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Whether it’s the moon looming large and bright, or the billions of twinkling stars, the nocturnal sky as we see it has fascinated humanity for aeons. The desire to explore the universe began as observations with the naked eye, and over the years, has continued to encompass the use of scientific instruments. Astronomical watches like the moon-phase timepieces by A. Lange & Söhne are witness to this undying curiosity
It is believed that primitive structures like the Stonehenge, built by ancient civilisations to make sense of celestial bodies and their alignment in relation to the earth, were some of the early methods to better understand the universe.
The study of celestial objects did not have its roots in scientific inventions, but in the human trait of curiosity. In The Dawn of Astronomy, British astronomer Sir Norman Lockyer, who lived from 1836-1920, breaks down ancient astronomy into three distinct phases and presented an observation prevalent across most ancient civilisations like Egypt, India and South America. First, a civilisation goes through the worship stage, where astronomical phenomena are viewed as the actions and warnings of gods; next, it progresses to using astronomy for terrestrial purposes like agriculture or navigation. The final step, he says, is to study astronomy solely for the sake of gaining knowledge.
Observations and predictions of the motion of objects visible to the naked eye preceded the assembly of astronomical observatories in ancient Mesopotamia, Greece, India and Egypt. Early ideas about the universe came into being, thanks to Ptolemy whose comprehensive treatise on astronomy, The Almagest, the only surviving treatise of its kind, estimated that the earth was the centre of the universe. The Babylonians later laid the foundation for the study of the universe with the discovery of the repetitive, cyclical nature of lunar eclipses. Even as astronomy went through a period of stagnancy in medieval Europe until the 13th century, it flourished in the Islamic world with the discovery of the Andromeda Galaxy by Persian astronomer Azophi.
In the early stages of lunar observation, people were interested in the progression of the moon across the nocturnal skies and its changing faces. It was only until the telescope was invented in the 17th century that the focus shifted to the moon’s surface.
In Saxony, too, the earth’s satellite, its orbital progression, and its influence on various spheres of life intrigued laymen and scholars alike. The Nebra sky disc, a bronze disc dating back to 2000 BC unearthed in Saxony-Anhalt is testament to the celestial achievements by those native to Saxony. The disc was marked by a blue-green patina inlaid with gold symbols of the Pleiades star cluster, and featured the full moon and crescent moon.
Many millennia later, Augustus, the elector of Saxony, laid the cornerstone for the discipline of astronomy and lunar research. He commissioned Europe’s first large scientific apparatus and instrument collection that formed the art chamber in Dresden. Over 10,000 objects including astrological and astronomical instruments occupied the Dresden art chamber, which was the precursor of the present-day Mathematics and Physics Salon.
“ The watchmakers at A. Lange & Söhne leverage all the potentials of science and technology to emulate its orbit with extreme precision and to reproduce its radiance as brilliantly as possible ”
The famous lunar map by the Dresden astronomer Wilhelm Gotthelf Lohrmann is an example of Saxony’s fascination with lunar observation during the 19th century. A century later, in the 1960s, Dresden native Ursula Seliger created an extensive series of detail- rich pencil drawings compiled in three volumes. These drawings are currently stored at the Palitzsch Museum in Dresden. The museum was named after Johann George Palitzsch, the so-called “peasant- astronomer” from Dresden, who went on to become famous for discovering Halley’s Comet. Such was the extent to which Saxony contributed to the study of celestial phenomena.
A young watchmaker by the name of Ferninand Adolph Lange was enrolled in Dresden’s technical University, where he acquired an education that set into motion an apprenticeship with the renowned master clockmaker Johann Christian Friedrich Gutkaes, who recognised the young Lange’s unusual watchmaking skills. After years
of journeying across Europe, Lange returned in 1841 with the hope of
establishing a manufactory in the Ore Mountains. He eventually built a
watch manufactory and pioneered a number of innovations that would forever revolutionize watchmaking. The company he founded in 1845, which is today known as A. Lange & Söhne, was headquartered in Glashütte, not far from Dresden, in the state of Saxony.
The German watchmaker has since remained fascinated by the moon. Even today, the watchmakers at A. Lange & Söhne leverage all the potentials of science and technology to emulate its orbit with extreme precision and to reproduce its radiance as brilliantly as possible. Ever since the first collection was presented almost two decades ago, the Glashütte-based manufacture has developed no less than 15 calibres with moon-phase displays. A specialty in A. Lange & Söhne’s repertoire of timepieces, the moon-phase watch requires a correction by one day, once every 122.6 years, which is about 50 times more accurate than conventional displays. In fact, so accurate is its current mechanism that the new Richard Lange Perpetual Calendar “Terraluna” timepiece can run for over 1000 years before it deviates from the actual lunar cycle by one day.
A. Lange & Söhne’s revolutionary lunar discs have signature elements, such as its rich blue hue with a unique chromatic effect achieved by superimposing light waves. To produce this so-called interference phenomenon, the watchmaker partnered with scientists to develop a patent coating process for the solid-gold discs. Then, there’s the distinct presence of laser-cut stars that stand out against the vibrant blue tint. The term blue moon refers to the rare phenomenon of the second full moon within a given calendar month, Most mechanical moon-phase indications must be corrected by one day every “once in a blue moon”. The reason behind this is that the period of time between two new moons is rounded down to 29.5 days even though it is actually 44 minutes and three seconds longer.
The A. Lange & Söhne moon-phase watches, however, are much more precise with most of them reproducing the lunar month with an accuracy of 99.998 %. A good example is the Richard Lange Perpetual Calendar “Terraluna” that is adorned with over 2000 stars in five different sizes and which emphasise the lure of the night sky. The orbital moon-phase display of this timepiece is one of the greatest innovations in precision watchmaking. The timepiece depicts the changing orbital position of the moon in relation to the earth and sun with unmatchable accuracy.
*This article was first published in the March-April edition of Signé (UAE) | 0.89186 | 3.750428 |
New Horizons will make its closest approach in the wee hours of Jan. 1 – 12:33 a. m. EST. Closest approach will bring the spacecraft within 2,200 miles ( 3,500 kilometers ) of Ultima Thule.
Our team worked hard to determine if Ultima was detected by LORRI at such a great distance, and the result is a clear yes , said New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute in Boulder, Colorado.
The new target is roughly 1.6 billion kilometres ( 1 billion miles ) beyond Pluto, making it by far the most distant body in the solar system to get a close-range inspection. New Horizons launched in 2006, with a primary mission to perform a six – month reconnaissance of Pluto and its moons. At the time of these observations, Ultima Thule was 107 million miles ( 172 million kilometers ) from the New Horizons spacecraft and 4 billion miles ( 6.5 billion kilometers ) from the Sun.
The New Horizons spacecraft is speeding through space at 32,000 miles ( 51,500 kilometers ) per hour, traveling almost a million miles per day. We will have to wait till January 1, 2019, to know what’s exactly going around the smallest object in the Kuiper belt.
It flew past Pluto in 2015, providing the first close-up views of the dwarf planet. When New Horizons first glimpsed the rocky iceball in August it was just a dot. Mission scientists plan to use images like these to study many more ancient Kuiper Belt objects from New Horizons if an extended mission is approved. “This is pure exploration”, said Alan Stern, the mission’s principal investigator.
NASA scientists have used the probe’s Long Range Reconnaissance Imager ( LORRI ) to snap images of the object’s neighborhood of space, and were able to pick it out of a cluster of brightly lit stars. The Goblin’s orbit is very skewed, and so is Sedna’s and Biden’s.
The image field is extremely rich with background stars, which makes it difficult to detect faint objects, said Hal Weaver, New Horizons project scientist and LORRI principal investigator from the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland.
In these first images, Ultima appears only as a bump on the side of a background star that’s roughly 17 times brighter, but Ultima will be getting brighter – and easier to see – as the spacecraft gets closer.
Promisingly, the scientists used data from the Hubble Space Telescope to predict the spot where they through Ultima Thule would be. Secondly, these images are now the most distant ever taken from Earth ( New Horizons just broke its own record ). “We now have Ultima in our sights from much farther out than once thought possible. We are on Ultima’s doorstep, and an amazing exploration awaits”! Johns Hopkins University Applied Physics Laboratory.
A NASA spacecraft is hurtling toward a historic New Year’s Day flyby of the most distant planetary object ever studied, a frozen relic of the early solar system called Ultima Thule. New Horizon’s encounter with Ultima Thule will be the most distant planetary encounter in the history of space exploration, and it has now set its sights on its target for the first time. Much more precise than we have ever tried before. It may even be two objects. NASA hopes the flyby will reveal the answers. Will the spacecraft make it? Now, its team has taken New Horizons 100 times farther. The photo was captured by the spacecraft’s Long Range Reconnaissance Imager, or LORRI, on 16 August, part of a sequence of 48 images taken during the spacecraft’s first attempt to spot 2014 MU69, nicknamed Ultima Thule by the New Horizons team.
One AU is the average Earth-sun distance – about 93 million miles ( 150 million kilometers ). For context, Pluto’s distance is around 34 AU, so 2015 TG387 is about two-and-a-half times further away from the sun than Pluto is right now.
The signal will take over 6 hours to reach mission control, mission team members said. “Except you weren’t dialing up from 4 billion miles away”, Stern said. Not only does it lie farther away than any cosmic object He added that the object will get closer by days and so it will get brighter and bigger to been seen easily. Distant observations of the Pluto system begin Jan. 15 and will continue until late July 2015; closest approach to Pluto is July 14.
These distant objects are like breadcrumbs leading us to Planet X, Sheppard said, emphasizing their importance in expanding and redefining our knowledge of the Solar System’s evolution.
The New Horizons probe was launched in January 2006 and has been making its way through the Solar System since then. The object was discovered as part of the team’s ongoing hunt for unknown dwarf planets and Planet X. The newly found object, called 2015 TG387, was discovered about 80 astronomical units ( AU ) from the Sun. Circling a “very elongated” orbit, the celestial body never comes closer to the Sun ( a point called perihelion ) than 65 AU. TG387 is one of the few known objects that never comes close enough to the solar system’s giant planets, like Neptune and Jupiter, to have significant gravitational interactions with them.
We think there could be thousands of small bodies like 2015 These so-called Inner Oort Cloud objects like 2015 TG387, 2012 VP113, and Sedna are isolated from most of the Solar System’s known mass, which makes them immensely interesting, said Scott Sheppard, from Carnegie.
“The discovery of 2012 VP113 led Sheppard and Trujillo to notice similarities of the orbits of several extremely distant solar system objects, and they proposed the presence of an unknown planet several times larger than Earth – sometimes called Planet X or Planet 9 – orbiting the Sun well beyond Pluto at hundreds of AUs. TG387 out on the solar system’s fringes, but their distance makes finding them very difficult”, Tholen said.
For some 99 percent of its 40,000-year orbit, it would be too faint to see, even with today’s largest telescopes. Officially designated 2015 TG387, Follow-up observations were obtained in 2015, 2016, 2017 and 2018 to determine 2015 TG387’s orbit. Only 2012 VP113 and Sedna, at 80 and 76 AU respectively, have more distant perihelia than 2015 TG387 is likely on the small end of being a dwarf planet, since it has a diameter of roughly 300 kilometers.
The team ran computer simulations to understand how different hypothetical Planet X orbits would affect the orbit of 2015 TG387’s orbit stable for the age of the solar system, but it was actually shepherded by PlanetX’s gravity, which keeps the smaller 2015 TG387 away from the massive planet. The simulations included a Super-Earth-mass planet at several hundred AU on an elongated orbit. Astronomers have discovered the most distant object in the solar system. Does our solar system have an undiscovered planet?
Astrophysicists at the University of Toronto have found that a close encounter with Jupiter about four billion years ago may have resulted in another planet’s ejection from the Solar System altogether. It has only enough fuel to achieve 130 meters per second. Since that time, many new objects have been discovered at much greater distances than Pluto. Accepted theory can not explain the phenomenon.
This also means the Goblin takes 40,000 years to complete one orbit of the sun. If all goes well, the Parker Solar Probe will fly straight through the wispy edges of the sun’s corona, or outer atmosphere, in November. In April 2017, the spacecraft will begin its Grand Finale phase. The Swedish-designed equipment will help scientists better understand the interaction of radiation from the sun, also known as solar wind, with the moon’s surface. | 0.87804 | 3.466247 |
Look up at the night sky, and what do you see? Space, glittering and gleaming in all its glory. Astronomically speaking, space is really quite close, lingering just on the other side of that thin layer we call an atmosphere. And if you think about it, Earth is little more than a tiny island in a sea of space. So it is quite literally all around us.
By definition, space is defined as being the point at which the Earth’s atmosphere ends, and the vacuum of space begins. But exactly how far away is that? How high do you need to travel before you can actually touch space? As you can probably imagine, with such a subjective definition, people tend to disagree on exactly where space begins.
The first official definition of space came from the National Advisory Committee for Aeronautics (the predecessor to NASA), who decided on the point where atmospheric pressure was less than one pound per square foot. This was the altitude that airplane control surfaces could no longer be used, and corresponded to roughly 81 kilometers (50 miles) above the Earth’s surface.
Any NASA test pilot or astronaut who crosses this altitude is awarded their astronaut wings. Shortly after that definition was passed, the aerospace engineer Theodore von Kármán calculated that above an altitude of 100 km, the atmosphere would be so thin that an aircraft would need to be traveling at orbital velocity to derive any lift.
This altitude was later adopted as the Karman Line by the World Air Sports Federation (Fédération Aéronautique Internationale, FAI). And in 2012, when Felix Baumgartner broke the record for the highest freefall, he jumped from an altitude of 39 kilometers (24.23 mi), less than halfway to space (according to NASA’s definition).
By the same token, space is often defined as beginning at the lowest altitude at which satellites can maintain orbits for a reasonable time – which is approximately 160 kilometers (100 miles) above the surface. These varying definitions are complicated when one takes the definition of the word “atmosphere” into account.
When we talk about Earth’s atmosphere, we tend to think of the region where air pressure is still high enough to cause air resistance, or where the air is simply thick enough to breath. But in truth, Earth’s atmosphere is made up of five main layers – the Troposphere, the Stratosphere, the Mesosphere, the Thermosphere, and the Exosphere – the latter of which extend pretty far out into space.
The Thermosphere, the second highest layer of the atmosphere, extends from an altitude of about 80 km (50 mi) up to the thermopause, which is at an altitude of 500–1000 km (310–620 mi). The lower part of the thermosphere, – from 80 to 550 kilometers (50 to 342 mi) – contains the ionosphere, which is so named because it is here in the atmosphere that particles are ionized by solar radiation.
Hence, this is where the phenomena known as Aurora Borealis and Aurara Australis are known to take place. The International Space Station also orbits in this layer, between 320 and 380 km (200 and 240 mi), and needs to be constantly boosted because friction with the atmosphere still occurs.
The outermost layer, known as the exosphere, extends out to an altitude of 10,000 km (6214 mi) above the planet. This layer is mainly composed of extremely low densities of hydrogen, helium and several heavier molecules (nitrogen, oxygen, CO²). The atoms and molecules are so far apart that the exosphere no longer behaves like a gas and the particles constantly escape into space.
It is here that Earth’s atmosphere truly merges with the emptiness of outer space, where there is no atmosphere. Hence why the majority of Earth’s satellites orbit within this region. Sometimes, the Aurora Borealis and Aurora Australis occur in the lower part of the exosphere, where they overlap into the thermosphere. But beyond that, there is no meteorological phenomena in this region.
Interplanetary vs. Interstellar:
Another important distinction when discussing space is the difference between that which lies between planets (interplanetary space) and that which lies between star systems (interstellar space) in our galaxy. But of course, that’s just the tip of the iceberg when it comes to space.
If one were to cast the net wider, there is also the space which lies between galaxies in the Universe (intergalactic space). In all cases, the definition involves regions where the concentration of matter is significantly lower than in other places – i.e. a region occupied centrally by a planet, star or galaxy.
In addition, in all three definitions, the measurements involved are beyond anything that we humans are accustomed to dealing with on a regular basis. Some scientists believe that space extends infinitely in all directions, while others believe that space is finite, but is unbounded and continuous (i.e. has no beginning and end).
In other words, there’s a reason they call it space – there’s just so much of it!
The exploration of space (that is to say, that which lies immediately beyond Earth’s atmosphere) began in earnest with what is known as the “Space Age“, This newfound age of exploration began with the United States and Soviet Union setting their sights on placing satellites and crewed modules into orbit.
The first major event of the Space Age took place on October 4th, 1957, with the launch of Sputnik 1 by the Soviet Union – the first artificial satellite to be launched into orbit. In response, then-President Dwight D. Eisenhower signed the National Aeronautics and Space Act on July 29th, 1958, officially establishing NASA.
Immediately, NASA and the Soviet space program began taking the necessary steps towards creating manned spacecraft. By 1959, this competition resulted in the creation of the Soviet Vostok program and NASA’s Project Mercury. In the case of Vostok, this consisted of developing a space capsule that could be launched aboard an expendable carrier rocket.
Along with numerous unmanned tests, and a few using dogs, six Soviet pilots were selected by 1960 to be the first men to go into space. On April 12th, 1961, Soviet cosmonaut Yuri Gagarin was launched aboard the Vostok 1 spacecraft from the Baikonur Cosmodrome, and thus became the fist man to go into space (beating American Alan Shepard by just a few weeks).
On June 16th, 1963, Valentina Tereshkova was sent into orbit aboard the Vostok 6 craft (which was the final Vostok mission), and thus became the first woman to go into space. Meanwhile, NASA took over Project Mercury from the US Air Force and began developing their own crewed mission concept.
Designed to send a man into space using existing rockets, the program quickly adopted the concept of launching ballistic capsules into orbit. The first seven astronauts, nicknamed the “Mercury Seven“, were selected from from the Navy, Air Force and Marine test pilot programs.
On May 5th, 1961, astronaut Alan Shepard became the first American in space aboard the Freedom 7 mission. Then, on February 20th, 1962, astronaut John Glenn became the first American to be launched into orbit by an Atlas launch vehicle as part of Friendship 7. Glenn completed three orbits of planet Earth, and three more orbital flights were made, culminating in L. Gordon Cooper’s 22-orbit flight aboard Faith 7, which flew on May 15th and 16th, 1963.
In the ensuing decades, both NASA and Soviets began to develop more complex, long-range crewed spacecraft. Once the “Race to the Moon” ended with the successful landing of Apollo 11 (followed by several more Apollo missions), the focus began to shift to establishing a permanent presence in space.
For the Russians, this led to the continued development of space station technology as part of the Salyut program. Between 1972 and 1991, they attempted to orbit seven separate stations. However, technical failures and a failure in one rocket’s second stage boosters caused the first three attempts after Salyut 1 to fail or result in the station’s orbits decaying after a short period.
However, by 1974, the Russians managed to successfully deploy Salyut 4, followed by three more stations that would remain in orbit for periods of between one and nine years. While all of the Salyuts were presented to the public as non-military scientific laboratories, some of them were actually covers for the military Almaz reconnaissance stations.
NASA also pursued the development of space station technology, which culminated in May of 1973 with the launch of Skylab, which would remain America’s first and only independently-built space station. During deployment, Skylab suffered severe damage, losing its thermal protection and one of its solar panels.
This required the first crew to rendezvous with the station and conduct repairs. Two more crews followed, and the station was occupied for a total of 171 days during its history of service. This ended in 1979 with the downing of the station over the Indian Ocean and parts of southern Australia.
By 1986, the Soviets once again took the lead in the creation of space stations with the deployment of Mir. Authorized in February 1976 by a government decree, the station was originally intended to be an improved model of the Salyut space stations. In time, it evolved into a station consisting of multiple modules and several ports for crewed Soyuz spacecraft and Progress cargo spaceships.
The core module was launched into orbit on February 19th, 1986; and between 1987 and 1996, all of the other modules would be deployed and attached. During its 15-years of service, Mir was visited by a total of 28 long-duration crews. Through a series of collaborative programs with other nations, the station would also be visited by crews from other Eastern Bloc nations, the European Space Agency (ESA), and NASA.
After a series of technical and structural problems caught up with the station, the Russian government announced in 2000 that it would decommission the space station. This began on Jan. 24th, 2001, when a Russian Progress cargo ship docked with the station and pushed it out of orbit. The station then entered the atmosphere and crashed into the South Pacific.
By 1993, NASA began collaborating with the Russians, the ESA and the Japan Aerospace Exploration Agency (JAXA) to create the International Space Station (ISS). Combining NASA’s Space Station Freedom project with the Soviet/Russian Mir-2 station, the European Columbus station, and the Japanese Kibo laboratory module, the project also built on the Russian-American Shuttle-Mir missions (1995-1998).
With the retirement of the Space Shuttle Program in 2011, crew members have been delivered exclusively by Soyuz spacecraft in recent years. Since 2014, cooperation between NASA and Roscosmos has been suspended for most non-ISS activities due to tensions caused by the situation in the Ukraine.
However, in the past few years, indigenous launch capability has been restored to the US thanks to companies like SpaceX, United Launch Alliance, and Blue Origin stepping in to fill the void with their private fleet of rockets.
The ISS has been continuously occupied for the past 15 years, having exceeded the previous record held by Mir; and has been visited by astronauts and cosmonauts from 15 different nations. The ISS program is expected to continue until at least 2020, but may be extended until 2028 or possibly longer, depending on the budget environment.
As you can clearly see, where our atmosphere ends and space begins is the subject of some debate. But thanks to decades of space exploration and launches, we have managed to come up with a working definition. But whatever the exact definition is, if you can get above 100 kilometers, you have definitely earned your astronaut wings!
We have written many interesting articles about space here at Universe Today. Here is Why is Space Black?, How Cold is Space?, Space Debris Illustrated: The Problem in Pictures, What is Interplanetary Space?, What is Interstellar Space?, and What is Intergalactic Space?
Astronomy Cast has episodes on the subject, like the Space Stations Series, Episode 82: Space Junk, Episode 281: Explosions in Space, Episode 303: Equilibrium in Space, and Episode 311: Sound in Space. | 0.85262 | 3.88305 |
Globular clusters and the challenge of blue straggler stars
Globular clusters are some of the most spectacular astronomical objects observed through the telescope. Like a glittering jewel in the optical field of view, a globular cluster contains a myriad of stars. So far, about 160 globular clusters are known to surround the Galactic centre in a roughly spherical halo.1
Because the stars of a globular cluster are closely associated visually, astronomers believe they are closely associated in space and the same distance away from Earth. Evolutionists further assume that all the stars formed from the same collapsing cloud of gas at about the same time and have held together subsequently by mutual gravitational attraction. Thus, the stars all began with a similar chemical composition and share a common evolutionary history. Their main differences are believed to be due to their different masses. Because the stars have so many similarities, evolutionists believe that globular clusters provide a straightforward way of testing their stellar evolutionary theory, which seeks to explain the behaviour of stars over billions of years.2
When the brightness and colour of each star in a globular cluster are plotted on a colour-magnitude diagram, they have the characteristic pattern shown in Figure 1. The shape of this plot is assumed to support the correctness of stellar evolutionary theory.
According to theory, the energy emitted by each star is derived almost entirely from thermonuclear fusion.2,3The section of the graph from A to B is called the ‘main sequence’ and each point represents a star that has supposedly been ‘burning’ hydrogen steadily for millions of years, not changing much over all that time. According to theoretical calculations, the more massive the star, the faster it ‘burns’ its fuel. So the points near A are for the smallest and least luminous stars that burn their hydrogen the slowest. The points near B represent the largest and brightest stars that are converting their hydrogen into helium most quickly.
Calculations indicate that once a significant portion of the star’s hydrogen has been converted to helium, the temperature and luminosity of the star changes drastically and it becomes larger and redder, and no longer plots on the main sequence.2 The points from B to C are interpreted as such stars. The brightest and reddest stars, called red giants, plot at point C and the line B–C is called the red giant branch.3 Remember that all the stars are assumed to have formed at about the same time. Thus, if stars on the red giant branch are much more evolved, they then must have been much more massive than the stars still on the main sequence.
A third sequence of stars, called the horizontal branch, extends from D to E. These stars are interpreted to be the most evolved, having passed through the red giant phase.3 They must have been the most massive of all the stars that originally formed in the globular cluster.
In this way the colour-magnitude plot is interpreted to represent progressive stages in stellar evolution, starting with the least evolved stars at point A and moving through points B, C and D to the most evolved stars at point E. Of particular interest is point B, the turn-off point, which represents the most massive star still on the main sequence. According to evolutionary theory, this point would gradually move downwards over millions of years as stars of successively lower mass burn up their hydrogen and evolve away. In picturesque language, this point is often described as ‘burning down like a candle’.3
Significantly, the main sequence turn-off can be used to estimate the age of the globular cluster from stellar evolution theory. Once the magnitude or luminosity of the star at the turn-off point has been determined, the mass of the star can be estimated from a mass-luminosity relationship using our Sun as reference. Similarly, from the mass of the star, an ‘age’ can be calculated from nuclear fusion models for main-sequence stars.4 In this way, evolutionists have determined the ‘age’ of globular clusters surrounding our Galaxy and, surprisingly, they are all 13–15 billion years old.5
Blue straggler stars
This story sounds convincing until we realize that there is no way of testing it. By adding secondary explanations, the story can accommodate any astronomical observation. Indeed, the situation is not as simple as the simple theory claims.
For example, most globulars are revolving around the Galaxy in highly eccentric orbits with a period of some 100 million years.5 In 15 billion years, each cluster would have orbited the Galaxy over one hundred times, passing though the Galaxy disk twice each time. This raises the question of how the star clusters could have remained together and compact for all that time.
Furthermore, stars toward the end of the red giant branch and in the horizontal branch have masses that are much lower than those of stars once on the main sequence from which they have supposedly evolved. Again, explanations are devised for how stars lose mass as they evolve from the main sequence.6
Also, the age of the globular clusters, calculated from the main sequence turn-off, has been the subject of ongoing revision. The problem is that the age of the stars in the globular clusters must be less than the age of the universe as calculated from the Hubble constant.7,8
And then there are blue straggler stars. According to theory, the main sequence should not be populated above the main sequence turn-off (point B, Figure 1) because all stars of greater luminosity and mass should have long ago evolved away. However, stars have been observed in this region for every globular cluster studied.9
‘Some globular clusters also have a small number of enigmatic blue stragglers, stars with an atypical blue colour and high luminosity. They look much hotter and younger than the rest of the cluster’s stars.’10
According to theory, they should not be there, but they are. They should have evolved away from the main sequence but for some reason, they are straggling behind, hence the term, blue straggler stars. Although blue stragglers have been known for some 50 years, their study has only blossomed in the last decade with the advent of powerful new hardware and software that can analyze individual stars in the densely packed cluster.
So, how are blue straggler stars explained? Remember that the stellar evolution theory involving billions of years is not an issue. The theory has already been accepted as correct. If the basic theory is above challenge then, clearly, the blue stragglers must have either been kept young, are intruders from a different stellar population, or have a different chemical composition that caused them to burn more slowly.
At first, it was suggested that the enigmatic blue stars were not really members of the cluster. Perhaps the cluster image was polluted with other stars that just happened to lie along the line of sight or perhaps the cluster somehow captured some younger stars. However, it was found that the blue stragglers tended to concentrate in the cores of clusters and have consistent radial velocities.9
Another idea was that stars in the cluster’s horizontal branch coincidentally crossed the extended main sequence. However, blue stragglers are significantly different from horizontal branch stars.9
Perhaps the blue stragglers are not being kept young but represent stars that formed within the cluster long after the first cycle of star birth—a younger generation of stars. However, a secondary period of star formation is unlikely because of the extreme lack of star forming materials in globular clusters.9
By far the most preferred explanations today are ones that increase the mass of a star long after the cluster originally formed.9 In this way, the star can be old and blue at the same time. One idea is that blue stragglers were part of a binary system in which the larger star exhausted its core hydrogen and dumped its mass on the smaller star. An alternative is that the binary pair lost angular momentum and coalesced. Another thought is that two stars collided and joined together. Such stellar collisions have been proposed to explain the large number of blue straggler stars observed in M80:
‘ … in the September 10th Astrophysical Journal … they turned up 305 blue stragglers in this image of the 7th-magnitude cluster taken with the Hubble Space Telescope’s Wide Field and Planetary Camera 2 … There is no clear correlation between the numbers of blue stragglers and the overall stellar density in other clusters, write the scientists; thus the implication of M80’s preponderance of stragglers is unclear. Ferraro’s team suggests that M80 is in the middle of an evolutionary phase in which stellar collisions are generating the huge population of blue stragglers that are retarding the overall collapse of the cluster’s core. Further study, such as tallying the cluster’s binaries, is needed to support this scenario.’11
A Creation framework
How long did it take for the 160 or so globular clusters to form? Evolutionists believe it took at least 3 billion years. But from Genesis 1:14–19, 1:31–2:3, and Exodus 20:11 it is clear that they formed in much less than one Earth day during Creation week. This would feature an abrupt formation process for globular clusters. Evidently, no new globular clusters are evolving in the Milky Way, suggesting that the globular cluster formation process has changed significantly since the Milky Way formed or is not operating in our galaxy today.
Stellar models based on a 6-Day Creation are very different from those based on billions of years of evolution. Additional variables become relevant once a young universe is assumed. For example, energy supplied by gravitational collapse might be a major source of stellar radiation within a creationist model. Furthermore, issues of design and purpose need to be considered. Creationists do not need to invent special theories to explain the presence of blue stragglers in globular clusters. Blue stragglers could simply be higher mass stars (e.g. spectral class A, main sequence) and indicators of youth. In fact, there is evidence that blue stragglers are indeed higher mass stars.
So, how much stellar evolution has taken place in the Galaxy’s globular clusters since their origin? According to stellar evolution theory, at least 13–15 billion years’ worth, beginning with the birth and death of Population III stars before the globular clusters formed.12 However, from a creationist perspective very little change would have occurred in the globular clusters since they were formed rapidly some 6,000 years ago. And since globular clusters have completed much less than one orbit of the Galaxy there has been little dynamical time and change in them since. The compact size of globular clusters reflects their abrupt, rapid formation process, and their youthfulness.
- Astronomy picture of the day: Globular Cluster M5, <antwrp.gsfc.nasa.gov/apod/ap951019.html>, 11 March 2002. Return to text.
- Abell, G.O., Morrison, D. and Wolff, S.C., Exploration of the Universe, 6th Ed., Saunders College Pubpshing, Philadelphia, p. 483, 1993. Return to text.
- Abell et al., Ref. 2, pp. 493–494. Return to text.
- Measuring a Globular Star Cluster’s Distance and Age, The ESA/ESO Astronomy Exercise Series, Exercise 4, <www.astroex.org/english/exercise4/>, 11 March 2002. Return to text.
- Abell et al., Ref. 2, p. 485. Return to text.
- Late stellar evolution, <www.oan.es/ciencia/viejas>, 13 March 2002. Return to text.
- Globular star clusters, <www.seds.org/messier/glob.html>, 11 March 2002. Return to text.
- How do we measure the size and the age of the Universe, <imagine.gsfc.nasa.gov/docs/science/mysteries_11/age.html>, 11 March 2002. Return to text.
- Danforth, C., Blue stragglers: a study of stellar longevity, <casa.colorado.edu/~danforth/science/bss/index.html>, 7 March 2002. Return to text.
- Moche, D.L., Astronomy: A Self-Teaching Guide, John Wiley & Sons, p. 143, 1993. Return to text.
- NewsNotes, M80’s bounty of blue stragglers, Sky & Telescope, 98(4):18, 1999. Return to text.
- Bernitt, R., Stellar evolution and the problem of the ‘first’ stars, TJ 16(1):12–14, 2002. Return to text.
- Abell et al., Ref. 2, p. 493. Return to text.
- Blue stragglers in globular clusters, Astronomy Picture of the Day, <antwrp.gsfc.nasa.gov/apod/ap971104.html>,
3 March 2002. Return to text. | 0.875927 | 3.974135 |
Climbing to the top of the Urucum plateau, a shock of rust-red land thrust 1 kilometer above the Brazilian savanna, is a journey into Earth's deep past. Despite the region's heavy, erosive rainfall, the surface of the plateau has remained largely unchanged for some 70 million years, making it Earth's oldest known landscape. Walk along it and you're only a few meters below the surface that dinosaurs once trod.
That startling picture emerges from a study published this month in Earth and Planetary Science Letters by a team led by Paulo Vasconcelos, a geochemist at the University of Queensland in Brisbane, Australia. Until recently, scientists could estimate erosion only by looking at the sediment sloughed off of a surface. But new geochemical tools developed by, among others, Vasconcelos and his colleagues measure erosion from rock that's left behind. "They all converge to the same story," Vasconcelos says. "Though it's taken some time to convince people."
Earth scientists say ancient landscapes could exist atop other inselbergs, a German term for the isolated plateaus that dot geologically quiet regions in the Southern Hemisphere that have not been reshaped by plate tectonics or planed away by ice sheets. Geologists had suspected that these inselbergs, found in Brazil, Australia, and southern Africa, are old—enduring while erosion stripped away the surrounding landscape. Now, that history is emerging. "It's almost like the movies," says William Dietrich, a geomorphologist at the University of California, Berkeley. "You expect to see exotic animals wandering around."
For decades, geomorphologists have fixated on regions where plate tectonics accelerates geologic change, thrusting up mountains, opening rifts, and creating traps for oil and gas. "Where do most geologists go?" asks Paul Bierman, a geologist at the University of Vermont in Burlington. "They go to the mountains. Or to oil." But the new geochemical tools are turning geoscientists on to the charms of the planet's slow parts.
Vasconcelos and his team used four different geochemical dating systems to flesh out the story of the Urucum plateau and its neighbor, the Santa Cruz. One took advantage of grains of the mineral manganese oxide that formed when the surface was first exposed to rain. The grains incorporated trace amounts of radioactive potassium, which has steadily decayed into argon ever since, providing a clock that shows the landscape formed 60 million to 70 million years ago. Another gauge of erosion comes from a set of isotopes—of helium, beryllium, and aluminum—that form when cosmic rays bombard surface rocks. The high abundances of these isotopes suggest the plateaus shed only 1 meter of material every 10 million years; the surrounding landscape, meanwhile, likely eroded at 100 times that rate, the group concludes. "They put together an erosional history that's very compelling and exceptional," Dietrich says. "I don't know something so cleverly dated."
The results raise a new question, says Jane Willenbring, a geomorphologist at the Scripps Institution of Oceanography in San Diego, California: "What makes landscapes persist for millions of years?" Until now, the oldest known surfaces had been found in parched regions like the Atacama Desert in Chile or the dry valleys of Antarctica, where water-driven erosion is slow. Paradoxically, the longevity of the Brazilian plateaus depends on water, says Ken Farley, a geochemist at the California Institute of Technology in Pasadena and a co-author of the paper. They are rich in a type of iron oxide called hematite, which reacts with quartz dissolved in rainwater to form tough blocks of rock that armor the soil. "It's just iron oxide, nothing else there," Farley says.
Similar plateaus protected by iron or silica probably exist throughout the slow lands. "Vasconcelos's finding has the potential to motivate other researchers to come back to ancient and slow landforms," says Fabiano Pupim, a geomorphologist at the Federal University of São Paulo in Diadema, Brazil.
One lure is the long histories they hold. "This surface has seen a lot of geochemical processes," Vasconcelos says. "If something very drastic happened on the entire planet, a signature should be left." He's developing a technique to tease out rainfall and temperature histories from oxygen isotopes in goethite, an iron oxide that caps inselbergs in Brazil and Australia. These surfaces can also help scientists judge how often rare, powerful intraplate earthquakes strike a region. If the ancient cap is unbroken, any faults found in the rock below it must be associated with even older earthquakes, says Bierman, who recently used an isolated ancient plateau in South Africa to judge the seismic hazard to a nuclear power plant.
Inselbergs hold another gift: deposits of concentrated iron ore, protected from washing away by the impermeable surface. Left alone, the Urucum might exist for another 30 million years. But now, humanity is doing the job much faster. When the team visited earlier this decade, most of the plateau's surface had been lost to mining, Farley says. "If we went back there, I'm not sure this material would be left." | 0.83673 | 3.38216 |
Glass deposits on Martian surface may provide an insight into ancient signs of life on the planet
A team of researchers from Brown University, used data from NASA’s Mars Reconnaissance Orbiter (MRO) and were able to detect glass deposits within impact craters on Mars which are assumed to have formed in the scorching heat of a violent impact. These glass depositions might just provide an insight into ancient signs of life on the Red planet.
Earlier astronomical studies have shown that it is possible to preserve ancient bio-signatures in an impact glass.
Kevin Cannon, a PhD student at Brown University said: “Knowing this, we wanted to go look for them on Mars and that is what we did here. Before this paper, no one had been able to definitively detect them on the Martian surface”.
Cannon and a co-author Jack Mustard, who is professor of Earth, environmental and planetary sciences at the Brown University together showed that there are considerably large glass deposits present in several well preserved ancient craters that are scattered across the Martian surface.
The study basically pointed out that these glass deposits are relatively common impact features on Mars and they can be used for further exploration
Generally, scientists need to measure the spectra of light that gets reflected off the planet’s surface for remote identification of different mineral and rock types.
However, the impact glass is a bit different as it does not have any particular strong spectral signal.
Jack Mustard said: “Glasses tend to be spectrally bland or weakly expressive, so signatures from the glass tend to be overwhelmed by the chunks of rock mixed in with it. But Kevin found a way to tease that signal out.”
Cannon, carried out an experiment in the laboratory by mixing the powders of Martian rocks which had similar composition and then fired them in an oven in such a way so as to form glass. He then measured the spectral signal using this glass.
Next, Cannon recorded the spectral signal that he got from the lab glass and then by using algorithmic designs he was able to pick out the similar signals from the satellite’s data i.e. from MRO.
With this technique the duo were able to detect even smaller amounts of deposits around several crater central peaks.
Finding deposits on central peaks is an indication that they have an impact origin and it is already a known fact that the impact glass can preserve ancient signs of life. This knowledge can open new fields in the Mars expedition and going forward glass deposits can be the targets for future exploration.
The duo researchers said: “We think these could be interesting targets for future exploration. In fact, we have a particular spot in mind.”
Hargraves, is one of the craters that has been found to contain glass and it located near the Nili Fossae trough that is a long depression which stretches across the Martian surface.
As of now the Nili Fossae trough is believed to date from a time when Mars was a much wetter place and hence it has lots of scientific significance.
Says Mustard: “If you had an impact that dug in and sampled that subsurface environment, it’s possible that some of it might be preserved in a glassy component. That makes this a pretty compelling place to go look around, and possibly return a sample.”
Readers can get complete details of this research which has been published online in the journal Geology. | 0.803973 | 3.692822 |
The outer planets generally have lots of little moons orbiting them. As a result, things can get a bit crowded. When moons orbit a planet in similar orbits, their gravitational tugs on each other can cause the orbits to shift over time. Sometimes this causes them to collide, but often gravity tugs moons into resonances. These resonances keep their orbits stable and keep the moons from hitting each other.
The Galilean moons of Jupiter are probably the best example of this. The orbits of Io, Europa and Ganymede have a 1:2:4 resonance. For every one orbit of Ganymede, Europa orbits twice, and Io orbits four times. This pattern keeps the moons locked in a stable pattern. Saturn’s moons Hyperion and Titan have a similar resonance, where Titan orbits four times for every three orbits of Hyperion.
Sometimes, however, moons can be found in much stranger resonant patterns. Two small moons of Saturn, Janus and Epimetheus, share almost the same orbit. Their orbits are so close to each other you would think they’d collide. But instead, they do an interesting orbital dance. When one of the moons orbits slightly closer to Saturn, it gradually catches up with the other. When the two are relatively close, the gravity of the inner moon pulls the outer moon toward Saturn. In turn, the gravity of the outer moon pulls the inner moon away from Saturn a bit. Essentially the two moons switch orbits, and after a near-miss, they speed apart again.
The gravitational dance of small moons can be complex, though they generally orbit within a similar orbital plane. Now a paper in Icarus shows how moons can dance when they have different orbital planes.1
The two innermost moons of Neptune, Naiad and Thalassa, have a similar distance from the planet. Naiad orbits Neptune every seven hours, while Thalassa takes a half-hour longer to make an orbit. But Naiad’s orbit is tilted about five degrees from Thalassa’s. From Thalassa’s point of view, Naiad wobbles up and down as it catches up and speeds away from Thalassa. In this new paper, the team showed that Naiad’s wobbling pattern is locked in a resonance with the orbit of Thalassa, and this resonance connects the two moons in a stable pattern.
Orbital dynamics can be complex and subtle. This discovery shows yet again how resonant orbits can happen in strange and wondrous ways.
Brozović, Marina, et al. “Orbits and resonances of the regular moons of Neptune.” Icarus (2019): 113462. ↩︎ | 0.806478 | 3.883367 |
China Sets its Sights on Mars, Capturing the Sharpless Nebulas, and the Creation of Heavy Metals
In June’s issue of Sky & Telescope, we cover the history of China’s space program as they lay the groundwork to build a research base on the Moon. The end of this decade may see China’s space agency on Mars and traveling to other star systems. M101 shines bright and beautiful in the summer skies. This year, we are visiting the various star-forming regions, also known as HII regions, that can be found along its spiral arms. We also provide a guide that can help you capture this galaxy and other night-sky objects with video equipment, so you can share your deep-sky adventures with others. Our top picks from the Sharpless Catalog are a great place to start your career as an astronomy movie director — these star-producing marvels and star remnants are a wonder to behold! But we wouldn’t be here to see them without the Population III stars that created heavy elements like iron, oxygen, calcium, and zinc. These first stars made planets possible, and now astronomers are using chemistry to study the oldest stars in existence. The ancient myth of Ophiuchus, the Serpent Bearer, has nothing on these ancient stars, but he is slowly gaining fame as a possible 13th figure of the zodiac. Look for him this month using our guide to this notorious constellation.
A Galaxy-Hop Around M101
Join the author as he explores the Pinwheel Galaxy and surrounding objects.
By Alan Whitman
Treasures of the Sharpless Catalog
Sample some of the delights in the first comprehensive catalog of nebulae.
