnant of supernova is more than about 3 times the solar mass, the force towards the centre cannot be balanced by the repulsive force of neutrons. As a result, the mass further shrinks and forms a tiny mass. It causes the formation of black hole.
The black hole is a body whose escape velocity is more than that of the speed of light. So, even light cannot escape from the black hole and anything inside the black hole cannot be observed form outside the event horizon.
Concluding the life cycle of a star
Hence, a life of a star starts form the dust particles and clouds, passes through different phases and finally end up being white dwarf, neutron star or black hole, depending upon its size.
Found out that something is missing or incorrect?
Comment below and let us know 🤗 | 0.877791 | 3.475574 |
A balloon-borne telescope is a type of airborne telescope, a sub-orbital astronomical telescope that is suspended below one or more stratospheric balloons, allowing it to be lifted above the lower, dense part of the Earth's atmosphere. This has the advantage of improving the resolution limit of the telescope at a much lower cost than for a space telescope. It also allows observation of frequency bands that are blocked by the atmosphere.
Balloon-borne telescopes have the disadvantage of relatively low altitude and a flight time of only a few days. However, their maximum altitude of about 50 km is much higher than the limiting altitude of aircraft-borne telescopes such as the Kuiper Airborne Observatory and Stratospheric Observatory for Infrared Astronomy, which have a limiting altitude of 15 km. A few balloon-borne telescopes have crash landed, resulting in damage to, or destruction of the telescope.
The balloon obscures the zenith from the telescope, but a very long suspension can reduce this to a range of 2°. The telescope must be isolated from the induced motion of the stratospheric winds as well as the slow rotation and pendulum motion of the balloon. The azimuth stability can be maintained by a magnetometer, plus a gyroscope or star tracker for shorter term corrections. A three axis mount gives the best control over the tube motion, consisting of an azimuth, elevation and cross-elevation axis.
|Name||Active||Description and purpose|
|Stratoscope I||1957–59||12-inch telescope attached to a polyethylene balloon. This was the first balloon-borne astronomical telescope. It took photographic images of the sun, showing granulation features. In 1959 it was flown again, this time with a television transmitter.|
|Stratoscope II||1963–71||36-inch telescope with a tandem balloon system.|
|THISBE||1973–76||Infrared telescope used for observations of extended sources, including OH airglow, the zodiacal light, and the central galaxy region.|
|HIREGS||1991–98||High-resolution spectrometer for examining gamma ray and hard X-ray emissions from solar flares and galactic sources. It used an array of liquid nitrogen-cooled germanium detectors.|
|BOOMERanG experiment||1997–2003||Microwave telescope with cryogenic detectors that was carried on long-duration flights over the antarctic. It was used to map the cosmic microwave background radiation (CMBR).|
|MAXIMA||1998–99||Microwave telescope with a cryogenic receiver that was used to measure the CMBR.|
|HERO||2001–10||Hard X-ray telescope that flew successfully beginning in 2001 but crashed in 2010, destroying the telescope.|
|BLAST||2003–||Submillimetre telescope with a 2 m aperture. It was destroyed during the third flight, but was rebuilt and completed a fourth flight in 2010.|
|InFOCμS||2004–||Hard X-ray telescope with a 49 cm2 collecting area.|
|HEFT||2005||Hard X-ray telescope that uses grazing-incidence optics.|
|Sunrise||2009–||1 m ultraviolet telescope with image stabilization and adaptive optics for observing the Sun.|
|PoGOLite||2011–||Telescope for polarised hard X-rays and soft gamma-rays.|
- Kitchin, Christopher R. (2003). Astrophysical techniques (4th ed.). CRC Press. p. 83. ISBN 0-7503-0946-6.
- Cheng, Jingquan (2009). The principles of astronomical telescope design. Astrophysics and space science library. 360. Springer. pp. 509–510. ISBN 978-0-387-88790-6.
- Kidd, Stephen (September 17, 1964). "Astronomical ballooning: the Stratoscope program". New Scientist. 23 (409): 702–704. Retrieved 2011-02-28.
- Zimmerman, Robert (2010). The universe in a mirror: the saga of the Hubble Telescope and the visionaries who built it. Princeton University Press. p. 18. ISBN 978-0-691-14635-5.
- Hofmann, W.; Lemke, D.; Thum, C. (May 1977). "Surface brightness of the central region of the Milky Way at 2.4 and 3.4 microns". Astronomy and Astrophysics. 57 (1–2): 111–114. Bibcode:1977A&A....57..111H.
- Boggs, S. E.; et al. (October 2002). "Balloon flight test of pulse shape discrimination (PSD) electronics and background model performance on the HIREGS payload". Nuclear Instruments and Methods in Physics Research Section A. 491 (3): 390–401. Bibcode:2002NIMPA.491..390B. doi:10.1016/S0168-9002(02)01228-7.
- Masi, S. (2002). "The BOOMERanG experiment and the curvature of the universe". Progress in Particle and Nuclear Physics. 48 (1): 243–261. arXiv:astro-ph/0201137. Bibcode:2002PrPNP..48..243M. doi:10.1016/S0146-6410(02)00131-X.
- Rabii, B.; et al. (July 2006). "MAXIMA: A balloon-borne cosmic microwave background anisotropy experiment". Review of Scientific Instruments. 77 (7): 071101. arXiv:astro-ph/0309414. Bibcode:2006RScI...77g1101R. doi:10.1063/1.2219723.
- Malik, Tariq (April 29, 2010). "Huge NASA Science Balloon Crashes in Australian Outback". space.com. Retrieved 2011-02-28.
- Devlin, Mark. "Balloon-borne Large-Aperture Submillimeter Telescope: home page". blastexperiment. Archived from the original on 2011-06-03. Retrieved 2011-02-28.
- Tueller, J.; et al. (2005). "InFOCμS hard X-ray imaging telescope". Experimental Astronomy. 20 (1–3): 121–129. Bibcode:2005ExA....20..121T. doi:10.1007/s10686-006-9028-3.
- Chen, C. M. Hubert; et al. (September 2006). "In-flight Performance of the Balloon-borne High Energy Focusing Telescope". Bulletin of the American Astronomical Society. 38: 383. Bibcode:2006HEAD....9.1812C.
- Schmidt, W.; et al. (June 2010). "SUNRISE Impressions from a successful science flight". Astronomische Nachrichten. 331 (6): 601. Bibcode:2010AN....331..601S. doi:10.1002/asna.201011383.
- "PoGOLite: home page". Archived from the original on 2014-04-20. Retrieved 2015-06-11. | 0.812581 | 3.836743 |
Researchers have found an organic molecule essential to biology in interstellar space for the first time, announced experts Tuesday, a discovery that could help solve a long-time mystery.