By Ron Brecher
China Launches to Center Stage
A bold series of successful and proposed missions are catapulting China to prominence in space.
By Andrew Jones
Astronomers are illuminating the universe’s early days by studying chemical patterns in the oldest stars.
By Brian Ventrudo
Exploring the Deep Sky with Video
With a little tech, you can see farther and share the view.
By Rod Mollise
Beyond the Printed Page:
Read the history of the Herschel 400 Observing Program and take on the challenge yourself.
Enjoy our complete list of constellation names and abbreviations. It also includes a brief history and pronunciation guide.
Learn all about this unique finder and how to build one yourself.
Use this Solar Eclipse Circumstance Calculator to discover what 2020’s annular solar eclipse will look like in your area.
ALSO IN THIS ISSUE:
Ophiuchus and Friends
The celestial serpent bearer has plenty of interesting company.
By Fred Schaaf
A Martian Sneak Peek
One of the best showings of the Red Planet in decades starts now.
By Bob King
Peering Over the Limb
Spot evidence of these hidden farside features during favorable librations.
By Charles Wood
The First Plowman
Boötes is home to one globular cluster and many great galaxies.
By Sue French
Table of Contents
See what else June's issue has to offer. | 0.885319 | 3.026713 |
Gliese 667 is a triple star system about 22 light years from Earth in the constellation of Scorpius. Two of these stars–Gliese 667 A and B–are Sun-like and orbit each other relatively closely.
The third is much more interesting. Gliese 667C a red dwarf that is about a third of the mass of our Sun and only about 1 per cent as bright. It orbits the other two stars at a much greater distance: some 200 astronomical units or about 30 billion kilometres.
Red dwarfs are particularly interesting for astronomers because their small mass makes it much easier to spot orbiting planets. What’s more, their low luminosity means that these stars’ habitable zones are much closer than for brighter stars.
Since current planet spotting techniques favour closer planets, astronomers know they are much more likely to find planets in the habitable zone around red dwarfs. In fact, today’s news is a good example.
Today, Philip Gregory at the University of British Columbia in Canada says that Gliese 667Chas three planets sitting squarely in the middle of its habitable zone.
Gregory is a pioneer of new statistical techniques for evaluating the data from planet-hunting instruments. “The excitement generated by … many … exoplanetary discoveries has spurred a significant effort to improve the statistical tools for analyzing data in this field,” he says.
So he’s used a new technique to re-examine data on Gliese 667C taken by the High Accuracy Radial velocity Planet Searcher, HARPS, attached the European Southern Observatory’s 3.6 metre telescope in Chile.
He says this analysis indicates that the most likely number of planets around Gliese 667C is 6 with orbital periods of 7 days, 28 days, 31 days, 39 days, 53 days and 91 days. Only two of these were already known.
However, the most interesting news is that the 28, 31 and 39 day-planets are all smack bang in the middle of the habitable zone, he says.
These planets are all larger than Earth but the 39 day period planet (planet e) is only just over twice Earth’s mass. That makes it “the lowest mass planet in the habitable zone detected to date,” says Gregory.
That’s exciting news which will make Gliese 667C the target of significant interest in the near future from astrobiologists wanting to know more about these potentially Earth-like places. And with three to examine around a single star, they will be spoilt for choice.
Ref: arxiv.org/abs/1212.4058: Evidence for Multiple Planets in the Habitable Zone of Gliese 667C: A Bayesian Re-analysis of the HARPS data | 0.841595 | 3.770415 |
There is a black patch of space in NGC 1999, and for years astronomers have thought it was just a dense cloud of gas and dust, blocking light from passing through. But the Herschel infrared space telescope – which has the ability to peer into these dense clouds — has made an unexpected discovery. This black patch is actually a hole that has been blown in the side of the nebula by the jets and winds of gas from the young stellar objects in this region of space. “No-one has ever seen a hole like this,” said Tom Megeath, of the University of Toledo in the USA. “It’s as surprising as knowing you have worms tunneling under your lawn, but finding one morning that they have created a huge, yawning pit.”
Any previous descriptions of NCG 1999 said that the ominous dark cloud in the center was actually a condensation of cold molecular gas and dust so thick and dense that it blocks light. And astronomers had no reason to believe otherwise, until Herschel’s powerful infrared eyes took a look from space.
When Herschel looked in the direction of this nebula to study nearby young stars, the cloud continued to look black. But, that should not be the case. Herschel’s infrared eyes are designed to see into such clouds. Either the cloud was immensely dense or something was wrong.
Investigating further using ground-based telescopes, astronomers found the same story however they looked: this patch looks black not because it is a dense pocket of gas but because it is truly empty. Something has blown a hole right through the cloud.
Stars are born in dense clouds of dust and gas. Although jets and winds of gas have been seen coming from young stars in the past, it has always been a mystery exactly how a star uses these to blow away its surroundings and emerge from its birth cloud. With Herschel, this may be the first time we can see this process.
The astronomers think that the hole must have been opened when the narrow jets of gas from some of the young stars in the region punctured the sheet of dust and gas that forms NGC 1999. The powerful radiation from a nearby mature star may also have helped to clear the hole. Whatever the precise chain of events, it could be an important glimpse into the way newborn stars disperse their birth clouds. | 0.839306 | 3.791264 |
This composite Hubble image shows IRAS 20324+4057, a protostar in a very early evolutionary stage.
This light-year-long knot of interstellar gas and dust resembles a caterpillar on its way to a feast. But the meat of the story is not only what this cosmic caterpillar eats for lunch, but also what’s eating it. Harsh winds from extremely bright stars are blasting ultraviolet radiation at this “wanna-be” star and sculpting the gas and dust into its long shape.
The culprits are 65 of the hottest, brightest known stars, classified as O-type stars, located 15 light-years away from the knot, towards the right edge of the image. These stars, along with 500 less bright, but still highly luminous B-type stars make up what is called the Cygnus OB2 association. Collectively, the association is thought to have a mass more than 30,000 times that of our sun.
The caterpillar-shaped knot, called IRAS 20324+4057, is a protostar in a very early evolutionary stage. It is still in the process of collecting material from an envelope of gas surrounding it. However, that envelope is being eroded by the radiation from Cygnus OB2. Protostars in this region should eventually become young stars with final masses about one to ten times that of our sun, but if the eroding radiation from the nearby bright stars destroys the gas envelope before the protostars finish collecting mass, their final masses may be reduced.
Spectroscopic observations of the central star within IRAS 20324+4057 show that it is still collecting material quite heavily from its outer envelope, hoping to bulk up in mass. Only time will tell if the formed star will be a “heavy-weight” or a “light-weight” with respect to its mass.
This image of IRAS 20324+4057 is a composite of Hubble Advanced Camera for Surveys data taken in green and infrared light in 2006, and ground-based hydrogen data from the Isaac Newton Telescope in 2003. The object lies 4,500 light-years away in the constellation Cygnus.
Image: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) | 0.860542 | 3.805351 |
This story appears in the November 2018 issue of National Geographic magazine.
Do you know the current phase of the moon? Most of us don’t have any idea; nowadays we hardly need to know. But before there were streetlamps and electric lights everywhere, people watched the night sky diligently. So when a very bright comet appeared in 1607, people were frightened and fascinated.
German astronomer Johannes Kepler thought deeply about what he saw that year. He reasoned that the spectacular tail of what we now call Halley’s comet (named after English scientist Edmond Halley, who computed its orbit) was probably caused by the sun’s warmth somehow evaporating or liberating material from the comet’s surface. Kepler imagined exploring those star scapes: “Given ships or sails adapted to the breezes of heaven, there will be those who will not shrink from even that vast expanse,” he wrote.
Ships, after all, were common enough in the 16th and 17th centuries, and they were driven by the winds, which are themselves created in part by the sun’s warmth. Kepler lived during a moment in history when, thanks to Nicolaus Copernicus, we came to understand that we’re aboard a planet orbiting a star. Perhaps it was natural, then, for Kepler to envision humankind sailing the starry heavens.
As I sat in Carl Sagan’s astronomy classes at Cornell University in 1977, sailing through space certainly seemed natural to me. Sagan vividly described his vision of a craft that could operate within the constraints of gravity and the mechanics of orbits, yet glide among the stars. It would sail the cosmic ocean, driven by the force of starlight in the vastness of space.
The dream that our professor outlined is now being realized by the Planetary Society, the world’s largest nongovernmental space organization, which Sagan co-founded in 1980 (and I now lead). In June 2015 the society tested its own crowdfunded, flight-by-light spacecraft, LightSail 1. As this article goes to press, we’re preparing for the scheduled autumn launch from Cape Canaveral of its successor, LightSail 2, to be vaulted into Earth orbit on the SpaceX Falcon Heavy rocket.
Some three centuries after Kepler first wrote about stellar sailing, scientists discovered that light is pure energy—that property in nature that makes things go, run, or happen. These days we know just how much energy is in each packet of light, or photon. Although photons have absolutely no mass, they nevertheless carry momentum.
We probably all recognize that a rolling bowling ball has momentum, which it transfers to bowling pins. When the ball strikes, the pins go down and the points rack up. Furthermore, if you were to experience a bowling ball rolling into your rib cage (as I did while appearing on a kids TV show), you’d notice its momentum quite strongly.
In contrast, the momentum of light is a concept outside our ordinary experience: When you’re out in the sun, you don’t feel that sunlight can push you around. The force of light, a single photon in particular, is tiny—so on Earth the sunlight pressure, as it’s called, is overwhelmed by the other forces and pressures you encounter, such as friction and gravity.
What if we could harness the energy of a tremendous number of photons and we had nothing holding us back? There’s only one place we know of to get away from all the friction and gravity: outer space.
Since the 1920s, people have imagined spacecraft that would be so low mass and so big that the pressure of photons would push them through space the same way molecules of gas—air—push sailing ships across the sea.
Solar sailing is elegant not only in concept but also in its efficiency. Once in orbit, there’s no fuel needed. Although the propulsive force is quite small—barely nine micro-newtons (two-millionths of a pound) per square meter (or yard) of shiny sail—unlike a conventional rocket engine, it never runs out of fuel. Because the sun shines around the clock, the small bit of energy imparted every second builds and builds.
Here’s how LightSail 2 will fly. Our spacecraft starts no bigger than a loaf of bread: 4 x 4 x 12 inches, a standard size and shape for today’s cubical satellites, or CubeSats. It’s fun to realize that since there’s hardly any air in Earth orbit, there’s no need for spacecraft to have sleek, aerodynamic shapes.
Small compartments in the spacecraft hold very shiny sails; in orbit, they’ll be unfurled to a square more than 18 feet on each side. As sunlight pushes the sails, ground control can cue the craft’s very small electric motors to make it twist in space. As we orbit Earth, we will fly edge-on toward the sun, then twist or tack the spacecraft to present its sails right across the sunbeams, then tack again edge-on with each orbit.
It’s just like a sailing ship except it’s in space, driven directly by sunlight. And instead of being built in an enormous shipyard by the sea, the LightSail is built in small labs on land in California (albeit with access to some pretty good surfing).
During our LightSail 2 mission, we anticipate building orbital energy so that our noble little craft will climb to a higher and higher orbit. We hope it will send back beautiful pictures of itself and the Earth below. And we believe it will fundamentally advance the technology of spaceflight. These LightSail missions are part of a global effort to lower the cost of space exploration, so missions could be flown that would otherwise be cost prohibitive or impossible.
For example: Now and then, the sun ejects an enormous amount of energy called a coronal mass ejection, or CME. These streams of charged particles, which can ruin the electronics aboard satellites, move very rapidly through space—but not nearly as rapidly as photons of light.
As Kepler himself pointed out, an object that is in close orbit to the sun goes faster than an object that’s in orbit farther out, because of the sun’s gravitational pull. If we were to attempt to put a satellite in an orbit at about the same distance from the sun as, say, Venus is, and we planned to have our spacecraft keep pace with the Earth—well, it wouldn’t. Instead, it would literally fall into the sun. To stay in such an orbit, a spacecraft would need another constant outward force. A solar sail could provide that continuous push, and the instruments on board could detect a CME and send us a warning signal. We could maneuver nearby Earth-orbiting satellites so that they essentially turn their backs to the stream of particles—and our vital spacecraft would suffer little damage.
With this same feature of solar sailing, we could send a spacecraft outfitted with infrared telescopes to orbit in step with Earth. The craft could point its heat-sensing telescope away from the sun, scan the icy blackness of space, and perhaps detect the glow of a dangerous asteroid on a collision course with Earth. Or a solar-sail spacecraft could be placed in orbit almost permanently above Earth’s North or South Pole to monitor weather and climate. Solar sailing is a fantastic technology that is just in its infancy.
Think about the modern world we inhabit and the vast influence of exploration. The electronics or paper you’re reading, the car you drive, the plane or train you ride, the food you eat, and the clothes you’re wearing are all available to you because our ancestors figured out how to navigate the trackless ocean … the uncharted continents … the infinitude of space.
At the Planetary Society, our mission is to advance space science and exploration. Most people on Earth live day to day and night to night without thinking too much about space—but when we do, we can accomplish great things. By inviting the world’s citizens to play a role in LightSail missions—to advocate for science funding, attend Planetary Society events, subscribe to launch updates—we give them a chance to be part of the future, to democratize space, and to help us all gain an important new perspective of the cosmos and our place within it. To the stars!
Mechanical engineer Bill Nye is CEO of the Planetary Society and an on-air expert on National Geographic’s series MARS (season two premieres November 12). He is host of Bill Nye Saves the World on Netflix and a best-selling author whose book Everything All at Once is out in paperback this month. His Emmy Award–winning program Bill Nye the Science Guy helped introduce the millennial generation to science and engineering. | 0.898474 | 3.681687 |
Development and Performance Characterization Of Colour Star Trackers
Star trackers provide an essential component to a satellite mission requiring high-precision and high-accuracy attitude measurements. A star tracker operates by taking pictures of the celestial sphere and attempting to identify the stars in the image using a combination of the geometric and brightness patterns. The star-positions in the image then determine the attitude of the sensor in the inertial frame. I propose extending the capability of star trackers by including the colour properties of the stars into the star identification process; hence, colour star tracking.Current generation star trackers exist in a variety of forms, with a variety of additional potential designs and operational algorithms proposed in the literature. However, they all share the common trait of using a combination of geometric and monochrome brightness derived patterns to identify stars. Including colour information with the geometric and brightness properties into the identification process represents a new branch in the field of star tracker design. The process of measuring colour also causes a reduction in the amount of light gathered by the sensor, decreasing the number of stars observed. The challenge in colour star tracking becomes establishing that the additional information provided by colour to star patterns is greater than the loss of observable stars due to the measurement process. While superficially brief, accomplishing it touches upon a wide range of topic areas. This includes most research developed for monochromatic star trackers including imaging hardware, optics, noise rejection, parameter estimation, signal detection, data mining, pattern matching, and astronomy. Additionally, using colour necessitates introducing the topics of stellar photometry, spectral filtering, and colour imaging.The approach to colour star tracker development, presented here, considers three aspects to the operation of the technology: colour measurement, star detection, and star pattern matching. In the measurement of colour analysis, a new set of estimation techniques are developed to estimate the colour and position of stars using colour-filter-array and trichroic prism cameras. Validation of the proposed techniques is achieved through a combination of laboratory and nigh-sky testing of hardware prototypes. The detection performance of the colour star tracker designs centres on a comparison with equivalent monochrome designs. By considering primitive detection algorithms, essentially raw thresholding, allows for a fair determination of the relative performance. Numerical simulations of potential designs examine the percentage of the celestial sphere where sufficient quantity of stars can be observed to yield identification. Finally, extending the results of the detection analysis allows for a determination of the ambiguity within observed star scenes. While not explicitly pattern matching, this analysis establishes a baseline for the performance to be expected from practical pattern matching algorithms. Together, the combined results establish the overall expected increase in performance of colour star tracking over equivalent monochrome designs.A critical goal of any star tracker design is to maximize the region of sky where the star tracker can successfully return an attitude solution. Additionally, the reliability of achieving correct attitude solutions must also be a factor. The work presented demonstrates that, given the correct design circumstances, colour star trackers can supersede their monochrome counterparts in these two aspects. Specifically by resolving formerly ambiguous scenes and increasing the total number of scenes that can yield a solution. As a consequence, colour measurement should now become a viable and explicit consideration in future star tracker design processes. | 0.80366 | 3.599097 |
First of all, there is no such thing as black holes! There is only misunderstanding about how stars and their systems move in space. When scientists finally understand how our own planet moves around the sun in a downward spiral orbit while our sun moves down through space in a shallow orbit; then they will begin to understand the relative motion of the other star systems, which are moving toward us and away from us and in all directions. When we learn how particles move through space, which includes the sun and its orbiting planets, we will then, understand much more about this machine we call the universe.
Particles in space are always moving in a spiral orbit moving from low pressure to high and then back again. However, this pressure exists not just from the outside pushing in but also from the inside pushing out. Understanding these pressures and how they work is the heart of “other dimensional science”. Understanding how these star systems move through space, will also accurately answer the questions of red giants and white dwarfs, as well as… the death and birth of stars, which do not exist. It is true that stars get bigger and smaller as they orbit from one pressure zone to another and consequently, they do change color as a result, but stars do not nova and then disappear. I would love to view a star nova through a powerful telescope, a star nova is a spectacular thing to see but when it’s all over with, that star is still there, we just can’t see it any longer because it has moved from one pressure spectrum to another!
Currently, the earth is orbiting down from low pressure into high pressure. It takes 12,000 years to complete this quarter cycle before we enter into the next cycle, which will take us once again… from relative low pressure to high, and we begin another 12,000 year cycle.
The earth and the machinery which surrounds it, work a lot like a washing machine or any machine, for that matter. When you have working parts, the parts of the machine get hot in certain places and so the machine changes gears. It all works like a clock in a way. Pressure builds up and finally moves the minute hand into the next position. This explains the motion of the poles which are shifting, the rising of water, which result in major floods and often permanent water displacement, volcanoes, earth quakes, hot and cold cycles, etc….
There comes a point where we reach the end of a cycle when the earth is at the maximum internal pressure which exists at the quantum level of space, and it must let that pressure go. It reacts much like a spring that has been wound so tight that it finally let’s go. When this happens… particles which are attached to one another in long chains, expand rapidly which causes everything on the earth to expand just a bit; the greatest effect is in the waters of the earth.
Now, the sun is also under great pressure and when we reach the end of a cycle, the sun which has been compressed changing colors as it goes through the different pressure spectrums, expands rapidly. This effect, like the water of the earth, affects the sun in the same manner because of its molten nature. The visual effect is much more spectacular when the sun once again, regains homeostasis. However, we do not see it as it has passed into the next cycle hidden by a blanket of electrons. These huge electron conduits, separate one macro particle structure from another.
Scientists will learn and understand this in the next few years as they continue to put particles under extreme pressure in the laboratory but will understand much more when they discover how to get a frequency signal inside of an electron conduit. When they can overcome the pressure of what I call E. Space and get a frequency signal inside, they will then be able to map the structure of an atomic particle which works exactly the same way as our solar system. Eventually, they will also understand “other dimensional particles” and how they fit into the machine and why. | 0.850087 | 3.43116 |
You can visit Mars through robotic spacecraft and interactive websites:
It took 4 days for the Apollo astronauts to travel 400,000 km to the Moon, in 1969-72. The fastest a mission to travel the 56,000,000 km to Mars took 4 1/2 months when Mars was nearest Earth. Since Earth orbits the Sun once a year, and Mars orbits in about 1.88 earth years (687 days), Mars and Earth are near one another only once every 2 years and 3 months. Astronauts on Mars would have to return quickly or plan to stay 2 years. It would be a dangerous voyage for astronauts to make, but perhaps some day they will. Mars has water, and its surface is rich in oxygen. Some of the supplies needed for a long stay are already there.
Mars' Similarities to Earth
Mars is similar to Earth with hills, cliffs, dry waterways, rocks and boulders, but its surface is very old, with the oldest regions formed between 4.6 and 3.5 billion years ago. Also, a Martian day is about 24 1/2 hours, and the planet's axis tilts 25° compared to Earth's 23° tilt, giving Mars seasons, albeit very cold ones. While air temperature rarely gets above freezing, sunshine easily penetrates the thin atmosphere to warm the soil. Images sensitive to infrared light (heat) show the temperature of the surface at the winter polar caps drops to -143 °C (-225 °F), but in summer the warmest soil near the equator occasionally reaches +27 °C (+81 °F)! Solar heating on Mars would be a definite possibility.
View taken by Mars Spirit Rover
Data from soil samples on Mars is still coming in. Some samples suggest the soil is similar to what someone might find in their backyard, with magnesium and potassium chloride, and other soluble minerals necessary for life, and traces of water. However with a pH between 8 and 9 (very alkaline) only vegetables like asparagus would grow, ruling out strawberries. There is also indication that microbial life may be able to live quite happily meters down in the soil. But, other samples taken by the Phoenix Lander in 2008 show perchlorates in the soil that could make plant growth impossible. Although it is no longer operating, scientists are still analyzing its data. Mars Science Laboratory is being prepared for launch in December 2011, with arrival on Mars in August 2012. It will place the Curiosity rover in Gale crater to look for conditions and evidence for microbial life.
Atmosphere about 0.7% that of Earth
Aside from being farther from the Sun, the greatest difference is that Mars is half the diameter of Earth, therefore less massive, with a little more than a third the gravity. If you weigh 120 pounds on Earth you would weigh about 46 pounds on Mars. The lower gravity holds only a thin atmosphere (about 0.7% of Earth's atmosphere) that is mostly carbon dioxide (CO2). Astronauts would require a supply of oxygen and pressurized suits to survive. Since terraforming can not be expected as a near-term solution, habitable structures on Mars would need to be constructed with pressure vessels similar to spacecraft.
The atmosphere may provide some protection from solar and cosmic radiation , gamma rays, especially since there is dust and clouds of water ice in the atmosphere.
Mars has clouds and dunes
Clouds in motion
Mars is littered with rocks, some of which look like basalt as we saw on the Moon
Mars atmosphere is not dense enough to protect from meteorites. Mars landscape is littered with what appear to be meteorites or volcanic debris.
Mars has little magnetic field to divert charged solar wind particles of protons and electrons. These would need to be deflected by thick walls or magnetic fields around buildings and space craft.
Water on Mars !!!
Warm ground temperatures also enable water beneath the surface to melt, and liquid water springs gush from the sides of craters, as seen by Mars Global Surveyor.
Water gushes from the side of a crater in Centauri Montes
Layered rock revealed along edges of craters may have been deposited by dust storms, or by water, just as layered rock occurs in Kentucky where a shallow sea once came and receded.
Victoria Crater as seen by Opportunity Rover
The edge of Victoria Cra]]ter showing rock layers
At the rim of Victoria Crater in 2007, the Opportunity Rover found more evidence of water in the past. "Blueberries" made of hematite a mineral, colored black to steel or silver-gray, brown to reddish brown, or red. It is stronger but more brittle than pure iron. Grey hematite is typically found in places where there has been standing water or mineral hot springs, such as those in Yellowstone National Park in the United States. The mineral can precipitate out of water and collect in layers at the bottom of a lake, spring, or other standing water.
Hematite from Michigan
Hematite "Blueberries" and "Razor Backs" in the bottom of Endurance Crater
Credit: Mars Exploration Rover Mission, JPL, NASA
Opportunity had seen Blueberries before, on the slopes and in the bottom of Endurance Crater in 2004. Also seen in this image it sent home are "Razor backs". These are hard minerals that are thought to have formed in cracks of surrounding softer rocks that have since eroded away, either by dust storms or water.
Opportunity started its exploration of Mars from its landing site in a small crater, then went to "stadium-sized" Endurance Crater, followed by the larger Victoria Crater which is about a km across (0.6 mi). It climbed out of Victoria in September 2008, and is making its way slowly toward Endeavor Crater, 12 km away and 22 km across (14 mi). The trip is expected to take several more monts, since it only moves 110 yards a day! Meanwhile, its twin, the little lame Spirit Rover with one bad wheel, is silent on the other side of Mars, where she explored a flat area called "Home Plate." Spirit became stuck when a wheel broke through the surface. Nature Magazine has wrote an obituary for her in January 2010. Both rovers run on solar power, and an accumulation of dust on their panels is so thick that only 25% of the sunlight reaching them gets through to make electricity. They are now programmed to take a deep sleep, and minimize power use, when not driving.
Eureka ! ("I found it", first quoted by Archimedes as he ran out of his bath when he realized how he might prove if the king's crown was made of pure gold. Archimedes then took to the streets naked, so excited by his discovery that he had forgotten to dress, crying "Eureka!" (Greek: "εὕρηκα!," meaning "I have found it!")) The most convincing evidence for water was when Phoenix Lander dug up soil, which when warmed gave off water vapor.
The low atmospheric pressure does not allow water to form on the surface. Water ice appears to be in the soil, and there are indications that beneath the CO2 ice (dry ice) polar caps is enough water ice H20, that if melted could cover the planet. Red hematite, which may form in the presence of water, is responsible for the reddish color of the soil everywhere on Mars. Perhaps some day we shall learn if Mars was once covered by a shallow sea.
North Pole on Mars is covered with both water ice and dry (carbon dioxide) ice as seen by Mars Global Surveyor
Since Titan (a Moon of Saturn which is smaller than Mars) has a thick atmosphere, this suggests Mars once had a thicker atmosphere, that could have held onto liquid water. But if it did, it has mysteriously disappeared. Some say the carbon dioxide from the atmosphere has combined with and become trapped within carbonate rocks. On Earth, carbonate rocks release their CO2 due to weathering and plate tectonics. Oxygen from the atmosphere could also have become iron oxides, such as hemitite Fe2O3.
Although it is smaller than Mars, Saturn's Moon, Titan, has a dense atmosphere while Mars has little. This suggests Mars could once have had more air surrounding it, although colder temperatures on Titan help hold its heavy atmosphere.
As well as being similar to Earth, with hills and dales, Mars has the deepest canyons, 5,000 km (3,000 miles) long, and many times the length and depth of the Grand Canyon on Earth. This canyon, discovered by Mariner 9 in 1971, is thought to be caused by subsidence, much like the Great Rift Valley on Earth. You can take a video tour of Valles Marineris courtesy of JPL's visualization team.
ESA Image of part of Mars' Valles Marineris Canyon, so long it would reach from New York to California.
The extinct volcano, Olympus Mons, higher than any mountain in the solar system, is three times the height of Mt Everest. Erosion along the sides of Olympus Mons are thought to be wind erosion, or perhaps Olympus Mons was once a volcanic island like the Hawaiian Islands on Earth.
Olympus Mons simulation from data
Sunset on Mars is unlike that on earth. The sky near the Sun is bluish, and the Sun is about half as wide as it appears from Earth.
Mars sunset in true colors
Now you are ready for a trip to Mars.
Size and distance of Mars' moons Phobos and Deimos
Mars' moons, Phobos and Deimos, appear to be captured asteroids. Phobos is tiny, about 1 / 140 th the size of our Moon, but so close to Mars it appears 1/3rd as wide as our Moon as it crosses the Martian night sky in about 4 hours. Phobos is closer to its planet than any other moon. Some day it will either impact Mars or break up and become a ring of debris.
Deimos is so small and distant, it can barely be seen. It's orbit is nearly circular and may be used to determine the mass of Mars.
Mars' moons Phobos and Deimos | 0.846175 | 3.610562 |
I was introduced to Interstellar by one of my physics teachers who, to say the least, was not impressed by the film. I watched the whole thing to get a better idea of how awful this film is (from an astronomer’s standpoint).
There were so many weird physics-breaking moments, such as zooming past galaxies as though they were a metre away, and inventing a highly selective (and creative) version of Newton’s 3rd Law. But there were three plot holes which just…
…they just hurt.
The Mass of a Wormhole
So we’ve established that aliens have opened a wormhole by Saturn. How this came about, don’t ask me!
Now bear in mind that a wormhole is theoretically just a very special black hole, and there is no-one stopping me from using Schwarzschild solutions to model this wormhole!
As we currently live in a mass-dominated universe, the smallest of new black holes created in the universe are about 5 times more massive than the Sun.
So, you know, I wouldn’t expect the solar system to still exist if something with FIVE TIMES MORE GRAVITATIONAL FORCE THAN THE SUN were just dropped into the middle of it! Did the writers not think about poor Saturn?
To clarify, I’ve added the before and after pictures of if a wormhole were really put into the solar system:
Out of astronomy and into fluid dynamics
A quick hydrodynamics lesson: the maximum height a wave can be is twice the depth of the body of water it’s in. If a lake is 1 m deep, the biggest natural wave that can occur is 2 m.
Estimate the depth of this water (taken from the film):
Now compare that to the wave that followed after.
We’re done here.
Newton’s (revised) Third Law
Life tip: If you are trying to escape a black hole (and are near the event horizon), you need an extremely high relativistic velocity. If you wanted to apply Newton’s Third law (for every action there is an equal and opposite reaction) on an object to escape, you would need to apply a lot of force in order to achieve sufficient velocity.
Escape velocity can easily be determined using v = √(2GM/r). For a black hole, M is huge, thus v is also huge.
So my question to you is…
Will simply detaching empty fuel tanks help you achieve relativistic speeds?
No. In interstellar, it does!
Let’s not forget Cooper’s (emotional) version of Newton’s Third Law:
“You have to leave something behind to go forward”
I know I’m a few years late, but boy I was mad! Let me know any film fails that bug you, because I know Interstellar isn’t the only one that needs a good beating!
OK. Rant over. Have a great weekend! | 0.862134 | 3.614164 |
In September 2018 astronomers announced the discovery of an exoplanet with 8.47 times Earth’s mass and twice Earth’s radius in the 40-Eridani star system, distant 17 light-years from our Sun. In the Star Trek universe, the Eridani constellation is mentioned as the star system where the planet Vulcan is located, homeworld of Commander Spock. In the episode “Amok Time”, first aired on September 15, 1967, the Enterprise visits the planet. As it orbits its sun on a very narrow orbit, surface temperatures are higher as on Earth. Also, the atmosphere is very thin, barely breathable, and non-Vulcans have a hard time adapting to the harsh environment. According to Star Trek lore, the desert-planet Vulcan orbits its sun together with the planet T´Khut, a geologically very active lava-planet.
In the movie Star Trek 2, released in 1982, the star 40-Eridani-A is mentioned as Vulcan’s sun. In 1991, Gene Roddenberry, creator of Star Trek, published a short article together with astrophysicists Baliunas, Donahue and Nassiopoulos, arguing that the constellation of Eridani would be the most fitting place for Spock’s homeworld.
The 40-Eridani system is a triple star system, with Eridani-A as primary star accompanied by a red and a white dwarf star, named respectively Eridani-B and Eridiani-C. Only Eridani-A is stable enough to host a hypothetical habitable planet. Eridani-B emits too much dangerous radiation and Eridani-C is prone to flares, sudden eruptions of energy and matter. As Eridani-A is smaller than our Sun, also the habitable zone, where a planet could exist with liquid water, is narrower. Unlike the fictional planet Vulcan, the real exoplanet seems to be a Super-Earth or a small gas giant. According to the published preliminary results, the planet orbits its star in just 39 to 40 Earth days, along the inner limit of the habitable zone.
Famously Commander Spock is the science officer aboard the Enterprise, including some notions on geology.
In the episode “The Apple”, Spock immediately notes the lush vegetation of the planet Gamma Trianguli VI. He correctly deduces that soil-nutrients (and therefore geology) plays a role in supporting this peculiar paradise-like world. With his sharp geological eye Spock identifies also hornblende and quartz in a collected rock. | 0.855391 | 3.277861 |
More than 93% of the mass in our body, and to a greater extent of everything we see on Earth, is stardust produced inside the cores of previous generations of stars; hydrogen molecular clouds collapse to form stars that through nuclear fusion convert the primordial hydrogen to heavier elements. These elements subsequently enrich the interstellar medium of the galaxies through super nova explosions and stellar winds. This process of star formation started soon after the Big Bang and continues to take place in the present day.
Today galaxies form stars at a rather leisurely pace. For example our Galaxy, and the majority of star forming galaxies in the local Universe, undergo a moderate star formation of approximately 2-3 stars per year. These “normal” galaxies are characterized by long lasting and smooth star formation episodes, converting gas into stars in a steady, gentle fashion. However, occasional interactions between massive galaxies, or mergers, trigger violent and short lived starburst events, that enhance the efficiency of the galaxies to convert gas into stars by a factor of 100.Such events though are known to be extremely rare in the current cosmic epoch.
But what about the past? Recent observations have revealed that our universe was about 50 times more active in the past and that the most of the stars in the universe were formed approximately ten billion years ago. There is also compelling evidence that the bulk of these stars were formed in massive galaxies that experienced high rates of star formation. Was the star-formation in these galaxies mainly driven by smooth cold gas accretion, similar to what we see in the majority of near-by star-forming galaxies, or rather by short-lived starburst events triggered by galaxy mergers? Is there a universal star-formation law that governs the efficiency at which galaxies form stars? What are the physical processes that shaped the evolution of the star formation activity in the galaxies over the last 10 billion years?
Key answers to these questions are hidden in the interstellar medium of the galaxies, which is mainly made of gas and dust. The molecular gas, i.e. the material from which stars are formed, and the dust, which is the product of previous generations of stars, determine the evolution of a galaxy and reflect its current and past star-formation events. By exploiting new data and by developing new techniques, I pursue a concurrent study of the molecular gas and dust in distant star-forming galaxies. By measuring the gas mass reservoirs, the star formation rates, the morphology and the dynamical state of galaxies at various epochs of the universe I aim to ``paint'' the picture of star-formation activity through cosmic time and provide a coherent view of the processes that shaped galaxy evolution.
My research combines the discovery and the study of the most remote galaxies in our Universe, robust mathematical modeling and the development of new computational and statistical techniques. My work, aside of enhancing our understanding of the universe and addressing questions that are interlinked to the human nature, also pushes the current instrumentation to its limits and guides the development of future astronomical facilities, paving the path for major advances in industry and technology.
They say that for great discoveries we need to be prepared for the unexpected. But first we need to engage with the unknown, and this is a key aspect of my research. | 0.802837 | 4.15824 |
NASA's Fermi finds youngest millisecond pulsar, 100 pulsars to date
An international team of scientists using NASA's Fermi Gamma-ray Space Telescope has discovered a surprisingly powerful millisecond pulsar that challenges existing theories about how these objects form.
At the same time, another team has located nine new gamma-ray pulsars in Fermi data, using improved analytical techniques.
A pulsar is a type of neutron star that emits electromagnetic energy at periodic intervals. A neutron star is the closest thing to a black hole that astronomers can observe directly, crushing half a million times more mass than Earth into a sphere no larger than a city. This matter is so compressed that even a teaspoonful weighs as much as Mount Everest.
"With this new batch of pulsars, Fermi now has detected more than 100, which is an exciting milestone when you consider that, before Fermi's launch in 2008, only seven of them were known to emit gamma rays," said Pablo Saz Parkinson, an astrophysicist at the Santa Cruz Institute for Particle Physics at the University of California Santa Cruz, and a co-author on two papers detailing the findings.
One group of pulsars combines incredible density with extreme rotation. The fastest of these so-called millisecond pulsars whirls at 43,000 revolutions per minute.
Millisecond pulsars are thought to achieve such speeds because they are gravitationally bound in binary systems with normal stars. During part of their stellar lives, gas flows from the normal star to the pulsar. Over time, the impact of this falling gas gradually spins up the pulsar's rotation.
The strong magnetic fields and rapid rotation of pulsars cause them to emit powerful beams of energy, from radio waves to gamma rays. Because the star is transferring rotational energy to the pulsar, the pulsar's spin eventually slows as the star loses matter.
Typically, millisecond pulsars are around a billion years old. However, in the Nov. 3 issue of Science, the Fermi team reveals a bright, energetic millisecond pulsar only 25 million years old.
The object, named PSR J1823−3021A, lies within NGC 6624, a spherical collection of ancient stars called a globular cluster, one of about 160 similar objects that orbit our galaxy. The cluster is about 10 billion years old and lies about 27,000 light-years away toward the constellation Sagittarius.
Fermi's Large Area Telescope (LAT) showed that eleven globular clusters emit gamma rays, the cumulative emission of dozens of millisecond pulsars too faint for even Fermi to detect individually. But that's not the case for NGC 6624.
"It's amazing that all of the gamma rays we see from this cluster are coming from a single object. It must have formed recently based on how rapidly it's emitting energy. It's a bit like finding a screaming baby in a quiet retirement home," said Paulo Freire, the study's lead author, at the Max Planck Institute for Radio Astronomy in Bonn, Germany.
Despite its sensitivity, Fermi's LAT may detect only one gamma ray for every 100,000 rotations of some of these faint pulsars. Yet new analysis techniques applied to the precise position and arrival time of photons collected by the LAT since 2008 were able to identify them.
"We adapted methods originally devised for studying gravitational waves to the problem of finding gamma-ray pulsars, and we were quickly rewarded," said Bruce Allen, director of the Max Planck Institute for Gravitational Physics in Hannover, Germany. Allen co-authored a paper on the discoveries that was published online today in The Astrophysical Journal.
Allen also directs the Einstein@Home project, a distributed computing effort that uses downtime on computers of volunteers to process astronomical data. In July, the project extended the search for gamma-ray pulsars to the general public by including Femi LAT data in the work processed by Einstein@Home users. | 0.830785 | 3.912268 |
New research on the TRAPPIST-1 system shows that the seven-planet system is between 5.4 and 9.8 billion years old, suggesting that it could be over twice as old as our Solar System. The age of the system is very important to understanding its habitability, as this a strong indication to the amount of radiation being released from its star. It can also tell us about the past, as it could reveal how much radiation it has already endured.
When the system was first announced in February 2017, scientists believed the system was at least 500 million years old. As this is the time taken for stars of such low mass – in this case, eight per cent the mass of the Sun – to contract to its current size. However there was not a known upper limit, as in theory, the system could be as old as the universe, which is 13.7 billion years old. So by understanding the age of this system, the conditions on the seven planets become clearer and more intriguing.
“Our results really help constrain the evolution of the TRAPPIST-1 system, because it has to have persisted for billions of years. This means the planets had to evolve together, otherwise the system would have fallen apart long ago,” says Adam Burgasser, an astronomer at the University of California, San Diego. Burgasser teamed up with Eric Mamajek, the deputy program scientist for NASA’s Exoplanet Exploration Program based at NASA’s Jet Propulsion Laboratory (JPL), California, United States, to calculate TRAPPIST-1’s age.
There are many factors to take into account when considering how a star’s radiation affects a planet’s habitability. For instead, Burgasser and Mamajek confirmed that TRAPPIST-1’s radiation is relatively quiet compared to other ultra-cool dwarf stars. When you also include its old age, its radiation was most likely much less intense then it’s early years. But still, the planets sit extremely close to the star, which would mean the seven Earth-sized planets have been absorbing high-energy radiation for several billions of years. This could strip away the atmosphere and evaporate the liquid water, causing a similar environment to Mars.
On the contrary, the radiation is not as intense, and also the densities of TRAPPIST-1’s planets are lower than Earth. This could lead to the complex molecules within the planet evaporating into a thick atmosphere, which could trap large amounts of heat, creating a harsh environment comparable to Venus. As Burgasser explains, “If there is life on these planets, I would speculate that it has to be hardy life, because it has to be able to survive some potentially dire scenarios for billions of years.”
In terms of lifespan, the TRAPPIST-1 star could stick around for a long time. In fact, it could last longer than then current age of the universe, which is 13.7 billion years old. The life of a Sun-sized star is roughly 10 billion years, larger stars have shorter lives because they tend to use their fuel faster than dwarf stars. “Stars much more massive than the Sun consume their fuel quickly, brightening over millions of years and exploding as supernovae,” Mamajek says. “But TRAPPIST-1 is like a slow-burning candle that will shine for about 900 times longer than the current age of the universe.”
The TRAPPIST-1 system is becoming a clearer picture with each set of research results. Future observations with NASA’s Hubble Space Telescope and James Webb Space Telescope will analyse the atmospheres of the planets, and how similar they are to Earth’s.
Keep up to date with the latest space news in All About Space – available every month for just £4.99. Alternatively you can subscribe here for a fraction of the price! | 0.801262 | 3.988915 |
Astronomers have found a supermassive black hole (SMBH) with an unusually regular feeding schedule.
The behemoth is an active galactic nucleus (AGN) at the heart of the Seyfert 2 galaxy GSN 069. The AGN is about 250 million light years from Earth, and contains about 400,000 times the mass of the Sun.
The team of astronomers used the ESA’s XMM-Newton and NASA’s Chandra X-ray Observatory to observe the x-ray emissions of the SMBH. About every 9 hours, the black hole flares brightly with x-rays as material is drawn into it.
Astronomers have found two other stellar mass black holes that flare regularly as they feed, but this kind of regularity in a supermassive black hole has never been seen before.
The paper outlining this discovery is published in Nature and is titled “Nine-hour X-ray quasi-periodic eruptions from a low-mass black hole galactic nucleus.”
Lead author is Giovanni Miniutti from the ESA’s Center for Astrobiology in Spain.
According to the paper, the SMBH consumes about four Moons worth of material three times every day. That means every time the black hole feeds, it consumes about a million billion billion pounds of material.
“This black hole is on a meal plan like we’ve never seen before,” said Miniutti in a press release.
“This behavior is so unprecedented that we had to coin a new expression to describe it: “X-ray Quasi-Periodic Eruptions”.”
X-ray emissions from this SMBH have been known and observed since July 2010, but they were steady. The new paper is based on 54 days of observations beginning in December 2018, beginning with the ESA’s XMM-Newton Observatory.
That observatory spotted two bursts on December 24th. In January, XMM-Newton found three more of these regular bursts.
Then astronomers requested more observing time with NASA’s Chandra Observatory to investigate. Chandra observed five more of these events.
During the current regular eruptions, the X-ray flaring activity increases by two orders of magnitude over the background X-ray emissions. Each flare lasts just over one hour and occurs every nine hours.