Like humans, the organic molecules that make up the universe can lean left-handed or right-handed, a preference known as chirality. Most molecules on Earth lean left - but scientists don't know why.
The recently discovered interstellar molecule is the most complex ever discovered outside our solar system, and the first chiral molecule detected in interstellar space.
It's "a pioneering leap forward in our understanding of how prebiotic molecules are made in the universe and the effects they may have on the origins of life," said Brett McGuire, a chemist in Charlottesville, Virginia who co-authored the research.
Scientists have found chiral molecules in meteorites on Earth and comets in our solar system, but never before in interstellar space.
The molecule, propylene oxide, was found "near the center of our galaxy in an enormous star-forming cloud of dust and gas," the National Radio Astronomy Observatory (NRAO) said in a statement.
Scientists used an extremely sensitive radio telescope to detect the molecule. They presented their findings at the American Astronomical Society meeting in San Diego, California this week, and published a paper in the journal Science.
By skewing left or right, molecules have a biological advantage, because the congruence helps them build more complicated structures.
"Propylene oxide is among the most complex and structurally intricate molecules detected so far in space," said Brandon Carroll, a chemistry graduate student at the California Institute of Technology.
"Detecting this molecule opens the door for further experiments determining how and where molecular handedness emerges."
Certain biomolecules like amino acids - which make up proteins - are exclusively "left-handed," while some sugars, including those that comprise DNA, all lean right.
The origin of chirality in molecules remains a mystery, but scientists are hopeful that the interstellar discovery could finally solve the puzzle by clearing up what ingredients formed the base of our solar system.
Researchers have found more than 180 molecules in space that give off a distinct vibration scientists can detect with radio telescopes.
Larger, more complex molecules have more complicated vibration patterns, making them more difficult to identify.
Scientists hope that if they can understand the chirality of the propylene oxide molecule found in space, they can gain a better understanding of chiral molecules on Earth.
The study, known as the Prebiotic Interstellar Molecular Survey, is part of nearly a decade of research by the West Virginia-based NRAO, the organization that operates the ultra-sensitive Green Bank Telescope used in the research. The facility is part of the US National Science Foundation. | 0.898713 | 3.859443 |
Not quite Venus! Somewhere nice in Aussois, France (image Maurienne-tourisme)
We may have to wait a bit before we have samples from Venus (see last entry), but that doesn’t stop us finding out a lot more about our twin planet, thanks to ESA’s Venus Express probe. Twin planet! Well I guess that’s pushing it a bit. Venus is our nearest neighbour in the Solar System (minimum distance from the Earth 40 million kilometres, compared to about 60 million kilometres to Mars). The Earth and Venus are about the same size, have similar average densities and probably fairly similar bulk compositions (although we don’t know that for sure). But that’s about as far as the similarities go. Venus has an average surface temperature of 462°C, a surface pressure 90 times that on Earth and an atmosphere largely composed of carbon dioxide, with clouds formed of sulphuric acid droplets. Not a fun place.
Launched in November 2005, Venus Express arrived at its destination in April 2006. The principal objective of the mission is to understand the long-term dynamics of the Venusian atmosphere. In view of its size and mass, Venus should still be volcanically active, but this has never been directly confirmed. However, using data collected by Venus Express, a recent report in the journal Science gives details of young volcanic areas that probably formed as little as 250,000 years ago. Venus Express will be joined in December of this year by the Japanese probe Akatsuki, which is specifically designed to look for changes in Venus’s atmosphere and surface, including any associated with active volcanism on Venus.
And so, in view of the horrific nature of the Venusian climate, you might imagine that the recent International Venus Conference would be held somewhere like Death Valley, or the middle of the Gobi Desert. Not at all, it was held in the lovely French ski resort of Aussois (See photo above). The choice of venue was justified by one of the organisers with the throw away lines: “We had to pick somewhere” and “It’s a nice place to be”. Unlike Venus. The conference was discussed on a recent edition of BBC Radio 4’s excellent programme: The Material World. The programme also featured Dr David Rothery of the Open University discussing recent results from the Venus Express mission with the programme’s consistently entertaining presenter Quentin Cooper. Dr Rothery, who chairs the Open University’s level 1 and level 2 planetary science courses, specifically drew attention to the importance of the Venus Express data in demonstrating that, like Earth, Venus is almost certainly volcanically active. So perhaps they are twins after all.
Link: The Material World (24th June 2010) | 0.830061 | 3.587035 |
If you’ve ever held a real meteorite in your hand, you probably wanted to know, “Where has this rock been in space and where did it come from?” Until now, no one has been able to definitively establish where the majority of meteorites found on Earth came from because of the changes that occur in meteorites after they are ejected from the asteroids they were originally part of. The most common type of meteorite found on Earth, about 75% of those identified, are chondrites, stony bits of space rocks that didn’t undergo any melting while out in space. Two astronomers say have determined that most of these meteorites come from the asteroid belt between Mars and Jupiter. Using the GEMINI telescope, they found that asteroids in that region are similar to chondrites found on Earth.
This discovery is the first observational match between the most common meteorites and asteroids in the main belt. It also confirms the role of space weathering in altering asteroid surfaces.
To find the parent asteroid of a meteorite, the astronomers compared the spectra of a meteorite specimen to those of asteroids. This is a difficult task because meteorites and their parent asteroids underwent different processes after the meteorite was ejected. In particular, surfaces of asteroids are known to be altered by a process called “space weatheringâ€, which is probably caused by micrometeorite and solar wind action that changes the surface and spectra of asteroid surfaces.
Meteoroids are created, usually when there is a collision between asteroids. When an impact of a large asteroid occurs, the fragments broken off can follow the same orbit as the primary asteroid. These groups of fragments are called “asteroid families.†Until recently, most of the known asteroid families have been very old (they were formed 100 million to billions of years ago), and younger families are more difficult to detect because asteroid fragments are closer to each other.
In 2006, four new, extremely young asteroid families were identified, with an age ranging from 50,000 to 600,000 years. The astronomers, Thais Mothé-Diniz from Brazil and David Nesvorný from the US observed these asteroids, obtaining visible spectra. They compared the asteroids spectra to the spectra of an ordinary chondrite (the Fayetteville meteorite, shown in the top photo) and found they matched.
Identifying the parent asteroid of a meteorite is a unique tool when studying the history of our solar system because one can infer both the time of geological events (from the meteorite that can be analyzed through dating techniques) and their location in the solar system (from the location of the parent asteroid).
Meteorites are also a major tool for knowing the history of the solar system because their composition is a record of past geologic processes that occurred while they were still incorporated in the parent asteroid.