“By combining data from these two X-ray observatories, we have tracked these periodic outbursts for at least 54 days” said co-author Richard Saxton of the European Space Astronomy Centre in Madrid, Spain.
“This gives us a unique opportunity to witness the flow of matter into a supermassive black hole repeatedly speeding up and slowing down.”
During each of these outbursts, the X-ray flaring is 20 times brighter than during quiet periods. The temperature of the in-falling gas also rises. It rises from about 1 million degrees Fahrenheit in quieter periods to 2.5 million degrees Fahrenheit during flares. The higher temperature is about the same as the temperature of gas around most SMBHs that are actively growing.
The cause of these regular flares is unknown. The hot 2.5 million degree F. gas surrounding GSN 069 is the same temperature as gas surrounding other SMBHs. It’s a mystery because it’s simply too hot to be from the in-falling disc of material that surrounds black holes. But GSN 069 is a unique opportunity to study the phenomenon because the hot gas repeatedly forms then disappears.
Normally, this hot gas is caused by a star being torn apart and consumed by a black hole, or so astronomers think. But the regularity exhibited by GSN 069 is a mystery.
“We think the origin of the X-ray emission is a star that the black hole has partially or completely torn apart and is slowly consuming bit by bit,” said co-author Margherita Giustini, also of ESA’s Center for Astrobiology.
“But as for the repeating bursts, this is a completely different story whose origin needs to be studied with further data and new theoretical models.”
Again, seeing a supermassive black hole consume gas from a star is nothing new. It’s the regularity of GSN 069’s flaring that is the head-scratcher. The authors of the study suggest two possible explanations for the the SMBH’s regular feeding schedule:
- The amount of energy in the disk builds up until it becomes unstable and matter rapidly falls into the black hole producing the bursts. That cycle is repeating.
- There’s an interaction between the disk and a secondary body orbiting the black hole, perhaps the remnant of the partially disrupted star.
Thanks to the Chandra observations, the team of scientists knows that the source of the flaring X-rays is right in the heart of GSN 069. That’s where a SMBH is expected to be.
The combined data from Chandra and XMM-Newton also clearly show that the flaring, though regular, is slowly changing: both the size and the duration of the black hole’s ‘meals’ have decreased slightly, and the space between each meal is growing. It’s up to future observations to see if these trends continue.
GSN 069 is on the small side for an SMBH. Usually, an SMBH contains as much mass as several million or even several billion Suns, while GSN 069 contains only about 400,000 Suns worth of mass. That could help explain why this type of regular feeding hasn’t been seen before.
For larger SMBHs, much larger than this one, their brightness fluctuations are a lot slower. Rather than erupting every nine hours, it should take them months or even years to flare like this. That would explain why quasi-periodic eruptions (QPEs) like these haven’t been observed. X-Ray observatories are busy, and there’s no way to train one on a single target for that long.
There’ve been several cases where large increases or decreases in X-rays produced by black holes have been observed. Those observations relied on repeated observations over months, or even years.
Some of those changes are too fast to be explained by the standard theory of in-falling matter from a black hole’s accretion disk. But this discovery could explain those observations. They may be experiencing similar behavior as GSN 069. | 0.801428 | 3.928344 |
46 relations: Alpha Herculis, American Association of Variable Star Observers, Apparent magnitude, Asymptotic giant branch, Beta Gruis, Betelgeuse, Carbon star, Centre de données astronomiques de Strasbourg, Cepheid variable, Day, Eta Geminorum, General Catalogue of Variable Stars, Gravitational microlensing, HD 3346, Hypergiant, International Astronomical Union, L2 Puppis, Large Magellanic Cloud, Light curve, List of semiregular variable stars, Long-period variable star, Low-dimensional chaos in stellar pulsations, Mira variable, Mu Cephei, Normal mode, Omicron1 Centauri, Optical Gravitational Lensing Experiment, Overtone, Pi1 Gruis, Red giant, Rho Cassiopeiae, Rho Persei, RR Coronae Borealis, RV Tauri variable, RW Cygni, S Vulpeculae, S-type star, Sigma Librae, Slow irregular variable, Stellar classification, Supergiant star, T Centauri, UU Aurigae, V509 Cassiopeiae, Variable star designation, 15 Arietis.
Since its founding in 1911, the American Association of Variable Star Observers (AAVSO) has coordinated, collected, evaluated, analyzed, published, and archived variable star observations made largely by amateur astronomers and makes the records available to professional astronomers, researchers, and educators.
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 asymptotic giant branch (AGB) is a region of the Hertzsprung–Russell diagram populated by evolved cool luminous stars.
Beta Gruis (β Gruis, abbreviated Bet Gru, β Gru), also named Tiaki, is the second brightest star in the southern constellation of Grus.
Betelgeuse, also designated Alpha Orionis (α Orionis, abbreviated Alpha Ori, α Ori), is the ninth-brightest star in the night sky and second-brightest in the constellation of Orion.
A carbon star is typically an asymptotic giant branch star, a luminous red giant, whose atmosphere contains more carbon than oxygen; the two elements combine in the upper layers of the star, forming carbon monoxide, which consumes all the oxygen in the atmosphere, leaving carbon atoms free to form other carbon compounds, giving the star a "sooty" atmosphere and a strikingly ruby red appearance.
The Centre de Données astronomiques de Strasbourg (CDS; English translation: Strasbourg Astronomical Data Center) is a data hub which collects and distributes astronomical information.
A Cepheid variable is a type of star that pulsates radially, varying in both diameter and temperature and producing changes in brightness with a well-defined stable period and amplitude.
A day, a unit of time, is approximately the period of time during which the Earth completes one rotation with respect to the Sun (solar day).
Eta Geminorum (η Geminorum, abbreviated Eta Gem, η Gem), also named Propus, is a triple star system in the constellation of Gemini.
The General Catalogue of Variable Stars (GCVS) is a list of variable stars.
Gravitational microlensing is an astronomical phenomenon due to the gravitational lens effect.
HD 3346, also known as V428 Andromedae, is an orange giant star approximately 620 light-years away in the constellation of Andromeda.
A hypergiant (luminosity class 0 or Ia+) is among the very rare kinds of stars that typically show tremendous luminosities and very high rates of mass loss by stellar winds.
The International Astronomical Union (IAU; Union astronomique internationale, UAI) is an international association of professional astronomers, at the PhD level and beyond, active in professional research and education in astronomy.
L2 Puppis (also known as HD 56096) is a giant star in the constellation of Puppis and is located between the bright stars Canopus and Sirius.
The Large Magellanic Cloud (LMC) is a satellite galaxy of the Milky Way.
In astronomy, a light curve is a graph of light intensity of a celestial object or region, as a function of time.
This is a list of semiregular variable stars.
The descriptive term long-period variable star refers to various groups of cool luminous pulsating variable stars.
Low-dimensional chaos in stellar pulsations is the current interpretation of an established phenomenon.
Mira variables ("Mira", Latin, adj. - feminine form of adjective "wonderful"), named for the prototype star Mira, are a class of pulsating variable stars characterized by very red colours, pulsation periods longer than 100 days, and amplitudes greater than one magnitude in infrared and 2.5 magnitude at visual wavelengths.
Mu Cephei (μ Cep, μ Cephei), also known as Herschel's Garnet Star, is a red supergiant star in the constellation Cepheus.
A normal mode of an oscillating system is a pattern of motion in which all parts of the system move sinusoidally with the same frequency and with a fixed phase relation.
Omicron1 Centauri (ο1 Cen, ο1 Centauri) is a star in the constellation Centaurus.
The Optical Gravitational Lensing Experiment (OGLE) is a Polish astronomical project based at the University of Warsaw that runs a long-term variability sky survey (1992-present).
An overtone is any frequency greater than the fundamental frequency of a sound.
π1 Gruis (Pi1 Gruis) is a semiregular variable star in the constellation Grus around 530 light-years from Earth.
A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses) in a late phase of stellar evolution.
Rho Cassiopeiae (ρ Cas, ρ Cassiopeiae) is a yellow hypergiant star in the constellation Cassiopeia.
Rho Persei (Rho Per, ρ Persei, ρ Per) is a star in the northern constellation of Perseus.
RR Coronae Borealis (RR CrB, HD 140297, HIP 76844) is a M3-type semiregular variable star located in the constellation Corona Borealis with a parallax of 2.93mas being a distance of.
RV Tauri variables are luminous variable stars that have distinctive light variations with alternating deep and shallow minima.
RW Cygni is a semiregular variable star in the constellation Cygnus, about a degree east of 2nd magnitude γ Cygni.
S Vulpeculae is a star located in the constellation Vulpecula.
An S-type star (or just S star) is a cool giant with approximately equal quantities of carbon and oxygen in its atmosphere.
Sigma Librae (σ Librae, abbreviated Sig Lib, σ Lib) is a binary star in the constellation of Libra.
A slow irregular variable (ascribed the GCVS types L, LB and LC) is a variable star that exhibit no or very poorly defined periodicity in their slowly changing light emissions.
In astronomy, stellar classification is the classification of stars based on their spectral characteristics.
Supergiants are among the most massive and most luminous stars.
T Centauri is a variable star located in the far southern constellation Centaurus.
UU Aurigae is a carbon star and binary star in the constellation Auriga.
V509 Cassiopeiae (V509 Cas or HR 8752) is one of two yellow hypergiant stars found in the constellation Cassiopeia, which also contains Rho Cassiopeiae.
Variable stars are designated using a variation on the Bayer designation format of an identifying label (as described below) combined with the Latin genitive of the name of the constellation in which the star lies.
15 Arietis (abbreviated 15 Ari) is a single variable star in the northern constellation of Aries.
Mu Cephei variable, SR Variable, SR variable, SRA variable, SRB variable, SRC variable, SRD variable, Semi-regular variable, Semi-regular variable star, Semiregular variable, Semiregular variable stars, Semiregular variables, UU Herculis variable. | 0.836256 | 3.840616 |
- Eccentricity of Orbit: measures the ellipticity of orbit (ranges 0-1, with 0 as spherical and 1 as very elliptical)
- Density: mass per unit volume; mass in grams and volume in cubic centimeters
- Oblateness: measures how much the middle section of the planet bulges
- Surface Gravity: the larger the surface gravity, the thicker the atmosphere as gravity pulls in more gases
- Albedo: measures the fraction of light reflected compared to the amount of light received from the Sun; the higher the albedo, the more reflective the surface
- Escape Velocity: minimum speed or velocity needed to escape the planet’s gravitational pull
- Rotation: most planets rotate in counter-clockwise direction (prograde); others rotate in the clockwise direction (retrograde)
- Rotational period is shortest for gaseous planets and longest for Venus
- Roche Limit: about two and a half times the radius of the planet; within the Roche Limit, matter cannot accretes to form moons because the tidal force of the planet tears matter apart to form rings
Giant Planets: Giant planets have lighter elements such as hydrogen and helium in their atmospheres. They have stronger gravity and are at larger distances from the Sun. Jupiter, Saturn, and Neptune are stormy with great spots of lasting storms and belts and zones. However, Uranus is comparatively bland and uniform. All giant planets are home to convection, or hot gases rising and cold gases falling.
Terrestrial Planets: Terrestrial planets have heavier elements such as carbon, oxygen, and nitrogen. Mercury is most heavily cratered while Earth is least cratered. Larger terrestrial planets have plate tectonics. Earth has a sizable magnetic fields that can protect it from solar wind particles and Van Allen Belts. Earth has the “Goldilocks phenomenon,” or the right conditions for the development of life. | 0.864941 | 3.439851 |
A family portrait of the PH1 planetary system: The newly discovered planet is depicted in this artist’s rendition transiting the larger of the two eclipsing stars it orbits. Off in the distance, well beyond the planet orbit, resides a second pair of stars bound to the planetary system. Image Credit: Haven Giguere/Yale.
A planet has been discovered orbiting in a four-star system — and no, that doesn’t mean the accommodations and conditions are excellent. It literally means four stars, where a planet is orbiting a binary star system that in turn is orbited by a second distant pair of stars. This is the first system like this that has ever been found, and its discovery demonstrates the power of citizen scientists, as it was found by a joint effort of amateurs participating on the Planet Hunters website under the guidance of professional astronomers.
This is might be an extremely rare planetary setup, astronomer Meg Schwamb from Yale says, as only six planets are currently known to orbit two stars, and none of these are orbited by other stellar companions. Astronomers are calling the newly found world a ‘circumbinary’ planet.
“Circumbinary planets are the extremes of planet formation,” said Schwamb, Planet Hunters scientist and lead author of a paper about the system presented Oct. 15 at the annual meeting of the Division for Planetary Sciences of the American Astronomical Society in Reno, Nevada. “The discovery of these systems is forcing us to go back to the drawing board to understand how such planets can assemble and evolve in these dynamically challenging environments.”
The planet is called PH1, for the first confirmed planet identified by the Planet Hunters citizen scientists, but it has the nickname of Tatooine, the planet in Star Wars that orbited two suns.
Planet Hunters uses data from the Kepler spacecraft, specially designed for looking for signs of planets.
The volunteers, Kian Jek of San Francisco and Robert Gagliano of Cottonwood, Arizona, spotted faint dips in light caused by the planet as it passed in front of its parent stars, a common method of finding extrasolar planets. Schwamb, a Yale postdoctoral researcher, led the team of professional astronomers that confirmed the discovery and characterized the planet, following observations from the Keck telescopes on Mauna Kea, Hawaii. PH1 is a gas giant with a radius about 6.2 times that of Earth, making it a bit bigger than Neptune.
“Planet Hunters is a symbiotic project, pairing the discovery power of the people with follow-up by a team of astronomers,” said Debra Fischer, a professor of astronomy at Yale and planet expert who helped launch Planet Hunters in 2010. “This unique system might have been entirely missed if not for the sharp eyes of the public.”
PH1 orbits outside the 20-day orbit of a pair of eclipsing stars that are 1.5 and 0.41 times the mass of the Sun. This planet is dense — it has perhaps about 170 times more mass than Earth — and is about half the diameter of Jupiter. It revolves around its host stars roughly every 138 days. Beyond the planet’s orbit at about 1000 AU (roughly 1000 times the distance between Earth and the Sun) is a second pair of stars orbiting the planetary system.
Gagliano, one of the two citizen scientists involved in the discovery, said he was “absolutely ecstatic to spot a small dip in the eclipsing binary star’s light curve from the Kepler telescope, the signature of a potential new circumbinary planet, ‘Tatooine,’ and it’s a great honor to be a Planet Hunter, citizen scientist, and work hand in hand with professional astronomers, making a real contribution to science.”
Jek expressed wonder at the possibility of the discovery: “It still continues to astonish me how we can detect, let alone glean so much information, about another planet thousands of light years away just by studying the light from its parent star.”
Source: Planet Hunters | 0.908033 | 3.645381 |
On a planet far, far away, it’s cloudy with a chance of iron rain
CAPE CANAVERAL, FLORIDA – On one faraway world, it is always cloudy with a chance of iron rain, according to Swiss and other European astronomers who have detected clouds full of iron droplets at a hot Jupiter-like planet 390 light-years away.
This planet is so hot on the sunny side — 4,350 degrees Fahrenheit (2,400 degrees Celsius) — that iron vaporizes in the atmosphere. The iron likely condenses on the cooler night side of the planet, almost certainly turning into rain.
“Like droplets of metal falling from the sky,” said Christophe Lovis of the University of Geneva who took part in the study.
The iron rain would be extremely dense and pack a pretty good punch, according to the research team whose study appears Wednesday in the journal Nature.
“It’s like in the heavy steel industry on Earth where they melt iron, and so you see this melting, flowing metal. That’s pretty much what we are talking about here,” Lovis said.
Discovered just a few years ago, the planet designated Wasp-76b is nearly twice the size of Jupiter, the largest in our solar system, yet takes less than two days to orbit its star. Because the planet’s rotation matches the time it takes to complete one orbit, the same side always faces the star.
So it is always daytime on the star-facing side, with clear skies. And it is always nighttime on the night side, where temperatures fall to about 2,700 degrees Fahrenheit (1,500 degrees Celsius) and the sky is continually overcast with iron rain, according to the researchers.
Strong wind — gusting at more than 11,000 mph (18,000 kph) — constantly sweeps some of the vaporized iron from the day to night side of the planet. Inside the day-to-night transition zone, clouds appear to form as temperatures begin to drop.
“Surprisingly, however, we do not see the iron vapor in the morning” as night transitions back into day, lead scientist David Ehrenreich of the University of Geneva said in a statement.
The astronomers concluded the most likely explanation is that it rains iron on the night side.
Ehrenreich and his team studied Wasp-76b and its extreme climate using a new instrument on the European Southern Observatory’s Very Large Telescope in Chile.
While vaporized iron previously has been detected at an even hotter, more distant Jupiterlike world, it is believed to remain in a gaseous state around that entire planet, Lovis said. At Wasp-76b, this is the first time iron condensation has been seen, he said.
There is no telling whether it is a steady drizzle or downpour, or what else might be raining down besides iron.
In a fun poster designed by Swiss graphic novelist Frederik Peeters for the research team, a dancing astronaut holds up an umbrella in front of an orange waterfall-like deluge.
“Singin’ in the Iron Rain,” the poster reads. “An evening on WASP-76B.” | 0.845004 | 3.666186 |
Tomorrow evening marks the peak of the Geminid meteor shower, which is one of the most anticipated sky shows of the year. Unfortunately, tonight’s full moon (and subsequently, tomorrow’s big and bright waning gibbous) will make all but the most stunning shooting stars a bit more challenging to peep. Despite the moonlight, scientists are expecting around 20-30 visible meteors per hour; and the peak usually lasts a few days, so still make sure you take some time to look up this weekend.
The Geminid meteor shower is nearly 200 years old according to records. The first recorded observation was in 1833 from a riverboat on the Mississippi River, and its fiery presence only continues to get stronger as the years burn on. This is said to be because Jupiter’s jumbo gravity has pulled the stream of particles from the shower’s source, the asteroid 3200 Phaethon, closer to Earth over the centuries.
3200 Phaethon is an Apollo asteroid with an orbit that brings it closer to the Sun than any other titled asteroid. Because of this, it was named after the Greek myth of Phaëthon, son of the sun god Helios. It was the first asteroid to be discovered using images from a spacecraft in 1983 (the year I was born!). Fun Fact: Phaethon is actually categorized as a potentially hazardous asteroid, or PHA, due to its size (3.6 miles/5.8 kilometers in diameter) and Earth minimum orbit intersection distance; however, there is no near-term threat of impact on the horizon.
The Geminids, as their name implies, appear to emanate from the constellation of Gemini, The Twins. To find Gemini in the Northern Hemisphere, locate the constellation Orion in the southwestern sky (remember: three bright stars in the hunter’s belt) and then look up high and to the left. In the Southern Hemisphere, Gemini appears to the lower right of Orion in the northwestern sky. Why not pick up some meteorite jewelry for the occasion?
Happy stargazing, friends! | 0.835099 | 3.313498 |
Graham Hancock says that enough studies have been done at this point for him to conclude that a series of cometary impacts that occurred between 11,600-12,800 years ago were the cause of a mass extinction event. In the work of Hancock and others, including Dr. Victor Clube, retired Dean of the Astrophysics Department at Oxford and former astronomer at the Royal Observatory, as well as Dr. Richard Firestone of the Lawrence Berkeley National Laboratory, in California.
These and others believe that the collapse of several Bronze Age civilizations in the Fertile Crescent was caused by meteoric impacts from the breakup of a larger body that is today known as Comet Encke and its accompanying Taurid complex, a stream of matter that is the largest in the inner Solar System. Taurid meteor showers occur twice per year but the stream has a cycle of activity that peaks every 2,500 to 3,000 years, when there are larger impactors. The Royal Observatory in Scotland estimates that the next peak involving large-sized meteors from the Taurids will begin sometime between the years 2400-3000 AD. Some astronomers note that dates for megalith structures such as Stonehenge are associated with these peaks.
Encke and the Taurids are believed to be remnants of a much larger comet, which has disintegrated over the past 20,000 to 30,000 years, breaking into several pieces and releasing material by normal cometary activity or perhaps occasionally by close encounters with the gravitational field of Earth or other planets. Due to the stream’s size, the Earth takes several weeks to pass through it, causing an extended period of meteor activity, compared with the much smaller periods of activity in other showers. The Taurids are also made up of weightier material, pebbles instead of dust grains. Many astronomers consider these to be the cause of the 1908 Tunguska event. I wrote about all of this at length in this book.
Graham believes that we are capable of solving this problem, of sweeping the cosmic environment. But this is just the tip of the iceberg of what’s covered in this interview with the great Graham Hancock. | 0.914016 | 3.503827 |
There’s additional news from LIGO (the Laser Interferometry Gravitational Observatory) about gravitational waves today. What was a giant discovery just a few months ago will soon become almost routine… but for now it is still very exciting…
LIGO got a Christmas (US) present: Dec 25th/26th 2015, two more black holes were detected coalescing 1.4 billion light years away — changing the length of LIGO’s arms by 300 parts in a trillion trillion, even less than the first merger observed in September. The black holes had 14 solar masses and 8 solar masses, and merged into a black hole with 21 solar masses, emitting 1 solar mass of energy in gravitational waves. In contrast to the September event, which was short and showed just a few orbits before the merger, in this event nearly 30 orbits over a full second are observed, making more information available to scientists about the black holes, the merger, and general relativity. (Apparently one of the incoming black holes was spinning with at least 20% of the maximum possible rotation rate for a black hole.)
The signal is not so “bright” as the first one, so it cannot be seen by eye if you just look at the data; to find it, some clever mathematical techniques are needed. But the signal, after signal processing, is very clear. (Signal-to-noise ratio is 13; it was 24 for the September detection.) For such a clear signal to occur due to random noise is 5 standard deviations — officially a detection. The corresponding “chirp” is nowhere near so obvious, but there is a faint trace.
This gives two detections of black hole mergers over about 48 days of 2015 quality data. There’s also a third “candidate”, not so clear — signal-to-noise of just under 10. If it is really due to gravitational waves, it would be merging black holes again… midway in size between the September and December events… but it is borderline, and might just be a statistical fluke.
It is interesting that we already have two, maybe three, mergers of large black holes… and no mergers of neutron stars with black holes or with each other, which are harder to observe. It seems there really are a lot of big black holes in binary pairs out there in the universe. Incidentally, the question of whether they might form the dark matter of the universe has been raised; it’s still a long-shot idea, since there are arguments against it for black holes of this size, but seeing these merger rates one has to reconsider those arguments carefully and keep an open mind about the evidence.
Let’s remember also that advanced-LIGO is still not running at full capacity. When LIGO starts its next run, six months long starting in September, the improvements over last year’s run will probably give a 50% to 100% increase in the rate for observed mergers. In the longer run, the possibility of one merger per week is possible.
Meanwhile, VIRGO in Italy will come on line soon too, early in 2017. Japan and India are getting into the game too over the coming years. More detectors will allow scientists to know where on the sky the merger took place, which then can allow normal telescopes to look for flashes of light (or other forms of electromagnetic radiation) that might occur simultaneously with the merger… as is expected for neutron star mergers but not widely expected for black hole mergers. The era of gravitational wave astronomy is underway. | 0.848538 | 3.950271 |
The diversity and quantity of moons in the Solar System suggest a manifold population of natural satellites exist around extrasolar planets. Of peculiar interest from an astrobiological perspective, the number of sizable moons in the stellar habitable zones may outnumber planets in these circumstellar regions. With technological and theoretical methods now allowing for the detection of sub-Earth-sized extrasolar planets, the first detection of an extrasolar moon appears feasible. In this review, we summarize formation channels of massive exomoons that are potentially detectable with current or near-future instruments. We discuss the orbital effects that govern exomoon evolution, we present a framework to characterize an exomoon's stellar plus planetary illumination as well as its tidal heating, and we address the techniques that have been proposed to search for exomoons. Most notably, we show that natural satellites in the range of 0.1-0.5 Earth mass (i) are potentially habitable, (ii) can form within the circumplanetary debris and gas disk or via capture from a binary, and (iii) are detectable with current technology.
- Extrasolar planets
- Planetary science
ASJC Scopus subject areas
- Agricultural and Biological Sciences (miscellaneous)
- Space and Planetary Science | 0.837177 | 3.578046 |
Today, after 16 years of exemplary service, NASA will officially deactivate the Spitzer Space Telescope. Operating for over a decade beyond its designed service lifetime, the infrared observatory worked in tandem with the Hubble Space Telescope to reveal previously hidden details of known cosmic objects and helped expand our understanding of the universe. In later years, despite never being designed for the task, it became an invaluable tool in the study of planets outside our own solar system.
While there’s been no cataclysmic failure aboard the spacecraft, currently more than 260 million kilometers away from Earth, the years have certainly taken their toll on Spitzer. The craft’s various technical issues, combined with its ever-increasing distance, has made its continued operation cumbersome. Rather than running it to the point of outright failure, ground controllers have decided to quit while they still have the option to command the vehicle to go into hibernation mode. At its distance from the Earth there’s no danger of it becoming “space junk” in the traditional sense, but a rogue spacecraft transmitting randomly in deep space could become a nuisance for future observations.
From mapping weather patterns on a planet 190 light-years away in the constellation Ursa Major to providing the first images of Saturn’s largest ring, it’s difficult to overstate the breadth of Spitzer’s discoveries. But these accomplishments are all the more impressive when you consider the mission’s storied history, from its tumultuous conception to the unique technical challenges of long-duration spaceflight.
A Scope for the Shuttle
While the Spitzer Space Telescope might have been launched in 2003, its origins date back to the Apollo era. As NASA’s ability to launch large payloads into space improved, astronomers began to consider the possibility of an orbiting infrared observatory. An IR telescope in space would vastly outperform a similarly sized telescope on Earth due to the fact that most of the infrared radiation from space is absorbed by water vapor and carbon dioxide in the atmosphere. While it would be a considerable technical challenge to build, launch, and operate such a telescope, there was no question it would be able to do more useful science than anything that could be built on the ground.
In 1976, Hughes Aircraft Corporation released their preliminary design study for the Shuttle Infrared Telescope Facility (SIRTF), a cryogenically cooled IR telescope that would be mounted inside the cargo bay of the Space Shuttle. Thanks to the promised rapid reusability of the Shuttle, the SIRFT could be regularly upgraded and reflown to take advantage of improvements in IR imaging technology.
Unfortunately, the reality of the Space Shuttle program turned out to be very different than what was originally envisioned. Rather than launching regularly and cheaply like a commercial airliner, the Shuttle ended up being just as slow and expensive a ride into space as more traditional rockets. To make matters worse, experiments performed during the STS-51-F mission showed that IR observations made from the Shuttle were complicated by the aura of dust and heat that surrounded the winged orbiter.
By the mid-80s, it became clear SIRTF wasn’t going to work as a part of the Shuttle. It would need to be a free-flying instrument, which naturally made the design considerably more complex. SIRTF would not only have to fit onto a smaller rocket, but it would also need to have its own means of communication, propulsion, navigation, and power generation.
Beating the Heat
Throughout the 1990s, the SIRTF concept went through several revisions. Now called Space Infrared Telescope Facility to differentiate itself from the earlier Shuttle-centric design, the new telescope needed to be small and light enough to be carried on a Delta II rocket. Optimizing a design for spaceflight is never easy, but in the case of the SIRTF, it posed some unique challenges.
For optimal performance, the IR sensors would need to be cooled down to near absolute zero. This means a cryogenic coolant and insulation, which adds mass and bulk to the spacecraft. The easiest way to reduce launch mass would be to load less coolant onboard, but that reduces the useful life of the telescope: an exceptionally difficult compromise to make.
To solve the problem, a radical change was made to the original concept. Rather than operating in low Earth orbit like the Hubble Space Telescope, SIRTF would be launched into deep space. At that distance, the cooling system would no longer have to contend with the heat radiating from the Earth. Naturally the spacecraft would be heated by the sun as well, but that could be mitigated with a passive solar shield. SIRTF would still need to bring along liquid helium to cool the sensors, but in deep space it would require far less.
With these changes to the mission parameters, it was estimated that the SIRTF could keep its instruments cooled to approximately 5 Kelvin ( -268 °C, -450 °F) for up to 5 years.
Spitzer’s Evolving Mission
The SIRTF was launched aboard a Delta II rocket on August 25th, 2003. As was customary at the time, NASA didn’t officially change the spacecraft’s name to the Spitzer Space Telescope until it was ready to begin observations. It was named after Dr. Lyman Spitzer, an early proponent of space telescopes who helped lobby Congress for the funding necessary to build the Hubble before his death in 1997.
From December 2003 to May 2009, Spitzer observed the energy from distant galaxies, young forming stars, and exoplanets at wavelengths between 3.6 μm and 160 μm. After that point the liquid helium ran out, and the temperature of the instrumentation rose to approximately 30 K (−243 °C, −406 °F). This limited the telescope’s observations to a minimum wavelength of 4.5 μm, and marked the beginning what mission controllers referred to as the “Spitzer Warm Mission”.
By the time the so-called warm phase of the mission started, Spitzer was already years beyond its original design lifetime. But the discoveries it made during this period, either on its own or when working in conjunction with other instruments and observatories, were no less impressive. Data from Spitzer helped identify a galaxy that lies an incredible 32 billion light-years from Earth, and techniques such as transit photometry and gravitational microlensing enabled it to perform exoplanet research which had never even been considered in its original mission.
Scientific observations have continued to the present day, though in recent years, declining battery health and the ever-increasing distance between Spitzer and Earth has made downloading the resulting data more difficult.
The Future of Infrared Astronomy
The Spitzer Space Telescope has already outlived the European Space Agency’s similar William Herschel Telescope, and NASA’s Wide-field Infrared Survey Explorer (WISE) isn’t sensitive enough to perform the same sort of observations. Naturally there’s plenty of data to sift through for the time being, but after today, how long will astronomers have to wait before new IR observations can be made?
Spitzer’s direct successor, known as SAFIR (Single Aperture Far InfraRed), is at this point just a concept with no firm timeframe for its construction or launch. The European Space Agency is looking to launch Euclid in 2022, though it will only be able to look as far into the infrared wavelengths as Spitzer. NASA also continues to operate Stratospheric Observatory For Infrared Astronomy (SOFIA), a modified Boeing 747 that flies high enough to avoid the majority of the IR-blocking water vapor in the atmosphere.
But certainly the most exciting prospect on the horizon is the James Webb Space Telescope (JWST). Slated to be launched next year, the JWST won’t be able to see all of the same IR wavelengths that Spitzer did during its cold phase, but the telescope’s incredibly large 6.5 meter diameter mirror will allow it to observe objects that are dimmer and farther away than ever before. | 0.858901 | 3.690497 |
This happens at around the time when the Moon's orbit carries it around the far side of the Earth as seen from the Sun, at around the same time that it passes full moon.
This distance between the Earth and Moon will be 0.0025 AU (378,000 km).
The exact positions of the Sun and Moon in the sky will be:
|Object||Right Ascension||Declination||Constellation||Angular Size|
The coordinates above are given in J2000.0.
|The sky on 31 May 2020|
9 days old
All times shown in EDT.
The circumstances of this event were computed using the DE405 planetary ephemeris published by the Jet Propulsion Laboratory (JPL).
This event was automatically generated by searching the ephemeris for planetary alignments which are of interest to amateur astronomers, and the text above was generated based on an estimate of your location.
|04 Aug 2047||– The Moon at aphelion|
|05 Aug 2047||– Full Moon|
|12 Aug 2047||– The Moon at apogee|
|13 Aug 2047||– Moon at Last Quarter| | 0.879564 | 3.168623 |
Gamma ray telescopes could detect starships powered by black hole
In the course of looking for possible signs of extra-terrestrial intelligence (ETI), scientists have had to do some really outside-of-the-box thinking. Since it is a foregone conclusion that many ETIs would be older and more technologically advanced than humanity, those engaged in the Search for Extra-Terrestrial Intelligence (SETI) have to consider what a more advanced species would be doing.
A particularly radical idea is that spacefaring civilizations could harness radiation emitted from black holes (Hawking radiation) to generate power. Building on this, Louis Crane, a mathematician from Kansas State University (KSU), recently authored a study that suggests how surveys using gamma telescopes could find evidence of spacecraft powered by tiny artificial black holes.
The study, "Searching for Extraterrestrial Civilizations Using gamma Ray Telescopes," recently appeared online. This is the second paper published by Dr. Crane on the subject, the first of which was co-authored by Shawn Moreland (a physics grad student with KSU) and published in 2009 – titled "Are Black Hole Spacecraft Possible?"
In the first paper, Crane and Westmoreland explored the possibility of using Hawking radiation from an artificial black hole. They concluded that it was at the edge of possibility, but that quantum gravity effects (which are currently unknown) could be an issue. In her most recent paper, Crane took things a step further by describing how the resulting gamma-rays such a system would produce could aid in the search for ETIs.
The concept of a black hole-powered spacecraft was first introduced by famed science fiction author Arthur C. Clarke in his 1975 novel Imperial Earth. A similar idea was presented by Charles Sheffield in his 1978 short story "Killing Vector." In both cases, Clarke and Sheffield describe how advanced civilizations could extract energy from rotating black holes to meet their energy needs.
Aside from being pure science-fiction gold, the ability to harness a black hole to generate power would offer some pretty hefty advantages. As Dr. Crane described to Universe Today via email: "An advanced civilization would want to harness a microscopic black hole because it could throw in matter and get out energy. It would be the ultimate energy source. In particular, it could propel a starship large enough to be shielded to relativistic velocities. None of the starship concepts NASA studied turned out to be viable… It might be the only possibility."
In addition, the signatures associated with this sort of technological activity (aka "technosignatures") would indicate a very high level of advancement. Given the sheer energy requirements for creating an artificial black hole, plus the technical challenges associated with harnessing it, the process would be beyond anything less than a Type II civilization on the Kardashev Scale.
"To produce an artificial black hole, we would need to focus a billion-ton gamma ray laser to nuclear dimensions," said Dr. Crane. "It's like making as many high-tech nuclear bombs as there are automobiles on Earth. Just the scale of it is beyond the current world economy. A civilization which fully utilized the solar system would have the resources."
That's not even the least of the technical challenges, most of which well are beyond what humanity is capable of. These include the sheer amount of power it would take to power the gamma-ray laser, where this energy would be stored, and how these emissions would be focused onto an atom-sized space. As Crane indicated, there are suggestions for how this could be done, but they remain highly speculative.
Aside from the concept itself, the idea of a black hole-powered civilization is also interesting because of the possibilities that it presents for SETI research. As with other signs of technological activity (a.k.a. "technosignatures"), a civilization harnessing tiny, artificial black holes created with gamma ray lasers could be detectable thanks to a little thing known as "spillover."
This concept was described by Prof. Philip Lubin in a 2016 study, where he suggested that evidence of ETIs could be found by searching for signs of directed energy. Consistent with Lubin's own research involving lasers for planetary defense and laser propulsion (for NASA and as part of Breakthrough Starshot), Lubin suggested that errant flashes of laser energy (aka "spillover") could indicate a technologically advanced civilization.
In the same way, SETI researchers could rely on gamma-ray telescopes to search for signs of spillover from gamma ray lasers. Dr. Crane said, "If some advanced civilization already had such starships, current VHE gamma ray telescopes could detect it out to 100 to 1000 light years if we were in its beam. They could be distinguished from natural sources by their steadily changing redshift over a period of years to decades. To investigate this, astronomers would need to keep time series of frequency curves of the point-like gamma ray sources. This does not seem to be something they currently do."
What is perhaps most exciting, though, is the fact that astronomers may have already found signs of some Type II Kardashev civilizations that use this type of method for energy production. As Dr. Crane explained, several point-like gamma ray sources have been detected in the universe for which no natural explanation has been given.
Future observations using space-based telescopes like the Fermi Gamma-ray Space Telescope (FGST), and ground-based facilities like the High Energy Stereoscopic System (HESS) and the Very Energetic Radiation Imaging Telescope Array System (VERITAS), could reveal whether these sources could actually be artificial in nature.
Coupled with next-generation instruments that have greater resolution and imaging capabilities, gamma-ray laser spillover and other potential technosignatures could be out there, just waiting to be identified. In the meantime, humanity still has a long way to go before it can begin to contemplate building this kind of technology.
Much like Dyson spheres, Alderson disks, space elevators, and the ability to move stars, this kind of Type II megaproject is just going to have to wait humanity can tackle a few smaller challenges. Something more our speed, like finding ways to settle on other planets in our solar system, or learning how to use Earth's resources sustainably. | 0.895075 | 3.409286 |
Swedish instrument has landed on the Moon
On January 3, 03:26 Swedish time, the Chinese Chang'E-4 spacecraft landed successfully on the far side of the Moon. The Swedish Institute of Space Physics (IRF) has developed one of the scientific instruments on board. The aim of the instrument is to study how the solar wind interacts with the lunar surface.
It is an historic event as it is the first time a spacecraft is landing on the far side of the Moon. It is also the second time Swedish instrumentation is used on the lunar surface; 50 years ago Hasselblad cameras were used during the Apollo missions.
The Advanced Small Analyzer for Neutrals (ASAN) instrument was developed by the Swedish Institute of Space Physics in Kiruna - in collaboration with the Chinese National Space Science Center (NSSC). The instrument investigates how the solar wind, a flow of charged particles from the Sun, interacts with the lunar surface. ASAN is mounted on the rover of Chang'E-4, which makes it possible to perform measurements at different locations. The measurements could shed light on the processes responsible for the formation of water on the Moon.
"The successful landing means that Sweden is back on the Moon and this is exciting. The next step for ASAN is the instrument commissioning. The first science data are expected before February, 11th", says Martin Wieser, researcher at the Swedish Institute of Space Physics and principal investigator of ASAN.
Landing on the lunar far side is complex as the landing site is not visible from Earth. To communicate with the lander, the Chinese National Space Agency (CSNA) has previously launched the Queqiao communication relay satellite into a halo orbit about 65 000km further out than the Moon.
Even after the landing there are challenges for Chang'E-4. The rover needs solar power to operate. After sunset, this power source is not available and the temperatures will drop significantly during the two-week-long lunar night.
"The lunar night is especially difficult, but both the rover and our instrument are designed to withstand these extreme conditions. ASAN is mounted inside a thermally insulated payload compartment that is open during daytime and closed during night time to cope with the low temperatures. We keep our fingers crossed that all systems will work as designed", says Martin Wieser.
The ASAN experiment is a collaboration between the Swedish Institute of Space Physics (IRF) who has developed, built and tested the ASAN ASAN instrument, and the National Space Science Center, Chinese Academy of Sciences (NSSC/CAS) ), who is responsible for the integration of ASAN on the Chang'E-4 rover and for ASAN science operations.
Martin Wieser, researcher at IRF and ASAN principal investigator.
+ 46 70 277 1287
+ 46 980 79 198
Earlier press releases (Swedish):
Institutet för rymdfysik, IRF, är ett statligt forskningsinstitut under Utbildningsdepartementet. IRF bedriver grundforskning och forskarutbildning i rymdfysik, atmosfärfysik och rymdteknik. Mätningar görs i atmosfären, jonosfären, magnetosfären och runt andra planeter med hjälp av ballonger, markbaserad utrustning (bl a radar) och satelliter. För närvarande har IRF instrument ombord på satelliter i bana runt två planeter: jorden och Mars. IRF har ca 100 anställda och bedriver verksamhet i Kiruna (huvudkontoret), Umeå, Uppsala och Lund.
* * * * * * * * * * * *
The Swedish Institute of Space Physics (IRF) is a governmental research institute which conducts research and postgraduate education in atmospheric physics, space physics and space technology. Measurements are made in the atmosphere, ionosphere, magnetosphere and around other planets with the help of ground-based equipment (including radar), stratospheric balloons and satellites. IRF was established (as Kiruna Geophysical Observatory) in 1957 and its first satellite instrument was launched in 1968. The head office is in Kiruna (geographic coordinates 67.84° N, 20.41° E) and IRF also has offices in Umeå, Uppsala and Lund. | 0.818755 | 3.446165 |
The large space rock that will zip past Earth this Halloween is most likely a dead comet that, fittingly, bears an eerie resemblance to a skull.
Scientists observing asteroid 2015 TB145 with NASA's Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii, have determined that the celestial object is more than likely a dead comet that has shed its volatiles after numerous passes around the sun.
The belated comet has also been observed by optical and radar observatories around the world, providing even more data, including our first close-up views of its surface. Asteroid 2015 TB145 will safely fly by our planet at just under 1.3 lunar distances, or about 302,000 miles (486,000 kilometers), on Halloween (Oct. 31) at 1 p.m. EDT (10 a.m. PDT, 17:00 UTC).
The first radar images of the dead comet were generated by the National Science Foundation's 305-meter (1,000-foot) Arecibo Observatory in Puerto Rico. The radar images from Arecibo indicate the object is spherical in shape and approximately 2,000 feet (600 meters) in diameter and completes a rotation about once every five hours.
"The IRTF data may indicate that the object might be a dead comet, but in the Arecibo images it appears to have donned a skull costume for its Halloween flyby," said Kelly Fast, IRTF program scientist at NASA Headquarters and acting program manager for NASA's NEO Observations Program.
Managed by the University of Hawaii for NASA, the IRTF's 3-meter (10 foot) telescope collected infrared data on the object. The data may finally put to rest the debate over whether 2015 TB145, with its unusual orbit, is an asteroid or is of cometary origin.
"We found that the object reflects about six percent of the light it receives from the sun," said Vishnu Reddy, a research scientist at the Planetary Science Institute, Tucson, Arizona. "That is similar to fresh asphalt, and while here on Earth we think that is pretty dark, it is brighter than a typical comet which reflects only 3 to 5 percent of the light. That suggests it could be cometary in origin -- but as there is no coma evident, the conclusion is it is a dead comet."
Radar images generated by the Arecibo team are available at:
Asteroid 2015 TB145 was discovered on Oct. 10, 2015, by the University of Hawaii's Pan-STARRS-1 (Panoramic Survey Telescope and Rapid Response System) on Haleakala, Maui, part of the NASA-funded Near-Earth Object Observations (NEOO) Program. The next time the asteroid will be in Earth's neighborhood will be in September 2018, when it will make a distant pass at about 24 million miles (38 million kilometers), or about a quarter the distance between Earth and the sun.
Radar is a powerful technique for studying an asteroid's size, shape, rotation, surface features and surface roughness, and for improving the calculation of asteroid orbits. Radar measurements of asteroid distances and velocities often enable computation of asteroid orbits much further into the future than would be possible otherwise.
NASA places a high priority on tracking asteroids and protecting our home planet from them. In fact, the U.S. has the most robust and productive survey and detection program for discovering near-Earth objects (NEOs). To date, U.S.-funded assets have discovered over 98 percent of the known NEOs.
In addition to the resources NASA puts into understanding asteroids, it also partners with other U.S. government agencies, university-based astronomers, and space science institutes across the country, often with grants, interagency transfers and other contracts from NASA, and also with international space agencies and institutions that are working to track and better understand these objects. In addition, NASA values the work of numerous highly skilled amateur astronomers, whose accurate observational data helps improve asteroid orbits after they are found.
NASA's Jet Propulsion Laboratory, Pasadena, California, hosts the Center for Near-Earth Object Studies for NASA's Near-Earth Object Observations Program within the agency's Science Mission Directorate.
More information about asteroids and near-Earth objects is at these websites:
News Media ContactDC Agle
Jet Propulsion Laboratory, Pasadena, Calif. | 0.847503 | 3.632001 |
Sidney van den Bergh (1929- )
A world expert in galaxy classification and the measurement of cosmic distances, he made several estimates of the size and age of the Universe
Sidney van den Berg was born in 1929 in Wassenaar, Netherlands. He spent one year at the University of Leiden and then went to Princeton University in the United States on a scholarship. He received his bachelor’s degree from Princeton in 1950, and his master’s from Ohio State University in 1952. He finished his studies in 1956 with a doctoral degree from the University of Göttingen in Germany.
He was hired as a professor at Ohio State University the same year he graduated, and he stayed there until 1958 when he accepted a professorship at the David Dunlap Observatory of the University of Toronto in Ontario. He became involved in expanding the observatory’s facilities, perfecting computerized calculation techniques, and developing the field of polychrome photometry. For the latter, he collaborated with Robert D. McClure to design a photometric system that would go on to be used around the world for photometric studies.
Van den Bergh’s main specialty was the study of meteors, but his interests quickly diversified and by 1960 he had already published numerous articles on globular clusters, interstellar clouds, galaxies and supernovae. In 1962, he added the Moon to his list of studied celestial objects. Subsequent years, however, were primarily devoted to the study of variable stars, globular clusters, interstellar clouds, galaxies and supernovae.
His work on the classification and evolution of galaxies, as well as on the extragalactic distance scale, led him to make several estimates of the size and age of the Universe. He thus became a world expert in the field of matter.
Van den Bergh began his interest in comets in 1973 and discovered a new comet in 1974 that bears his name. In 1986, he was able to obtain remarkable images of the jets emanating from Halley’s comet.
In 1977, he was named Director of the Dominion Astrophysical Observatory in Victoria, British Columbia, and he occupied the post starting in 1978. Four years later, he became President and Chairman of the Board of the Canada-France-Hawaii Telescope Corporation. He retired in 1986, but retained a researcher position at the Dominion Astrophysical Observatory in Victoria.
Today, van den Bergh focuses his research on the classification and the evolution of galaxies using images taken with the Hubble Space Telescope. He retains an interest in a number of diverse subjects: among others, he published an article in 1992 that refuted the idea of an astronomical significance for the Nazca lines of Peru, and one in 1994 demonstrating that it is unlikely supernova explosions caused mass extinctions on Earth.
Van den Bergh has published more than 500 scientific articles. He received numerous awards for his work and was named an Officer of the Order of Canada. Asteroid 4230 bears his name in his honour. | 0.929697 | 3.29891 |
New technology is giving astronomers the boost they need to find life on other planets.
A recent study published in the journal Science Advances describes a new method for gauging the surface gravity of stars. And researchers say this will help to identify planets within habitable regions in outer space – the so-called Goldilocks Zones.
“If you don’t know the star, you don’t know the planet,” says the study’s co-author Jaymie Matthews of UBC’s Department of Physics and Astronomy.
Described as the “timescale technique,” this new approach looks to improve upon planet detection methods by more accurately measuring the size and mass of stars (and thus their gravitational pull) through an analysis of variations in a star’s brightness over time. Previous methods of detection relied exclusively on photometric measurements, which are less reliable the more distant (and faint) the star’s light source. According to the study’s authors, the timescale technique “can measure surface gravity in stars for which no other analysis is now possible.”
This comes on the heels of last year’s confirmation that over 1000 exoplanets (planets outside our solar system) have now been identified, a dozen of which are thought to be within habitable regions around stars. Top among them is Kepler-452b, confirmed by NASA to be a planet 60% larger than Earth and 1,400 light-years away, orbiting a star of approximately the same temperature as the Sun.
Our technique can tell you how big and bright is the star and if a planet around it is the right size and temperature to have water oceans and maybe life.
These new discoveries are all due to the Kepler mission, launched by NASA in 2009 to aid in the detection of Earth-like planets within our Milky Way galaxy. The Kepler spacecraft monitors the light intensity of over 145,000 stars – still only a tiny fraction of the 200 billion stars in the Milky Way.
The end goal of this search is to identify exoplanets within the Goldilocks Zone – areas around stars that are suitable for sustaining life (as in the fairy tale, they’re “not too hot” and “not too cold”). What counts as a habitable zone depends on a planet’s distance from its star but also on the luminosity of the star, both of which will go into determining whether or not liquid water is present. And, along with liquid water, it is theorized that in order to sustain life a planetary body must also possess an active core and be of a size and density able to support an atmosphere.
In our solar system, liquid water has been observed or theorized to exist on a number of bodies – on Enceladus, a moon of Saturn, on two moons of Jupiter, Ganymede and Europa, and, most recently, liquid water has been detected on Mars.
Of the new study, Professor Matthews says, “Our technique can tell you how big and bright is the star and if a planet around it is the right size and temperature to have water oceans and maybe life.”
The study to find life on other planets was headed by University of Vienna’s Thomas Kallinger and involved a team of astronomers from Canada, Germany, France and Australia. | 0.919294 | 3.917909 |
Miguel Zumalacárregui knows what it feels like when theories die. In September 2017, he was at the Institute for Theoretical Physics in Saclay, near Paris, to speak at a meeting about dark energy and modified gravity. The official news had not yet broken about an epochal astronomical measurement—the detection, by gravitational wave detectors as well as many other telescopes, of a collision between two neutron stars—but a controversial tweet had lit a firestorm of rumor in the astronomical community, and excited researchers were discussing the discovery in hushed tones.
Zumalacárregui, a theoretical physicist at the Berkeley Center for Cosmological Physics, had been studying how the discovery of a neutron-star collision would affect so-called “alternative” theories of gravity. These theories attempt to overcome what many researchers consider to be two enormous problems with our understanding of the universe. Observations going back decades have shown that the universe appears to be filled with unseen particles—dark matter—as well as an anti-gravitational force called dark energy. Alternative theories of gravity attempt to eliminate the need for these phantasms by modifying the force of gravity in such a way that it properly describes all known observations—no dark stuff required.
At the meeting, Zumalacárregui joked to his audience about the perils of combining science and Twitter, and then explained what the consequences would be if the rumors were true. Many researchers knew that the merger would be a big deal, but a lot of them simply “hadn’t understood their theories were on the brink of demise,” he later wrote in an email. In Saclay, he read them the last rites. “That conference was like a funeral where we were breaking the news to some attendees.”
The neutron-star collision was just the beginning. New data in the months since that discovery have made life increasingly difficult for the proponents of many of the modified-gravity theories that remain. Astronomers have analyzed extreme astronomical systems that contain spinning neutron stars, or pulsars, to look for discrepancies between their motion and the predictions of general relativity—discrepancies that some theories of alternative gravity anticipate. These pulsar systems let astronomers probe gravity on a new scale and with new precision. And with each new observation, these alternative theories of gravity are having an increasingly hard time solving the problems they were invented for. Researchers “have to sweat some more trying to get new physics,” said Anne Archibald, an astrophysicist at the University of Amsterdam.
Confounding observations have a way of leading astronomers to desperate explanations. On the afternoon of March 26, 1859, Edmond Lescarbault, a young doctor and amateur astronomer in Orgères-en-Beauce, a small village south of Paris, had a break between patients. He rushed to a tiny homemade observatory on the roof of his stone barn. With the help of his telescope, he spotted an unknown round object moving across the face of the sun.
He quickly sent news of this discovery to Urbain Le Verrier, the world’s leading astronomer at the time. Le Verrier had been trying to account for an oddity in the movement of the planet Mercury. All other planets orbit the sun in perfect accord with Isaac Newton’s laws of motion and gravitation, but Mercury appeared to advance a tiny amount with each orbit, a phenomenon known as perihelion precession. Le Verrier was certain that there had to be an invisible “dark” planet tugging on Mercury. Lescarbault’s observation of a dark spot transiting the sun appeared to show that the planet, which Le Verrier named Vulcan, was real. | 0.908277 | 3.868563 |
Water is made of hydrogen and oxygen, but the debate is all about the hydrogen. There are 2 stable isotopes of hydrogen, light and heavy, or 1H and 2D for deuterium. The deuterium to hydrogen ratio in water (and other compounds but water is the most common) has been debated and measured in many locations. The Sun does not make deuterium, but it is the first thing that it burns up (if H is charcoal, D is lighter fluid). The only supply of deuterium–like hydrogen itself–is the Big Bang. So any hydrogen that has been processed through stellar furnaces will lose deuterium.
The earth’s oceans have higher D/H ratios than the sun, so the question has been around for a long time, where did Earth get its oceans? The standard model has been that comets supplied the water for the Earth’s oceans during the “Late Heavy Bombardment” some 3.85 billion years ago. Comets are thought to come from a vast cloud–the Oort Cloud–orbiting the Sun about 1 lightyear away. The gravitational attraction is so weak, that just about anything can change their orbit, and people have suggested passing stars or even gamma-ray bursts are enough to scatter comets, some of which end up making close encounters with the inner solar system and us.
These Oort Cloud comets are thought to predate the Sun, and are leftovers from the “proto-solar nebula” that made the Sun and the planets. Where did this nebula come from? Well our Sun is just 4.5 billion years old, the nebula maybe 5 billion years old, but our Milky Way galaxy is 12 billion years old. So there have been many supernova and Wolf-Rayet stars that shed dust into the galaxy from which our planet’s silicon and carbon and oxygen come from. But the one thing they cannot make, is deuterium. So the deuterium has to be primordial.
Here’s a paper from January 2014 arguing this sort of point: http://arxiv.org/abs/1401.6035 “Chemo-dynamical deuterium fractionation in the early solar nebula: The origin of water on Earth and in asteroids and comets” The word “fractionation” is the keyword–they want to find a way to make the D/H ratio go up by distillation (lighter H heads out toward Jupiter, heavier D stays near the Earth), so that we don’t need extra primordial ice to make the oceans. Their conclusion is that they can explain away the anomaly using locally made materials. This is the standard model, even if it needs a bit of tweaking. After all, if all the silicon and oxygen and carbon was made locally in stars, then most of the deuterium should have been processed locally too.
Then along comes Lauren Ilsedore Cleeves. She is part of team on the Hershel IR telescope that observes a distant proto-stellar nebula with lots of really cold water in it, publishes a 2011 paper, http://arxiv.org/abs/1110.4600 “Detection of the Water Reservoir in a Forming Planetary System”. Her team interprets it as ice grains which sputter water vapor from cosmic rays. And there’s lots of it. It appears that proto-stellar disks are full of primordial ice, rather than recycled supernovae or Wolf-Rayet water. Hence, this paper in Science, where she does a really *big* simulation and says the D/H water in the Earth’s oceans can’t be fractionated in the proto-planetary nebula, it must be interstellar.
Okay, we know why its controversial, but why is this important?
Well, for one thing, if it is interstellar, it means that our galaxy is chock full of water, and then every other planetary system that we’ve spotted could easily have water in it. This is the justification for “planet-finding” missions. (Of course, none of the extra-solar planets have the right temperature, composition, and size to look like a twin of Earth, but that’s a different problem.)
But unfortunately, Cleeves has proven too much. If the water is interstellar, then it wasn’t made in stars–which of course would ruin the D/H ratio too. But if it wasn’t made in stars, then it is primordial, Big Bang created. But if it is primordial, then where did the oxygen in the water come from, since the BB doesn’t make oxygen? Cleeves has solved one problem–the elevated D/H ratio–by creating another–the origin of Oxygen in the interstellar water.
Now as it happens, I’m working on a theory and simulation that says that the Big Bang *did* make oxygen, lots of it, so that the missing “dark matter” of the galaxies is nothing more nor less than ice, as found in comets. And since we have already shown that comets carry fossil bacteria and bio-engineered magnetites, then we don’t need to wait for the planet-finder mission to find us a Cinderella-zone Earthlike planet–we have billions of habitable comets moving in and out of Cinderella zones, flourishing and freezing like the mosquito population of Canada.
Follow UD News at Twitter! | 0.923124 | 3.733433 |
This artist's concept depicts an itsy bitsy planetary system -- so compact, in fact, that it's more like Jupiter and its moons than a star and its planets. Astronomers using data from NASA's Kepler mission and ground-based telescopes recently confirmed that the system, called KOI-961, hosts the three smallest exoplanets known so far to orbit a star other than our sun. An exoplanet is a planet that resides outside of our solar system.
The star, which is located about 130 light-years away in the Cygnus constellation, is what's called a red dwarf. It's one-sixth the size of the sun, or just 70 percent bigger than Jupiter. The star is also cooler than our sun, and gives off more red light than yellow.
The smallest of the three planets, called KOI-961.03, is actually located the farthest from the star, and is pictured in the foreground. This planet is about the same size as Mars, with a radius only 0.57 times that of Earth. The next planet to the upper right is KOI-961.01, which is 0.78 times the radius of Earth. The planet closest to the star is KOI-961.02, with a radius 0.73 times the Earth's.
All three planets whip around the star in less than two days, with the closest planet taking less than half a day. Their close proximity to the star also means they are scorching hot, with temperatures ranging from 350 to 836 degrees Fahrenheit (176 to 447 degrees Celsius). The star's habitable zone, or the region where liquid water could exist, is located far beyond the planets.
The ground-based observations contributing to these discoveries were made with the Palomar Observatory, near San Diego, Calif., and the W.M. Keck Observatory atop Mauna Kea in Hawaii.
NASA's Ames Research Center in Moffett Field, Calif., manages Kepler's ground system development, mission operations and science data analysis. JPL managed the Kepler mission's development.
For more information about the Kepler mission visit http://www.nasa.gov/kepler. | 0.861299 | 3.356761 |
Rogue planets sound adventurous, like pirates of the final frontier minus the scurvy. The reality is much more depressing: these bodies are untethered to a star, so they’re doomed to dance around the void solo. To make things even sadder, new research suggests certain rogue planets, namely the Jupiter-sized ones, are far lonelier than previously suggested.
A leading idea about the origin of rogue planets suggests they were kicked out of their parent systems when two planetary bodies got in a gravitational tussle. Over the last few years, various surveys have attempted to pin down how common these cosmic nomads are—for example, in 2011, a group of astronomers suggested Jupiter-sized rogue planets could be more common than main sequence stars in the Milky Way.
But recently, a team of researchers at Warsaw University Observatory in Poland analysed 2,600 microlensing events detected by the Optical Gravitational Lensing Experiment (OGLE-IV) between 2010 and 2015, and found that Jupiter-mass rogue planets could be at least ten times less common than this 2011 estimate. Microlensing is a technique used to study objects that are extremely far away from Earth, that relies on examining how light from one source (a star) bends from the gravitational field of another lens (in this case, a planet). The technique is useful because it doesn’t rely on how bright the object of interest is, and rogue exoplanets are dark.
This study analysed a much larger sample of events than the 2011 study, which observed only 474 microlensing events, which could help explain the discrepancy in the two paper’s findings. Through their calculations, the group at Warsaw University suggests there are no more than 0.25 rogue Jupiter-mass planets per Milky Way main-sequence star. At the same time, the team posits rogue planets similar to Earth’s mass could be pretty abundant—possibly as many as two rogue Earth-sized planets per main sequence star.
“A previous analysis of 474 microlensing events found an excess of ten very short events (1–2 days)...indicating the existence of a large population of unbound or wide-orbit Jupiter-mass planets,” the team wrote. “These results, however, do not match predictions of planet-formation theories and surveys of young clusters.”
There’s still much to learn about these nomadic worlds. Some scientists, for example, think the hypothetical object known as Planet 9 could have been a rogue planet in its early life. Others posit our solar system might have had a fifth gas giant that was ejected and left to wander the cosmos.
The argument over the abundance of rogue planets isn’t going away any time soon, and more survey data will surely help us to better pin down the abundance of these cosmic nomads. Still, one thing’s for sure—these wandering planets sure could use a friend. [Nature]
More Space Posts:
Fistful of Stars is a five minute-long virtual reality experience that takes the viewer on a tour through the vast star-forming region known as the Orion Nebula.
The worst thing about these boots is that they’re not available for us sorry sacks of flesh here on Earth.
Most people (incorrectly) assume the moon is barren and boring.
It’s small, falling apart due to stress, and apparently, desperately in need of validation. | 0.90718 | 3.974025 |
Mercury's Mysterious Bright Spot
A mysterious bright area on the surface of Mercury is seen near the top center of this 2009 image. The MESSENGER probe also imaged this spot in its second flyby of the planet on Oct. 6, 2008. Color images from MESSENGER's Wide Angle Camera reveal that the irregular depression and bright halo have distinctive color.
As the World Turns: MESSENGER's Home Movie of Earth
This image, taken while MESSENGER was 34,692 miles (55,831 kilometers) above Earth, shows the Galapagos Islands as tiny specks peeking through clouds. The line dividing day and night cuts through South America, with night about to fall on the western half of the continent. The large bright spot to the west of South America is the Sun’s light scattering off ocean waves.
MESSENGER Flyby of Venus a Dress Rehearsal for Mercury
Venus 2 Flyby. As the MESSENGER spacecraft approaches the brightly illuminated Venus on June 5, 2007, it will begin a carefully planned sequence of science observations designed to practice activities planned seven months later at the first flyby of Mercury.
MESSENGER's New View of Mercury
As NASA's MESSENGER spacecraft approached Mercury on January 14, 2008, it captured this view of the planet's rugged, cratered landscape illuminated obliquely by the sun.
Huge Impact Crater on Planet Mercury
A mosaic of images collected by MESSENGER as it departed Mercury on October 6, 2008. The Wide Angle Camera on MESSENGER imaged the surface through 11 color filters ranging in wavelength from 430 to 1020 nm. This false-color image reflects various wavelengths of light reflecting from the surface.
MESSENGER's Solar System Family Portrait
The MESSENGER spacecraft, which is headed for orbit around Mercury, collected this series of images to complete a "family portrait" of our Solar System as seen from the inside looking out. The majority of this mosaic was obtained on 3 November 2010. Uranus and Neptune remained too faint to detect with even the longest camera exposure time, but their positions are indicated.
Is Mercury the Incredible Shrinking Planet? MESSENGER Spacecraft May Find Out
Artist's impression of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft in orbit at Mercury.
One Crater, Many Rays
Bright rays spread across this Messenger spacecraft photo and radiate from Debussy crater, located at the top. The March 29, 2011 image shows just a small portion of Debussy's large system of rays in greater detail than ever previously seen. Debussy's rays extend for hundreds of kilometers across Mercury's surface.
First Color Photo of Mercury from Orbit
On March 29, 2011, NASA's Messenger spacecraft became the first probe ever to orbit Mercury. This image is the first color photo Mercury, showing the planet's southern polar region, acquired by Messenger from its new orbit. The Messenger probe arrived in orbit around Mercury on March 17 after three previous flybys of the planet.
Mercury's horizon, as seen from orbit by NASA's Messenger spacecraft
A view of the horizon of Mercury, taken by NASA's Messenger spacecraft on March 29, 2011. The picture shows a stretch of land about 750 miles long, from top to bottom. | 0.804452 | 3.541996 |
Across much of the world Centaurus A (NGC 5128; mag 7.8) will be well placed, high in the sky. It will reach its highest point in the sky at around midnight local time.
At a declination of -43°01', it is easiest to see from the southern hemisphere but cannot be seen from latitudes much north of 26°N.
At magnitude 7.0, NGC5128 is quite faint, and certainly not visible to the naked eye, but can be viewed through a pair of binoculars or small telescope.
The position of NGC5128 is as follows:
|Object||Right Ascension||Declination||Constellation||Magnitude||Angular Size|
The coordinates above are given in J2000.0.
|The sky on 13 April 2017|
16 days old
All times shown in EDT.
The circumstances of this event were computed using the DE405 planetary ephemeris published by the Jet Propulsion Laboratory (JPL).
This event was automatically generated by searching the ephemeris for planetary alignments which are of interest to amateur astronomers, and the text above was generated based on an estimate of your location. | 0.901567 | 3.105604 |
Smallest-ever star discovered by astronomers
The smallest star yet measured has been discovered by a team of astronomers led by the University of Cambridge. With a size just a sliver larger than that of Saturn, the gravitational pull at its stellar surface is about 300 times stronger than what humans feel on Earth.
The star is likely as small as stars can possibly become, as it has just enough mass to enable the fusion of hydrogen nuclei into helium. If it were any smaller, the pressure at the centre of the star would no longer be sufficient to enable this process to take place. Hydrogen fusion is also what powers the Sun, and scientists are attempting to replicate it as a powerful energy source here on Earth.
These very small and dim stars are also the best possible candidates for detecting Earth-sized planets which can have liquid water on their surfaces, such as TRAPPIST-1, an ultracool dwarf surrounded by seven temperate Earth-sized worlds.
The newly-measured star, called EBLM J0555-57Ab, is located about six hundred light years away. It is part of a binary system, and was identified as it passed in front of its much larger companion, a method which is usually used to detect planets, not stars. Details will be published in the journal Astronomy & Astrophysics.
"Our discovery reveals how small stars can be," said Alexander Boetticher, the lead author of the study, and a Master's student at Cambridge's Cavendish Laboratory and Institute of Astronomy. "Had this star formed with only a slightly lower mass, the fusion reaction of hydrogen in its core could not be sustained, and the star would instead have transformed into a brown dwarf."
EBLM J0555-57Ab was identified by WASP, a planet-finding experiment run by the Universities of Keele, Warwick, Leicester and St Andrews. EBLM J0555-57Ab was detected when it passed in front of, or transited, its larger parent star, forming what is called an eclipsing stellar binary system. The parent star became dimmer in a periodic fashion, the signature of an orbiting object. Thanks to this special configuration, researchers can accurately measure the mass and size of any orbiting companions, in this case a small star. The mass of EBLM J0555-57Ab was established via the Doppler, wobble method, using data from the CORALIE spectrograph.
"This star is smaller, and likely colder than many of the gas giant exoplanets that have so far been identified," said von Boetticher. "While a fascinating feature of stellar physics, it is often harder to measure the size of such dim low-mass stars than for many of the larger planets. Thankfully, we can find these small stars with planet-hunting equipment, when they orbit a larger host star in a binary system. It might sound incredible, but finding a star can at times be harder than finding a planet."
This newly-measured star has a mass comparable to the current estimate for TRAPPIST-1, but has a radius that is nearly 30% smaller. "The smallest stars provide optimal conditions for the discovery of Earth-like planets, and for the remote exploration of their atmospheres," said co-author Amaury Triaud, senior researcher at Cambridge's Institute of Astronomy. "However, before we can study planets, we absolutely need to understand their star; this is fundamental."
Although they are the most numerous stars in the Universe, stars with sizes and masses less than 20% that of the Sun are poorly understood, since they are difficult to detect due to their small size and low brightness. The EBLM project, which identified the star in this study, aims to plug that lapse in knowledge. "Thanks to the EBLM project, we will achieve a far greater understanding of the planets orbiting the most common stars that exist, planets like those orbiting TRAPPIST-1," said co-author Professor Didier Queloz of Cambridge' Cavendish Laboratory. | 0.866933 | 3.877673 |
HST is a space-based great observatory that observes at ultraviolet through near infrared wavelengths. High resolution imaging and wide-ranging spectroscopic capabilities enable forefront research across all domains of astrophysics. Time on HST is awarded through an open peer-reviewed competition.
The Hubble Space Telescope's launch in 1990 sped humanity to one of its greatest advances in that journey. Hubble is a telescope that orbits Earth. Its position above the atmosphere gives it a view of the universe that typically far surpasses that of ground-based telescopes.
Thirty years since launch, the Hubble Space Telescope continues its role at the forefront of astronomy, ranging from our own Solar System to the high-redshift universe.
Through the middle of the next decade, HST will remain the only space-based telescope providing spectroscopy and high-resolution imaging at UV, optical, and near-infrared wavelengths. With the launch of JWST in 2021, the bold science questions pursued with HST will be bolstered by the complementary capabilities of the two observatories.
Using the Hubble Telescope
The Space Telescope Science Institute (STScI) will be at the Virtual 236th American Astronomical Society Meeting (AAS) meeting with an exhibit booth and several associated events highlighting...
The 236th American Astronomical Society (AAS) meeting will include updates to help the astronomical community prepare for JWST science. STScI Virtual Town Hall Tuesday,...
Speaker: Dr. Benne Holwerda (University of Louisville) One of the largest spiral galaxies in the known local universe, UGC 2885, was recently nicknamed Rubin’s Galaxy in... | 0.859733 | 3.030721 |
Alan Hale: First news from Pluto
A major milestone in our exploration of the solar system took place a week and a half ago, when the New Horizons spacecraft, after a 9-year-long journey which included a close gravity-assist flyby of Jupiter, passed by Pluto and through its system of moons on Tuesday, July 14. This was the first time we have explored a previously-unexplored major world in our solar system since the passage of the Voyager 2 spacecraft by Neptune in August 1989.
For the first few decades following Pluto's discovery by Clyde Tombaugh at the Lowell Observatory in Flagstaff, Arizona in 1930 we knew very little about Pluto other than the fact that it existed in the cold, outer reaches of the solar system. Even its size was a matter of much conjecture, although as time went by it started to become apparent that Pluto was a rather small world, certainly not much larger than Earth and quite likely significantly smaller. The watershed moment in our understanding of Pluto came in 1978 with the discovery of Pluto's large moon Charon by U.S. Naval Observatory astronomer James Christy, and this soon told us that Pluto was, surprisingly, quite a bit smaller and less massive than our own moon.
About one decade after Charon's discovery, its orbit around Pluto was aligned so that, for a few years, from our vantage point here on Earth Pluto and Charon periodically passed in front of and behind each other; this allowed us to determine their approximate diameters as being 1470 and 750 miles, respectively. Pluto was then near its closest point to the sun (out of its 248-year orbital period), and when it passed directly in front of a dim background star we were able to determine that it possessed a thin atmosphere. In the years since then images taken with the Hubble Space Telescope revealed the presence of various dark and light features on Pluto's surface, but at such a low resolution that it was difficult to tell much in the way of anything definitive. In recent years images with Hubble have also revealed the presence of four smaller moons: Nix and Hydra which were discovered in 2005, Kerberos in 2011, and Styx in 2012.
Enter New Horizons, which passed 7800 miles above Pluto's surface when it flew through the Pluto system last week. Because the spacecraft's mission team wanted New Horizons to devote the entirely of its flyby time to collecting images and data, there was very little in the way of "real-time" data that came back to Earth; it would, in fact, be a long and tantalizing thirteen hours (which included the 4-hour travel time for the radio signals) after the flyby before the first transmissions arrived at Earth telling us that the flyby had been successful.
It will take approximately another sixteen months for all the images and data that New Horizons collected during its flyby of Pluto and its moons to be transmitted back to Earth, and that process has only recently begun. But the images and data that we have already received as of now have proven to be especially surprising, and are causing us to rethink almost everything we thought we knew about this world and its moons.
One of the most striking surface features on Pluto is a large, light-colored heart-shaped region that has been unofficially dubbed "Tombaugh Regio." Some close-up images of a part of this feature that have recently arrived reveal a wide frozen plain that is divided up into irregular segments that are bordered by narrow troughs, with some of these containing small knobby hills and others containing darker-colored material. Probably the most surprising thing about this feature is that there is not a single impact crater on it, which means that it is very young, geologically speaking (no more than 100 million years old, and quite possibly much younger); this in turn means that Pluto is surprisingly active geologically, although the mechanism for this activity remains a mystery for now.
Another region of Pluto contains mountains that rise as much as 11,000 feet above the surrounding surface; the lack of craters in this area tells us, again, that the surface here is very young from a geological perspective. Charon, meanwhile, also has some rather interesting surface features, including a dark, reddish-colored region (informally dubbed "Mordor") near its north pole that may be surface-level organic (i.e., carbon-containing) material; a large canyon, 600 miles long and four to six miles deep, cutting across its midsection; and a large surface depression with an apparent peak jutting out from its middle. Much of Charon's surface is also essentially crater-free, indicating that it, too, is geologically quite active.
Among other findings, data gathered when New Horizons passed behind Pluto as seen from Earth shows that Pluto's atmosphere, albeit very thin, extends as much as 1000 miles above Pluto's surface. The atmosphere is mainly made up of nitrogen, although there is also some methane present, and Pluto is apparently rather rapidly losing what little atmosphere it has as it recedes farther from the sun. Meanwhile, recently received images of Nix and Hydra reveal them to be irregularly shaped objects roughly 25 to 30 miles across, with Nix containing a large red-tinted region that may be an impact crater.
The data and images that we have received thus far only barely scratch the surface of what New Horizons collected when it passed through the system, with the overwhelming majority of that data and images still to come during the weeks and months ahead. But it is already clear from what we have now that Pluto and its moons are far more enigmatic than we had previously suspected. We can only speculate about the surprises from these mysterious worlds that lie in wait for us as the data gathered by New Horizons makes its way home.
Alan Hale is a professional astronomer who resides in Cloudcroft. He is involved in various space-related research and educational activities throughout New Mexico and elsewhere. His web site is http://www.earthriseinstitute.org. | 0.873952 | 3.787795 |
Planets are in the news, as Pluto’s dubious planetary status is under the microscope once again.
Recently, a debate over the defining qualities of a planet was held at the Harvard-Smithsonian Center for Astrophysics, and three of the top names in planetary science presented their cases to the attending audience.
Now, although the audience overwhelmingly voted in favor of Pluto’s planethood, that’s not binding. This wasn’t an International Astronomical Union vote or anything like that.
But it did put the solar system back in the news cycle, and that reminded me of a puzzly planetary story.
In the 1600s, Galileo Galilei was doing amazing work with his telescope, redefining our understanding of the solar system and our place in it. He was doing controversial work, but he still wanted to be able to prove he was the primary person behind a given discovery, so he mailed a letter to his colleague, Johannes Kepler.
Galileo sent Kepler this anagram: s m a i s m r m i l m e p o e t a l e u m i b u n e n u g t t a u i r a s
When properly solved, the anagram reads “Altissimum planetam tergeminum observavi,” meaning “I have observed the most distant planet to have a triple form.” You see, Galileo had glimpsed Saturn and its famous rings, but due to the poor magnification of his telescope, he’d mistaken the rings themselves for two moons orbiting the planet.
This was a tremendous discovery, adding to our knowledge of what was (at the time) the furthest reaches of our solar system.
But Kepler, while trying to untangle the anagram, came to a different solution. Believing that Galileo’s latest discovery involved Mars, not Saturn, Kepler’s solution read “Salue umbistineum geminatum Martia proles,” meaning Mars has two moons. (The ambiguity of Latin V’s and U’s didn’t help matters.)
So, while Kepler was wrong in his solution, he was unintentionally correct about Mars! (Phobos and Deimos, the two moons of Mars, wouldn’t be confirmed until 1877.)
Amazingly enough, this wouldn’t be the only time Galileo relied on Kepler and anagrams to prove provenance when it came to his discoveries.
In 1611, Galileo sent another anagram to Kepler: Haec immatura a me iam frustra leguntur o.y.
Properly unscrambled, the message reads “Cynthiae figuras aemulatur mater amorum,” or “The mother of love imitates the shape of Cynthia.” This one requires a little more explanation. The mother of love was Venus, and Cynthia was the Moon, meaning that Venus, when observed from Earth, has phases just like the moon.
[Click here for a larger version of this image.]
This probably sounds less important than Galileo’s studies of Saturn, but it’s not. This was an earthshaking discovery, because it was observable evidence that Venus had to pass on both sides of the sun, meaning that Venus orbited the sun. This violated the geocentric model of the solar system so strongly espoused by the church!
It was evidence like this that led to Galileo’s battle with the Inquisition.
And, weirdly enough, there might be one more twist to this story.
Some historians believe that Kepler also solved this Galilean anagram incorrectly, and that his solution once again revealed an unintentional discovery about the solar system.
According to the as-yet-unverified story, Kepler’s solution read “Macula rufa in Jove est gyratur mathem…,” which translates as “There is a red spot in Jupiter, which rotates mathem[atically].” (Again, yes, there’s the Great Red Spot on Jupiter, but there was no way for Kepler to have known that at the time.)
It’s hard to believe that Kepler could twice unravel a Galileo anagram and twice make accidental predictions about the solar system. While the first story is widely accepted, the second is viewed with far more skepticism.
But either way, it just goes to show that anagrams, while delightful, might not be the best method for announcing your great discoveries.
Thanks for visiting PuzzleNation Blog today! You can share your pictures with us on Instagram, friend us on Facebook, check us out on Twitter, Pinterest, and Tumblr, and be sure to check out the growing library of PuzzleNation apps and games! | 0.85327 | 3.409636 |
The People’s Republic of China (PRC) hit world headlines on 3 January 2019, and earned universal acclaim, when its unmanned Chang’e 4 probe was the first to make a successful landing on the dark side of the moon, touching down in the South Pole-Aitken basin, the largest and oldest crater on the moon, and the largest known impact-formed structure in the solar system.
Chang’e (嫦娥) is the name of the ancient Chinese moon goddess, hence its adoption by the Chinese lunar exploration programme.
This impressive technological achievement, bringing together cutting-edge contributions in the fields of rocket science, telecommunications, mathematics, computing and artificial intelligence (AI), underlines the rapidity of China’s advance towards becoming not only the 21st century’s industrial powerhouse, but its leading technological and scientific centre, capable of challenging US hegemony in every sphere.
A great technological achievement
Interference from the bulk of the moon itself makes direct communication with the surface impossible, which is a major reason that the far side of the moon has remained unexplored until now, some 50 years after the first moon landings.
The following passage from the Guardian underlines the significance of China’s achievement:
“The landing was described as ‘an impressive accomplishment’ by Nasa administrator Jim Bridenstine.
“Martin Wieser, a scientist at the Swedish Institute of Space Physics and principal investigator on one of the instruments onboard Chang’e, said: ‘We know the far side from orbital images and satellites, but we don’t know it from the surface. It’s uncharted territory and that makes it very exciting.’
“A significant challenge faced by the Chinese team was the inability to communicate directly with the spacecraft. Signals to and from the rover are being relayed through a satellite called Queqiao (Magpie Bridge). Queqiao is in a ‘halo orbit’ on the other side of the moon, from where it can communicate with both Chang’e and the Earth.
“During the final phases of the approach, however, Chang’e 4 was on its own and could not be operated remotely. Starting from an altitude of 15km, the craft used a rocket booster to decelerate.
“At 100 metres above the lunar surface, the probe briefly hovered to identify obstacles and measured the slopes on the surface. Using a hi-tech camera and laser measurements to avoid boulders and ditches, it selected a relatively flat area and resumed a slow, vertical descent, touching down softly in the Von Karman Crater within the South Pole-Aitken Basin, according to a report by the Xinhua news agency.
“Chang’e 4 targeted the Von Kármán crater, which was predicted to have a smooth volcanic floor and which sits within the great Aitken basin.
“‘This is a great technological accomplishment as it was out of sight of Earth, so signals are relayed back by their orbiter, and most of the landing was actually done autonomously in difficult terrain,’ said Prof Andrew Coates, a space scientist at UCL’s Mullard Space Science Laboratory. ‘The landing was almost vertical because of the surrounding hills.’” (Far side of the moon: China’s Chang’e 4 probe makes historic touchdown by Hannah Devlin and Kate Lyons, 3 January 2019, our emphasis)
The highlighted passages in the above quotation notes that the autonomous landing demonstrates the extent to which the successful application of AI was necessary to achieve the safe descent of the probe, with both measurements and decision-making being made by pre-programmed logical algorithms.
The probe’s roving explorer module is now conducting preliminary geological surveys, helping us to understand the differing composition of the near and far sides of the moon. There are also on-board experiments to test the feasibility of growing plants on the moon, within its relatively weak gravitational field. Two weeks after landing, in fact, a young cotton seedling had successfully sprouted in the carefully controlled conditions on-board.
“This is the first time humans have done biological growth experiments on the lunar surface,” said Xie Gengxin, who led the design of the experiment.
“Plants have been grown previously on the International Space Station, but this is the first time a seed has sprouted on the moon. The ability to grow plants in space is seen as crucial for long-term space missions and establishing human outposts elsewhere in the solar system, such as Mars.
“Harvesting food in space, ideally using locally extracted water, would mean astronauts could survive for far longer without returning to Earth for supplies.” (Giant leaf for mankind? China germinates first seed on moon by Hannah Devlin, The Guardian, 15 January 2019)
Social significance of the landing
The likelihood of ‘space colonies’ in the near future is overstated and not a realistic prospect that will meaningfully affect our economy and ecology – and certainly not a get-out-of-jail-free card for humanity, which faces real and pressing ecological challenges on Earth, and which capitalism is demonstrating on a daily basis that it has no ability to solve.
But in the ongoing battle for independence and freedom by ‘small’ and non-imperialist countries, in the face of the imperial domination of conglomerate corporate capitalism, the ability of independent states to defend themselves economically and militarily is of the greatest significance for all of us. And, in this regard, China’s mastery of these crucial fields of technology can only be greeted with the greatest enthusiasm.
Socialism v capitalism
There is a further economic argument, of the greatest importance to all who believe that humanity has a brighter future to be built based on cooperation, and an economy and culture aimed at achieving decent and sustainably high living standards for the whole working population of our planet.
It is worth noting that a recent editorial in the Economist magazine, for example, lambasted the “naivety” of a new generation of “millennial socialists”, opining that they have not understood the mechanism to correct the imperfections of capitalism – namely, socialism. With cool reassurance, and flying in the face of all evidence, its author concluded that capitalism remains the only realistic system and that the answer to society’s evident problems is to be found in better application of “budgets, bureaucracies and businesses”. (Millennial socialism, 14 February 2019)
Crude as were the arguments in this piece, they are part of a renewed anti-socialist offensive, as capitalism struggles on through a decade of recession, increasing national isolation and trade war, the disastrous impoverishment of the vast mass of humanity, and seemingly endless imperial adventures of destabilisation, coup attempts and wars of intervention to enable a tiny clique of financiers to cling desperately to the wealth of the planet, cleaving it from its rightful owners.
Can socialism deliver a way out?
The incredible record of rapid industrialisation and technological achievement that are the historical legacy of the first great socialist revolution in Russia, the October Revolution of 1917, should by rights have settled this argument. But the great legacy of emancipation and liberation of humanity, which resulted in the social, cultural, scientific and technological, military and diplomatic powerhouse that was the Soviet Union, are heavily maligned and disputed; thanks largely to the decline and fall of Khrushchevite revisionism, and the ignominious collapse of the once mighty USSR.
Thus there persists a widely prevalent dogma, admittedly fostered and promulgated by the capitalists themselves, that “socialism is incapable of making technological, scientific and cultural advances”. This is essentially a rehash of Francis Fukuyama’s triumphalist ‘End of History’ thesis.
Martin Woolf of the Financial Times underpinned this notion the day before the lunar landing, penning an anti-China rant entitled The future might not belong to China, in which he instructed his readers: “Do not extrapolate from the recent past.
“The view widely held in the 1980s that Japan would be ‘number one’ turned out to be badly mistaken. In 1956, Nikita Khrushchev, then first secretary of the Communist Party of the Soviet Union, told the west that ‘We will bury you!’ He proved utterly wrong. The examples of Japan and the Soviet Union highlight three frequent mistakes: extrapolating from the recent past; assuming that a period of rapid economic growth will be indefinitely sustained; and exaggerating the benefits of centralised direction over those of economic and political competition. In the long run, the former is likely to become rigid and so brittle, while the latter is likely to display flexibility and so self-renewal.”
This is an optimistic (for the capitalists) assessment to say the least. We will leave Khrushchev out of the picture for now, but let the reader note that neither Mao Zedong nor Josef Stalin made such inflammatory statements at the UN, but rather sent their representatives to run rings around imperialism in every sphere, while advancing the cause of the liberation of humanity unceasingly and tirelessly. These two giants of proletarian struggle really did bury tsarist imperialism, German militarist-fascist imperialism, the Chinese empire and Japanese imperialism, and were doing an excellent job of seeing off the remaining capitalist gangsters until Khrushchev appeared on the scene. But the interested reader can read Harpal Brar’s Perestroika, the Complete Collapse of Revisionism to find out more.
The most glaringly false premise expressed by this notoriously reactionary journalist is that the imperialist west is characterised by ‘economic and political competition’. Economically, free-competition capitalism has not existed for over a century!
Lenin long ago outlined the features of monopolist capitalism, which has concentrated industrial and banking capital in its own hands to an ever-increasing degree, controlling markets and spheres of interest, and carving up the entire territory of the world between a handful of economically powerful cliques and nations. (Imperialism, the Highest Stage of Capitalism, 1916)
It was this monopolist position of capitalism that drove the imperialist powers into World War One, and the colossal loss of a staggering 40 million workers’ lives in the internecine war for a redistribution of the world’s colonies and markets. Lenin’s profound insight into the lack of competition and freedom for the world’s masses, languishing under the rule of imperialism, has only been proven increasingly correct by the subsequent development of capitalist imperialism.