Original News Source: Astronomy and Astrophysics | 0.833727 | 3.97837 |
Astronomers have discovered an Earth-like planet Kepler-1649 just 219 light-years away which could be a major step forward in the search for alien life, Joinfo.com reports with reference to Daily Mail.
This newly discovered world is only slightly larger than Earth and orbits a low-temperature star called M5V that’s one-fifth the diameter of our Sun.
Astronomers say this planet, which is a close relative of Venus, will be a prime candidate for looking for life in the next generation of space missions.
The new planet was found by astronomers using Nasa’s Kepler space telescope.
Its tight orbit causes the flux of sunlight reaching the planet to be 2.3 times as great as the solar flux on Earth.
If orbiting planets such as Kepler-1649 huddle close to their star, they could in theory fall within the habitable zone where life is possible.
The discovery will provide insight into the nature of planets around M dwarf stars which are small, cool and relatively common in our universe.
‘Planets like Kepler-1649b will be prime candidates for atmospheric and habitability studies in the next generation of space missions’, researchers said in the paper which is published in The Astronomical Journal.
While Earth and Venus evolved to have similar sizes and densities, it remains unclear what factors led to the dramatic divergence of their atmospheres.
According to SETI Institute scientist Isabel Angelo, the study of planets similar to the Venus analog Kepler-1649 is ‘becoming increasingly important in order to understand the habitable zone boundaries of M dwarfs.
‘There are several factors, like star variability and tidal effects, that make these planets different from Earth-sized planets around Sun-like stars’, she said. | 0.823448 | 3.113515 |
The first binary black-hole merger observed by LIGO
In 2015 scientists have observed for the first time gravitational waves, arriving at the earth from a cataclysmic event in the distant universe. The gravitational waves were detected on September 14, 2015 at 5:51 a.m. Eastern Daylight Time (9:51 a.m. UTC) by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA. The signal was observed for about 0.2 seconds during which it increased both in frequency and amplitude. Its frequency lay between 35 Hz and 250 Hz and it had a peak amplitude (gravitational-wave strain) of 10-21.
The signal matches the predictions of general relativity for those of an inspiral and merger of two black holes with masses of 36 and 29 solar masses, respectively. The black hole resulting from the merger has mass of about 62 solar masses. About 3 times the mass of the sun was converted into gravitational waves in a fraction of a second—with a peak power output about 50 times that of the whole visible Universe. From the observations a distance of about 410 Megaparsecs (1.3 billion light years) to the black hole system was inferred.
The numerical-relativity simulations below show inspiral und merger of the binary black hole system as observed by LIGO.
Note: Publication of these images and movies requires proper credits and written permission. Please contact Elke Müller in advance of publication or for higher-resolution versions. | 0.809786 | 3.670132 |
Facts about Jupiter
Did you know that Jupiter is the largest planet in our solar system? Well it is, and it’s also quite famous too, well not famous like an actor! It is famous for its Red Spot! Read on and find out about this mysterious Red Spot.
Everything you need to know about Jupiter
This famous Red Spot is famous for its raging gas storms, which give it quite an impressive and even frightening and scary look too. It’s also called the ‘Eye of Jupiter’ because of its shape. Not sure that the place of the Red Spot is a journey we want to take!
- Jupiter also has rings, which are similar to Saturn, but you can’t see them all that well. You can only see its rings when Jupiter passes in front of the sun as it lights them up for us to see here down on Earth. There are three rings and they’re called Gossamer, Main and Halo.
- Now this is amazing! Jupiter has over 50 moons. The four largest were discovered by Galileo in 1610. Their names are Io, Europa, Ganymede and Callisto. Weird names indeed!
- Jupiter is the largest planet in our Solar system. It is so massive that more than 1,300 Earths could fit inside it. No way, that is absolutely humongous.
There are thick, colourful clouds that have deadly poisonous gases in them that surround Jupiter. Now those are clouds you won’t want to be near. As the planet spins really, really fast, this whips up the atmosphere and creates bands around the planet. Wow!
If you were to head down into Jupiter, the thin, cold atmosphere, which is made of hydrogen and helium gas, gets thicker and hotter as you go down. It slowly, slowly turns into a thick, dark fog. About 1,000km down the pressure squeezes the atmosphere so hard that it becomes like liquid. It’s actually a liquid metal. Whoa, imagine travelling 1,000km down into Jupiter?
- What lies between the atmosphere and the ocean? Amazingly nothing. It is like a sea without a surface, so you wouldn’t be able to go rowing there! The sky magically becomes the ocean!
- Right in the middle of this raging planet is a rocky core. It’s slightly bigger than Earth, but it weighs 20 times more!
- Around the core is an ocean of liquid hydrogen, about 1,000km deep.
- Jupiter has loads and loads of storms raging on the surface, obviously with that famous Red Spot, which is actually the largest hurricane in our Solar System. It’s been storming around for over three hundred years.
- If you were brave enough to put foot on Jupiter, you would weigh two and a half times as much as you would on Earth, because it has a strong magnetic field. Best you pack bigger clothes!
- Jupiter has loads of moons circling around it happily. This is unbelievable; four of these moons are bigger than Pluto.
- What does Jupiter mean? Well Jupiter was known as Zeus in Greek mythology, who over threw his father Saturn to become king of the gods. He then split the universe with his brothers Neptune and Pluto.
- Jupiter is about 749,954,304km from the sun and 588,000,000km from Earth. Those are quite some distances!
- The average temperature in the cloud tops of planet Jupiter is -148⁰C. Wow that’s seriously cold. As you go deeper it then gets seriously hot!
- Eight spacecraft have taken a trip to Jupiter! The Juno Mission is on its way there and will arrive in July 2016! Not too far from now.
- The Red Spot is actually the size of Earth! That is one mighty sized storm.
- Jupiter is like one massive vacuum cleaner. It sucks up all the comets, asteroids and meteorites, which would otherwise head on our way. Thanks Jupiter!
- Jupiter takes 9 hours and 55 minutes to spin on its axis. So this means that a day on Jupiter is less than 10 hours long.
- Ganymede, one of Jupiter’s moons, is the largest in the whole wide massive solar system.
- This is pretty cool. As Jupiter has heaps of gravity, it is used to catapult space craft on deep space missions further away! That’s how the Voyager missions in 1975 managed to get their work done.
Jupiter is one raging, interesting and surprising planet. Well done, you’re now Jupiter smart…use your knowledge wisely! | 0.826073 | 3.166189 |
Astronomers have made a new measurement of how fast the universe is expanding, using an entirely different kind of star than previous endeavors. The revised measurement, which comes from NASA’s Hubble Space Telescope, falls in the center of a hotly debated question in astrophysics that may lead to a new interpretation of the universe’s fundamental properties.
Scientists have known for almost a century that the universe is expanding, meaning the distance between galaxies across the universe is becoming ever more vast every second. But exactly how fast space is stretching, a value known as the Hubble constant, has remained stubbornly elusive.
Now, University of Chicago professor Wendy Freedman and colleagues have a new measurement for the rate of expansion in the modern universe, suggesting the space between galaxies is stretching faster than scientists would expect. Freedman’s is one of several recent studies that point to a nagging discrepancy between modern expansion measurements and predictions based on the universe as it was more than 13 billion years ago, as measured by the European Space Agency’s Planck satellite.
As more research points to a discrepancy between predictions and observations, scientists are considering whether they may need to come up with a new model for the underlying physics of the universe in order to explain it.
“The Hubble constant is the cosmological parameter that sets the absolute scale, size and age of the universe; it is one of the most direct ways we have of quantifying how the universe evolves,” said Freedman. “The discrepancy that we saw before has not gone away, but this new evidence suggests that the jury is still out on whether there is an immediate and compelling reason to believe that there is something fundamentally flawed in our current model of the universe.”
In a new paper accepted for publication in The Astrophysical Journal, Freedman and her team announced a new measurement of the Hubble constant using a kind of star known as a red giant. Their new observations, made using Hubble, indicate that the expansion rate for the nearby universe is just under 70 kilometers per second per megaparsec (km/sec/Mpc). One parsec is equivalent to 3.26 light-years distance.
This measurement is slightly smaller than the value of 74 km/sec/Mpc recently reported by the Hubble SH0ES (Supernovae H0 for the Equation of State) team using Cepheid variables, which are stars that pulse at regular intervals that correspond to their peak brightness. This team, led by Adam Riess of the Johns Hopkins University and Space Telescope Science Institute, Baltimore, Maryland, recently reported refining their observations to the highest precision to date for their Cepheid distance measurement technique.
How to Measure Expansion
A central challenge in measuring the universe’s expansion rate is that it is very difficult to accurately calculate distances to distant objects.
In 2001, Freedman led a team that used distant stars to make a landmark measurement of the Hubble constant. The Hubble Space Telescope Key Project team measured the value using Cepheid variables as distance markers. Their program concluded that the value of the Hubble constant for our universe was 72 km/sec/Mpc.
But more recently, scientists took a very different approach: building a model based on the rippling structure of light left over from the big bang, which is called the Cosmic Microwave Background. The Planck measurements allow scientists to predict how the early universe would likely have evolved into the expansion rate astronomers can measure today. Scientists calculated a value of 67.4 km/sec/Mpc, in significant disagreement with the rate of 74.0 km/sec/Mpc measured with Cepheid stars.
Astronomers have looked for anything that might be causing the mismatch. “Naturally, questions arise as to whether the discrepancy is coming from some aspect that astronomers don’t yet understand about the stars we’re measuring, or whether our cosmological model of the universe is still incomplete,” Freedman said. “Or maybe both need to be improved upon.”
Freedman’s team sought to check their results by establishing a new and entirely independent path to the Hubble constant using an entirely different kind of star.
Certain stars end their lives as a very luminous kind of star called a red giant, a stage of evolution that our own Sun will experience billions of years from now. At a certain point, the star undergoes a catastrophic event called a helium flash, in which the temperature rises to about 100 million degrees and the structure of the star is rearranged, which ultimately dramatically decreases its luminosity. Astronomers can measure the apparent brightness of the red giant stars at this stage in different galaxies, and they can use this as a way to tell their distance.
The Hubble constant is calculated by comparing distance values to the apparent recessional velocity of the target galaxies — that is, how fast galaxies seem to be moving away. The team’s calculations give a Hubble constant of 69.8 km/sec/Mpc — straddling the values derived by the Planck and Riess teams.
“Our initial thought was that if there’s a problem to be resolved between the Cepheids and the Cosmic Microwave Background, then the red giant method can be the tie-breaker,” said Freedman.
But the results do not appear to strongly favor one answer over the other say the researchers, although they align more closely with the Planck results.
NASA’s upcoming mission, the Wide Field Infrared Survey Telescope (WFIRST), scheduled to launch in the mid-2020s, will enable astronomers to better explore the value of the Hubble constant across cosmic time. WFIRST, with its Hubble-like resolution and 100 times greater view of the sky, will provide a wealth of new Type Ia supernovae, Cepheid variables, and red giant stars to fundamentally improve distance measurements to galaxies near and far.
The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C. | 0.829556 | 4.11159 |
You put a drop of alcohol on your hand and feel your hand get cooler as the alcohol evaporates, but what has this to do with coffee, climate and physics?
Erasmus Darwin (1731-1802) was the grandfather of Charles of “Origin of the Species” fame. As a member of the Lunar Society (so-called because the members used to meet on evenings on which there was a full moon so that they could continue their discussions into the night and still see their way home) he would conduct all sorts of scientific experiments and propose various imaginative inventions. Other members of the Lunar Society included Matthew Boulton, Josiah Wedgwood and Joseph Priestley. The society was a great example of what can happen when a group of people who are interested in how things work get together and investigate things, partly just for the sake of it.
One of the things that Darwin had noticed was that when ether* evaporates from your hand, it cools it down, just as alcohol does. Darwin considered that in order to evaporate, the ether (or alcohol or even water) needed the heat that was provided by his hand, hence his hand started to feel cooler. But then he considered the corollary, if water (ether or alcohol) were to condense, would it not give off heat? He started to form an explanation of how clouds form: As moist air rises, it cools and expands until the moisture in the air starts to condense into droplets, clouds.
As with many such ideas, we can do a ‘back of the envelope’ calculation to see if Darwin could be correct, which is where we could also bring in coffee. The arabica growing regions are in the “bean belt” between 25 °N and 30 °S. In the sub-tropical region of that belt, between about 16-24°, the arabica is best grown at an altitude between 550-1100 m (1800-3600 ft). In the more equatorial regions (< 10º), the arabica is grown between 1100-1920m (3600-6300 ft). It makes sense that in the hotter, equatorial regions, the arabica needs to be grown at higher altitude so that the air is cooler, but can we calculate how much cooler it should be and then compare to how much cooler it is?
We do this by assuming that we can define a parcel of air that we will allow to rise (in our rough calculation of what is going on)¹. We assume that the parcel stays intact as it rises but that its temperature and pressure can vary as they would for an ideal gas. Assuming that the air parcel does not encounter friction as it rises (so we have a reversible process), what we are left with is that the rate of change of temperature with height (dT/dz) is given by the ratio of the gravitational acceleration (g) to the specific heat of the air at constant pressure (Cp) or, to express it mathematically:
dT/dz = -g/Cp = Γa
Γa is known as the adiabatic lapse rate and because it only depends on the gravitational acceleration and the specific heat of the gas at constant pressure (which we know/can measure), we can calculate it exactly. For dry air, the rate of change of temperature with height for an air parcel is -9.8 Kelvin/Km.