Politically, on the other hand, Lenin pointed out in his brilliant work The State and Revolution the Marxist doctrine that “democracy is the very best shell” in in which to conceal the real state of affairs: namely the dictatorship of the bourgeoisie. (1917)
As if to highlight the charade that is bourgeois ‘democracy’ (political competition, if it pleases Mr Wolf), US president Donald Trump and the US establishment took it upon themselves to ‘appoint’ a new president of Venezuela, just a week after the Chinese moon landing, specifically tasked with helping them get their hands on the largest oil reserves on Earth, in the Orinoco basin.
In so doing, they cast aside inconvenient trifles such as the right of sovereign nations to self-determination, as enshrined in the United Nations charter and international law; and the inconvenient fact that their appointee, one Mr Guaido, did not even stand in the last presidential election, let alone win it. Guaido is ‘our man’, and that’s all that matters – that is the democracy, the ‘political competition’, celebrated by these paid hacks of imperialism.
Planning and investment
China’s rise, and its ability, despite huge market encroachment into its economy, to have central direction and planning, and large-scale investment in infrastructure and social projects, underpins the technological advances that make such showcase missions as the Chang’e 4 moon landing possible.
Transforming itself from the sick man of Asia into a great centre of enlightenment, economic might and world civilisation in the space of 70 years would not have been possible were the foundations not laid by its thoroughgoing anti-colonial and anti-feudal national-liberation struggle, and without the leading role of the Communist Party of China (CPC).
The achievement of the USSR in being the first nation to put human beings into space is now downplayed and glossed over in contemporary articles and histories in the west. For our part, we will never forget that on 12 April 1961, aboard the spacecraft Vostok 1, Soviet cosmonaut Yuri Alekseyevich Gagarin became the first human being to travel into space. During the flight, the 27-year-old test pilot and industrial technician also became the first man to orbit the planet, a feat accomplished by his space capsule in 89 minutes.
Moreover, Soviet cosmonaut Valentina Tereshkova became the first woman to fly into space when she launched on the Vostok 6 mission on 16 June 1963.
These were landmarks of achievement for the Soviet economic and social system and for the world’s working class; for women’s equality and for socialism. They also showed that Soviet socialism had the ability to make huge technological investments and achievements.
Should we feel pride in China’s achievement?
Gill Scott-Heron, the well-known New York poet and lyricist, famously wrote of the USA’s moon landing in 1969:
A rat done bit my sister Nell
With whitey on the moon …
I can’t pay no doctor bills
But whitey’s on the moon.
The United States is one of the most racist societies on earth, and the powerful capitalist class has long pushed the ideology of white supremacy on the white working class, which has for many years found its social complement in black nationalism.
But leaving this aside – although this early split of workers along lines of racial ‘identity’ is perhaps the single greatest factor in the impotence of the US working-class movement – there is a broader idea expressed in this poem.
Namely, that the poor and oppressed proletariat of the US, particularly its most oppressed black population, could take no pride in the much-trumpeted technological achievements of the US imperialists while they were deprived of the most basic human necessities of decent and sanitary housing, adequate diet, medical care, etc.
Interestingly, this is a theme of criticism that imperialism has become adept at revising and directing at formerly oppressed and colonised peoples who have gone on to develop marvels of technical achievement – whether these be satellite launches, missile programmes, or the development of nuclear technology. It is a criticism especially thrown at those countries that have had the temerity to join the ‘nuclear club’ without imperialist permission – China, the DPRK, India and Pakistan.
But to accuse developing nations of having ‘inhuman’ priorities while their populations live in poverty on the one hand no longer applies to China, which has lifted a staggering 700 million of its citizens out of poverty over the past 40 years ((almost 1.5 times the population of the EU)), and on the other hand, is deliberately and entirely to miss the point.
In our grotesquely unevenly developed planet, where the needs of the impoverished masses are neglected and trampled underfoot by the callous economic train and war juggernaut of imperialism, it is the political, economic and technological dominance of the finance capitalists that reinforce their domination, and thereby the poverty of the masses. The drive of small nations to break out of imperialism’s technological and industrial stranglehold upon the world economy is of vital interest to the oppressed masses – and it is in this light that such developments must be viewed.
Simple administration is not enough to escape the debt trap in which the huge banks ensnare poorer nations and entire continents; to truly overturn inequality, a social revolution against capitalism is necessary, and the proletariat of each nation must necessarily first reckon with its own bourgeoisie. China has taken this road – hence its success.
It is the European and American proletariats that languish behind in this regard. But British and American workers cannot hope to win power if they don’t even set themselves the task – if their ideological determination and resolve are clouded and subdued; if our faith in the possibility of building a bright future without exploitation of man by man and nation by nation is lost.
“The chief endeavour of the bourgeoisie of all countries and of its reformist hangers-on is to kill in the working class faith in its own strength, faith in the possibility and inevitability of its victory, and thus to perpetuate capitalist slavery. For the bourgeoisie knows that if capitalism has not yet been overthrown and still continues to exist, it owes it not to its own merits, but to the fact that the proletariat has still not enough faith in the possibility of its victory.
“It cannot be said that the efforts of the bourgeoisie in this respect have been altogether unsuccessful. It must be confessed that the bourgeoisie and its agents among the working class have to some extent succeeded in poisoning the minds of the working class with the venom of doubt and scepticism.” (Report on the work of the central committee to the eighteenth congress of the CPSU(B) by JV Stalin, 10 March 1939)
Yes indeed. But the story is not over.
The US seeks to undermine China as an economic competitor, and as a power capable of resisting its plans for global domination. This is the meaning and content of USA’s ‘pivot to Asia’ strategy launched under former president Barack Obama and continued under the regime of President Trump.
In short, the rise of China is creating a multipolar (and therefore safer) world in which other states’ latitude to develop independently is greater, and the possibilities for revolutionary action are increased.
We send our warmest greeting to the scientists of the Chinese lunar exploration programme, to the Chinese workers and peasants, and to the leaders of the dictatorship of the proletariat and of the People’s Republic of China. | 0.841163 | 3.161783 |
Born in the Universe: The Panspermia Theory
Since 2004, NASA’s Cassini spacecraft has been orbiting Saturn to study the giant planet’s moons and rings using an array of complex instruments, one of them being a vacuum cleaner, designed to analyze dust particles. This instrument has now detected the faint but distinct signature of dust coming from beyond our solar system: 36 grains of interstellar dust rich in minerals such as magnesium silicates and oxides, as well as iron, that were left over from the death of a distant star.
It is a widely accepted hypothesis that current life on Earth descended from an RNA world, an episode of life on Earth during which RNA (ribonucleic acid) was the only genetic material. The 'panspermia' theory states that this wasn't a spontaneous process that just happened by luck, but that the building blocks and molecules necessary for life to develop are abundant all over the Universe and that 'seeds of life' can be propagated through space from one location to another by comets, asteroids, meteorites etc.
Recently, an experiment conducted by Cornelia Meinert, an associate scientist at the Université Nice Sophia Antipolis in France, demonstrated that the building blocks of RNA are indeed present in interstellar environments. By treating a mixture of water, methanol and ammonia very similar to a comet and hitting it with the same radiation that would have been given off by the Sun from millions of years ago, a huge diversity of molecules was created. The most sensational however was the discovery of ribose, which is the sugar that forms the backbone of RNA.
In another study last year, Karen Smith and her team at NASA's Goddard Astrobiology Laboratory analyzed eight different meteorites and found that they contained up to 600 parts-per-billion of vitamin B3. They also simulated interstellar conditions in the lab and suggested that the radiation powering various chemical reactions in cloud nebulae could have produced vitamin B3 on ice grains.
"Vitamin B3, also called nicotinic acid or niacin, is a precursor to NAD (nicotinamide adenine dinucleotide), which is essential to metabolism and likely very ancient in origin", according to Smith. "It is always difficult to put a value on the connection between meteorites and the origin of life; for example, earlier work has shown that vitamin B3 could have been produced non-biologically on ancient Earth, but it’s possible that an added source of vitamin B3 could have been helpful."
Although hard evidence remains to be found, the number of discoveries that support the panspermia theory is growing steadily. Last year, observations made by ESO with the ALMA radiotelescope in the Atacama desert in Chile revealed the presence of vast quantities of complex organic molecules around a very young star (MWC480), situated 455 light years away.
A type of single-celled algae called Nannochloropsis Oculatatiny appears to be able to survive a space trip without any trouble, as well as an eight-legged critter called “water bear,” that can suspend all biological activity in extreme environments and survive the vacuum of open space and solar radiation combined for at least 10 days. Scientists have also found that a certain strain of bacteria named Bacillus Safensis grows about 60% better on the ISS than on Earth, and recent research has yielded a number of microrganisms that could potentially withstand many of the same extreme conditions found on Mars and other distant planets.
According to Professor Avi Loeb, chair of the Department of Astronomy at the Harvard University, it is possible for life to be carried by rocks and other matter that is ejected from one planet, maybe after the impact of an asteroid, and land on another planet. This can happen if the two planets are in the same planetary system but also, with smaller likelihood, if they are in different systems.
He suggests that if life spreads via panspermia, it does it in a characteristic pattern that we could identify. His research shows that this pattern would be similar to the outbreak of an epidemic. He states that there is a biological similarity between panspermia and disease spread: Any species that evolves panspermia abilities would have enormous fitness advantages.
Many scientists believe that we will soon find traces of alien micro-organisms. This first fingerprints of life could be identified in the atmospheres of extra-solar planets through spectrographs on the next generation of telescopes, but they may also be found on planets and moons within our solar system. Such a find would of course immediately raise the question of how we can be shure that no contamination by terrestrial organisms has taken place. Just the same, the panspermia theory is a keystone in the search for extraterrestrial life for future generations. | 0.915487 | 3.948851 |
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Interesting facts about space.
The Cassini Imaging Team discovered Methone (pronounced me-thoh-nee) on June 1, 2004. This tiny moon orbits between two of Saturn's mid-sized icy moons, Mimas and Enceladus, at a radius of about 194,000 kilometers (120,456 miles) from its planet. Astronomers have suggested two differing theories to explain the presence of Methone and two other small sister moons, Pallene and Anthe. The first theory indicates that the three little moons may have fragmented off of either Mimas or Enceladus. The second theory, on the other hand, suggests that all five moons--the three small moons and the two mid-size ones--may be the sad remnants of a larger menagerie of moons that floated around in that area--which is situated close to Saturn. Methone orbits its gigantic parent planet in 24 hours.
and here is another
"For the smallest craters that we're looking at, we think we're starting to see where the Moon has gone through so much fracturing that it gets to a point where the porosity of the crust just stays at some constant level. You can keep impacting it and you'll hit regions where you'll increase porosity here and decrease it there, but on average it stays constant," Dr. Soderblom continued to explain to the press on September 10, 2015.
On July 20, 1969, astronaut Neil Armstrong radioed back from the surface of the Moon, "... the Eagle has landed". Most of us believe that the landing occurred as broadcast. Not all, however. More than 30 years after the fact, Fox TV aired "Conspiracy Theory: Did We Really Go to the Moon?". In doing so, the Fox entertainers unleashed a lively cabal of kooks and NASA-bashers on a scientifically naive audience without benefit of editorial balance. Polls suggest that perhaps 6% of Americans believe in the authenticity of these claims.
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In Western astrology, the Sun represents who we are in the world, the outward projection of our personality, and the mark we wish to make. By contrast, the moon governs our emotions, our primal instincts, and our unconscious mind. It represents a feminine energy, and is often personified as a goddess or mother. In other words, those deep intuitive urges-those passionate feelings we can't quite describe-are embodied in the moon. No wonder so many love poems have been penned under the influence of its rays!
The Farmer's Almanac defines a blue moon as the third full moon in a season of four full moons. This is the correct definition of a blue moon. Since a season is three months long, most seasons will have three full moons. However, on occasion a season will have four. When this happens, the third is a true blue moon.
The moon, unlike other celestial objects, or even earthly objects for that matter, has ambivalent connotations in the pages of tradition and folklore. The full moon is more so because of its enigmatic aura and understated presence. The full moon has always been witness to many incidents; pages of descriptions dot more books than not about several events unfolding on a full moon night. It somehow brings out an ominous feeling in a storyline. | 0.923696 | 3.058037 |
On Monday (October 7, 2019), the International Astronomical Union’s Minor Planet Center announced the discovery of 20 new moons orbiting Saturn, bringing the planet’s total number of moons to 82. That surpasses Jupiter, which has 79, and makes Saturn the planet with the most known moons in our solar system.
Using some of the largest telescopes in the world, we are now completing the inventory of small moons around the giant planets. They play a crucial role in helping us determine how our solar system’s planets formed and evolved.
According to the researchers, each of the newly discovered moons is about 3 miles (5 km) in diameter. Seventeen of them orbit Saturn backwards, or in a retrograde direction, meaning their movement is opposite to the planet’s rotation around its axis. One of the newly discovered retrograde moons is the farthest known moon around Saturn.
The other three moons orbit in the same direction as Saturn rotates. Two of these three moons are closer to the planet and take about two years to travel once around Saturn. The third, and the more-distant retrograde moons, each take more than three years to complete an orbit.
The outer moons of Saturn appear to be grouped into three different clusters, according to how they orbit the planet. The newly discovered retrograde moons appear to belong to a group of moons, named after Norse mythology, thought to be fragments of a much bigger parent moon that was smashed to pieces in the solar system’s violent past. Sheppard said:
This kind of grouping of outer moons is also seen around Jupiter, indicating violent collisions occurred between moons in the Saturnian system or with outside objects such as passing asteroids or comets.
In the solar system’s youth, the sun was surrounded by a rotating disk of gas and dust from which the planets were born. It is believed that a similar gas-and-dust disk surrounded Saturn during its formation. The fact that these newly discovered moons were able to continue orbiting Saturn after their parent moons broke apart indicates that these collisions occurred after the planet-formation process was mostly complete and the disks were no longer a factor.
The Carnegie Institution for Sciences is hosting a contest to come up with names for the newly discovered moons. The moons must be named after giants from Norse, Gallic, or Inuit mythology. Contest details are here. Here’s a video about the contest:
Bottom line: Astronomers have found 20 new moons orbiting Saturn, bringing the planet’s total number of moons to 82.
Eleanor Imster has helped write and edit EarthSky since 1995. She was an integral part of the award-winning EarthSky radio series almost since it began until it ended in 2013. Today, as Lead Editor at EarthSky.org, she helps present the science and nature stories and photos you enjoy. She also serves as one of the voices of EarthSky on social media platforms including Facebook, Twitter and G+. She and her husband live in Tennessee and have two grown sons. | 0.825618 | 3.663072 |
If you thought tails were just for comets and cats, this asteroid is about to prove you wrong.
On August 27 astronomers spotted an unusually fuzzy looking object in survey images taken with the Pan-STARRS telescope in Hawaii. The multiple tails were discovered in Hubble images taken on September 10, 2013. When Hubble returned to the asteroid two weeks later, its appearance had totally changed — it looked as if the entire structure had swung around!
While this object is on an asteroid-like orbit, it looks like a comet, and is sending out tails of dust into space. Because nothing like this has ever been seen before, astronomers are scratching their heads to find an adequate explanation for its mysterious appearance.
One interpretation is that the asteroid’s rotation rate has increased to the point where dust is falling off the surface and escaping into space, where it is swept out into tails by the pressure of sunlight. According to this theory, the asteroid’s spin has been accelerated by the gentle push of sunlight. Based on an analysis of the tail structure, the object has ejected dust for at least five months.
Careful modeling by team member Jessica Agarwal of the Max Planck Institute for Solar System Research in Lindau, Germany, showed that the tails could have been formed by a series of impulsive dust-ejection events. Radiation pressure from the Sun smears out the dust into streamers.
“Given our observations and modeling, we infer that P/2013 P5 might be losing dust as it rotates at high speed,” says Agarwal. “The Sun then drags this dust into the distinct tails we’re seeing.”
The asteroid could possibly have been spun up to a high speed as pressure from the Sun’s light exerted a torque on the body. If the asteroid’s spin rate became fast enough, suggests lead investigator David Jewitt of UCLA, the asteroid’s weak gravity would no longer be able to hold it together. Dust might avalanche down towards the equator, and maybe shatter and fall off, eventually drifting into space to make a tail. So far, only a small fraction of the main mass, perhaps 100 to 1000 tons of dust, has been lost. The asteroid is thousands of times more massive, with a radius of up to 240 meters.
“In astronomy, where you find one, you eventually find a whole bunch more.”
– David Jewitt, UCLA
Jewitt’s interpretation implies that rotational breakup may be a common phenomenon in the asteroid belt; it may even be the main way in which small asteroids die. “In astronomy, where you find one, you eventually find a whole bunch more,” Jewitt said. “This is just an amazing object to us, and almost certainly the first of many more to come.”
Space… it’s like a box of chocolates, you never know what you’re gonna get.
Source: Hubble news release | 0.858824 | 4.005888 |
Light from a supernova explosion in the nearby starburst galaxy M82 is reverberating off a huge dust cloud in interstellar space.
The supernova, called SN 2014J, occurred at the upper right of M82, and is marked by an "X." The supernova was discovered on Jan. 21, 2014.
The inset images at top reveal an expanding shell of light from the stellar explosion sweeping through interstellar space, called a "light echo." The images were taken 10 months to nearly two years after the violent event (Nov. 6, 2014 to Oct. 12, 2016). The light is bouncing off a giant dust cloud that extends 300 to 1,600 light-years from the supernova and is being reflected toward Earth.
SN 2014J is classified as a Type Ia supernova and is the closest such blast in at least four decades. A Type Ia supernova occurs in a binary star system consisting of a burned-out white dwarf and a companion star. The white dwarf explodes after the companion dumps too much material onto it.
The image of M82 reveals a bright blue disk, webs of shredded clouds, and fiery-looking plumes of glowing hydrogen blasting out of its central regions.
Close encounters with its larger neighbor, the spiral galaxy M81, is compressing gas in M82 and stoking the birth of multiple star clusters. Some of these stars live for only a short time and die in cataclysmic supernova blasts, as shown by SN 2014J.Located 11.4 million light-years away, M82 appears high in the northern spring sky in the direction of the constellation Ursa Major, the Great Bear. It is also called the "Cigar Galaxy" because of the elliptical shape produced by the oblique tilt of its starry disk relative to our line of sight.
###The M82 image was taken in 2006 by the Hubble Space Telescope's Advanced Camera for Surveys. The inset images of the light echo also were taken by the Advanced Camera for Surveys. The science team members are Y. Yang of Texas A&M University, College Station, and the Weizmann Institute of Science, Rehovot, Israel; P.J. Brown of Texas A&M University, College Station; L. Wang of Texas A&M University, College Station, and Purple Mountain Observatory, China; D. Baade, A. Cikota, F. Patat, and J. Spyromilio of the European Organization for Astronomical Research in the Southern Hemisphere, Garching, Germany; M. Cracraft and W.B. Sparks of the Space Telescope Science Institute, Baltimore, Maryland; P.A. Hoflich of Florida State University, Tallahassee; J. Maund and H.F. Stevance of the University of Sheffield, U.K.; X. Wang of Tsinghua University, Beijing Shi; and J.C. Wheeler of the University of Texas at Austin.
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 conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.
For images and more information about the light echo and Hubble, visit:
Weizmann Institute of Science, Israel | 0.903791 | 3.851868 |
General relativity tells us that everything, even light, is affected by the mass of an object. When a beam of light passes near a large mass, its path is deflected. This shift in the direction of light is known as gravitational lensing, and it was one of the first confirmed effects of Einstein’s theory.
In cosmology, there are two types of gravitational lensing, and both play an important role in understanding the evolution of the universe. The first is weak lensing, where light from a distant galaxy passes through a cluster of galaxies, but not close to any particular galaxy. The bending of light is small, which means the shape of the galaxy is distorted slightly. By looking at these distortions, astronomers can measure the average density of matter in the universe. This helps us understand dark energy.
The second type is strong lensing, and it is rarer. For strong lensing, a distant galaxy has to be nearly blocked by a closer one. In this case, the light of the distant galaxy is strongly distorted, often into arcs of light surrounding the closer galaxy. Since the amount of distortion depends on the mass of the closer galaxy, it lets us measure the amount of dark matter in the galaxy. It also allows us to measure the expansion rate of the universe.
But because strongly lensed galaxies are rare, it has been difficult to find enough lensed galaxies for a good survey. To put good constraints on the measure of dark matter and dark energy, we need many more strongly lensed galaxies to study. Fortunately, we’re starting to find them.
Recently a team used an AI program to find lensed galaxies in sky survey data. After training the program on known lensed and unlensed galaxies, it then combed through observations to find more than 300 candidates lensed galaxies. Many of them were then confirmed by follow-up observations with the Hubble Space Telescope.
Now that the method has proved useful, the team plans to analyze other sky-survey data, with the goal of finding at least a thousand strongly lensed galaxies. If they are successful, the work will become a powerful tool for understanding the cosmos.
Reference: Huang, X., et al. “Finding Strong Gravitational Lenses in the DESI DECam Legacy Survey.” The Astrophysical Journal 894.1 (2020): 78. | 0.820446 | 4.024703 |
Every molecule on Earth—from simple N2 to complex DNA—has its origins in space. And astrochemist Ewine van Dishoeck of Leiden University has spent her career investigating the basic chemistry in interstellar space that makes those molecules possible.
▸ Current position: Professor of molecular astrophysics, Leiden University
▸ Hometown: Leiden, the Netherlands
▸ Age: 63
▸ Education: B.Sc., chemistry, 1976, B.Sc., mathematics, 1977, M.Sc., chemistry, 1980, and Ph.D., astrochemistry, 1984, Leiden University
▸ Favorite celestial object: “The Ophiuchus molecular cloud is a star-forming region, a nursery of more than 100 young stars. It also contains some of the chemically richest solar-mass protostars.”
Van Dishoeck uses telescopes on the ground and in orbit to figure out what molecules are present in interstellar space and where they form. In her lab, she recreates interstellar conditions to study potential formation reactions more closely. Her work is helping scientists understand where molecular complexity comes from.
To make her research possible, van Dishoeck has taken lead roles in the design and construction of various telescopes and other advanced equipment. For instance, she was involved in planning the Herschel Space Observatory, a telescope that looked at cold, dusty regions of space where new stars, called protostars, are beginning to form. She was also an adviser to the famous Atacama Large Millimeter Array (ALMA) telescope, in Chile, and a member of the research team there that detected the peptidelike molecule methyl isocyanate in space for the first time. Van Dishoeck says her soul is in that telescope—appropriate because ALMA means “soul” in Spanish.
Fresh off of winning the 2018 Kavli Prize in Astrophysics, she sat down with C&EN to talk about her journey from theoretical chemistry to astrochemistry, and what it’s like to wait three decades for data. This interview has been edited for length and clarity.
You haven’t always been an astrochemist. How did you make that transition?
I’m a chemist by origin. I started in ab initio quantum chemical calculations and then moved gradually into astronomy, but I’ve sort of kept my connections and my feet in chemistry. My work has linked the two better together and made sure also that chemistry is not a niche topic in astronomy but that it’s fully integrated. As one of my colleagues [Xander Tielens, an astronomer at Leiden University] says, we really have a molecular universe. Even in galaxies far away from Earth you still see molecules like carbon monoxide, like water.
The grandfather of this field was Alexander Dalgarno of Harvard University, my Ph.D. adviser. He really brought molecular physics, chemistry, and astronomy together. I was fortunate to work in an era where the observational techniques improved so much. I put effort into making sure new telescopes would happen because we could see their potential for astrochemistry.
I didn’t leave theoretical chemistry, my original research area. I was and am still using it. The only thing I needed to do was focus on molecules that were of astrophysical relevance. So like OH, CH, CH2, water. But then I had to learn. I wanted to calculate a reaction rate under interstellar conditions. What is my energy source? It’s obviously not a standard light bulb or a laser. I needed to get used to different units, to different scales.
The scale of astrochemistry research is very different from what many bench chemists are used to. Explain what that’s like.
You know, it takes about 30 years from conceiving missions to when they actually happen. So it’s very long timescales that we’re dealing with. I had my first meeting about the Herschel Space Observatory, which was so important to pinning down water formation and water chemistry in interstellar clouds, in 1982. I was still a Ph.D. student. We got our first data in 2009.
It is important to have that long-term vision. Of course science shifts. But you focus on the unique parameters of the mission. Herschel was built to study water from space because it is difficult to observe water from Earth. Our atmosphere interferes. No matter what happens in science during the 20 or 30 years that you are waiting for data, water remains the prime target.
A large part of the fun is always the unexpected. These new facilities are so sensitive: In the case of Herschel, no one had predicted that ionized water, H2O+, would be seen so strongly. Yet the first spectra we got, we saw the water and H2O+. That was a big surprise.
What projects are you working on now?
Scientifically, I am enjoying the wonderful data from ALMA, which allows us to zoom in on the birthplaces of stars and planets and determine their chemical composition. In terms of new instruments, the focus is on the James Webb Space Telescope (JWST), the current big project from NASA. [JWST is the successor to the Hubble Space Telescope.]
I got involved in 1997, then I became co-principal investigator on one of its instruments, the Mid-Infrared Instrument. We delivered our hardware in 2008. It will finally be launched in 2021. We have already selected all the targets we are going to observe in the Taurus and Serpens constellations.
When you build an instrument, one of the attractive things is you get guaranteed time on the instrument. And that means you are the first ones on that fantastic new instrument to get data.
Mid-infrared spectroscopy is good for small molecules without a dipole moment, which ALMA can’t see. It has incredible sensitivity. In the protoplanetary disks around young stars, where new planets are likely forming, we will be able to probe the chemical composition of the gas. Not just see water but see how much methane there is, carbon dioxide, ammonia, acetylene. All very simple molecules, but they are the major carbon and oxygen and nitrogen reservoirs that we have in these regions. That is ultimately the gas from which planets are being made.
There’s one more project that I’m also involved in that will happen a little bit later, in 2025. The European Southern Observatory [in northern Chile] is building the Extremely Large Telescope (ELT), which has a 39-meter-diameter primary mirror. Our institute in Leiden is leading the building of one of the three instruments on that, again a mid-infrared spectrometer. [Scientists expect ELT to produce higher-resolution images and spectra than JWST.] I’m involved on the science team.
For projects launching beyond 2025, I say it’s the next generation of scientists that has to be involved. I provide advice. So in that sense the mid-infrared instrument on the ELT is really my last one.
Is that sad for you?
No, no, no. I’ve had a really good run. There will still be instruments that I can use. ALMA will still be fantastic for the next 20, 30 years. JWST will be up there for five to 10 years. So there’s plenty to work on.
CORRECTION: This story was updated Oct. 23, 2018, to correct the photo caption of the molecular cloud. The image was captured by the Spitzer Space Telescope, not the Hubble. | 0.892495 | 3.721043 |
The early photographs and data of the European Space Agency show that comet 67P/Churyumov-Gerasimenko is covered with simple organic molecules.
Recently, researchers presented the initial observation of Comet. The information is quite significant for the future missions of Rosetta. Matt Taylor, the project scientists of the mission states that these findings are the paradigm of the entire mission.
Previously, numerous other spacecraft passed nearby the comet. However, this is the first time when a spacecraft has touched the surface of the comet. In the beginning, Rosetta took measurements of the comet. The data revealed the exact location of the 67/P comet. It uncovers that the comet is approximately 325 million miles away from the sun. Hence, it is a complicated task for astronomers to study the comet through a ground-based telescope.
Additionally, data gathered from Rosetta demonstrates that Comet 67P/Churyumov-Gerasimenko is a dumb-bell shaped comet.
Paul Weissman, an interdisciplinary scientist at the European Space Agency discussed the current state of the mission. He informs that planetary scientists do not have much information regarding the comets. Presently, they are exploring the undiscovered region of solar system.
Most of the result of research is collected from Rosetta’s data of April and September. It was the time period when the spacecraft was moving towards the direction of comet. The spacecraft is expected to reach its closest point to the sun sometime in the month of August.
The outcome of the study is published in detail in the Journal Science | 0.842892 | 3.334537 |
Descent Imager / Spectral Radiometer (DISR)
Instrument of the Huygens probe onboard the Cassini spacecraft
During the descent of the Huygens probe through Titan's atmosphere in January 2005, the Descent Imager / Spectral Radiometer (DISR) tokk images and performed measurements at various spectral ranges and spatial resolutions. These provided information about the composition of the haze layer, the presence of methane clouds and the nature of Titan's surface.
Saturn's moon Titan is the second-largest moon in the Solar System after Jupiter's moon Ganymede, larger even than the planet Mercury - and it is the only moon that has an atmosphere worth mentioning. On the ground, Titan's atmosphere has one-and-a-half times the pressure of Earth's atmosphere, and like it, consists mainly of nitrogen - however, it contains neither oxygen nor carbon dioxide. Instead, it comprises methane and possibly the noble gas Argon.
The temperature on the moon's surface is approximately -180 degrees Celsius, which eliminates the possibility of liquid water. However, methane can occur both in a gaseous and in a liquid state under these conditions. Therefore, methane's role on Titan may be similar to that of water on Earth - with a precipitation cycle involving clouds, rain and evaporation. Lakes or even oceans of methane and ethane are conceivable, but no one knows what Titan's surface actually looks like, as it is hidden beneath an impenetrable, orange haze.
In the wake of the Voyager 1 flyby of Titan, several initiatives were started to promote a mission to Titan. In 1997, the Cassini/Huygens mission was launched, which has reached the Saturnian system in July 2004. The Cassini spacecraft delivered the Huygens probe to Titan in January 2005 and then started to explore the Saturnian system until 2017.
The Huygens payload comprises six instruments, five of were built to carry out measurements during the descent through the atmosphere (starting at about 160 km altitude). One of these instruments is the Descent Imager / Spectral Radiometer (DISR), which took images and spectral measurements in different directions at various spectral ranges and spatial resolutions. The detectors of the DISR are a 512 x 256 CCD for the visible, two linear arrays of 132 photodiodes each for the infrared and two photodiodes for the violet spectral range. Light from the foreoptics of three surface imagers (high resolution, medium resolution and side looking), two visible spectrometers (upward and downward looking) and the Solar Aureole Imager (SA) is conducted by fiber optics to the CCD.
DISR instrument description
The DISR experiment consists of a sensor head box (SH) conducting the optics and the related detectors and of a separate electronics assembly (EA) box connected by a cable ( View of the instrument from above during assembly, optical fibres not connected, without cover) The SH is located on the experiment platform of the Huygens entry probe at a jettisonable cover such that it will be exposed to Titan's atmosphere with an unobstructed view upwards and downwards. It is an optical assembly containing 11 independent scientific data functions.
Measurements are made in the visible wavelength range and in the infrared. Most data at visible wavelengths will be collected by a CCD imaging detector, where each CCD pixel is permanently assigned to a certain data function. Thus, no complex mechanisms are needed to reconfigure the instrument to collect different data. This CCD detectector is a contribution of MPS. In addition, two simple violet radiometers looking up resp. down, each consisting of a PIN diode and a filter, are included. For infrared measurements, a single grating spectrometer is used which is equipped with two linear focal plane detector arrays consisting of InGaAs diodes. They are supported by CCD multiplexers. This component has been developed at DESPA, Observatoire de Paris. A small shutter permits a digital form of synchronous detection and a high signal-to-noise ratio.
Inflight calibration is performed by means of optical fibers connecting all subsystems to a single calibration source (three 1 W tungsten halogen lamps). The main optics and the sensors are mounted on a titanium support frame. Cooling of the device is achieved by conducting heat from the detectors to the ambient Titan atmosphere. Small heaters will stabilize the detector temperature at about 185 K.
The CCD array is divided in nine areas: three are used for the imager (downward looking in the visible and the IR channel, outward looking), four for measurements of the solar aureole at two wavelengths and two polarization angles, and two for the IR measurements (upward and downward looking spectrometers). The CCD was developed under contract of MPS at Loral in Tustin, Ca. It is is a high-resolution 2 phase frame transfer CCD with implied electronic shutter function so that no mechanical shutter is required. The size of the detector (512 x 256 pixels) is well adapted to the data transmission capability since all derived data must be immediately transferred to the Cassini orbiter.
The key functions of the electronics assembly are:
- power supply
- electric interface to the spacecraft
- housekeeping measurements
- detector drivers
- signal processors
- microprocessor and memory
- image compressor
while the sensor head contains only the part of the electric circuitry directy related to the detectors.
The instrument will consume about 15 W excluding the surface science lamp and the hardware data compressor which allows an on-line 6:1 compression of the image data within 750 ms and which will only be switched on for short time intervals.
The scientists working on DISR at the MPS were:
- Horst Uwe Keller (DISR co-investigator, project lead at MPS)
- Jörg-Rainer Kramm
- Björn Grieger
- Yuri Skorov
- Stefan Schröder
The MPS was responsible for development, qualification and pre-calibration of the CCD detector and its associated operation electronics. The image compression board was developed in co-operation with the Technische Universität Braunschweig, Institut für Datenverarbeitung.
In the scientific analysis of DISR data, the MPS focusses on investigating the aerosol distribution in the atmosphere and the materials on the surface of Titan.
|Lunar and Planetary Laboratory at University of Arizona
Contribution: Responsibilty for the entire DISR instrument
|Jet Propulsion Laboratory
Contributions: Software for data compression and modeling programs
|United States Geological Survey
Contribution: Hardware and software for image display and analysis
|Departement de Recherche Spatiale, Observatoire de Paris
Contributions: detectors for IR spectrometers, associated electronics, mechanical obturator, laboratory data and software for analysis and interpretation of spectral reflection measurements of the surface and of atmospheric gases
|Technische Universität Braunschweig, Institut für Datenverarbeitung
Contribution: DCT image data processor
|Lockheed Martin Astronautics - Flight Systems
Built the propulsion module subsystem for the CASSINI Spacecraft, have also assembled the DISR instrument.
|Cassini Project at NASA JPL|
|Huygens Probe at NASA JPL|
|Lunar and Planetary Laboratory (LPL) at University of Arizona|
|Saturn at LPL|
|Titan at LPL| | 0.85323 | 4.036054 |
On the dwarf planet Ceres, volcanoes rage — but instead of hot lava coming out of them as on Earth, they spew brine and ice.
The new evidence for the dwarf planet's icy volcanism, called cryovolcanism, came from NASA's Dawn space probe, which orbits Ceres and also studied the nearby asteroid Vesta.
Previously, Dawn identified a strange mountain and other features that seemed to have been created by an ice volcano. [Ceres Probably Has An Ice Volcano (Video)]
Now, scientists at the Max Planck Institute for Solar System Research (MPS) have found evidence of such volcanic activity in action at the Occator impact crater, whose central pit has a bright, mineral salt material coating it that forms an upraised dome.
The scientists found that the salty stuff in the crater is younger than the crater itself: It's only about 4 million years old, against the crater's 30-million-year age. That means the mineral salts welled up from below the surface, just as magma does on Earth. Such cryovolcanism has also been seen on Pluto and Saturn's moon Enceladus. At a distance of 257.4 million miles (444 million kilometers) from the sun, Ceres is the closest object that researchers have spotted that activity on.
Dawn has been following Ceres for two years. MPS scientists have found evidence of complicated activity on the dwarf planet's surface: fractures, avalanches and younger, smaller craters.
"In these data, the origin and evolution of the crater as it presents itself today can be read more clearly than ever before," Andreas Nathues, lead author on the new work and the MPS team's framing camera lead investigator, said in a statement.
Occator crater is in the northern hemisphere of Ceres and is 57 miles (92 km) in diameter. The crater hosts a 7-mile-wide pit in the center, and its rim rises to 2,460 feet (750 meters) from the surface. Within the pit is a bright dome about 1.8 miles (2.9 km) across, which is made of the younger, bright material the MPS scientists found. Data from infrared cameras shows that it contains salts called carbonates.
One thing that makes researchers think the dome is cryovolcanic, rather than just something buried beneath the crater site, is that other, later impacts did not expose similar material.
To estimate the age of the crater and the dome, the team counted craters in the area. Lots of cratering means a given patch of surface is older and has been exposed longer.
The odds are that the impact that made Occator allowed the brine to come closer to the surface, eventually erupting out.
The new work was detailed Feb. 17 in The Astronomical Journal. | 0.833939 | 3.987126 |
Several large facilities are now operational in the milli and submillimetric bands. There is ALMA (Atacama Large Millimeter / submillimeter Array) installed in Chile. It is an international project (Europe, United States and Japan), each member country participating in the construction and management of its own antennas.
Started in 2003 at the same time as the decommissioning of ESO’s 15 m SEST satellite dish, the ALMA network now includes 66 radio telescopes whose parabolas measure between 12 m and 7 m in diameter and work between 0.32-3.6 mm or between 936-83 GHz. The base can reach 16 km in length. It is the most powerful radioastronomy facility in the world. It reaches the resolution of a spatial VLBI of 0.0001 “or 0.1 mas at 850 microns or 345 GHz for a base of 10 km and an SNR = 30, which is not yet an optimized value.
ALMA was inaugurated in 2014 and cost $ 1.4 billion, including $ 5 million per antenna. By spreading this cost among the 1.1 billion inhabitants of the participating countries and broken down over its lifetime beyond a century, each European and American citizen contributes $ 1.2 / year or € 1 / year. $ 0.2 / yr or 30 yen / yr.
We will see in the records on astrophysics and cosmology that ALMA has to his credit important discoveries concerning the dynamics of primordial galaxies, Lyman-alpha emitters, quasars, black holes and protoplanetary disks among many other discoveries.
The second major facility is the CfA’s submarine beam array (SMA) in Hawaii, practically at the top of Mauna Kea (Pu’u Poli’ahu) at 4080 m altitude and has been operational since 1998. It has 8 parables 6 m in diameter work between 0.3 and 1.7 mm (999-42 GHz but limited between 700-180 GHz in practice) and the base can reach 509 meters.
Other radio astronomical observatories used in the millimetric bands to study both stellar (protostar) sites and the molecular components and properties of the more distant galaxies or pulsars include the well-known 100 m diameter GBT radio telescope at Green Bank West Virginia presented below from different angles.
With its 100×110 m diameter parabola, the GBT is the largest orientable radio-telescope. Since 2004, he replaces the Green Bank branch which collapsed in 1988, thankfully without victim. The GBT is 145 m high, its disc is 100×110 m in diameter and the installation weighs 8500 tons. His parable consists of 2004 moving panels managed by 2209 actuators that maintain its curvature to near 76 microns (RMS). In general, the movements of the panels do not exceed a few centimeters according to the astronomer D.J.Pisano of the University of West Virginia who uses the GBT to study the clouds of hydrogen. The GBT operates between 100 MHz and 116 GHz (and more generally between 290 MHz and 1 GHz) and has a gain of 51 dB at 432 MHz! | 0.845696 | 3.243049 |
Seeing is believing: Four lessons of the new black hole image
Black holes are cosmic prisons, where nothing escapes, not light or even data. But lots did come out of Wednesday's first image of the shadowy edge of a supermassive black hole. Here are four things we learned:
SEEING IS BELIEVING
Scientists have known for decades that black holes exist, but only indirectly. Three years ago, they essentially heard the sound of two smaller black holes crashing together to form a gravitational wave. The image revealed Wednesday showed the edges of the black hole—called the "event horizon"—for the first time.
There actually were a few academic holdouts who denied black holes existed, but now they can't, said Boston University astronomer Alan Marscher, who was on one of four imaging teams.
The new image shows a glowing ring that was obviously a black hole and its surroundings, said Harvard's Sheperd Doeleman, director of the Event Horizon Telescope team.
"We saw something so true," Doeleman said. "We saw something that really had a ring to it if you can use that phrase."
He said the team "uncovered part of the universe that was off-limits to us."
EINSTEIN IS RIGHT AGAIN
Each major astrophysics discovery of the last few decades tends to confirm Albert Einstein's general theory of relativity. It's a comprehensive explanation of gravity that the former patent clerk thought of in 1915 before computers and with much weaker telescopes.
On Wednesday, Einstein's predictions about the shape and glow of a big black hole proved right, and astronomer after astronomer paid homage to the master.
"Today general relativity passed another crucial test," said University of Waterloo astronomer Avery Broderick, a co-discoverer. "The Einstein equations are beautiful. So often in my experience, nature wants to be beautiful".''
It sounds strange to keep saying Einstein is right, but every time his general relativity theory is confirmed, "we kill a cloud of alternative theories" and gain better understanding how to create an even more comprehensive theory of physics, said Ethan Vishniac of Johns Hopkins University. He wasn't part of the discovery team.
GRAVITY IS POWERFUL
The black hole that scientists took a picture of is in the center of a galaxy called M87 and it is far bigger than anything in the Milky Way. Its mass—the chief measurement of a black hole—is 6.5 billion times as much as our sun's. The event horizon stretches about the breadth of our solar system.
"M87's huge black hole mass makes it really a monster even by supermassive black hole standards," said Sera Markoff, a discovery team member at the University of Amsterdam.
Some black holes are inactive, but not this one, she said. And that means it converts nearby gas and matter into energy with 100 times more efficiency than the nuclear fusion that powers the stars.
Black holes like these "temporarily become the most powerful engines in the universe," Markoff said.
WORKING TOGETHER WORKS
The project succeeded because of international cooperation among 20 countries and about 200 scientists at a cost of $50 million to $60 million, according to the National Science Foundation.
To get an image of a faraway black hole, scientists had to get eight radio telescopes on several continents, including Antarctica, to look at the same place at the same time. In getting the instruments connected, they essentially created one Earth-size connected telescope.
The amount of data generated was so massive that it could not be transmitted over the internet, so it was flown to data centers by jet.
The data collected was equivalent to a lifetime collection of selfies from 40,000 people, said discovery team member Daniel Marrone of the University of Arizona.
And just to start to take pictures the weather had to be good at all eight telescopes on the same days in April 2017. The scientists had only 10 days to look and got four perfect weather days, three of them at the start.
It then took more than a year for that data to be processed into the first glimpse of images that scientists saw in the summer of 2018.
Those images were so good that scientists at first worried that it was just too good to be true, Boston University's Marscher said.
© 2019 The Associated Press. All rights reserved. | 0.895604 | 3.6529 |
Recently, astronomers at the University of Geneva discovered a somewhat unusual planet with the telescope of the European Southern Observatory in Chile. This is a cloudy world, the atmosphere of which is so rich in iron that it rains from the sky. The exoplanet was named Wasp-76b and, according to an official press release, has such bizarre temperatures and chemistry that super-hot days allow iron to evaporate into the planet's atmosphere. At night it cools down, condenses and falls back – in the form of metal drops – iron rain. Wasp-76b is similar to Jupiter and is located in the constellation Pisces 390 light years from Earth. But how did scientists find out?
An exoplanet is a planet that is outside of our solar system. The first exoplanets were discovered in the 1980s, and by the end of January 2020, scientists were aware of the existence of 4,173 such planets.
According to a study published in the journal Nature, Wasp-76b is completely “blocked”. This means that one and the same half of the planet is always facing its sun and the other half is covered in darkness. The temperature on the sunny side reaches 2398 degrees Celsius, causing iron to evaporate in the atmosphere. When this happens, a strong wind carries iron to the dark side, where it cools and condenses, after which iron rain begins on the exoplanet. According to the study's authors, a press release published on the ESO website looks like metal drops are falling from the sky. If you've seen iron melt, remember that it becomes a flowing metal under the influence of high temperatures.
Read more news from the world of popular science and high technology on our channel in Yandex.Zen
Wasp-76b was launched a few years ago and is almost twice the size of Jupiter – the largest gas giant in our solar system – but it takes less than two days to orbit its star. Since the rotation of the planet coincides with the time it takes to complete the orbit, the same side is always facing the star. On this side, which does not look into the abyss of the cosmic ocean, it is always a day and the sky is clear. On the dark side, however, the temperature drops to around 1482 degrees Celsius and the sky is constantly covered by clouds from which metal precipitation falls.
Strong gusts of wind, the speed of which exceeds 6835 kilometers per hour, constantly transport part of the evaporated iron from the day to the night side of the planet. Clouds appear to form within the day-to-night transition zone as the temperature begins to drop. At the same time, iron vapor is not visible in the morning, the researchers find. The astronomers concluded that the most likely explanation is that there is iron rain on the dark side. The team was able to use the new Very Large Telescope tool from the European Southern Observatory in Chile to examine in detail the extreme climate of an exoplanet similar to Jupiter.
Although previously vaporized iron was discovered in an even hotter and more distant world, it is believed that it remains in a gaseous state throughout the planet. Researchers believe the first case of iron condensation was recorded on Wasp-76b. In one way or another, a traveler who chooses Wasp-76b definitely needs a durable umbrella (preferably made of metal) that melts at much higher temperatures.
In a fun illustration that graphic artist Frederick Peters created especially for the research team, a dancing astronaut holds an umbrella in front of an orange waterfall. "We sing in the rain of iron," says the inscription above. | 0.898821 | 3.584447 |
There’s something haunting the Ghost Nebula, located just 1,500 light years from Earth. It’s being driven to extinction by a star called Gamma Cassiopeiae, several light years away. Ultraviolet radiation from that powerful star actually makes the Ghost Nebula emit hydrogen-alpha radiation, which appears in red. The result is that the nebula is being destroyed, and the nebula killer’s lust for dust isn’t done: Several other nebulas in the area are slowly being wiped out by Gamma Cassiopeiae.
The European Space Agency’s Mars Express orbiter photographed this region of the red planet called Greeley Crater, combining data collected over 16 Mars orbits. The tan flat surface seen here, scarred with so many craters of different sizes, indicates this Martian area has seen a lot of meteorite impacts.
Galaxy NGC 5033, some 40 million light years away, seems similar to our own Milky Way in shape and size (about 100 million light years across), but differs in a few major ways. It has a very active galactic core, fueled by a supermassive black hole. This active nucleus means it’s classified as a Seyfert galaxy, and what we are seeing is the black hole devouring all the stars around it, causing the center to radiate in different wavelengths of the electromagnetic spectrum. Sadly, there’s nothing we can do for these stars; they’ve certainly been gobbled up by now, because their light took 40 million years to get to Hubble’s camera.
Before we mosey from Mars, check out this false color mound captured by the ExoMars Trace Gas Orbiter’s Colour and Stereo Surface Imaging System, called CaSSIS. This mound is located in an area called Juventae Chasma—just north of Valles Marineris, also known as the Martian Grand Canyon. Scientists study mounds like these to learn how the sediment was laid down over time. If we can figure out the composition of the layers and how they are formed, then we’ll gain greater understanding about ancient activity in this region.
Eat your heart out, Weather Channel: What we’re seeing is a cold front in space, in the galaxy cluster Perseus. This dance of galactic gas was caused by two galaxy clusters colliding with each other; the younger, colder region lies on the right, while the older gas departs the region on the left. When these astral bodies clash, their inner gas is shaken loose and expelled out into space. It is usually much colder than the rest of the galaxy, so the gas creates a cosmic cold front of galactic proportions. This incredible image was captured using three different x-ray observatories: NASA’s Chandra, ESA’s XMM-Newton, and the German Aerospace Centre-led ROSAT satellite.
This swirling tempest was captured by NASA’s Juno spacecraftNASA some 32,000 miles above Jupiter’s clouds, and for astronomers, this type of clarity is like candy. No more hazy bands of atmosphere! Rich details like the anticyclone known as White Oval A5 are yet another testimonial to how Juno, now in its 15th science orbit of the gas giant, has revolutionized research on the gas giant. | 0.895741 | 3.996455 |
So it's been an interesting week for comets. 2I/Borisov, the second interstellar comet we've ever seen, split in half; the comet we were hoping would be the brightest of the year (C/2019 Y4 ATLAS) instead disintegrated; and the first interstellar comet we've ever seen, 'Oumuamua, may be a shard shredded off a planet that got torn apart by its dying host star.
As for 'Oumuamua, well. It's a weird one, and a lot of people have been trying to figure it out. This idea that it’s a survivor of catastrophe has the quality of being new and somewhat different but also plausible. So let's take a look.
The first alien visitor to our solar system ever found shocked astronomers when it first appeared in 2017. Seen in observations by the Pan-STARRS telescope, it immediately was seen to be weird, moving on an orbit that looked like it came from deep interstellar space. The orbit was hyperbolic, meaning the object was moving too quickly to be bound to the Sun. It must have come from another star.
Then it got weirder. It tumbles, flipping end over end, roughly once every eight hours. These observations also indicated it's extremely elongated, at least five times longer than it is wide, so it's kinda cigar-shaped. That’s bizarre. We don’t see any objects in our solar system that elongated.
Then it got weirder again. As it headed away from the Sun it slowed down, as expected from the Sun's gravity pulling it, but it wasn't slowing down rapidly enough. The most likely reason is that it was outgassing, with ice turning to gas and expanding away, acting like a very low-power rocket. But sunlight-reflecting dust escaping with the gas would make it easy to see, yet nothing was seen around it!
This caused speculation that it’s an alien spaceship, which is … unlikely. Or it could be a fractal snowflake. That too is bizarre but maybe more likely … ? Another thought is that it may have a hard crust around it, preventing a lot of gas from escaping.
The overarching thing here is that it's weird and we don't have a good explanation for it. And that's where the new research comes in.
They looked at what would happen if an object like a rubble pile asteroid — literally a bunch of rocks held together by their own gravity, a very common structure for small bodies in our solar system — got too close to its star. They found that if it gets too close, the tides from the star will tear it apart. That's old news (in that we know things getting too close to stars can be ripped into pieces), but they also found that the heat from the passage does two things. First, the object is sintered; tiny particles break off and recollect onto it, and as they do they tend to fall on the ends pointing toward and away from the star due to tides, elongating the object. That's pretty cool! Second, a lot of stuff that vaporizes at lower temperatures goes away, leaving behind a hardened crust.
This does explain a lot of 'Oumuamua’s behavior and appearance. But they also found that long-period comets (with orbits hundreds or thousands of years long) that pass very close to their host stars can also break up and create shards like 'Oumuamua in a similar way, providing a second creation path.
And there's a third that's pretty interesting. They looked at planets being the source. A super-Earth, bigger and more massive than Earth, on a highly elliptical orbit its star (maybe poked gravitationally by a second star in the system and dropped too close to the first star) can be disrupted in the same way, and if the pass is close enough the process winds up being similar to what happens to the rubble pile asteroids and long-period comets. It may be somewhat less likely, but a single event like that can create a lot of 'Oumuamuas. Billions. More.
If the star is a white dwarf — the remains of a star like the Sun after it uses up its nuclear fuel and blows off its outer layers, leaving just the hot and very dense core behind — then this process is really efficient. White dwarfs have immense gravity, and can easily tear a planet to shreds. Moreover, we have tons of evidence this actually happens. That’s terrifying — the idea of planets being torn apart like the Cookie Monster going to town on a snickerdoodle — but the Universe really seems to like ripping up perfectly good things like asteroids and comets and planets.
So this work is theoretical, using physical models of how objects break up, so the question is: Is it right? The prediction it makes is that we'll see a lot more objects as elongated as 'Oumuamua, so what we need to do is find more! Extrapolating from these observations indicates that interstellar bodies like 'Oumuamua are relatively common, it's just that we haven't been able to see them (and follow up on them with big observatories) until recently. So we'll see. If the next ten in a row are more like Borisov then that's hard to explain this way, but if they look more like 'Oumuamua then maybe this idea holds water.
I love that there are so many ideas about what this thing is. But that's par for the course in science; when something new and strange is found, tons of ideas bubble up. More observations eliminate lots of them, and the ones that survive get tested even more. Eventually one or a few survive, and these become the standard against which other ideas must compete.
It's like evolutionary science for science itself, and the process helps us find our way to the truth. I’m really curious what the truth is about 'Oumuamua, and hopefully we’ll have a lot more such beasts to look at that will help us along the path to finding it. | 0.915041 | 3.669624 |
Comet Hale–Bopp, shortly after passing perihelion in April 1997
|Discovered by||Alan Hale|
|Discovery date||July 23, 1995|
|The Great Comet of 1997,|
|Orbital characteristics A|
|Semi-major axis||186 AU|
|Orbital period||2520–2533 yr|
(Barycentric 2391 yr)
|Last perihelion||April 1, 1997|
|Next perihelion||4385 ± 2.0 AD|
Comet Hale–Bopp (formally designated C/1995 O1) is a comet that was perhaps the most widely observed of the 20th century and one of the brightest seen for many decades.
Alan Hale and Thomas Bopp discovered Comet Hale–Bopp separately on July 23, 1995 before it became visible to the naked eye. It is difficult to predict the maximum brightness of new comets with any degree of certainty, but Hale–Bopp met or exceeded most predictions when it passed perihelion on April 1, 1997. It was visible to the naked eye for a record 18 months, twice as long as the Great Comet of 1811, the previous record holder. Accordingly, Hale–Bopp was dubbed the Great Comet of 1997.
Hale had spent many hundreds of hours searching for comets without success, and was tracking known comets from his driveway in New Mexico when he chanced upon Hale–Bopp just after midnight. The comet had an apparent magnitude of 10.5 and lay near the globular cluster M70 in the constellation of Sagittarius. Hale first established that there was no other deep-sky object near M70, and then consulted a directory of known comets, finding that none were known to be in this area of the sky. Once he had established that the object was moving relative to the background stars, he emailed the Central Bureau for Astronomical Telegrams, the clearing house for astronomical discoveries.
Bopp did not own a telescope. He was out with friends near Stanfield, Arizona, observing star clusters and galaxies when he chanced across the comet while at the eyepiece of his friend's telescope. He realized he might have spotted something new when, like Hale, he checked his star maps to determine if any other deep-sky objects were known to be near M70, and found that there were none. He alerted the Central Bureau for Astronomical Telegrams through a Western Union telegram. Brian G. Marsden, who had run the bureau since 1968, laughed, "Nobody sends telegrams anymore. I mean, by the time that telegram got here, Alan Hale had already e-mailed us three times with updated coordinates."
Hale–Bopp's orbital position was calculated as 7.2 astronomical units (AU) from the Sun, placing it between Jupiter and Saturn and by far the greatest distance from Earth at which a comet had been discovered by amateurs. Most comets at this distance are extremely faint, and show no discernible activity, but Hale–Bopp already had an observable coma. A precovery image taken at the Anglo-Australian Telescope in 1993 was found to show the then-unnoticed comet some 13 AU from the Sun, a distance at which most comets are essentially unobservable. (Halley's Comet was more than 100 times fainter at the same distance from the Sun.) Analysis indicated later that its comet nucleus was 60±20 kilometres in diameter, approximately six times the size of Halley.
Its great distance and surprising activity indicated that comet Hale–Bopp might become very bright when it reached perihelion in 1997. However, comet scientists were wary – comets can be extremely unpredictable, and many have large outbursts at great distance only to diminish in brightness later. Comet Kohoutek in 1973 had been touted as a 'comet of the century' and turned out to be unspectacular.
Hale–Bopp became visible to the naked eye in May 1996, and although its rate of brightening slowed considerably during the latter half of that year, scientists were still cautiously optimistic that it would become very bright. It was too closely aligned with the Sun to be observable during December 1996, but when it reappeared in January 1997 it was already bright enough to be seen by anyone who looked for it, even from large cities with light-polluted skies.
The Internet was a growing phenomenon at the time, and numerous websites that tracked the comet's progress and provided daily images from around the world became extremely popular. The Internet played a large role in encouraging the unprecedented public interest in comet Hale–Bopp.
As the comet approached the Sun, it continued to brighten, shining at 2nd magnitude in February, and showing a growing pair of tails, the blue gas tail pointing straight away from the Sun and the yellowish dust tail curving away along its orbit. On March 9, a solar eclipse in China, Mongolia and eastern Siberia allowed observers there to see the comet in the daytime. Hale–Bopp had its closest approach to Earth on March 22, 1997, at a distance of 1.315 AU.
As it passed perihelion on April 1, 1997, the comet developed into a spectacular sight. It shone brighter than any star in the sky except Sirius, and its dust tail stretched 40–45 degrees across the sky. The comet was visible well before the sky got fully dark each night, and while many great comets are very close to the Sun as they pass perihelion, comet Hale–Bopp was visible all night to northern hemisphere observers.
After its perihelion passage, the comet moved into the southern celestial hemisphere. The comet was much less impressive to southern hemisphere observers than it had been in the northern hemisphere, but southerners were able to see the comet gradually fade from view during the second half of 1997. The last naked-eye observations were reported in December 1997, which meant that the comet had remained visible without aid for 569 days, or about 18 and a half months. The previous record had been set by the Great Comet of 1811, which was visible to the naked eye for about 9 months.
The comet continued to fade as it receded, but is still being tracked by astronomers. In October 2007, 10 years after the perihelion and at distance of 25.7 AU from Sun, the comet was still active as indicated by the detection of the CO-driven coma. Herschel Space Observatory images taken in 2010 suggest comet Hale–Bopp is covered in a fresh frost layer. Hale–Bopp was again detected in December 2010 when it was 30.7 AU away from the Sun, and on August 7, 2012, at a 33.2 AU distance from the Sun. Astronomers expect that the comet will remain observable with large telescopes until perhaps 2020, by which time it will be nearing 30th magnitude. By this time it will become very difficult to distinguish the comet from the large numbers of distant galaxies of similar brightness.
The comet likely made its previous perihelion 4,200 years ago, in July 2215 BC. The estimated closest approach to Earth was 1.4 AU, and it may have been observed in ancient Egypt during the 6th dynasty reign of the Pharaoh Pepi II (Reign: 2247 - c. 2216 BC). Pepi's pyramid at Saqqara contains a text referring to an "nhh-star" as a companion of the pharaoh in the heavens, where "nhh" is the hieroglyph for long hair.
Hale–Bopp may have had a near collision with Jupiter in early June 2215 BC, which probably caused a dramatic change in its orbit, and 2215 BC may have been its first passage through the inner Solar System. The comet's current orbit is almost perpendicular to the plane of the ecliptic, so further close approaches to planets will be rare. However, in April 1996 the comet passed within 0.77 AU of Jupiter, close enough for its orbit to be measurably affected by the planet's gravity. The comet's orbit was shortened considerably to a period of roughly 2,533 years, and it will next return to the inner Solar System around the year 4385. Its greatest distance from the Sun (aphelion) will be about 370 AU, reduced from about 525 AU.
The estimated probability of Hale-Bopp's striking Earth in future passages through the inner Solar System is remote, about 2.5×10−9 per orbit. However, given that the comet nucleus is around 60 km in diameter, the consequences of such an impact would be apocalyptic. Weissman conservatively estimates the diameter at 35 km; an estimated density of 0.6 g/cm3 then gives a cometary mass of 1.3×1019 g. At a probable impact velocity of 52.5 km/s, impact energy can be calculated as 1.9×1032 ergs, or 4.4×109 megatons, about 44 times the estimated energy of the K-T impact event.
Over many orbits, the cumulative effect of gravitational perturbations on comets with high orbital inclinations and small perihelion distances is generally to reduce the perihelion distance to very small values. Hale–Bopp has about a 15% chance of eventually becoming a sungrazing comet through this process.
Comet Hale–Bopp was observed intensively by astronomers during its perihelion passage, and several important advances in cometary science resulted from these observations. The dust production rate of the comet was very high (up to 2.0×106 kg/s), which may have made the inner coma optically thick. Based on the properties of the dust grains—high temperature, high albedo and strong 10 μm silicate emission feature—the astronomers concluded the dust grains are smaller than observed in any other comet.
Hale–Bopp showed the highest ever linear polarization detected for any comet. Such polarization is the result of solar radiation getting scattered by the dust particles in the coma of the comet and depends on the nature of the grains. It further confirms that the dust grains in the coma of comet Hale–Bopp were smaller than inferred in any other comet.
One of the most remarkable discoveries was that the comet had a third type of tail. In addition to the well-known gas and dust tails, Hale–Bopp also exhibited a faint sodium tail, only visible with powerful instruments with dedicated filters. Sodium emission had been previously observed in other comets, but had not been shown to come from a tail. Hale–Bopp's sodium tail consisted of neutral atoms (not ions), and extended to some 50 million kilometres in length.
The source of the sodium appeared to be the inner coma, although not necessarily the nucleus. There are several possible mechanisms for generating a source of sodium atoms, including collisions between dust grains surrounding the nucleus, and "sputtering" of sodium from dust grains by ultraviolet light. It is not yet established which mechanism is primarily responsible for creating Hale–Bopp's sodium tail, and the narrow and diffuse components of the tail may have different origins.
While the comet's dust tail roughly followed the path of the comet's orbit and the gas tail pointed almost directly away from the Sun, the sodium tail appeared to lie between the two. This implies that the sodium atoms are driven away from the comet's head by radiation pressure.
The abundance of deuterium in comet Hale–Bopp in the form of heavy water was found to be about twice that of Earth's oceans. If Hale–Bopp's deuterium abundance is typical of all comets, this implies that although cometary impacts are thought to be the source of a significant amount of the water on Earth, they cannot be the only source.
Deuterium was also detected in many other hydrogen compounds in the comet. The ratio of deuterium to normal hydrogen was found to vary from compound to compound, which astronomers believe suggests that cometary ices were formed in interstellar clouds, rather than in the solar nebula. Theoretical modelling of ice formation in interstellar clouds suggests that comet Hale–Bopp formed at temperatures of around 25–45 kelvins.
Spectroscopic observations of Hale–Bopp revealed the presence of many organic chemicals, several of which had never been detected in comets before. These complex molecules may exist within the cometary nucleus, or might be synthesised by reactions in the comet.
Detection of argon
Hale–Bopp was the first comet where the noble gas argon was detected. Noble gases are chemically inert and highly volatile, and since different noble elements have different sublimation temperatures, they can be used for probing the temperature histories of the cometary ices. Krypton has a sublimation temperature of 16–20 K and was found to be depleted more than 25 times relative to the solar abundance, while argon with its higher sublimation temperature was enriched relative to the solar abundance. Together these observations indicate that the interior of Hale–Bopp has always been colder than 35–40 K, but has at some point been warmer than 20 K. Unless the solar nebula was much colder and richer in argon than generally believed, this suggests that the comet formed beyond Neptune in the Kuiper belt region and then migrated outward to the Oort cloud.
Comet Hale–Bopp's activity and outgassing were not spread uniformly over its nucleus, but instead came from several specific jets. Observations of the material streaming away from these jets allowed astronomers to measure the rotation period of the comet, which was found to be about 11 hours 46 minutes.
Binary nucleus question
In 1997 a paper was published that hypothesised the existence of a binary nucleus to fully explain the observed pattern of comet Hale–Bopp's dust emission observed in October 1995. The paper was based on theoretical analysis, and did not claim an observational detection of the proposed satellite nucleus, but estimated that it would have a diameter of about 30 km, with the main nucleus being about 70 km across, and would orbit in about three days at a distance of about 180 km. This analysis was confirmed by observations in 1996 using Wide-Field Planetary Camera 2 of the Hubble Space Telescope which had taken images of the comet that revealed the satellite.
Although observations using adaptive optics in late 1997 and early 1998 showed a double peak in the brightness of the nucleus, controversy still exists over whether such observations can only be explained by a binary nucleus. The discovery of the satellite was not confirmed by other observations. Also, while comets have been observed to break up before, no case had been found of a stable binary nucleus until the subsequent discovery of P/2006 VW139. Given the very small mass of this comet, the orbit of the binary nucleus would be easily disrupted by the gravity of the Sun and planets.
In November 1996, amateur astronomer Chuck Shramek (1950–2000) of Houston, Texas took a CCD image of the comet which showed a fuzzy, slightly elongated object nearby. His computer sky-viewing program did not identify the star, so Shramek called the Art Bell radio program Coast to Coast AM to announce that he had discovered a "Saturn-like object" following Hale–Bopp. UFO enthusiasts such as remote viewing proponent, and Emory University political science professor Courtney Brown soon concluded that there was an alien spacecraft following the comet.
Several astronomers claimed that the object was simply the 8.5-magnitude star SAO141894, including Alan Hale. They noted that the star did not appear on Shramek's computer program because the user preferences were set incorrectly. Art Bell claimed to have obtained an image of the object from an anonymous astrophysicist who was about to confirm its discovery. However, astronomers Olivier Hainaut and David Tholen of the University of Hawaii stated that the alleged photo was an altered copy of one of their own comet images.
Thirty-nine members of the Heaven's Gate cult committed mass suicide in March 1997 with the intention of teleporting to a spaceship which they believed was flying behind the comet. Nancy Lieder claims to receive messages from aliens through an implant in her brain, and she stated that Hale–Bopp was a fiction designed to distract the population from the coming arrival of "Nibiru" or "Planet X", a giant planet whose close passage would disrupt the Earth's rotation, causing global cataclysm. Her original date for the apocalypse was May 2003, which passed without incident, but various conspiracy websites continued to predict the coming of Nibiru, most of whom tied it to the 2012 phenomenon. Despite these predictions, as of the year 2020 the mystery planet Nibiru has not crashed into the Earth.
Its lengthy period of visibility and extensive coverage in the media meant that Hale–Bopp was probably the most-observed comet in history, making a far greater impact on the general public than the return of Halley's Comet in 1986, and certainly seen by a greater number of people than witnessed any of Halley's previous appearances. For instance, 69% of Americans had seen Hale–Bopp by April 9, 1997.
Hale–Bopp was a record-breaking comet—the farthest comet from the Sun discovered by amateurs, with the largest well-measured cometary nucleus known after 95P/Chiron, and it was visible to the naked eye for twice as long as the previous record-holder. It was also brighter than magnitude 0 for eight weeks, longer than any other recorded comet.
Carolyn Shoemaker and her husband Gene, both famous for co-discovering comet Shoemaker–Levy 9, were involved in a car crash after photographing the comet. Gene died in the crash and his ashes were sent to the Moon aboard NASA's Lunar Prospector mission along with an image of Hale–Bopp, "the last comet that the Shoemakers observed together".
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Nobody sends telegrams anymore...
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|Wikimedia Commons has media related to Comet Hale-Bopp.|
- CometBase: Comet Hale-Bopp
- Cometography.com: Comet Hale-Bopp
- NASA Hale-Bopp page
- Shadow and Substance.com: Static orbital diagram
- Comet Nucleus Animation
- Kramer, Emily A.; Fernandez, Yanga R.; Lisse, Carey M.; Kelley, Michael S.P.; Woodney, Laura M. (2014). "A dynamical analysis of the dust tail of Comet C/1995 O1 (Hale–Bopp) at high heliocentric distances". Icarus. 236: 136–145. arXiv:1404.2562. Bibcode:2014Icar..236..136K. doi:10.1016/j.icarus.2014.03.033.
- Hale-Bopp at the JPL Small-Body Database | 0.853371 | 3.839661 |
“Weather” in clusters of galaxies may explain a long-standing puzzle, according to a team of researchers at the University of Cambridge. The scientists used sophisticated simulations to show how powerful jets from supermassive black holes are disrupted by the motion of hot gas and galaxies, preventing gas from cooling, which could otherwise form stars. The team published their work in the journal Monthly Notices of the Royal Astronomical Society.
Typical clusters of galaxies have several thousand member galaxies, which can be very different from our own Milky Way and vary in size and shape. These systems are embedded in very hot gas known as the intracluster medium (ICM), all of which live in an unseen halo of so-called ‘dark matter’.
A large number of galaxies have supermassive black holes in their centers, and these often have high-speed jets of material stretching over thousands of light-years that can inflate very hot lobes in the ICM.
The researchers, based at the Kavli Institute for Cosmology and the Institute of Astronomy, performed state-of-the-art simulations looking at the jet lobes in fine detail and the X-rays emitted as a result. The model captures the birth and cosmological evolution of the galaxy cluster, and allowed the scientists to investigate with unprecedented realism how the jets and lobes they inflate interact with a dynamic ICM.
They found that the mock X-ray observations of the simulated cluster revealed the so-called “X-ray cavities” and “X-ray bright rims” generated by supermassive black hole-driven jets, which itself is distorted by motions in the cluster, remarkably resemble those found in observations of real galaxy clusters.
Dr. Martin Bourne of the Institute of Astronomy in Cambridge led the team. He commented: “We have developed new computational techniques, which harness the latest high-performance computing technology, to model for the first time the jet lobes with more than a million elements in fully realistic clusters. This allows us to place the physical processes that drive the liberation of the jet energy under the microscope.”
As galaxies move around in the cluster, the simulation shows they create a kind of ‘weather’, moving, deforming and destroying the hot lobes of gas found at the end of the black hole jets. The jet lobes are enormously powerful and if disrupted, deliver vast amounts of energy to the ICM.
The Cambridge team believe that this cluster weather disruption mechanism may solve an enduring problem: understanding why ICM gas does not cool and form stars in the cluster center. This so-called “cooling flow” puzzle has plagued astrophysicists for more than 25 years.
The simulations performed provide a tantalizing new solution that could solve this problem. Dr. Bourne commented: “The combination of the huge energies pumped into the jet lobes by the supermassive black hole and the ability of cluster weather to disrupt the lobes and redistribute this energy to the ICM provides a simple and yet elegant mechanism to solve the cooling flow problem.”
A series of next-generation X-ray space telescopes will launch into orbit over the next decade. These advanced instruments should help settle the debate – and if intergalactic weather really does stop the birth of stars.
Reference: “AGN jet feedback on a moving mesh: lobe energetics and X-ray properties in a realistic cluster environment” by Martin A Bourne, Debora Sijacki and Ewald Puchwein, 26 September 2019, Monthly Notices of the Royal Astronomical Society.
The simulations have been performed on the STFC DiRAC HPC facilities which are part of the national e-Infrastructure. The research was funded by the European Research Council, STFC and the Kavli Foundation. | 0.873827 | 4.106413 |
|West wall of Aristarchus crater seen obliquely by the LROC Narrow Angle Cameras from an altitude of only 26 kilometers. Scene is about 12 kilometers wide at the base, NAC observation M175569775, LRO orbit 11008, November 10, 2011. View the full resolution west wall panoramic image HERE [NASA/GSFC/Arizona State University].|
Lunar Reconnaissance Orbiter Camera
Arizona State University
The Aristarchus plateau is one of the most geologically diverse places on the Moon: a mysterious raised flat plateau, a giant rille carved by enormous outpourings of lava, fields of explosive volcanic ash, and all surrounded by massive flood basalts. A relatively recent asteroid (or comet) slammed into this geologic wonderland, blowing a giant hole in the ground revealing a cross section of over 3000 meters (9800 ft) of geology. No wonder planners for the Apollo missions put this plateau high on its list of targets for human exploration. This amazing image was acquired on 10 November 2011 as LRO passed north-to-south about 70 km east of the crater's center while it was slewed 70° to the west. The spacecraft was only 26 km (16.2 miles) above the surface; about two times lower than normal. For a sense of scale, that altitude is only a little over twice as high as a commercial jets fly above the Earth!
|Full panoramic view of the west wall of Aristarchus crater revealing impact melt deposits, exposures of high reflectance, anorthosite, streamers of pyroclastic ash and blocks up to 100 meters in size. Full width of panorama is about 25 km, M175569775 [NASA/GSFC/Arizona State University].|
|Six sections, reluctantly reduced from their original 40 centimeter-per-pixel resolution, lifted from LROC Narrow Angle Camera observation M168516102R, LRO orbit 9968, August 20, 2011 (when the LRO orbit was briefly lowered to an average 25 kilometer high perilune, are unparalleled examples of the west-northwestern Aristarchus crater wall's variety of textures. Solar illumination incidence angle was 42.43° centered on 24.36°N, 312.18°E from 25.05 km altitude [NASA/GSFC/Arizona State University].|
|Dawn View of Aristarchus: Sunrise lighting enhances surface texture on Aristarchus crater (40 km diameter). Northwest (upper left) of the crater is the mysterious Aristarchus plateau, to the east, southeast, and south lies the edge of the vast mare Oceanus Procellarum. Small white arrows indicate approximate corners of the NAC panorama, In the full size LROC context image, a vertical line on the right shows the LRO orbit ground track when the Featured Image NAC panorama was acquired. (LROC WAC mosaic) [NASA/GSFC/Arizona State University].|
|Early afternoon Aristarchus: Early afternoon WAC mosaic of Aristarchus crater to compare with the sunrise mosaic above. Again, small white arrows indicate the approximate corners of the Featured Image NAC panorama, and in the original context image a vertical line on the right (beyond the field of view of this crop from the original) shows LRO orbit ground track [NASA/GSFC/Arizona State University].|
The floor of Aristarchus crater provides explorers a unique opportunity to study a wide variety of lunar rocks and geologic processes, possibly including how lunar granite forms. Diverse materials such as dark, multilayered mare basalts in the walls, bright crustal rocks in the central peak, impact melt, and even regional pyroclastic materials blanketing the crater are brought to the floor and accumulated through mass wasting, creating a bountiful trove of
Jump to the full resolution west wall panoramic image, and view our flyover video on Youtube.
Previous LROC Aristarchus Featured Images:
Geologic Diversity of the Aristarchus Plateau
Striated Blocks in Aristarchus Crater
Aristarchus Plateau Pyroclastics
Central peak of Aristarchus (with fly-over) | 0.840251 | 3.479096 |
Gibbous ♑ Capricorn
Moon phase on 26 May 2013 Sunday is Waning Gibbous, 16 days old Moon is in Sagittarius.Share this page: twitter facebook linkedin
Previous main lunar phase is the Full Moon before 1 day on 25 May 2013 at 04:25.
Moon rises in the evening and sets in the morning. It is visible to the southwest and it is high in the sky after midnight.
Moon is passing about ∠24° of ♐ Sagittarius tropical zodiac sector.
Lunar disc appears visually 4.1% wider than solar disc. Moon and Sun apparent angular diameters are ∠1973" and ∠1894".
Next Full Moon is the Strawberry Moon of June 2013 after 27 days on 23 June 2013 at 11:32.
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 16 days old. Earth's natural satellite is moving from the middle to the last part of current synodic month. This is lunation 165 of Meeus index or 1118 from Brown series.
Length of current 165 lunation is 29 days, 15 hours and 28 minutes. This is the year's longest synodic month of 2013. It is 10 minutes longer than next lunation 166 length.
Length of current synodic month is 2 hours and 44 minutes longer than the mean length of synodic month, but it is still 4 hours and 19 minutes shorter, compared to 21st century longest.
This New Moon true anomaly is ∠143.3°. At beginning of next synodic month true anomaly will be ∠168.8°. 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°).
Moon is reaching point of perigee on this date at 01:45, this is 12 days after last apogee on 13 May 2013 at 13:31 in ♊ Gemini. Lunar orbit is starting to get wider, while the Moon is moving outward the Earth for 14 days ahead, until it will get to the point of next apogee on 9 June 2013 at 21:40 in ♊ Gemini.
This perigee Moon is 358 375 km (222 684 mi) away from Earth. It is 4 133 km closer than the mean perigee distance, but it is still 11 981 km farther than the closest perigee of 21st century.
2 days after its ascending node on 24 May 2013 at 00:40 in ♏ Scorpio, the Moon is following the northern part of its orbit for the next 10 days, until it will cross the ecliptic from North to South in descending node on 6 June 2013 at 00:59 in ♉ Taurus.
2 days after beginning of current draconic month in ♏ Scorpio, the Moon is moving from the beginning to the first part of it.
At 04:47 on this date the Moon is meeting its South standstill point, when it will reach southern declination of ∠-20.182°. Next 13 days the lunar orbit will move in opposite northward direction to face North declination of ∠20.200° in its northern standstill point on 8 June 2013 at 19:16 in ♊ Gemini.
After 13 days on 8 June 2013 at 15:56 in ♊ Gemini, the Moon will be in New Moon geocentric conjunction with the Sun and this alignment forms next Sun-Moon-Earth syzygy. | 0.848363 | 3.139091 |
Liquid water is a requirement for life on Earth. But in other, much colder worlds, life might exist beyond the bounds of water-based chemistry.
Taking a simultaneously imaginative and rigidly scientific view, Cornell chemical engineers and astronomers offer a template for life that could thrive in a harsh, cold world – specifically Titan, the giant moon of Saturn. A planetary body awash with seas not of water, but of liquid methane, Titan could harbor methane-based, oxygen-free cells that metabolize, reproduce and do everything life on Earth does.
Their theorized cell membrane, composed of small organic nitrogen compounds and capable of functioning in liquid methane temperatures of 292 degrees below zero, is published in Science Advances, Feb. 27. The work is led by chemical molecular dynamics expert Paulette Clancy, the Samuel W. and Diane M. Bodman Professor of Chemical and Biomolecular Engineering, with first author James Stevenson, a graduate student in chemical engineering. The paper’s co-author is Jonathan Lunine, the David C. Duncan Professor in the Physical Sciences in the College of Arts and Sciences’ Department of Astronomy.
Lunine is an expert on Saturn’s moons and an interdisciplinary scientist on the Cassini-Huygens mission that discovered methane-ethane seas on Titan. Intrigued by the possibilities of methane-based life on Titan, and armed with a grant from the Templeton Foundation to study non-aqueous life, Lunine sought assistance about a year ago from Cornell faculty with expertise in chemical modeling. Clancy, who had never met Lunine, offered to help.
“We’re not biologists, and we’re not astronomers, but we had the right tools,” Clancy said. “Perhaps it helped, because we didn’t come in with any preconceptions about what should be in a membrane and what shouldn’t. We just worked with the compounds that we knew were there and asked, ‘If this was your palette, what can you make out of that?’”
On Earth, life is based on the phospholipid bilayer membrane, the strong, permeable, water-based vesicle that houses the organic matter of every cell. A vesicle made from such a membrane is called a liposome. Thus, many astronomers seek extraterrestrial life in what’s called the circumstellar habitable zone, the narrow band around the sun in which liquid water can exist. But what if cells weren’t based on water, but on methane, which has a much lower freezing point?
The Latest on: Methane-based life
via Google News
The Latest on: Methane-based life
- Astronomer Mike Brown on the Solar System's Outer Reacheson April 27, 2020 at 1:40 pm
If we find microbial life in Europa, if we find life spewing out the vents on Enceladus, if we find hints of some sort of weird, methane-based life on Titan, then we would know that life is really ...
- Which Moons in Our Solar System Have Best Chance for Life?on April 23, 2020 at 2:41 am
Titan is often thought to have an environment similar to that on primordial Earth. Although methane-based life forms are only seen as being hypothetical today, scientists have modeled certain ...
- Volunteering to Make a Differenceon April 3, 2020 at 5:00 pm
It’s really almost a life-changing experience ... “Even as a researcher, I can make a huge impact on poor communities.” Whether he helps develop methane-based electricity for areas that don’t have any ...
- NASA maps Saturn's moon Titan, which may support extraterrestrial lifeon November 19, 2019 at 5:55 am
"Titan has an active methane-based hydrologic cycle that has shaped ... with some even suggesting it could support life. Earlier this year, NASA announced the latest mission in its New Frontiers ...
- US Chemical Export Outlook: Expected to Soar as Shale Strengthens Industryon March 30, 2017 at 9:03 am
“Chemical producers are clearly looking to take advantage of continued low natural gas prices in the U.S., which is enabling the significant expansion of these methane-based projects ... biotechnology ...
- Our Next Trip to Saturn Will Be to Search For Alien Lifeon December 20, 2016 at 8:18 am
So, why only search for life-as-we-know-it when we can visit ... A hypothetical model of a methane-based cellular organism living in Titan’s oceans. Image: James Stevenson E2T would also ...
- It's Time to Go Alien Hunting on Titanon March 2, 2015 at 12:10 am
methane-based cell that's stable in Titan's sub-zero oceans. They call their alien life form an "azotosome" : The azotosome is made from nitrogen, carbon and hydrogen molecules known to exist in ...
- The Top 13 Space Stories of 2006on December 7, 2014 at 2:39 am
"I'm betting 10 years of my life that they are." For five years ... "That kind of system, in motion like that, with a contained weather cycle—it's just ideal for a methane-based organism," McKay says.
- Methane Migraineon May 1, 2012 at 7:53 pm
"The other major component is to assure that when agencies analyze projects, they are free and equipped to look at the full range of life-cycle impacts of the ... directly related to the operation of ...
- Life Newson December 23, 2011 at 5:47 pm
A team of scientists from Cornell University believe that oxygen-free, methane-based life forms could exist on Titan. Such life forms would be unlike anything we know on Earth and live in ...
via Bing News | 0.877434 | 3.53704 |
New observations from the infrared Herschel Space Observatory reveal that an exploding star expelled the equivalent of between 160,000 and 230,000 Earth masses of fresh dust. This enormous quantity suggests that exploding stars, called supernovae, are the answer to the long-standing puzzle of what supplied our early universe with dust.
“This discovery illustrates the power of tackling a problem in astronomy with different wavelengths of light,” said Paul Goldsmith, the NASA Herschel project scientist at NASA’s Jet Propulsion Laboratory, Pasadena, Calif., who is not a part of the current study. “Herschel’s eye for longer-wavelength infrared light has given us new tools for addressing a profound cosmic mystery.”
Cosmic dust is made of various elements, such as carbon, oxygen, iron and other atoms heavier than hydrogen and helium. It is the stuff of which planets and people are made, and it is essential for star formation. Stars like our sun churn out flecks of dust as they age, spawning new generations of stars and their orbiting planets.
Astronomers have for decades wondered how dust was made in our early universe. Back then, sun-like stars had not been around long enough to produce the enormous amounts of dust observed in distant, early galaxies. Supernovae, on the other hand, are the explosions of massive stars that do not live long.
The new Herschel observations are the best evidence yet that supernovae are, in fact, the dust-making machines of the early cosmos.
“The Earth on which we stand is made almost entirely of material created inside a star,” explained the principal investigator of the survey project, Margaret Meixner of the Space Telescope Science Institute, Baltimore, Md. “Now we have a direct measurement of how supernovae enrich space with the elements that condense into the dust that is needed for stars, planets and life.”
The study, appearing in the July 8 issue of the journal Science, focused on the remains of the most recent supernova to be witnessed with the naked eye from Earth. Called SN 1987A, this remnant is the result of a stellar blast that occurred 170,000 light-years away and was seen on Earth in 1987. As the star blew up, it brightened in the night sky and then slowly faded over the following months. Because astronomers are able to witness the phases of this star’s death over time, SN 1987A is one of the most extensively studied objects in the sky.
Initially, astronomers weren’t sure if the Herschel telescope could even see this supernova remnant. Herschel detects the longest infrared wavelengths, which means it can see very cold objects that emit very little heat, such as dust. But it so happened that SN 1987A was imaged during a Herschel survey of the object’s host galaxy — a small neighboring galaxy called the Large Magellanic Cloud (it’s called large because it’s bigger than its sister galaxy, the Small Magellanic Cloud).
After the scientists retrieved the images from space, they were surprised to see that SN 1987A was aglow with light. Careful calculations revealed that the glow was coming from enormous clouds of dust — consisting of 10,000 times more material than previous estimates. The dust is minus 429 to minus 416 degrees Fahrenheit (about minus 221 to 213 Celsius) — colder than Pluto, which is about minus 400 degrees Fahrenheit (204 degrees Celsius).
“Our Herschel discovery of dust in SN 1987A can make a significant understanding in the dust in the Large Magellanic Cloud,” said Mikako Matsuura of University College London, England, the lead author of the Science paper. “In addition to the puzzle of how dust is made in the early universe, these results give us new clues to mysteries about how the Large Magellanic Cloud and even our own Milky Way became so dusty.”
Previous studies had turned up some evidence that supernovae are capable of producing dust. For example, NASA’s Spitzer Space Telescope, which detects shorter infrared wavelengths than Herschel, found 10,000 Earth-masses worth of fresh dust around the supernova remnant called Cassiopea A. Hershel can see even colder material, and thus the coldest reservoirs of dust. “The discovery of up to 230,000 Earths worth of dust around SN 1987A is the best evidence yet that these monstrous blasts are indeed mighty dust makers,” said Eli Dwek, a co-author at NASA Goddard Space Flight Center in Greenbelt, Md.