So, a difference in mountain height of 1000 m would lead to a temperature drop of 9.8 ºC. Does this explain why coffee grows in the hills of Mexico at around 1000 m but the mountains of Columbia at around 1900 m? Not really. If you take the mountains of Columbia as an example, the average temperature at 1000 m is about 24ºC all year, but climb to 2000 m and the temperature only drops to 17-22ºC. How can we reconcile this with our calculation?
Firstly of course we have not considered microclimate and the heating effects of the sides or plateaus of the mountains together with the local weather patterns that will form in different regions of the world. But we have also missed something slightly more fundamental in our calculation, and something that will take us back to Erasmus Darwin: the air is not dry.
Specific heat is the amount of energy that is required to increase the temperature of a substance by one degree. Dry air has a different specific heat to that of air containing water vapour and so the adiabatic lapse rate (g/Cp) will be different. Additionally however we have Erasmus Darwin’s deduction from his ether: water vapour that condenses into water droplets will release heat. Condensing water vapour out of moist air will therefore affect the adiabatic lapse rate and, because there are now droplets of water in our air parcel, there will be clouds. When we calculate the temperature variation with height for water-saturated air, it is as low as 0.5 ºC/100 m (or 5 K/Km), more in keeping with the variations that we observe in the coffee growing regions†.
We have gone from having our head in the clouds and arrived back at our observations of evaporating liquids. It is fascinating what Erasmus Darwin was able to deduce about the way the world worked from what he noticed in his every-day life. Ideas that he could then either calculate, or experiment with to test. We have very varied lives and very varied approaches to coffee brewing. What will you notice? What will you deduce? How can you test it?
*ether could refer to a number of chemicals but given that Erasmus Darwin was a medical doctor, is it possible that the ether he refers to was the ether that is used as an anaesthetic?
†Though actually we still haven’t accounted for microclimate/weather patterns and so it is still very much a ‘rough’ calculation. The calculation would be far better tested by using weather balloons etc. as indeed it has been.
¹The calculation can be found in “Introduction to Atmospheric Physics”, David Andrews, Cambridge University Press | 0.816727 | 3.219988 |
The origin of Earth's Moon has long been a puzzle. Solving this conundrum has deep implications for the nature of planetary formation, Earth's geophysical and geochemical history, and for that elusive quality of we call habitability for small rocky worlds across the Universe.
In essence; the question is how the rocky parts of the Moon and Earth got to be so similar in elemental composition. The most favored hypothesis is that an early version of the Earth was hit by another planet-scale object some 4.5 billion years ago. That 'Giant Impact' could have mixed up material from the two bodies, and as the Moon assembled from the detritus it would naturally share a composition with the larger Earth.
But getting all aspects of this picture to fit with the observed properties of the Earth-Moon system is not so easy. That leaves room for other possibilities, such as the 'synestia' idea where both the Earth and Moon formed from the same spinning cloud of molten filth left from an even larger proto-planetary collision. Now another proposal has been made by Hosono et al. where there was indeed a collision involved, but the Earth at that time was already a molten world - an ocean of magma. Rather than a Giant Impact this might have been a Giant Splash, making it much easier for blobs of material from the early Earth to be flung into orbit to coalesce as the Moon, with its near identical composition.
The challenge of decoding what's right under our noses is a sobering reminder of the complex questions involved in learning about planetary histories.
As I wrote in a recent piece here, the origin of certain heavy elements on Earth is getting a lot of astrophysical attention these days. Researchers are particularly focussed on the r-process elements, thought to be forged in environments of intense neutron flux. Since the gravitational-wave detection of neutron star collisions these 'kilonova' events have become a hot favorite (no pun intended) for producing much of the gold, platinum, and uranium in the Galaxy.
But there are other options. A new study by Siegel, Barnes, and Metzger published in Nature suggests that an even rarer astrophysical event - the 'collapsar' - might actually fit the bill for dominating r-process element production. A collapsar is a rapidly spinning massive star that winds up collapsing and creating a supernova. As part of this process a disk of material forms, spinning and accreting on the central mass. That disk resembles the environment in neutron star mergers where lots of r-process elements are thought to be produced. In fact, as this research shows, a collapsar event might expel even more of these heavy elements. The upshot being that, despite their rarity, collapsars could produce more than 80% of the r-process elements in the Universe.
Exactly which phenomenon will win out in the end remains to be seen. The heaviest elements play critical roles in the formation and geophysical history of planets, so understanding their origins has broad implications.
There's a dirty little not-so-secret secret about exoplanets: The vast majority of our discoveries to date have been strongly biased towards worlds on comparatively small, short-period orbits. The simple reason being that techniques like transit detection or radial-velocity measurement generally need to catch repeat orbits, or have very long data timelines in order to allow confidence in the reality of the planets that show up.
But it is these longer-period planets - akin to worlds like Jupiter or Saturn in our own solar system - that are essential for testing our ideas of planet formation and for filling in the blanks on whether a system has the right stuff for supporting life on any of its worlds.
Finding planets like these takes patience and forward planning. Now a study by Rickman et al. has yielded the fruits of 20 years of astronomical observation using Geneva University's EULER telescope at La Silla Observatory in Chile. Specifically, the team has revealed a haul of five newly-identified objects circling their stars with orbital periods of between 15 and 40 years. Three of these are hefty gas-giant worlds, two are likely brown-dwarf or sub-stellar objects weighing in at more than ten times the mass of Jupiter.
Slowly we're beginning to fill in the gaps in our knowledge of all exoplanets, not just the most convenient ones. | 0.939139 | 4.050451 |
SPICA: an infrared telescope to look back into the early universe
by Arwen Rimmer
|“The fact is that these questions can only be investigated by observations in the infrared,” said Roelfsema. “You can’t do this from the ground because the Earth’s atmosphere blocks it. So, space-based observations are required.”|
SPICA stands for Space Infrared Telescope for Cosmology and Astrophysics, a next generation observatory with heretofore unseen capability in the far infrared. In theory, it will be able to study stellar nurseries and protoplanetary discs, analyze exoplanets, and shed much needed light on galaxy and planet formation. SPICA will be able to see the adolescent universe at only one billion years of age in high resolution. Dr. Peter Roelfsema, the proposal lead, believes that these capabilities will allow astronomers to shed light on three of the four fundamental questions.