Herschel is led by the European Space Agency with important contributions from NASA. | 0.90541 | 4.098917 |
In physics (especially astrophysics), redshift happens when light or other electromagnetic radiation from an object moving away from the observer is increased in wavelength, or shifted to the red end of the spectrum. In general, whether or not the radiation is within the visible spectrum, "redder" means an increase in wavelength – equivalent to a lower frequency and a lower photon energy, in accordance with, respectively, the wave and quantum theories of light.
Redshifts are an example of the Doppler effect, familiar in the change in the apparent pitches of sirens and frequency of the sound waves emitted by speeding vehicles. A redshift occurs whenever a light source moves away from an observer. Cosmological redshift is seen due to the expansion of the universe, and sufficiently distant light sources (generally more than a few million light years away) show redshift corresponding to the rate of increase in their distance from Earth. Finally, gravitational redshifts are a relativistic effect observed in electromagnetic radiation moving out of gravitational fields. Conversely, a decrease in wavelength is called blueshift and is generally seen when a light-emitting object moves toward an observer or when electromagnetic radiation moves into a gravitational field.
Although observing redshifts and blueshifts have several terrestrial applications (such as Doppler radar and radar guns), redshifts are most famously seen in the spectroscopic observations of astronomical objects.
A special relativistic redshift formula (and its classical approximation) can be used to calculate the redshift of a nearby object when spacetime is flat. However, many cases such as black holes and Big Bang cosmology require that redshifts be calculated using general relativity. Special relativistic, gravitational, and cosmological redshifts can be understood under the umbrella of frame transformation laws. There exist other physical processes that can lead to a shift in the frequency of electromagnetic radiation, including scattering and optical effects; however, the resulting changes are distinguishable from true redshift and not generally referred as such (see section on physical optics and radiative transfer).
Other articles related to "red shift, shifts":
... The red shift caused by the curvature of space-time, a time dilation expressed by the metric component, is suffered not only by the photon but also by the atom with which it interacts and is thus ... The red shift that is detectable is caused by the increase in rest mass that fundamental particles undergo when raised to the higher level ... Gravitational red shift in this theory is interpreted not as a loss of gravitational potential energy by the photon but as a gain of gravitational potential energy by the apparatus measuring it ...
... Red Shift's two initial releases were designed, but not coded, by Gollop just after he left school (Time Lords and Islandia) ... and coding Nebula and Rebelstar Raiders for Red Shift ... In 1984, a group of Harlow-based Red Shift programmers split off to form SLUG ...
... is under orders to help the other remaining former heralds Red Shift and Firelord as they combat the Annihilation wave fleet ... and Galactus now captured and Firelord half-dead, Stardust and Red Shift are the only two active heralds ... Stardust and Red Shift were presumed dead after holding back a massive energy blast from Galactus' absorbing device ...
... transfer and physical optics can result in shifts in the wavelength and frequency of electromagnetic radiation ... In such cases the shifts correspond to a physical energy transfer to matter or other photons rather than being due to a transformation between reference frames ... These shifts can be due to such physical phenomena as coherence effects or the scattering of electromagnetic radiation whether from charged elementary particles, from particulates, or from fluctuations of ...
Famous quotes containing the words shift and/or red:
“What is the life of man! Is it not to shift from side to side?from sorrow to sorrow?to button up one cause of vexation!and unbutton another!”
—Laurence Sterne (17131768)
“The silence is death.
It comes each day with its shock
to sit on my shoulder, a white bird,
and peck at the black eyes
and the vibrating red muscle
of my mouth.”
—Anne Sexton (19281974) | 0.804733 | 4.167328 |
A composite image of Chandra X-ray data shows a rainbow of reds, yellows, green, blue and purple, from lower to higher energies. Optical data from the Digitized Sky Survey, shown in pale yellow and blue, offer a starry background for the image. Optical: DSS
An arc of hot gas that spewed from the Kepler Supernova offers tantalizing clues that the cataclysmic stellar explosion of 1604 was not only more powerful than previously thought but also farther away according to a recent study using Chandra X-ray Observatory data published in the September 1, 2012 edition of The Astrophysical Journal.
A new star appeared in the autumn skies of 1604. Although it was described by other astronomers, it was famous astronomer Johannes Kepler who thoroughly detailed the the second supernova sighting in a generation. The star shined more brilliant than Jupiter and remained visible – even during the day – over several weeks.
Look for Kepler’s Supernova at the foot of the constellation Ophiuchus, the Serpent Bearer, in visible light and you won’t see much. But the hot gas and dust glow brightly in the X-ray images from Chandra. Astronomers have long puzzled over Kepler’s Supernova. Astronomers now know the explosion that created the remnant was a Type Ia supernova. Supernovae of this class occur when a white dwarf, the white-hot dead core of a once Sun-like star, gains mass by either merging with another white dwarf or drawing gas onto its surface from a larger companion star until temperatures soar and thermonuclear processes spiral out of control resulting in a detonation that destroys the star.
Kepler’s Supernova is a bit different because the expanding debris cloud is shaped by gas and dust clouds throughout the area. Most Type Ia supernovae are symmetrical; nearly perfect expanding bubbles of material. A quick look at the Chandra image of the supernova and one notices the bright arc of material across the top edge of shockwave. In one model, a pre-supernova white dwarf and its companion were moving through a nebulous area creating a bow shock, like a boat plowing through water, in front. Another model suggests that the glowing arc is the edge of the supernova shockwave as it passes through an area of increasingly dense gas and dust. Both models push the distance of the supernova from the previously believed 13,000 light-years to more than 20,000 light-years from Earth, scientists say in the paper.
Scientists also found large amounts of iron by looking at the X-ray light from Chandra meaning that the explosion was far more powerful than an average Type Ia supernova. Astronomers have observed a similar Type Ia supernova using Chandra and an optical telescope in the Large Magellanic Cloud.
Kepler’s Supernova is the last Milky Way supernova visible to the naked eye. It was the second supernova to be observed in that generation after SN 1572 in Cassiopeia studied by the famous astronomer Tycho Brahe.
About the author: John Williams is owner of TerraZoom, a Colorado-based web development shop specializing in web mapping and online image zooms. He also writes the award-winning blog, StarryCritters, an interactive site devoted to looking at images from NASA’s Great Observatories and other sources in a different way. A former contributing editor for Final Frontier, his work has appeared in the Planetary Society Blog, Air & Space Smithsonian, Astronomy, Earth, MX Developer’s Journal, The Kansas City Star and many other newspapers and magazines. Follow John on Twitter @terrazoom. | 0.810347 | 3.956173 |
This peculiar galaxy, beautifully streaked with tendrils of reddish dust, is captured here in wonderful detail by the NASA/ESA Hubble Space Telescope.
The galaxy is known as NGC 1022, and is officially classified as a barred spiral galaxy. You can just about make out the bar of stars in the center of the galaxy in this image, with swirling arms emerging from its ends. This bar is much less prominent than in some of the galaxy’s barred cousins and gives the galaxy a rather squat appearance; but the lanes of dust that swirl throughout its disk ensure it is no less beautiful.
Hubble observed this image as part of a study into one of the universe’s most notorious residents: black holes. These are fundamental components of galaxies and are thought to lurk at the hearts of many — if not all — spirals. In fact, they may have quite a large influence over their cosmic homes. Studies suggest that the mass of the black hole sitting at a galaxy’s center is linked with the larger-scale properties of the galaxy itself. However, in order to learn more, we need observational data of a wider and more diverse range of galaxies — something Hubble’s study aims to provide. | 0.807261 | 3.633849 |
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other with his “armillae aequatoriae maximas,” with which he observed the comet of 1585, besides fixed stars and planets." The discovery by Galileo of the isochronism of the pendulum, followed by Huyghens's adaptation of that principle to clocks, has been one of the greatest aids to accurate observation. About the same time an equally beneficial step was the employment of the telescope as a pointer; not the Galilean with concave eye-piece, but with a magnifying glass to examine the focal image, at which also a fixed mark could be placed. Kepler was the first to suggest this. Gascoigne was the first to use it. Huyghens used a metal strip of variable width in the focus, as a micrometer to cover a planetary disc, and so to measure the width covered by the planet. The Marquis Malvasia, in 1662, described the network of fine silver threads at right angles, which he used in the focus, much as we do now. In the hands of such a skilful man as Tycho Brahe, the old open sights, even without clocks, served their purpose sufficiently well to enable Kepler to discover the true theory of the solar * See Dreyer's article on these instruments in Copernicus, Vol. I. They were stolen by the Germans after the relief of the Embassies, in 1900. The best description of these instruments is probably that contained in an interesting volume, which may be seen in the
library of the R. A. S., entitled Chinese Researches, by Alexander Wyllie (Shanghai, 1897).
system. But telescopic sights and clocks were required for proving some of Newton's theories of planetary perturbations. Picard's observations at Paris from 1667 onwards seem to embody the first use of the telescope as a pointer. He was also the first to introduce the use of Huyghens's clocks for observing the right ascension of stars. Olaus Römer was born at Copenhagen in 1644. In 1675, by careful study of the times of eclipses of Jupiter's satellites, he discovered that light took time to traverse space. Its velocity is 186, ooo miles per second. In 1681 he took up his duties as astronomer at Copenhagen, and built the first transit circle on a window-sill of his house. The iron axis was five feet long and one and a half inches thick, and the telescope was fixed near one end with a counterpoise. The telescope-tube was a double cone, to prevent flexure. Three horizontal and three vertical wires were used in the focus. These were illuminated by a speculum, near the object-glass, reflecting the light from a lantern placed over the axis, the upper part of the telescope-tube being partly cut away to admit the light. A divided circle, with pointer and reading microscope, was provided for reading the declination. He realised the superiority of a circle with graduations over a much larger quadrant. The collimation error was found by reversing the instrument and using a terrestrial mark, the azimuth error by star observation. The time was expressed in fractions of a second. He also constructed a telescope with equatorial mounting, to follow a star by one axial motion. In 1728 his instruments and observation records were destroyed by fire. Hevelius had introduced the vernier and tangent screw in his measurement of arc graduations. His observatory and records were burnt to the ground in 1679. Though an old man, he started afresh, and left behind him a catalogue of 1,500 stars. Flamsteed began his duties at Greenwich Observatory, as first Astronomer Royal, in 1676, with very poor instruments. In 1683 he put up a mural arc of 140°, and in 1689 a better one, seventy-nine inches radius. He conducted his measurements with great skill, and introduced new methods to attain accuracy, using certain stars for determining the errors of his instruments; and he always reduced his observations to a form in which they could be readily used. He introduced new methods for determining the position of the equinox and the right ascension of a fundamental star. He produced a catalogue of 2,935 stars. He supplied Sir Isaac Newton with results of observation required in his theoretical calculations. He died in 1719. Halley succeeded Flamsteed to find that the whole place had been gutted by the latter's executors. In 1721 he got a transit instrument, and in 1726 a mural quadrant by Graham. His successor in 1742, Bradley, replaced this by a fine brass quadrant, eight feet radius, by Bird; and Bradley's zenith sector was purchased for the observatory. An instrument like this, specially designed for zenith stars, is capable of greater rigidity than a more universal instrument; and there is no trouble with refraction in the zenith. For these reasons Bradley had set up this instrument at Kew, to attempt the proof of the earth's motion by observing the annual parallax of stars. He certainly found an annual variation of zenith distance, but not at the times of year required by the parallax. This led him to the discovery of the “aberration” of light and of nutation. Bradley has been described as the founder of the modern system of accurate observation. He died in 1762, leaving behind him thirteen folio volumes of valuable but unreduced observations. Those relating to the stars were reduced by Bessel and published in 1818, at Königsberg, in his wellknown standard work, Fundamenta Astronomiae. In it are results showing the laws of refraction, with tables of its amount, the maximum value of aberration, and other constants. Bradley was succeeded by Bliss, and he py Maskelyne (1765), who carried on excellent work, and laid the foundations of the Nautical Almanac (1767). Just before his death he induced the Government to replace Bird's quadrant by a fine new mural circle, six feet in diameter, by Troughton, the divisions being read off by microscopes fixed on piers opposite to the divided circle. In this instrument the micrometer screw, with a divided circle for turning it, was applied for bringing the micrometer wire actually in line with a division on the circle — a plan which is still always adopted. Pond succeeded Maskelyne in 1811, and was the first to use this instrument. From now onwards the places of stars were referred to the pole, not to the zenith; the zero being obtained from measures on circumpolar stars. Standard stars were used for giving the clock error. In 1816 a new transit instrument, by Troughton, was added, and from this date the Greenwich star places have maintained the very highest accuracy. George Biddell Airy, Seventh Astronomer Royal," commenced his Greenwich labours in 1835. His first and greatest reformation in the | Sir George Airy was very jealous of this honourable title. He rightly held that there is only one Astronomer Royal at a time, as there is only one Mikado, one Dalai Lama. He said that His Majesty's Astronomer at the Cape of Good Hope, His Majesty's Astrono | 0.863802 | 3.716182 |
Have you ever been to the beach?
If you’re from California like me, then I’m betting you have. If you’re from a place that’s not near an ocean and you’ve never been near the water all your life, then I’ll tell you a little bit about the tides.
They happen every day, twice a day. If you find yourself a nice comfortable spot overlooking the beach, you can see the waves come into the shore and then gently roll out again. If you stay for hours on end, you’ll see the water level eventually rise a bit.
And if you stay even longer, you’ll see the water level lower back down. When it’s high, it’s called high tide, and when it’s low, it’s called low tide.
The tides are partially responsible for the myth that the moon’s gravity affects you in some kind of metaphysical way. But this isn’t true at all.
So why do the tides happen?
It has to do with the moon’s gravity.
We know from Newton’s third law of motion and from universal mutual gravitation that just as the Earth’s gravity attracts the moon, the moon’s gravity attracts the Earth. We know that the two orbit around their center of mass, which is a point in space within Earth’s interior.
But we also know that gravity doesn’t affect the whole Earth equally. Gravity weakens the farther out it gets, and Earth is big enough that not all of it feels the same force of gravity from the moon.
Earth is a special planet in the solar system in that it’s covered in liquid water. And that liquid water is very, very movable. It sloshes around. The moon’s gravity actually pulls the oceans out a bit from the Earth’s sphere.
Here, the blue band around the Earth represents the sea level at high tide and low tide around the globe. Of course, the ocean doesn’t come out that far, but this diagram emphasizes the tides in order to make clear what’s happening.
Naturally, Earth’s interior is pulled towards the moon as well as it orbits around the center of mass. The oceans on the other side of the planet are just as sloshy as those on the side facing the moon, and they get left behind a little as Earth’s interior is pulled.
Essentially, high tide on the side of the Earth facing the moon is caused by the moon’s gravity. But high tide on the other side is caused by inertia—matter’s tendency to stay exactly where it is (or move exactly how it is).
The Earth gets pulled, and that half of the oceans gets left behind.
But only a little bit, obviously. Tides don’t change by much—they don’t flood the coastline, just creep up it a bit. They don’t get pulled out nearly as far as the diagram shows.
The image set below is a more realistic example of high tide and low tide.
The tides are the most obvious by the ocean, of course because water moves more freely than the rest of the Earth. But like I said, the moon’s gravity reaches all parts of Earth, and different parts of Earth’s rocky material feel that gravity differently.
Would you believe me if I told you that the Earth’s rocky bulk actually gets deformed a little over time?
It’s true. The Earth’s surface actually expands and contracts by a few centimeters as the Earth rotates. You never notice it, but the effect is there. That’s the moon’s gravity tugging on the Earth.
This effect is much more pronounced on an object like the moon. You realize, if Earth has tides because of its moon, so does every other planet in the solar system with a moon (or moons). Here’s an image of the effect of the tides on another moon in the solar system.
Meet Saturn’s moon, Iapetus! As we’ll explore in much later posts, Iapetus is a land of incredible contrasts. But it’s also small enough compared to Saturn to have tides of its own…
Yes, that mountainy ridge there formed for the same reason Earth has tides.
Why doesn’t our moon have a ridge like that? Probably because its planet is so much smaller than Iapetus’s planet, so the planet’s tidal forces on the moon aren’t strong enough to deform the land like that.
Saturn, after all, is nearly the size of Jupiter—and Jupiter isn’t too far from being the size of a tiny dwarf star.
Don’t worry, we’ll talk about that more later. I have plenty of posts planned for exploring the solar system.
So, we know how the tides form. The moon tugs on the Earth and makes the ocean bulge out a bit on either side. But how come the tides come in and out? Why do they change?
Well, that’s all because of the Earth’s rotation.
Okay, this diagram has a lot of information. Let’s break it down.
The tidal bulge, as it’s called, always stays oriented with the moon. That means that one high tide region is always facing the moon, and the other is always facing away from the moon.
Well, mostly. We’ll get into why the diagram has the tides rotated a bit in just a second.
Anyway, the tides stay angled the same relative to the moon. But that means they follow the moon in its month-long orbit. The Earth rotates all the way around once a day, so it essentially rotates inside the two tidal bulges.
What does this mean? As the tide “comes in” on a beach, the tide isn’t so much coming in as the Earth’s rotation carries you into the tide.
The thing is, though, the oceans aren’t completely movable. The continents act as friction against the tidal bulges, and so does the sea floor. So as the moon pulls on the tidal bulge in the opposite direction of the Earth’s rotation, Earth’s rotation slows down.
Seriously. Just 620 million years ago, Earth’s days were less than 22 hours long. The rotation has slowed down to 24 hours.
I know that sounds like an increase of speed…but consider this. In a greater amount of time, the Earth is rotating the same distance around. That means that it has slowed down.
This explains why the tides aren’t perfectly lined up with the moon. The continents hold them back a bit.
But here’s another thing. According to universal mutual gravitation, if the moon pulls on the tidal bulges, they must also pull on the moon. And since they’re angled a bit ahead of the moon in its orbit, they pull it forward in its orbit…
…and believe it or not, they actually speed the moon up a bit.
Speeding up the moon actually brings it that much closer to escape velocity, the velocity needed to escape Earth’s gravitational pull.
That won’t happen for thousands of years, but eventually, we will lose the moon.
But…wait a second. If the tides can pull on the moon, and the Earth can pull on the moon, and the moon can pull on the tides and the Earth, and the sun obviously pulls on the Earth since we’re in orbit, shouldn’t the sun control the tides, too?
The answer is yes…sort of.
The sun doesn’t have nearly as dramatic an effect on the tides as the moon. It may have stronger gravity than the moon, but it’s also much farther away, making its pull on the oceans quite weak.
What it can do is change how severe the moon can make the tides. As you can see above, during new moon and full moon when the sun and moon pull at the oceans in the same direction, tides are much more dramatic and rise higher up the coastlines.
During first and third quarter moon, however, the sun actually sort of cancels out the moon’s pull on the oceans. This makes tides much less dramatic.
When the sun increases the tides, they’re called spring tides, named for the way the ocean “springs” up from the ground a bit more. When the sun cancels out the tides, they’re called neap tides, taken from an Old English word that means “lacking power to advance.”
Understanding tides on Earth is the key to understanding tides throughout the solar system—and, indeed, the universe as a whole. That’s the wonder of a universe where the laws of physics are the same throughout.
We can always apply what we know of Earth to the bigger picture. And that’s what keeps us discovering. | 0.860218 | 3.200967 |
The European Space Agency monitors 10.000 asteroids – only 411 could be dangerous
The ‘ asteroid ‘ counter of the European Space Agency touched 10.000; many are the asteroids that skim over ‘ the Earth with gasps more or less close together. Of all the asteroids, the ones that pose a potential danger to our planet are 411. To categorize the asteroid number 10.000 was the Coordination Centre Near-Earth object (Near-Earth Object, Neo) which is located in Italy, at the center of the Space Agency Esrin.
Only about 411 of the 10.000 asteroids were defined as dangerous -The ten-thousandth asteroid belongs, like the others, of the population of ‘ Near-Earth asteroids ‘, i.e. those who can be dangerous, if even if they do not collide with our planet. At the moment they are only about 411 of the 10.000 asteroids that are defined as risky and the evaluation of the danger is made on a precautionary basis. Once the orbit had been scrutinized for a few of the asteroids, the probability of a real endanger is almost zero per cent for an asteroid to collide with Earth. Only 10% of them (about a thousand asteroids) have a size greater than one kilometer.
The European Coordination Centre aims to enhance the contribution of the old continent to this new enterprise: discover, characterize and control these objects, which may be ‘ potential assumed impactor to the population ‘ of Earth as evidenced by the ‘ superbolide ‘ that exploded in the skies of the Russian city of Chelyabinsk last February. There are only two data centers in the world where is centralized all information concerning the discoveries of new asteroids by astronomical observers. The first is that, at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, and the other is the ESA Centre.
Great developments in the discovery of these celestial bodies. The 10.000 asteroids observed is an important milestone that testifies how much there is still to do for the progress of astronomy in this field. Figuring that observation techniques dedicated to the discovery of these celestial bodies have recently made great strides just think that throughout the last century, from the discovery of the first asteroid, 433 Eros, which took place on 13 August 1898, in 2000, the number of known objects was about one thousand. To get to that figure today we should thank to networks of wide-field telescopes and high sensitivity that scan the skies every night looking for faint bright dots moving between the constellations.
ESA is able to make observations independently- ‘ Neo Centre of ESA is a merit of European countries – says Central Manager, Ettore Perozzi, and proves that onto the old continent, in collaboration with the Americans, we are able to make observations independently. In November 2013, will be launched an European satellite called Gaia, which will have the task of cataloging, with great precision as it never had before, all the stars of heaven ‘. Every picture ‘ will be analyzed in real-time and if an object appears in the image due to an asteroid, it will alert the network of telescopes on the ground to track, follow it and parse it. This will increase the number of asteroids discovered, and then there will be a calm atmosphere on Earth knowing precisely what goes around ‘. | 0.82688 | 3.395232 |
When the first hot Jupiters were detected about a generation ago, they were generally thought to be “oddballs” because we do not have anything like them in our own Solar System. However, as more and more of these bizarre, exotic, and puffed-up giant worlds were spotted over the last two decades, in orbit around distant stars beyond our own Sun, it began to look like our own Solar System is the true oddity.
Ever since the historic discovery of the first exoplanet in orbit around a Sun-like star, back in 1995, planet-hunting astronomers have been detecting a previously unknown, and well-hidden, treasure trove of weird, wild, and wonderful distant worlds. Some of these remote planets display an almost eerie similarity to the familiar planets inhabiting our own Solar System–while others are so exotic that their existence in nature both surprised and baffled their discoverers.
Hot Jupiters hug their parent-stars so closely that a “year” for them lasts only a few days. One of the most famous hot Jupiters, 51 Pegasi b, discovered in 1995, was the first exoplanet to be discovered circling a main-sequence (hydrogen-burning) star on the Hertzsprung-Russell Diagram of Stellar Evolution. 51 Pegasi b has an orbital period of about 4 days. This initial discovery of a hot Jupiter proved to be a surprise for planet-hunting astronomers who did not think that such close-in, giant, gas-laden worlds could really exist in nature. The mystery surrounding the formation of this very alien form of exoplanet has plagued the astronomical community for more than twenty years.
Even though the discovery of literally thousands of exoplanets has now become “business as usual” for astronomers on the hunt for these remote worlds, this has not always been the case. Indeed, the search for planets belonging to the families of stars beyond our own Sun, historically proved to be extremely challenging–as well as frustrating. At last, back in 1992, the first batch of truly weird exoplanets to be validated were detected in orbit around a very small, dense, and rapidly spinning stellar corpse termed a pulsar. Dr. Alexander Wolszczan of Pennsylvania State University, after carefully observing radio emissions flowing out from a compact millisecond pulsar with the unexciting name of PSR B1257 +12, made the determination that it was being circled by several very exotic little worlds. A pulsar is only about 12 miles in diameter–and it is really the collapsed core of what was once a massive main-sequence star. This strange, dense, and tiny stellar “oddball” is all that is left of a star that has finished burning its necessary supply of hydrogen fuel, and has “died” in the horrific, brilliant, and explosive tantrum of a supernova blast.
51 Pegasi b was discovered three years later by Dr. Michel Mayor and Dr. Didier Queloz of Switzerland’s Geneva Observatory. This discovery was quickly confirmed by a team of American planet-hunting astronomers using the Lick Observatory’s three-meter telescope poised at the summit of Mount Hamilton in California.
Of course, new theories were proposed to explain these “oddball’ hot Jupiters. Some astronomers suggested that these “roasters” were really enormous molten rocks; while still others proposed that they were gas-giant planets that had been born about 100 times further away from their parent-stars. According to this latter theory, hot Jupiters were ruthlessly thrown about 100 times closer to their stellar parents as a result of near-collisions with other sibling worlds. Alternatively, a binary stellar companion of their host star may have been the culprit behind this tragic kick towards their fiery, roiling stellar parent.
One theory put forward suggests that hot Jupiters are born at a distance from their star that is approximately the same as that of our own Solar System’s banded behemoth, Jupiter’s, distance from our Sun. Alas, these ill-fated giant worlds slowly lose energy as a result of their unfortunate dance with the protoplanetary accretion disk, which is a disk of gas and dust surrounding their parent-star, from which planets eventually emerge. The newborn giant planet, as a result, spirals into the well-lit and seething-hot inner regions of its planetary system, coming in from its much colder and very remote place of birth.
Hot Jupiters are likely doomed giants, destined to come to a final, fiery, and truly miserable end within the furious furnaces of their glaring parent-stars. However, until that final, fatal moment, these very unfortunate “roasters” orbit their host stars fast and close.
These puffy “roasters” are actually a mixed bag, displaying some diversity in their attributes. However, these exoplanets do share certain characteristics. All hot Jupiters have very low densities, large masses, brief orbital periods around their parent-stars, and almost circular orbits. Hot Jupiters also are likely to possess extreme and exotic atmospheres because of their brief orbital periods, relatively long days, and tidal locking. mkvmoviesking | 0.913696 | 3.915261 |
Exploding binary stars
9 December 2019
One of New Zealand’s most valuable export fish species is about to take on a new persona in the world of astronomy as the chosen name for a software package that could help unlock some of the secrets of the Universe.
CALLED HOKI BECAUSE it helps “fish through information” about the role of exploding binary stars in the life of our Universe, the computer code has been developed by postdoctoral research fellow Dr Héloïse Stevance who aims to bridge the gap between observations and theory.
“My goal is to write a little piece of software that makes that job very easy and very foolproof for the observer so that they have access to the theoretical code and can compare it to their observations. Focus more on the science and less on the nitty-gritty and the coding – that’s my job.”
Expected to be released in early 2020, Hoki leverages off the Binary Population and Spectral Synthesis (BPASS) codes developed by Héloïse’s fellow astrophysicist, Dr JJ Eldridge, whose pioneering computer models of how stars are born, live and die have caused waves throughout the academic community – and changed assumptions about the evolution of the Universe.
“What my models can predict is what the galaxies will look like at different ages,” JJ says, “and that tells you something about the stars that merged.”
This is where we come from, absolutely. We are made of stardust. That’s what Carl Sagan said – and it is true!
Stellar mergers and binary interactions
Where JJ differs from peers is the acceptance of the fact that most stars in the Universe are born in binary systems, where two stars orbit around each other and sometimes merge, rather than from single stars like the Sun. And BPASS models show that you only need 65-75 percent of the stars previously thought to exist because binaries interact and merge.
“That number of stars is important because it’s how we work out how much stuff is being formed, how many black holes there are, how many neutron stars there are and how many habitable planets there could be. Suddenly if you’re decreasing the number of stars, you’re decreasing all of that in the Universe.”
According to JJ, the reason why single star models were preferred back in the 90s was because binary stars were complicated and potentially involved years of computer time.
“Now we’ve got so much computing power it becomes so much easier and that’s starting to change entrenched views about single star models. Having the computational power to do things that were impossible before is changing people’s minds that maybe we can do things that we couldn’t.”
The BPASS models have also been used to investigate the future and predict what happens to stars 100 billion years from now even though the Universe is currently only 13.7 billion years old. Which raises the age-old question – could there be life forms in other galaxies?
“Will the Universe be more habitable in the future? The answer is probably yes because more of the young stars will die and there’ll be fewer supernovae and nasty things that can kill us,” JJ says.
Supernovae and the origins of life
Another key driver behind their research is the quest to know more about the collapse of stars called supernovae which produce different types of elements – like oxygen and iron – that are crucial to life as we know it. “The oxygen in your lungs right now was created in a supernova, it didn’t come out of nowhere,” says Héloïse. “This is where we come from, absolutely. We are made of stardust. That’s what Carl Sagan said – and it is true!”
The abundance of oxygen and iron has changed over the history of the Universe because it came from different ages of stars that exploded at different times. However, JJ says it’s more difficult to trace the origin of elements like gold, platinum and silver because they came from very rare events such as the neutron star mergers that have led to gravitational waves.
All of which comes back to their current research into gravitational wave events which received fresh impetus in 2017 when the LIGO observatory detected what is known by the purists as GW 170817 – a gravitational wave relatively close to earth that was produced by the dying minutes of two neutron stars spiralling together and finally merging.
Describing it as a violent cataclysmic event which produced “massive fireworks”, Héloïse says that neutron stars involve really “extreme physics” because they consist of a ball around 20 kilometres in diameter and 1.5 times the mass of the Sun with gravity so strong that the surface has virtually no discernible bumps on it.
“The Universe can make it, but how does it do it? And how can we reproduce what the Universe is physically making? Knowing that will tell us a lot about the stars that give rise to the things that we actually observe.”
Funded by a $936,000 Marsden Fund grant, the current focus for JJ and Héloïse is to use the BPASS and Hoki codes to investigate the stars and galaxies associated with the 2017 gravitational wave event by comparing their cosmological simulations with observations from multiple instruments and telescopes.
“The goal is to look at that galaxy and see what we can find with the BPASS models,” says Héloïse. “What can we learn about the stars in that galaxy that people haven’t found with their single star models?”
The Universe can make it, but how does it do it? And how can we reproduce what the Universe is physically making?
Collaboration produces new models
The development of BPASS involves a long-standing collaboration with Associate Professor Elizabeth Stanway from the University of Warwick who JJ has worked with since their PhD days at the University of Cambridge. “She’d been working on galaxies and I’d been working on stars,” says JJ, “and we kind of merged.”
Eighteen years later, Elizabeth remains part of JJ’s gravitational wave project which is also useful because Warwick has a rapid follow up telescope that can track light as quickly as possible. “We can’t do each other’s job, but we understand a lot about what each other does so have been able to make this BPASS code. It’s taken a long time and it is ongoing.”
The collaboration has been deepened by the skills which Héloïse has brought from the UK including a PhD and experience as a part time support astronomer at the Isaac Newton Telescope in Spain. Like Elizabeth, she is a member of the global Engrave collaboration which constantly tracks events like gravitational waves.
For her part, Héloïse is also determined to introduce best practice to her work and has written Hoki in Python which is considered the gold standard of astronomy. In the interests of generating more collaboration, the code will also be fully accessible under an open source licence.
And it seems that a new generation of stargazers is already being inspired to continue the research. Supported by tutorials from Héloïse, Hoki was successfully trialled at a UK summer school where JJ says students quickly embraced a model that would have traditionally taken much longer to understand. “Rather than taking them days or weeks to work out, it took them a few minutes.”
As for their research into the host galaxy of GW 170817, JJ expects to publish something in 2020. They don’t know what they’re going to find but say “we know this is important, we just don’t know how important.” | 0.843094 | 3.626931 |
The NASA/ESA Hubble Space Telescope had imaged NGC 6818 before, but it took another look at this planetary nebula, with a new mix of colour filters, to display it in all its beauty. By showing off its stunning turquoise and rose quartz tones in this image, NGC 6818 lives up to its popular name: Little Gem Nebula.
This cloud of gas formed some 3500 years ago when a star like the Sun reached the end of its life and ejected its outer layers into space. As the layers of stellar material spread out from the nucleus – the white stellar remnant at the centre of the image – they ended up acquiring unusual shapes.
NGC 6818 features pinkish knotty filaments and two distinct turquoise layers: a bright, oval inner region and, draped over it like sheer fabric, a spherical outer region.
The central star has a faint stellar companion 150 astronomical units away, or five times the distance between the Sun and Neptune. You can just about make this out: if you zoom in to the centre, you’ll notice the white dot in the middle is not perfectly round, but rather two dots very close together.
With a diameter of just over half a light-year, the planetary nebula itself is about 250 times larger than the binary system. But the nebula material is still close enough to its parent star for the ultraviolet radiation the star releases to ionise the dusty gas and make it glow.
Scientists believe the star also releases a high-speed flow of particles – a stellar wind – that is responsible for the oval shape of the inner region of the nebula. The fast wind sweeps away the slowly moving dusty gas, piercing its inner bubble at the oval ends, seen at the lower left and top right corners of the image.
NGC 6818 is located in the constellation of Sagittarius and is about 6000 light-years from Earth. It was first imaged by the Hubble Space Telescope’s Wide Field Planetary Camera 2 in 1997, and again in 1998 and 2000 using different colour filters to highlight different gases in the nebula. | 0.882096 | 3.61312 |
Black Hole Chokes on a Swallowed Star
26 January 2015
FORT DAVIS, Texas — A five-year analysis of an event captured by a tiny telescope at McDonald Observatory and followed up by telescopes on the ground and in space has led astronomers to believe they witnessed a giant black hole tear apart a star. The work is published this month in The Astrophysical Journal.
On January 21, 2009, the ROTSE IIIb telescope at McDonald caught the flash of an extremely bright event. The telescope’s wide field of view takes pictures of large swathes of sky every night, looking for newly exploding stars as part of the ROTSE Supernova Verification Project (RSVP). Software then compares successive photos to find bright “new” objects in the sky — transient events like the explosion of a star or a gamma-ray burst.
With a magnitude of -22.5, this 2009 event was as bright as the “superluminous supernovae” (a new category of the brightest stellar explosions known) that the ROTSE team discovered at McDonald in recent years. The team nicknamed the 2009 event “Dougie,” after a character in the cartoon South Park. (Its technical name is ROTSE3J120847.9+430121.)
The team thought Dougie might be a supernova, and set about looking for its host galaxy (which would be much too faint for ROTSE to see). They found that the Sloan Digital Sky Survey had mapped a faint red galaxy at Dougie’s location. The team followed that up with new observations of the galaxy with one of the giant Keck telescopes in Hawaii, pinpointing the galaxy’s distance at three billion light-years.
These deductions meant Dougie had a home — but just what was he? Team members had four possibilities: a superluminous supernova; a merger of two neutron stars; a gamma-ray burst; or a “tidal disruption event” — a star being pulled apart as it neared its host galaxy’s central black hole.
To narrow it down, they studied Dougie in various ways. They made ultraviolet observations with the orbiting Swift telescope, and took many spectra from the ground with the 9.2-meter Hobby-Eberly Telescope at McDonald. Finally, they used computer models of how the light from different possible physical processes that might explain how Dougie would behave — how it varies in brightness over time, and what chemical signatures it might show — and compared them to Dougie’s actual behavior.
In detail, Dougie did not look like a supernova. The neutron star merger and gamma-ray burst possibilities were similarly eliminated.
"When we discovered this new object, it looked similar to supernovae we had known already,” said lead author Jozsef Vinko of the University of Szeged in Hungary. “But when we kept monitoring its light variation, we realized that this was something nobody really saw before. Finding out that it was probably a supermassive black hole eating a star was a fascinating experience,” Vinko said.
Team member J. Craig Wheeler, leader of the supernova group at The University of Texas at Austin, elaborated. “We got the idea that it might be a ‘tidal disruption’ event,” he said, explaining that means that the enormous gravity of a black hole pulls on one side of the star harder than the other side, creating tides that rip the star apart.
“A star wanders near a black hole, the star’s side nearer the black hole is pulled” on more than the star’s far side, he said. “These especially large tides can be strong enough that you pull the star out into a noodle” shape.
The star “doesn’t fall directly into the black hole,” Wheeler said. “It might form a disk first. But the black hole is destined to swallow most of that material.”
Though astronomers have seen black holes swallow stars before — though less than a dozen times — this one is special even in that rare company: It’s not going down easy.
Models by team members James Guillochon of Harvard and Enrico Ramirez-Ruiz at the University of California, Santa Cruz, showed that the disrupted stellar matter was generating so much radiation that it pushed back on the infall. The black hole was choking on the rapidly infalling matter.
Based on the characteristics of the light from Dougie, and their deductions of the star’s original mass, the team has determined that Dougie started out as a Sun-like star, before being ripped apart.
Their observations of the host galaxy, coupled with Dougie’s behavior, led them to surmise that the galaxy’s central black hole has the “rather modest” mass of about a million Suns, Wheeler said.
Delving into Dougie’s behavior has unexpectedly resulted in learning more about small, distant galaxies, Wheeler said, musing “Who knew this little guy had a black hole?”
The paper’s lead author, Jozsef Vinko, began the project while on sabbatical at The University of Texas at Austin. The team also includes Robert Quimby of San Diego State University, who started the search for supernovae using ROTSE IIIb (then called the Texas Supernova Search, now RSVP) and discovered the category of superluminous supernovae while a graduate student at The University of Texas at Austin.
— END —
Dr. J. Craig Wheeler, Samuel T. and Fern Yanagisawa Regents Professor in Astronomy
The University of Texas at Austin
Dr. Jozsef Vinko, Assoc. Professor of Astronomy
University of Szeged, Hungary | 0.876752 | 3.825506 |
Listed below are the Disciplinary Core Ideas (DCI) for Earth and Space Science and bullet points for their specific grade band progression.
ESS1.B: Earth and the Solar System
- Seasonal patterns of sunrise and sunset can be observed, described, and predicted.
- The orbits of Earth around the sun and of the moon around Earth, together with the rotation of Earth about an axis between its North and South poles, cause observable patterns. These include day and night; daily changes in the length and direction of shadows; and different positions of the sun, moon, and stars at different times of the day, month, and year.
- The solar system consists of the sun and a collection of objects, including planets, their moons, and asteroids that are held in orbit around the sun by its gravitational pull on them.
- This model of the solar system can explain eclipses of the sun and the moon. Earth’s spin axis is fixed in direction over the short-term but tilted relative to its orbit around the sun. The seasons are a result of that tilt and are caused by the differential intensity of sunlight on different areas of Earth across the year.
- Kepler’s laws describe common features of the motions of orbiting objects, including their elliptical paths around the sun. Orbits may change due to the gravitational effects from, or collisions with, other objects in the solar system.
- Cyclical changes in the shape of Earth’s orbit around the sun, together with changes in the tilt of the planet’s axis of rotation, both occurring over hundreds of thousands of years, have altered the intensity and distribution of sunlight falling on the earth. These phenomena cause a cycle of ice ages and other gradual climate changes.
- The solar system appears to have formed from a disk of dust and gas, drawn together by gravity.
This is a table of the Disciplinary Core Ideas
of Earth and Space Science. If
coming from a Standard the specific bullet point used is highlighted
and additional performance Expectations that make use of the
Disciplinary Core Idea can be found below the table.
To see all Disciplinary Core Ideas, click on the title "Disciplinary Core Ideas."
Other Standards That Use This Disciplinary Core Idea: | 0.87427 | 3.348026 |
What might extraterrestrials look like? It's a question astrobiologists, authors and artists love to tackle, leading to everything from highly humanoid Vulcans and Klingons to exotic forms that borrow only from the most extreme examples of terrestrial life.
In both cases, however, those visions are limited. As a University of Oxford research team notes, past astrobiology efforts have largely taken Earth life and extrapolated through the application of chemistry, geology and physics to predict what aliens might look like.
It seems sensible, right? For example, eyes are widespread on our planet, so it makes sense that aliens would have them as well. We're carbon-based life-forms, so we might expect life-forms on the other side of the galaxy to follow suit.
However, according to the Oxford researchers, who published a November 2017 study in the journal International Journal of Astrobiology, natural selection is the firmest ground on which to base our predictions of alien life; natural selection being the directional force that led to life as we know it. In the absence of a designer, the authors stress, natural selection is necessary for the development of an organism, and we probably wouldn't recognize it as an organism if it didn't.
While natural selection is necessary for life, the researchers add that the emergence of complex life requires major transitions, in which multiple parts of an organism "strive to the same purpose." These transitions, in turn, are brought on by restrictive environmental conditions. Combine this line of thinking with the more mechanistic extrapolations of chemistry, geology and physics and you've got yourself a more robust means of predicting an alien's form.
And what might that form be? The researchers certainly don't bust out Klingons or Vulcans as examples, but they indeed might be more like us than we think – and they're not the only ones to think so.
As Joe McCormick and I discussed in our Stuff to Blow Your Mind podcast episode "Grizzly Bears from Outer Space," Cambridge paleobiologist Simon Conway Morris believes that aliens might look a lot like us, due in part to convergent evolution — the aspect of natural selection that sees the independent evolution of key biological features, such as eyes and wings.
Birds and bats, for instance, independently evolved the ability to fly. An alien life-form, sprung from the same process of natural selection, might very well evolve the same adaptations to sense and navigate its environment. Its eyes might look very different from ours, but they'd achieve the same purpose.
Conway Morris even goes so far as to apply this principle to cognition. In his 2005 Astronomy & Geophysics paper "Aliens like us?," Conway Morris states that a humanlike intelligence might just be a cosmic inevitability, though the physical brain responsible for it might, via coevolution, be rather inhuman.
And if aliens think like us, does that mean they'd philosophize like us as well? Author R. Scott Bakker presented just such a notion in his Journal of Consciousness Studiespaper "On Alien Philosophy."
Like us, Bakker argues, intelligent aliens would be bound by the same unknowns that confound us here on Earth. Perhaps they too are wondering what aliens look like, and how they might think. | 0.859646 | 3.386687 |
New Horizons: NASA Probe Prepares to Meet Mysterious "Ultima Thule"
NASA’s uncrewed New Horizons probe flew past Pluto, its primary target, in 2015, but its mission is far from over. Soon it will continue on through the Kuiper Belt, and just after midnight on January 1, 2019, New Horizons will perform a flyby of Ultima Thule. The name may sound like a dragon spell from Skyrim or the name of a kindly Norwegian innkeeper, but it’s actually the common name of Kuiper Belt object KBO 2014 MU69, which floats out in space beyond the edges of our solar system. It’s among a class of objects believed to be cosmic leftovers from the early times of planetary formation billions of years ago.