“We've been looking at them as guidelines from the very early days of the project,” he said. “SPICA has three fundamental science pillars which will directly address questions one, two and four; to track the drivers for galaxy evolution over cosmic time, to unravel the physical conditions for planet formation, and to establish the role of magnetic fields on star formation in dusty clouds. The fact is that these questions can only be investigated by observations in the infrared. You can’t do this from the ground because the Earth’s atmosphere blocks it. So, space-based observations are required.”
Measurements in the infrared wavelength illuminate cooler or dimmer matter, which is what is needed to study the early stages of planet and star formation. Previous infrared missions like Herschel have revealed a great deal about what astronomers involved in the mission call the “obscured universe,” but sensitivity has been limited because of the technical difficulties inherent to launching a large cryogenic telescope. SPICA will utilize cutting-edge technology in detectors, passive cooling, and heat shielding to see farther and with better spectral resolution than any infrared mission before it. The mechanical coolant system will keep the entire telescope (2.7-meter mirror, all instruments, and enclosing tube, altogether weighing about 400 kilograms) below 8 K. This is what makes SPICA unique. The major infrared observatories of the past had parts that were kept cold, but not the entire thing. And ISO, Spitzer, and Herschel all used a liquid coolant. This limits the working life of the telescope. And if something goes wrong with the supply, like it did with NASA’s WIRE, the mission can be cut short before its time. Cryogenic stores also create a much heavier payload, which significantly increases costs.
“There is a balance between science goals and programmatic constraints,” Roelfsema said. “But sometimes, these limits can produce great creativity. We had a problem with the projected weight and balance of the satellite in its orbit, which was also pushing costs higher. This was only recently solved in January. Our solution was to go ‘vertical’ with our design. The new alignment allows for a lighter, more stable payload, with the same instrument suite.”
|SPICA will provide the first definitive evidence of how the universe evolved, either proving the models, or disproving them and making way for new ones.|
There are the functional challenges of performing space science, and then there is the push to discovery, which is necessary to make the entire endeavor worthwhile. For SPICA, cryogenics R&D are a major focus at this stage, because none of their science goals are reachable if the telescope can’t be maintained at incredibly cold temperatures. The reason for this is to reduce detector noise below the level of intrinsic background noise. For infrared observations in space, the background limit is set by the instruments themselves, which put out radiation unless cooled to cryogenic temperatures. Dave Clements, a professor at Imperial College London and a member of the collaboration explains it thus:
Imagine doing optical astronomy with a mirror that is glowing red hot. This wouldn’t be easy because the mirror is probably brighter than the sources you’re looking at. This creates what we call a background, and you’ve got to measure everything relative to the background. There’s a famous law in physics called the Stefan-Boltzmann Law. All things being equal, since the SPICA mirror will be ten times cooler than Herschel’s was, it will be able to see objects that are 10,000 times fainter. That makes a lot of difference.
SPICA’s toolkit will peer into the past in a variety of ways. The telescope will be able to see through dust to the ancient convolutions of protoclusters. The mid-IR spectrometer/camera will do spectral mapping and imaging in the wavelength range of 12–36 microns with three channels: low, mid, and high resolution. SAFARI, an advanced spectrometer, will analyze the chemistry, physics, kinematics, and mineralogy of astronomical objects far and near. B-BOP, a polarimeter, will probe the role of magnetic fields in the formation and evolution of the interstellar web of dusty molecular filaments giving birth to most stars in our galaxy. Each instrument will be able to do much more than was briefly mentioned above, and will also work in concert with each other. This technological synergy will allow the team to approach fundamental topics in astrophysics like never before. Jan Tauber, the ESA study scientist for SPICA, explains how current formation theories are just that: theories. SPICA will provide the first definitive evidence of how the universe evolved, either proving the models, or disproving them and making way for new ones.
“We have a very good theory, overall, which suggests how galaxies and clusters of galaxies formed,” Tauber said. “But the details are not clear. There are issues understanding star formation in the very earliest galaxies using visible-light observations because of dust, which is a major obscuration problem. For example, the evolution of galaxies is believed to be driven by what we call feedback, which is basically a process of matter flowing in and out of galaxies. And there is a competition, if you like, between star formation driven processes and active nuclei processes that we don’t understand very well. These processes cannot be easily distinguished unless we go to the infrared.”
|“In my opinion, the range of science that will be influenced by SPICA is much bigger than the other two [M5] missions,” Clements said.|
If approved, SPICA will launch in the early 2030s. JWST, which is finally slated for launch next year, is also investigating the infrared, but at wavelengths of 0.6 to 28.5 microns, versus the spectral range of 12 to 230 microns for SPICA. NASA is also studying a space observatory called Origins that has similar goals as SPICA, but with a much larger and cooler telescope. If approved, its launch is scheduled for around 2035. So, if SPICA isn’t selected, scientists in the field will still have Origins to root for. Ad if Origins isn’t selected either, all these fundamental questions will just have to wait.
“In my opinion, the range of science that will be influenced by SPICA is much bigger than the other two [M5] missions,” Clements said. “You can send a probe to Venus, and perhaps see evidence of tectonic activity. But between now and when Envision is going to be launched there’s probably a whole bunch of other things going to Venus. Theseus will look for very high redshift gamma ray bursts. But over the life of that mission, they will be lucky to find maybe 120, perhaps less if the predictions are wrong. Whereas SPICA can do everything from solar system objects to the most distant objects in the universe. In my mind, we’ve got greater scientific potential than the other two missions.”
The group meetings all three M5 finalists have scheduled for this year have several vital purposes leading up to the final selection: to fine tune scientific goals, identify problems and figure out how to solve them, update members on any technical or programmatic changes, and delegate responsibilities, both short term and long term. Running an efficient and on-point conference is a perennial challenge no matter the field, and even more so when one has to cancel the in-person event at the last minute and transition to a teleconference. Roelfsema had planned for the meeting to go forward up until the Friday before, when feedback, especially from members in Italy, made it clear that too many people were planning on staying away, either out of a sense of personal precaution or because of direct intervention from their governments.
“Regardless, I am really pleased with how well it went,” Roelfsema said. “Beyond my expectations, possibly even beyond my hope. This was an experiment forced on us. We have never done anything on this scale before. We are quite used to telecoms with 10–15 people or so, because we are from all sides of the world. But on Monday (March 9th), we had almost 140 people in one ‘room.’ Tuesday we had three sessions going parallel. And I think all the information that needed to be conveyed got conveyed.”
But meetings are about more than itineraries and PowerPoints; there’s something both intangible and invaluable that occurs when people are in the same room.
“The clear disadvantage is that we didn’t have the ‘corridor talks’ which are really valuable,” Roelfsema said. “Science is a creative environment. We need to think of solutions for problems that have not been tackled before and may not even have been thought about before. So the personal interactions are important. We will have to have some more face-to-face meetings to catch up, hopefully over the summer. Accepting that challenge, it went really well.”
ESA is the main decision-maker on the continent for space activity and satellite regulations, and so takes over mission responsibilities for instrument housing and launch parameters when a project is approved. Everything they do is by necessity collaborative, bringing together agencies, universities, and industrial partners from all over the world. This can create a bureaucratic tangle, but in 50 years they have sent up almost 100 scientific missions with less than a tenth of NASA’s budget. SPICA will be a joint project with the Japan Aerospace Exploration Agency (JAXA).
Tauber spoke on the costs and benefits that a shared mission like this involves. “Some collaborations are easier than others,” he said. “The form of the involvement is very important. With SPICA, ESA will be in the lead. But we have an almost 50/50 collaboration with JAXA in every respect. This can make decision-making more difficult. Usually, we prefer to be in a position where one of the collaborating agencies is the clear leader, but in this situation, it’s a bit more complicated. The reward is that we can do a ‘large mission,’ like SPICA, with ‘medium-class’ resources.”
February 1, 2021, is the date of final submission for the three finalists, where each of them must deliver a Yellow Book. This is essentially a textbook about every aspect of their mission, with supporting technical documents to be reviewed by independently selected professionals. Pending approval, ESA itself then contracts with industry partners for the construction of said project. But will the deadline hold with COVID-19 disrupting work and travel all over the world?
“It may be that the current situation alters that schedule,” Tauber said. “How this is going to be managed I don't yet know. Some work can go on relatively undisturbed by teleworking, virtual meetings, and so on. But we are already seeing that there will probably be unavoidable delays. Programmatically, the M5 selection is just one cog in a many-wheeled system. Disturbing one part of the system disturbs many others.”
Even though SPICA is still in the design phase, and construction of the payload and instrument suite is more than a decade off, a considerable amount of research and development is done in the lab. This is true for all three finalists.
|“We are resigned to the selection process being delayed at the very least. The circumstances are difficult and we don't know what it will be like when the current difficulty is over,” Clements said.|
“In terms of proving the technology works, which is one thing all three missions need to do, we have to demonstrate a certain technological readiness level,” Clements said. “We need to do lab work for that, and all the labs, such as at University of Cambridge where some of the detector development work is being done, are shut right now. So, ESA may have to delay the deadline, because people haven’t been able to get into their labs for however many months. Or else they will have to allow a lower TRL [technology readiness level], which they are not likely to do, because that brings risks with it. This will probably all be decided at the next Science Programme Committee meeting, which I presume they will be having over Zoom or something similar.”
SPICA was first imagined in 1997 by JAXA scientists, and has adopted scientists from the Herschel and Planck missions along the way who see it as the next logical step in infrared observation. If it is selected next year, astronomers will be able to pull back the veil of the sky like never before. They will be able to see through the dust-obscured universe and into the beginnings of the first galaxies, observing formation and dissolution activity at every possible life-stage for the first time. They will be able to spectroscopically analyze heavy metal distribution, and see where all the water comes from. And SPICA won’t just be able to illuminate far-off locales; it will also be able to shed light on our own galaxy and solar system.
The scientific community has been working for more than 20 years to bring this project to fruition, and now that they are closer to launch than they’ve ever been, COVID-19 happens. Clements remarked on the general attitude of the team members in this unprecedented situation: “We are resigned to the selection process being delayed at the very least. The circumstances are difficult and we don't know what it will be like when the current difficulty is over. This all costs money, and governments may have less of that to spend on space missions by then. All we can do is wait and see.”
Note: we are temporarily moderating all comments submitted to deal with a surge in spam. | 0.905311 | 3.936685 |
DARK MATTER & DARK ENERGY | PUBLICATIONS
Second article with Alexander Vasilkoviy, dedicated to cosmology and the cosmological constant, and published in the Monthly Notices of the Royal Astronomical Society (this article being made available at the end of the PDF file).
Dark energy is an amazing nature phenomenon which was first discovered by observing far-distanced supernovas, halfway to the horizon of the world. This energy creates a "global anti-gravitation", which is reflected in an accelerated expansion of the universe as a whole. The theory proposed by the Moscow State University, explains the phenomenon of galaxies running away from each other in the near universe, which remained a puzzling fact since its discovery by Hubble in 1929. As it turned out, the dynamics of Hubble’s flows are driven by the anti-gravitation of dark energy, which forces the nearby galaxies to stream away from the Milky Way, and apart from each other, in an accelerated way.
In the observable universe, the vacuum dominates : by its energy density, it surpasses all the "usual" forms of matter. Vacuum creates an cosmic “anti-gravity”, which induces the present effect of accelerated cosmological expansion of the universe. But neither the galaxies, nor its own anti-gravity, nor even time itself are able to influence the space vacuum: it is absolutely motionless, immutable and eternal.
We live in four-dimensional space-time, which recently completed its cosmic evolution and presently, it almost reached its ideal, regular geometrically symmetric state, which will then last indefinitely.
Dark energy in the near Universe (I.V. Karachentsev, А.D. Chernin) (pdf, In Russian)
A publication in the magazine “Priroda” (“Nature”, in English), N° 11, 2008.
We are now at the beginning of a new, extraordinarily interesting phase of the development of sciences. It is remarkable that the science of microcosm (particle physics) and the science of the Universe (cosmology) are on the edge to become a unified science of the fundamental properties of the world around us.
With different approaches, they may answer the same questions: what is the matter which fills the today? what was its evolution in the past? what processes, occurring between elementary particles in the early Universe, led eventually to its current state?
The article discusses the evidence in favor of the existence of dark matter of the Universe, and the most popular candidates for these particles which form this this matter. We review and discuss several ongoing and planned experiments to search for dark matter particles. We discuss various experimental techniques, including how to register / detect direct interactions of dark matter particle with the matter of detectors, as well as products to their annihilation or decays.
About the properties of, and the search for the “axions”, the alleged particles of "dark matter".
The role of a chiral U(1) phase in the quark mass in QCD is analysed from first principles. In operator formulation, there is a parity symmetry and the phase can be removed by a change in the representation of the Dirac gamma matrices. Moreover, these properties are also realized in a Pauli-Villars regularized version of the theory. In the functional integral scenario, attempts to remove the chiral phase by a chiral transformation are thought to be obstructed by a nontrivial Jacobian arising from the fermion measure and the chiral phase may therefore seem to break parity. But if one starts from the regularized action with the chiral phase also present in the regulator mass term, the Jacobian for a combined chiral rotation of quarks and regulators is seen to be trivial and the phase can be removed by a combined chiral rotation. This amounts to a taming of the strong CP problem.
The universal “anti-gravitation” is a new physical phenomenon, found through astronomical observations of objects at distances of 5 - 8 billion light years. The anti-gravitation manifests itself as a cosmic repulsion, felt by distant galaxies, and this repulsion is stronger than the gravitational attraction of the galaxies between each other. For this reason, we observe an accelerated cosmological expansion.
This anti-gravitation is not created by galaxies, neither by any other bodies, and nor by a previously known form of energy / mass known as dark energy. The proportion of dark energy accounts for 70 – 80 % of all energy / mass of the observable Universe.
At the macroscopic level, the dark energy is described as a special kind of continuous medium, which fills the entire spac
e; this medium presents a positive density and a negative pressure. The physical nature of dark energy and its microscopic structure remain unknown : it is one of the most acute problems of fundamental science nowadays.
The article is devoted to the discussion of topics related to dark energy in the Universe. It is noted that despite the influence of dark energy, the generation of structure is still ongoing in the modern Universe, and will last for about 10 billion more years.
We comment some of the allegations formulated in the article of A.D. Chernin, “Dark energy and global anti-gravitation” (Russian ref.: UFN 178 267, 2008).
A critical analysis of the ideas set forth in the above mentioned articles "Dark energy and global anti-gravitation " (A.D. Chernin) and "Dark energy: myths and reality" (V.N.Lukach, V.А. Rubakov).
This article sets out ideas for an alternative understanding of this problem, on the basis of the author's modification of the GTR: the "Theory of global time".
Development of the author’s theory : "Dynamic theory of space in global time". Or, put shorter: the "Theory of global time" (TGT).
From a formal point of view, the GTR differs from TGT by an additional equation, which stipulated that the total energy density of all fields and of the space itself, is equal to zero. Therefore, in particular, in the TGT, where the Hamiltonian is different from zero, there is no problem of dark energy, and the quantum theory is naturally built on the basis of the non-zero Hamiltonian.
Meanwhile the bulk of the GTR solutions, found over the past century, are still valid (they come as the solution of the TGT when total energy is equal to zero).
Therefore, the TGT can be regarded as a consistent physical theory of space and time, which is a continuation / extension of the GTR.
The main result of the research was the discovery of dark energy in the near Universe, and evaluation of its local density, with the help of high-precision observation data. We have predicted and discovered (using the same data) local areas of outer space, in which Einstein’s anti-gravitation, created by dark energy, is stronger the the Newton gravitation created by dark matter and its baryons.
In the areas of anti-gravitation, we have discovered and studied a new type of cosmic motions : local flows of galactic run-up, accelerated by dark energy. The local density of dark energy measured in these areas happened to be equal (within the error margin) to its global density. This new independent empirical argument speaks in favor of Einstein’s anti-gravitation (in the same sense the Newtonian gravitation is considered as universal).
This result is incompatible with modified theories of gravity, which consider the dark energy as an effect possible on global distances, and only on such distances.
The structure and evolution of triple galaxy systems in the presence of the cosmic dark-energy background is studied in the framework of the three-body problem. Such dynamical models show that the anti-gravity created by dark energy makes a triple system less tightly bound, thereby facilitating its decay, with a subsequent transition to motion of the bodies away from each other in an accelerating regime with a linear Hubble-law dependence of the velocity on distance.
The article presents a model of cosmic medium, allowing to describe the physical nature and the microscopic structure of dark energy, possessing such properties as macroscopic negative pressure and positive density. It is stated that the cosmological constant Λ characterizes the elastic properties of the dark energy, and the “universal law of anti-gravitation” is a Hooke law of elasticity.
The evidence is based on the results of experiments made in superfluid ³He-B in a p-state, acting as an analogue of dark energy. In addition, to build the resonant curves of photoeffect in the near-Earth space medium, we used observations from space-based detectors, such as PAMELA, Fermi, as well as the detector AMS aboard the ISS.
Many recent highly precise and unmistakable observational facts achieved thanks to the tightly synchronized clocks of the GPS, provide consistent evidence that the gravitational fields are created by velocity fields of real space itself, a vigorous and very stable quantum fluid like spatial medium, the same space that rules the propagation of light and the inertial motion of matter.
It is shown that motion of this real space in the ordinary three dimensions round the Earth, round the Sun and round the galactic centers throughout the universe, according to velocity fields closely consistent with the local main astronomical motions, correctly induces the gravitational dynamics observed within these gravitational fields. In this spacedynamics the astronomical bodies all closely rest with respect to the real space, which forth-rightly leads to the observed null results of the Michelson light anisotropy experiments as well as to the absence of effects of the solar and galactic gravitational fields on the rate of clocks moving with Earth as recently discovered with the help of the GPS clocks.
This spacedynamics also eliminates the need of dark matter and dark energy to explain respectively the galactic gravitational dynamics and the accelerated expansion of the universe. It also straightforwardly accounts in terms of well known and genuine physical effects for all the other observed effects, caused by the gravitational fields on the velocity of light and on the rate of clocks, including all the new effects recently discovered with the help of the GPS. It moreover simulates the non-Euclidean metric underlying Einstein’s spacetime curvature.
Currently, in the world as seen by leading cosmologists, fundamental changes are taking place. They are associated with one of the most important "discoveries" made in 1998 : the detection of the "accelerating expansion of the universe", which almost immediately was recognized by the majority of cosmologists. Allegations of "accelerating the expansion of the universe" have given rise to a thriving industry of theoretical speculation. It forces to take a deeper look at these results, which gave rise to this "discovery", and not just to the advertised “explosive” conclusions.
It is necessary to take into account the FACT of isotropy of the density of matter in the observable universe. And it's not just spatial isotropy. By virtue of the limit of the speed of light, it is also an isotropy in time. From the existing interpretation of results, we inevitably conclude that at a distance of 10 - 15 billion light-years, i.e. 10 - 15 billion years ago, the density of matter and the local densities (observed by us now, in the near surroundings) are equal. A puzzling question arises : where is it, the expansion, the drop of density? From the observed global isotropy of matter, it follows that the concept of the “Big Bang” is empty.
However, we need a satisfactory answer to the FACT discovered by Hubble, the redshift.
The stable mutual spatial location of physical bodies in the pseudo-euclidian space obliges their lines in the space of events to be at equidistance. And the equidistance of these lines involves the emergence of a relative redshift in their spectra. It is a geometrical essence of matter. Physically, the redshift is a measure of a basic physical process of the Universe. It is the process of circulation of energy between different phases of the vacuum-similar medium. | 0.836538 | 4.035895 |
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