In a live NASA Science Chat on Wednesday, three of the top New Horizons team members explained the plan for the 2019 flyby, which, at a billion miles beyond Pluto, will be the most distant planetary flyby in human history. Given this fact, KBO 2014 MU69’s name is especially fitting, as Ultima Thule is a medieval phrase that means “beyond the known world.” But New Horizons is going to make it part of our known world.
“We’re gonna zoom right up to it, image it, find out what it’s made of, find out if it has moons or rings, and lots more about it,” Alan Stern, the New Horizons principal investigator, told viewers.
What we do know about Ultima Thule is that it’s about 23 miles across and approximately 10 times the size of an average comet. We also know its trajectory, which makes it the perfect candidate for New Horizons’ secondary mission objective.
Despite its status as a secondary mission, though, the Ultima Thule flyby is taking a good deal of prep. When the Earth-based team woke the probe back up in June, they did system checks and performed system updates to support the flyby, Alice Bowman, the New Horizons mission operations manager, told viewers on Wednesday.
“In August, we transitioned the spacecraft into a mode where we could take pictures, so we are taking pictures now of Ultima Thule,” said Bowman. “We call those optical navigation measurements, and we are using those to target the object.” The image below is an example of one such optical navigation measurement.
By tracking Ultima Thule, which was only discovered in 2014, scientists have been able to identify it as a classical Kuiper Belt object, which means it’s likely one of the oldest objects in our solar system. But because it is a poorly understood object, scientists need to keep monitoring it to make sure it moves as they expect.
Researchers need to know exactly where Ultima Thule is to get as close as they want. The New Horizons team plans to fly the New Horizons probe 2,200 miles from Ultima Thule, much closer than the 7,800 miles that separated it from Pluto in 2015. Most importantly, though, the simple fact is that we know very little about Ultima Thule, and this flyby will give us some of the first facts about the ancient object.
“This has all the elements of an unbelievable set of discoveries that are just outside our reach at the moment but will come into view soon,” Jim Green, NASA’s chief scientist, told viewers on Wednesday. “We know we’re gonna flyby January first, that’s a given. It has the excitement of what are we gonna see?”
Unfortunately, it’ll take quite some time before we find out what New Horizons sees. When the probe performs its epic flyby, it will begin sending its data back to Earth, but with the spacecraft sending a low-powered signal over 4 billion miles, the data won’t reach Earth for about a year. It’ll surely be worth the wait, though, to glimpse an object that may be even older than Earth. | 0.911084 | 3.025865 |
Astronomers have discovered a gamma ray source in the sky that acts like a natural clock. The object is called LS 5039, and consists of a massive blue star orbiting an unknown object – possibly a black hole. The two objects orbit each other closely, completing an orbit every four days. With each orbit, the black hole flies through the blue star’s stellar wind, and accelerates particles to gamma ray levels. This is the first time a source of gamma rays has been discovered with such a regular schedule.
Astronomers using the H.E.S.S. telescopes have discovered the first ever modulated signal from space in Very High Energy Gamma Rays – the most energetic such signal ever observed. Regular signals from space have been known since the 1960s, when the first radio pulsar (nicknamed Little Green Men-1 for its regular nature) was discovered. This is the first time a signal has been seen at such high energies – 100,000 times higher than previously known – and is reported today (24th November) in the Journal Astronomy and Astrophysics.
The signal comes from a system called LS 5039 which was discovered by the H.E.S.S. team in 2005. LS5039 is a binary system formed of a massive blue star (20 times the mass of the Sun) and an unknown object, possibly a black hole. The two objects orbit each other at very short distance, varying between only 1/5 and 2/5 of the separation of the Earth from the Sun, with one orbit completed every four days.
“The way in which the gamma ray signal varies makes LS5039 a unique laboratory for studying particle acceleration near compact objects such as black holes.” Explained Dr Paula Chadwick from the University of Durham, a British team member of H.E.S.S.
Different mechanisms can affect the gamma-ray signal that reaches Earth and by seeing how the signal varies, astronomers can learn a great deal about binary systems such as LS 5039 and also the effects that take place near black holes.
As it dives towards the blue-giant star, the compact companion is exposed to the strong stellar ‘wind’ and the intense light radiated by the star, allowing on the one hand particles to be accelerated to high energies, but at the same time making it increasingly difficult for gamma rays produced by these particles to escape, depending on the orientation of the system with respect to us. The interplay of these two effects is at the root of the complex modulation pattern.
The gamma-ray signal is strongest when the compact object (thought to be a black hole) is in front of the star as seen from Earth and weakest when it is behind the star. The gamma rays are thought to be produced as particles which are accelerated in the star’s atmosphere (the stellar wind) interact with the compact object. The compact object acts as a probe of the star’s environment, showing how the magnetic field varies depending on distance from the star by mirroring those changes in the gamma ray signal.
In addition, a geometrical effect adds a further modulation to the flux of gamma-rays observed from the Earth. We know since Einstein derived his famous equation (E=mc2) that matter and energy are equivalent, and that pairs of particles and antiparticles can mutually annihilate to give light. Symmetrically, when very energetic gamma rays meet the light from a massive star, they can be converted into matter (an electron-positron pair in this case). So, the light from the star resembles, for gamma rays, a fog which masks the source of the gamma rays when the compact object is behind the star, partially eclipsing the source. “The periodic absorption of gamma-rays is a nice illustration of the production of matter-antimatter pairs by light, though it also obscures the view to the particle accelerator in this system” said Guillaume Dubus, Astrophysical Laboratory of the Grenoble Observatory, LAOG.
Original Source: PPARC News Release | 0.89168 | 4.015886 |
The vast majority of stars in our Milky Way galaxy host planets, many of which may be capable of supporting life as we know it, a new study suggests.
Astronomers have detected eight new exoplanet candidates circling nearby red dwarf stars, which make up at least 75 percent of the galaxy's 100 billion or so stars. Three of these worlds are just slightly bigger than Earth and orbit in the "habitable zone," the range of distances from a parent star where liquid water could exist on a planet's surface.
The new finds imply that virtually all red dwarfs throughout the Milky Way have planets, and at least 25 percent of these stars in the sun's own neighborhood host habitable-zone "super-Earths," researchers said.
"We are clearly probing a highly abundant population of low-mass planets, and can readily expect to find many more in the near future even around the very closest stars to the sun," study lead author Mikko Tuomi, of the University of Hertfordshire in the United Kingdom, said in a statement.
Tuomi and his colleagues spotted the exoplanet candidates after combining data gathered by two instruments — the High Accuracy Radial velocity Planet Searcher (HARPS) and the Ultraviolet and Visual Echelle Spectrograph (UVES) — both of which are operated by the European Southern Observatory in Chile.
Both HARPS and UVES employ the radial-velocity technique, which detects exoplanets by noticing the tiny wobbles they induce in their parent stars' motion toward or away from Earth. "We were looking at the data from UVES alone, and noticed some variability that could not be explained by random noise," Tuomi said. "By combining those with data from HARPS, we managed to spot this spectacular haul of planet candidates."
The eight newfound candidates circle stars located between 15 and 80 light-years away from Earth. The worlds orbit their parent stars at distances ranging from 0.05 to four times the Earth-sun distance (which is about 93 million miles, or 150 million kilometers), researchers said.
The new detections bolster observations made by NASA's prolific Kepler space telescope, which launched in 2009 to hunt for alien worlds around stars that lie considerably farther away from Earth.
"This result is somewhat expected in the sense that studies of distant red dwarfs with the Kepler mission indicate a significant population of small-radius planets," said study co-author Hugh Jones, also from the University of Hertfordshire. "So it is pleasing to be able to confirm this result with a sample of stars that are among the brightest in their class."
The study was published March 3 in the Monthly Notices of the Royal Astronomical Society.
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This article originally published at Space.com here | 0.893201 | 3.846655 |
The whole dome of night sky was awash with color: cascades of yellow-green and blushes of crimson fanning from a darker point high overhead. As they fell in broad rays, they shifted and changed in brightness, sometimes intense in one place, then cool, then hot. It was like looking up into the heart of a flower of glorious light whose petals rippled in a breeze that could not be felt—a breath from beyond this planet.
That aurora (Latin for "dawn") lit up the night at my home in the Scottish Highlands more than a decade ago, but to this day I can picture its colors, shapes, and movements. The show peaked for less than an hour, but its tonal themes lingered longer. It seemed an act of magic, but I knew that science had unveiled this magic act: Electrically charged particles from the sun were making gases glow in the upper atmosphere.
Thousands of miles away, in Alaska, the aurora also caught the attention of Charles Deehr, a physicist at the Geophysical Institute of the University of Alaska Fairbanks. "That display on March 13-14, 1989, was one of the best in the last 50 years," he said.
I visited Deehr in March 2001 during the current phase of intense auroral activity. Deehr is a wiry man who retains, in his sixties, a youthful zest for new research ventures. His work in auroral forecasting mixes science and divination as he searches for patterns in the latest information sent from near-Earth satellites in hopes of predicting auroral activity a day or so in advance. Such forewarning makes it possible to prepare electrical systems on Earth and in space for disturbances.
Scientists use satellites to gauge an aurora's power, but it was the 1989 aurora's extreme reach that demonstrated to most of us how unusual it was. Most auroras are visible only in the higher latitudes (above 60 degrees), but that one showed up as far south as Key West in Florida and the Yucatán Peninsula in Mexico. People unnerved by the fiery tint in the sky phoned the police; others watched in awe. Within 90 seconds of the aurora's reaching the skies above Quebec, magnetic storms associated with it caused a province-wide collapse of the power grid, leaving six million Canadians without electricity for hours. At the same time, compass readings became unreliable, and there were reports of automatic garage doors opening and closing on their own. Radio transmissions and coastal navigation systems were disrupted, and information feeds from some satellites were temporarily lost.
These troubles were a clear illustration of the need to predict auroras. In the Middle Ages a glowing red aurora over middle latitudes was seen by some Europeans as an omen of bloody battle or other impending doom. The superstition may have faded, but in a time of increasing reliance on high-tech links, discovering what auroras might actually signify has taken on practical relevance and a new urgency.
Charles Deehr arrived in Fairbanks with several other graduate students in physics in 1958. They were participating in the International Geophysical Year (IGY), which brought together scientists from 67 countries to study Earth's surface, interior, and atmosphere. The great red aurora of February 1958—perhaps the most extraordinary of the century—had just occurred. This indicated explosive activity on the sun, ideal conditions for auroral research. "The preceding year had the most sunspot activity ever recorded, and we had fancy big auroras every night," Deehr said.
Since the mid-1800s it has been known that the number of sunspots—dark, cooler patches of intense magnetic activity that are often accompanied by major eruptions on the solar disc—peaks roughly every 11 years. Sunspot numbers are usually high for a couple of years or so before and after the crest of this wave, known as the solar maximum. Auroras are hooked in to that roller coaster. So when the sun is restless, as it was in the late 1950s, Earth's night skies may dance.
Deehr's group contributed to the discovery that there are two great ovals of auroral activity encircling the geomagnetic poles—one for the aurora borealis in the Northern Hemisphere, one for the mirroring aurora australis in the Southern. These typically bulge farther toward the Equator on Earth's night side and change shape a bit in the course of a single day. During a big aurora they may move even farther, giving people beyond the normal limits a glimpse of the lights.
The aurora of 1958 also coincided with the dawn of the space age. Our understanding of auroras comes in huge measure from linking insights gained through manned space missions to data and images from satellites, rockets, and observatories on the ground. The current research armory includes various craft in the International Solar-Terrestrial Physics (ISTP) program. Largely under the command of NASA, the European Space Agency, and Japan's Institute of Space and Astronautical Science, this international endeavor uses spacecraft to study the sun—including sunspot activity—and its effects on the Earth. The ISTP missions have roughly coincided with the present solar cycle, which reached solar maximum in 2000 and is likely to produce atmospheric fireworks for the next couple of years.
During my time with Charles Deehr, there had been a lull in auroral activity. "Things are picking up again," he said, pointing to a diagram on his laptop. Red lines spiraled from a central point like water jets from a garden sprinkler. "The sprinkler is the sun," Deehr explained. "There are sources on the sun that give off charged particles—electrons and positive ions-—at different speeds. This spray of superhot ionized gas, known as plasma, blows across interplanetary space in what is termed the solar wind.
There is always auroral activity somewhere over the Earth. But its strength and extent vary hugely, according to what the sun has been hurling at us in preceding days. Flares that release energy bursts as powerful as millions of volcanic eruptions and coronal mass ejections that send hurricane blasts of ten billion tons of plasma into space figure more often during active parts of the solar cycle.
The sun, like the Earth and most of the planets, is a huge magnet, with its own force field stretching far beyond it. This gets twisted into a spiral by the sun's rotation, and within it the solar wind particles course along magnetic field lines that channel their movements. The eye-catching computer graphics Deehr showed me were an attempt to model the path of that energy from the sun to beyond the Earth.
As they zoom toward near-Earth space, the particle streams hit the edge of our planet's own magnetic sheath—the magnetosphere. Deflected by the magnetosphere, like water meeting a rock, the solar wind swirls past Earth and then pushes in again on the night side, squeezing the magnetosphere and elongating it into a comet-shaped tail. On the day side, the magnetosphere grows when the solar breeze is light and shrinks in a solar gale.
Charged particles that get trapped in the "magnetotail," which may stretch millions of miles, can be sent hurtling back toward Earth. Then, in a variety of possible ways not yet fully understood, some eventually rain down into the upper atmosphere over the polar regions—the places where our protective magnetic envelope is most open to space.
Auroral light comes largely from electrons hitting oxygen and nitrogen atoms and molecules in the upper atmosphere, the same phenomenon that produces the glow in a neon lighting tube. But in the aurora the illumination can be 600 miles (965.6 kilometers) high, stretch for thousands of miles, and be linked to a magnetospheric power generator churning out three million megawatts or more—about four times the electricity the United States uses at peak summer demand.
I asked Deehr what my chances were for an aurora that night, my last in Fairbanks. He clicked a couple of keys. "Here's where we're seeing a piling up of fast and slow particles. When we plot out what we think is going to happen, our model says we could get some increase in auroral activity later today."
But my departure was not to be graced by an aurora. I was reminded of what he had said about forecasting them. "There are no guarantees. We're still about a hundred years behind the meteorologists—it's that bad, or good."
In the past few years the term space weather has become a catchall to include eruptions from the sun, variations in the solar wind, and changes in the magnetosphere, which can in turn affect the Earth's atmosphere, producing auroras. Part of the uncertainty in making space-weather predictions is the difficulty of relating an event in one part of this vast system—such as in the sun—to a later event on Earth, such as an auroral display. "A lot can happen in 93 million miles (149.7 million kilometers);" was how one space physicist put it. Scientists at NASA's Goddard Space Flight Center in Greenbelt, Maryland, are part of an international team at the forefront of research into auroras and connections between the sun and the Earth.
"One of the most important aspects of auroras is that the polar regions are where the magnetic field lines concentrate," said Mario Acuna as we stood on a walkway overlooking a huge space-hardware testing floor. Acuna, who was born in Argentina and still speaks in a warm, accented baritone, is a veteran of NASA science missions from the early satellite days. "So over a small region you can observe what is happening over a gigantic volume in space. The complexity lies in how we can relate this auroral picture to phenomena that are happening elsewhere in the magnetosphere."
To make sense of the system, he explained, we need, as in weather forecasting, to have enough instruments in key places to understand cause and effect—where the energy comes from, how it gets transformed, and where it ends up. "That's the strategy behind the multiplicity of craft flying today," he said. "They are operating in four key regions. There have been some major changes in thinking because of the results."
One accomplishment was when the ISTP's Polar spacecraft (under NASA control and working on the sunward side of Earth) and Japan's Geotail craft (working in the magnetotail on the night side) made the very first direct observations of a crucial hookup between the magnetic fields of the sun and the Earth. Called reconnection, this linkage is an important aspect of the transformation that allows the solar wind's energy to penetrate Earth's magnetic cocoon, leading to auroras.
Another recent breakthrough from Polar is the finding that waves of energy flowing along magnetic field lines at more than 6,000 miles (9,656 kilometers) a second become more intense as the lines converge near Earth. These Alfvén waves (named for Hannes Alfvén, the Swedish physicist and Nobel laureate who first proposed their existence) appear to be what power an auroral display, by accelerating particles down from space. That's the big picture. But what shapes the finer detail of the classic auroral patterns—the curtains, folds, and rays—still awaits explanation.
Head reeling with ideas from space physics, I needed to reconnect with the visible aurora and the feelings it can stir. Yellowknife is the capital of Canada's Northwest Territories and the top global destination for aurora tourism. Last year some 12,000 people came here to see auroras—a pursuit of the truly dedicated in this frost-bitten location.
Raven Tours, the oldest of the aurora enterprises, was founded by Bill Tait in 1981. Tait was away in Japan drumming up business, but Jared Minty, an eager young co-director, gave me the essential information. "In our current aurora tour season, which runs from mid-November through mid-April, we'll have more than 9,000 clients," he said happily. "The other main operators will also have a few thousand. Almost all these clients are Japanese."
I observed the Japanese enthusiasm for auroras that night at Prelude Lake, some miles from town. With each burst of celestial choreography, groups of people cheered and clapped, some of the women ululating in high-pitched tones. Japanese passion for auroras intensified during the 1990s. Ask the average Yellowknife resident, as I did over a beer in the Raven Bar, and many will say that the Japanese believe that conceiving a child under a good aurora increases the chances of having a gifted offspring. This urban myth may have started in April 1992 with an episode of Northern Exposure, a TV series set in small-town Alaska and filmed in Washington State. In it an aurora begins while a group of Japanese visitors are in a guesthouse, and they all run upstairs to try their luck under the northern lights.
"How can they say that about us?" asked Yukiko Suzuki. Yukiko, who is from Tokuyama in western Japan, had found aurora work in Yellowknife for the winter. "In Japan we cannot watch the northern lights, but we know how it's beautiful and great," she said. "That's why they're coming.”
Don Morin, part Chipewyan, part Cree, and a former Northwest Territories premier, gave me another perspective on the aurora. "Many of the original peoples of North America have medicine animals," he told me one night as we sat in a huge tepee at Aurora Village, established by his family to give tourists a flavor of tribal life in addition to aurora-viewing opportunities.
"So when you pass on, you're going to go into an animal spirit. That's the next stop." For Morin's people, spirit life after death is a two-stage process. "When you pass on again, you end up in the dancing spirit—that's the aurora spirit. When we were kids, we were told that you have to be quiet when the aurora comes out. You don't want to upset the spirits in the sky by calling them closer."
"They've always been sacred to us," said Suzan Marie, a Déné-Chipewyan and Cree woman from the South Slave region. "But of course with elders telling us as children not to whistle at the lights, we had to test to see if it was really true. We knew we shouldn't be doing it, and if they really started to move, we'd get frightened and not stay out too long."
Which, as in many tales, was the down-to-earth practicality that complements the elders' spiritual spin on the world.
In Norway I met a man at Tromsø's Auroral Observatory who bridges the contrasting responses to auroras. Asgeir Brekke is a physicist who has studied the northern lights for more than three decades, but he is also an expert on auroral lore and legend. The walls of his office are hung with an intriguing mix of images, from radar stations to figures from northern mythology. Brekke is a soft-spoken man with a sweep of graying hair, and as we talked, he probed the images of death and life that recur in stories of aurora in different cultures—the links to spirits and battles between supernatural forces in the sky.
"I think for many people the phenomenon was scary, but some brave souls had their own thoughts about it." He mentioned the Norwegian who in about 1250 proposed rational-sounding explanations for the northern lights. One was that Greenland's ice drew in so much power that it could light the beams of the aurora. Along similar lines, he said, other Scandinavians had wondered if the lights were reflections from the sea or even from the glinting scales of huge shoals of herring.
Brekke circled back to science. "The current satellite experiments and those fascinating pictures that show the auroral ring around the Pole are fantastic achievements," he said. "I feel that the northern lights give a linkage between science and art. Even though as a scientist you are supposed to have some sort of objectivity, like an artist, you are inspired by them."
In collaboration with Dagfinn Bakke, an artist in Lofoten, Brekke has produced a book of watercolor paintings, scientific accounts, folktales, and poetry to show how people in Norway have related to auroras over the centuries. As I'd now come to understand, Brekke's enthusiasm for the lights represents a common bond between people who live beneath them and those who study them from afar. When he ended our meeting by reading poems about auroras, it seemed only fitting.
Poetry and space physics? Of course there's a connection. Just look up when the heavens dance. | 0.804819 | 3.784252 |
A newly discovered system of two white dwarf stars and a superdense pulsar–all packed within a space smaller than the Earth’s orbit around the sun–is enabling astronomers to probe a range of cosmic mysteries, including the very nature of gravity itself.
The international team, which includes UBC astronomer Ingrid Stairs, reports their findings in the journal Nature on January 5.
Originally uncovered by an American graduate student using the National Science Foundation’s Green Bank Telescope, the pulsar – 4,200 light-years from Earth, spinning nearly 366 times per second – was found to be in close orbit with a white dwarf star and the pair is in orbit with another, more distant white dwarf.
The three-body system is scientists’ best opportunity yet to discover a violation of a key concept in Albert Einstein’s theory of General Relativity: the strong equivalence principle, which states that the effect of gravity on a body does not depend on the nature or internal structure of that body.
“By doing very high-precision timing of the pulses coming from the pulsar, we can test for such a deviation from the strong equivalence principle at a sensitivity several orders of magnitude greater than ever before available,” says Stairs, with UBC’s Department of Physics and Astronomy. “Finding a deviation from the strong equivalence principle would indicate a breakdown of General Relativity and would point us toward a new, revised theory of gravity.”
“This is the first millisecond pulsar found in such a system, and we immediately recognized that it provides us a tremendous opportunity to study the effects and nature of gravity,” says Scott Ransom of the National Radio Astronomy Observatory (NRAO), who led the study. “This triple system gives us a natural cosmic laboratory far better than anything found before for learning exactly how such three-body systems work and potentially for detecting problems with General Relativity that physicists expect to see under extreme conditions.”
When a massive star explodes as a supernova and its remains collapse into a superdense neutron star, some of its mass is converted into gravitational binding energy that holds the dense star together. The strong equivalence principle says that this binding energy will still react gravitationally as if it were mass. Virtually all alternatives to General Relativity hold that it will not.
Under the strong equivalence principle, the gravitational effect of the outer white dwarf would be identical for both the inner white dwarf and the neutron star. If the strong equivalence principle is invalid under the conditions in this system, the outer star’s gravitational effect on the inner white dwarf and the neutron star would be slightly different and the high-precision pulsar timing observations could easily show that.
“We have made some of the most accurate measurements of masses in astrophysics,” says Anne Archibald of the Netherlands Institute for Radio Astronomy and one of the authors of the study. “Some of our measurements of the relative positions of the stars in the system are accurate to hundreds of meters.” Archibald led the effort to use the measurements to build a computer simulation of the system that can predict its motions.
The NRAO’s Scott Ransom adds: “This is a fascinating system in many ways, including what must have been a completely crazy formation history, and we have much work to do to fully understand it.”
The scientists’ observational program used the National Science Foundation’s Green Bank Telescope, the Arecibo radio telescope in Puerto Rico, and the Westerbork Synthesis Radio Telescope in the Netherlands. They also studied the system using data from the Sloan Digital Sky Survey, the GALEX satellite, the WIYN telescope on Kitt Peak, Arizona, and the Spitzer Space Telescope. | 0.925065 | 4.064992 |
A report from the Inter-Agency Space Debris Coordination Committee (IADC), which is meeting during the 50th Session of the Scientific and Technical Sub-Committee to the Committee on the Peaceful Uses of Outer Space (COPUOS), states that the debris situation in low Earth orbit (LEO) may be reaching a catastrophic tipping point. This tipping point, known as the Kessler Effect, was first predicted by Donald Kessler from NASA in 1978. The Kessler Effect envisions a scenario where the density of objects in LEO is high enough that collisions between objects will cause a cascade of collisions with each collision generating space debris thereby increasing the likelihood of further collisions. One inference of this cascade event is that the distribution of debris in orbit could render space activities in LEO, including the use of satellites such as the recently launched Landsat 8, impossible for several generations.
The study presented by the IADC used six space debris models from six IADC members: ASI, ESA, ISRO, JAXA, NASA, and UKSA. Each of the models used a 2009 baseline environment for space debris larger than 10 centimeters, which was provided by ESA’s MASTER model. From this baseline, all six models used a future space traffic assumption based on space traffic from 2001 to 2009. From this point, each model used its own solar flux projection standard with a future post-mission disposal (PMD) compliance level assumption of 90% for both spacecraft and launch vehicle stages. All the models defined a “catastrophic collision” as one with an impact kinetic energy to target mass ratio of 40 joules per gram or greater.
The results of all six models programmed with these assumptions showed similar qualitative results in the increase in the amount of space debris larger than 10 centimeter in LEO over the next 200 years. The models varied in the number of catastrophic collisions from one every five years to one every nine years, but they did agree that the majority of catastrophic collisions will occur in LEO altitudes above 800 kilometers with the majority of debris accumulating between 800 kilometers and 1000 kilometers over the next 100 years due to the proliferation of space objects at those altitudes. Space debris below 800 kilometers is less likely to accumulate because of atmospheric drag, which was recently evidenced with the reentry of the Earth resource satellite Cosmos 1484 after nearly thirty years in orbit.
The study concludes that there is a growing instability in the current LEO environment, and that compliance with the current international space debris mitigation guidelines will be insufficient to restrict the population of LEO with space debris in the future and recommends aggressive measures to remove larger non-functioning spacecraft and launch stages in a cost-effective manner. However, aggressive space debris removal is easier said than done. Substantial legal and policy questions surrounding space debris remediation exist that need to be addressed. For example, there has yet to be a legally acceptable definition of what constitutes space debris and issues of liability for space debris remediation activities. There are also substantial political questions regarding the potential use of space debris removal methodologies as space weapons as well as the issue of who will pay for the enormous cost to perform space debris remediation activities. While these issues remain, and safe, cost-effective methods of remediation are developed, the implementation of effective space debris remediation activities is unlikely to begin in earnest. In the meantime, the space debris environment in LEO will continue to grow, while the window of opportunity to address these issues and begin remediation activities in earnest before the problem spirals out of control is rapidly shrinking. | 0.815007 | 3.819708 |
Quarter ♏ Scorpio
Moon phase on 8 August 2008 Friday is First Quarter, 7 days young Moon is in Scorpio.Share this page: twitter facebook linkedin
First Quarter is the lunar phase on . Seen from Earth, illuminated fraction of the Moon surface is 47% and growing larger. The 7 days young Moon is in ♏ Scorpio.
* The exact date and time of this First Quarter phase is on 8 August 2008 at 20:20 UTC.
Moon rises at noon and sets at midnight. It is visible high in the southern sky in early evening.
Moon is passing about ∠12° of ♏ Scorpio tropical zodiac sector.
Lunar disc appears visually 6% narrower than solar disc. Moon and Sun apparent angular diameters are ∠1782" and ∠1893".
Next Full Moon is the Sturgeon Moon of August 2008 after 8 days on 16 August 2008 at 21:16.
There is low ocean tide on this date. Sun and Moon gravitational forces are not aligned, but meet at big angle, so their combined tidal force is weak.
The Moon is 7 days young. Earth's natural satellite is moving through the first part of current synodic month. This is lunation 106 of Meeus index or 1059 from Brown series.
Length of current 106 lunation is 29 days, 9 hours and 45 minutes. It is 2 hours and 29 minutes shorter than next lunation 107 length.
Length of current synodic month is 2 hours and 59 minutes shorter than the mean length of synodic month, but it is still 3 hours and 10 minutes longer, compared to 21st century shortest.
This New Moon true anomaly is ∠39.2°. At beginning of next synodic month true anomaly will be ∠64.9°. 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°).
9 days after point of perigee on 29 July 2008 at 23:24 in ♊ Gemini. The lunar orbit is getting wider, while the Moon is moving outward the Earth. It will keep this direction for the next 2 days, until it get to the point of next apogee on 10 August 2008 at 20:18 in ♐ Sagittarius.
Moon is 402 257 km (249 951 mi) away from Earth on this date. Moon moves farther next 2 days until apogee, when Earth-Moon distance will reach 404 558 km (251 381 mi).
6 days after its descending node on 2 August 2008 at 01:21 in ♌ Leo, 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 16 August 2008 at 10:27 in ♒ Aquarius.
19 days after beginning of current draconic month in ♒ Aquarius, the Moon is moving from the second to the final part of it.
10 days after previous North standstill on 29 July 2008 at 06:17 in ♊ Gemini, when Moon has reached northern declination of ∠27.598°. Next 3 days the lunar orbit moves southward to face South declination of ∠-27.611° in the next southern standstill on 11 August 2008 at 22:13 in ♐ Sagittarius.
After 8 days on 16 August 2008 at 21:16 in ♒ Aquarius, the Moon will be in Full Moon geocentric opposition with the Sun and this alignment forms next Sun-Earth-Moon syzygy. | 0.848363 | 3.219993 |
Plumes on Europa May Enable the Hunt for Alien Life
Jupiter’s moon Europa likely has water plumes—great geysers of saline ocean blasting from its icy shell. That's what scientists announced earlier today, reaffirming previous observations of plume activity on the Galilean moon. The findings raise the stakes for the agency's next flagship planetary mission, slated to launch for Europa around 2022.
The plumes, which are estimated to rise 125 miles above Europa's surface, were captured using the Hubble Space Telescope, NASA's 26-year-old space-based orbiting observatory. "We are working at the limits of Hubble's unique capabilities," said William Sparks, an astronomer with the Space Telescope Science Institute, during a press teleconference. To find the plumes, scientists used what’s known as transit imaging operations, observing the silhouette of Europa against the bright surface of Jupiter. It took 50 million observation events to generate the plume images, which were carefully processed through specially designed software.
NASA teased the results last week, promising "surprising activity" on the moon. Plumes fit the bill, and have implications beyond celestial wonder and geologic thrill-seeking. Europa is an ocean world, and is thought to have all of the ingredients necessary for life. Though it is only about the size of our own moon, it hosts a saltwater ocean with twice the water of Earth's oceans. That water is sandwiched between an ice shell and a rocky mantle. When water touches rock, interesting chemical processes result—especially if there are hydrothermal vents from the planet's interior blasting hot water into the ocean. The conditions for life on Europa are at least as hospitable as what can be found in the deepest parts of Earth's ocean. The plumes help kick open the door for alien, Europan creatures, though what we might find there remains a mystery.
The problem has always been getting to Europa’s ocean to take a sample. The ice shell is likely many miles thick—beyond the drilling capacity even here on Earth. Plumes solve that problem. We don't need to go to the ocean; we can have the ocean come to us. The Europa Multiple Flyby Mission in development by NASA will see a spacecraft enter orbit around Jupiter, circling the gas giant hundreds of times. Each time it comes around to Europa, it will scan and image the icy world. This technique, rather than a direct Europa orbiter, allows the spacecraft to avoid the worst of the punishing radiation belt in the Jovian environment. Scientists can now plan trajectories that allow the spacecraft to fly through the plumes in order to analyze their composition.
However, nobody is promising life detection yet. The multiple flyby mission is designed to study habitability. Follow-up missions—likely Europa landers—would actually determine the life question. (The plumes help a lander as much as they do a flyby, since water that blasts from Europa's shell would rain back down to the surface. A lander could make extraordinary observations by drilling only a few inches down.) Lander concepts are currently under development at Jet Propulsion Laboratory in southern California. The multiple flyby spacecraft is being developed jointly by JPL and the Johns Hopkins University Applied Physics Laboratory in Maryland.
"For a long time, humanity's been wondering whether there is life beyond Earth," said Paul Hertz, director of the astrophysics division at NASA headquarters. "We're lucky to live in an era when we can address such evidence scientifically."
For now, the discovery could only have been made with the sensitivity of the Hubble. "Hubble is the only telescope that we have right now capable of observing Jupiter and Europa at this detail in ultraviolet light," said Jennifer Wiseman, senior Hubble project scientist at NASA's Goddard Space Flight Center. The space telescope's science mission was recently extended by five years, until 2021, at which time NASA will have to decide whether to keep the space telescope operational. The powerful James Webb Space Telescope, Hubble's successor, is slated to launch in 2018. "We're particularly excited about using the James Webb Space Telescope ... to look for additional evidence of Europa water,” Wiseman says. | 0.846903 | 3.738879 |
Scientists at the Nobel-winning LIGO project caught the birds in the act, pecking at a frosty pipe along one of the observatory’s 2.5-mile-long arms
For the LIGO observatory on Washington’s Hanford site, noise is a real buzz killer.
Any earthly sound — a truck rumbling past, the humming of a refrigerator in a nearby building, or the distant flutter of a plane’s propellers — can drown out the faint whispers from the cosmos that the Nobel Prize-winning project was designed to detect.
So when strange blips in the data started cropping up on summer afternoons, researchers were anxious to find the source and eliminate it.
“Any other noise makes it harder to hear the thing you’re listening for,” said University of Oregon physicist Robert Schofield, whose job is to ferret out racket from the environment and reduce its impact on some of the most sensitive instruments ever built.
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What the Laser Interferometer Gravitational-Wave Observatory is straining to hear are fleeting vibrations in the fabric of space and time called gravitational waves. First hypothesized by Albert Einstein, the waves are generated by cosmic cataclysms and radiate across the universe like ripples in a pond.
LIGO succeeded in capturing those ripples for the first time in 2015, thanks to its ability to detect fluctuations smaller than the diameter of a proton. The waves, which originated from the collision of two black holes a billion light-years away, registered as a faint chirp on the observatory’s instruments.
But the mysterious blips last summer didn’t look like gravitational waves, said physicist Beverly Berger, a member of the LIGO collaboration based in California who first spotted them. And there were no similar glitches at LIGO’s twin instrument in Louisiana.
The glitches at Hanford corresponded to sounds recorded by a microphone installed by Schofield and his colleagues as part of their endless quest to detect and stamp out noise.
“It was picking up sounds at about the same time, almost every day,” said Berger, who recounted the scientific detective story at a meeting of the American Physical Society last month.
It didn’t take long for Schofield to identify the prime suspect once he listened to the recordings.
“It sounded like pecks to me,” he said. “I immediately thought it must be ravens.”
Schofield had seen the big, black corvids at the site many times. On hot days, they often perched on frost-covered pipes connected to a nitrogen cryopump that helps maintain a vacuum inside the L-shaped instrument’s concrete arms, each 2.5 miles long.
When Schofield and his colleagues investigated on a 100-plus-degree day, they found the pipes covered with peck marks, and even spotted one bird in the act of scraping its beak through the frost. “They peck for a while and make themselves a snow cone,” he said.
It’s no surprise to Schofield that pecking by a 3-pound bird could throw a wrench into an enormous system like LIGO. Some of the other noise sources he’s dealt with include water flowing over a dam 15 miles away, wind pushing on the buildings and distant construction projects.
Though it has a lot of built-in buffering, the way LIGO works makes it very vulnerable to outside interference.
When the instrument is operating, identical laser beams travel through each arm and are reflected back by mirrors at the ends. When a gravitational wave passes through, it stretches one arm and compresses the other, leading to a minuscule mismatch in the reflected beams.
The difference is equivalent to the width of an atom over the distance from the Earth to the sun, Berger said. “It’s an incredible level of precision, which means you have to shut out basically the whole world in order to see it.”
And that means the ravens had to go.
The first thing the research team did was insulate the pipes so they wouldn’t attract birds looking for a cool oasis. Then Schofield and his colleagues identified the component inside the instrument that jiggled when the ravens pecked. A few weeks ago, they finished fixing it so the problem won’t happen again.
The instruments are being fine-tuned to boost their sensitivity even more, and are expected to resume the search next year.
Though ravens should plague the project nevermore, the incident did spawn a few riffs on Edgar Allan Poe’s classic poem.
One, from physicist Andrew Lundgren concluded:
“Eagerly I read your logbook, hoping that this humble rook
Might one day not be overlook’d — overlook’d in LIGO’s lore
That this somber, clever avian might find a place in LIGO’s lore
Part of science for evermore.” | 0.812209 | 3.046952 |
In early 1930, Pluto was discovered by a farm boy from Kansas with no formal training in astronomy. The announcement in March of Pluto’s discovery was a moment of excitement for both scientists and the public.
Clyde Tombaugh was born on February 4, 1906 in Illinois, and grew up on a farm in Kansas. He became interested in astronomy as a teenager after observing craters on the moon and rings around Saturn through his uncle’s three inch telescope. The family soon ordered a better telescope to encourage their son’s interests. When he was 20, Clyde Tombaugh began building his own telescopes.
By 1928 Tombaugh had built his third backyard telescope and used it to make drawings of Mars and Jupiter. He sent these to Vesto M. Slipher, the director of the Lowell Observatory in Flagstaff, Arizona, asking for comments. After a short correspondence, Slipher offered him a job at the observatory. His task would be to search for “Planet X.”
Planet X had been predicted by Percival Lowell. Lowell, a businessman and astronomer known for his belief that a network of canals existed on Mars and was evidence of an intelligent alien civilization, built the Lowell Observatory to prove his theory. But as it became more and more clear that there was no evidence for that theory, he began to focus on searching for a new planet. Lowell had observed some peculiarity in the orbits of Neptune and Uranus and figured there must be another planet with a mass comparable to Neptune’s orbiting the sun beyond Neptune. Lowell searched for the planet, which he called Planet X, from 1905 to his death in 1916.
For years after Lowell’s death, the Lowell observatory was hampered by an expensive legal battle with Lowell’s widow. In 1927 the observatory was ready to resume the search for Planet X, and it acquired a new 13 inch refracting telescope for the search.
Slipher assigned the task to Tombaugh, who arrived in Flagstaff in January 1929. First, he had to use the telescope to make many photographic plates, systematically taking pictures of regions of the night sky where the new planet might appear. For each region, Tombaugh made two photos, taken several days apart. He spent many cold nights in the unheated observatory dome carefully making the observations.
After creating many such pairs of plates, he would compare the two members of each pair. Distant stars would appear in the same position on both plates, but a planet would have moved in the several days between the two exposures. Tombaugh used a device called a blinking comparator to make the comparison. The device would present him with sections of the two photo plates to be compared, shifting between the two several times a second. Most of the time the photos were the same and Tombaugh would see nothing, but if an object had moved between the two exposures, Tombaugh would see a blink.
It was incredibly tedious work requiring intense concentration, but Tombaugh greatly preferred it to going back to work on the farm, so he persisted.
After months of searching, he had found several asteroids, but nothing that fit the criteria for Planet X. Finally, in February 1930, while scanning the plates he had taken a few weeks earlier, he saw something that moved. He determined that the object had moved about 3 mm on the plates between the two exposures, indicating an orbital distance of about 40-43 AU, putting it outside the orbit of Neptune at about the right place to be the predicted planet.
Tombaugh told Slipher he had found Planet X, and on March 13, 1930, the Observatory announced the finding of the new object. The announcement date was chosen to coincide with both the anniversary of Herschel’s discovery of Uranus in 1781 and Percival Lowell’s birthday in 1855.
The public and astronomers were enthusiastic about the new planet. Later that month the object was officially named Pluto, after the Roman god of the underworld, who could make himself invisible. The name was suggested by an 11 year old girl in England. A secondary reason for the name was that the first two letters are Percival Lowell’s initials.
Though exciting, the planet was tiny, just a dot on the photograph, and some astronomers doubted whether it was massive enough to affect the orbit of Uranus and Neptune.
Pluto’s mass was not known until 1978, when its moon Charon was discovered. Pluto’s mass is about 0.002 that of Earth, making it much too small to influence the orbit of Neptune.
Ultimately, Pluto lost its planet status. Other objects in the neighborhood of Pluto have been discovered in recent years, including several comparable in size to Pluto. In 2006, much to the disappointment of children around the world, the International Astronomical Union redefined the term “planet.” The new definition of a planet requires an object to orbit a star, be large enough to be made round by gravity, and have cleared its orbit of other debris. The third criterion disqualifies Pluto, which is now known as a dwarf planet.
After the discovery of Pluto, Tombaugh received a scholarship to study astronomy at the University of Kansas. He began as a freshman in 1932 and continued to work in astronomy for many years. Tombaugh was later known as one of only a few scientists to take UFOs seriously. He died in 1997, mercifully before the demotion of his planet to the status of a dwarf.
Read more at www.aps.org | 0.80385 | 3.242718 |
Big world around tiny star puts new spin on planet formation
Cape Canaveral, Fla. – A giant world discovered around a tiny star is putting a new spin on how planets form.
Astronomers reported Thursday they’ve found a Jupiter-like planet orbiting a star that’s a mere 12% the mass of our sun. There may even be another big gas planet lurking in this system 31 light-years away.
The Spanish-led team wrote in the journal Science that the newly confirmed planet did not form the usual, gradual way, where a solid core of merging particles takes shape before a gas buildup. Instead, in a surprise to scientists, the planet seems to have arisen straight from gas.
Lead author Juan Carlos Morales of the Institute of Space Studies of Catalonia said the planet may be almost as big as its star. A year there is about 200 days.
“It was very exciting finding this planet because it was completely unexpected,” Morales wrote in an email. The results indicate “a new population of massive planets may also exist around low-mass stars.”
Morales and his team maintain that gravitational instability in a young star’s disk of gas and dust could, in some cases, result in the quick formation of huge gas planets – even when the star is minuscule. This new world is “an extraordinary candidate” for this process, said Hubert Klahr of Max Planck Institute for Astronomy in Germany, part of the research team. “This find prompts us to review our models.”
In a companion article, Yale University astronomer Greg Laughlin, who was not involved in the study, pointed out that more than 4,000 so-called exoplanets have been confirmed in solar systems outside our own. While another new one, by itself, is no longer particularly noteworthy, he said, “one that challenges current theories of planet formation can animate astronomers.”
The planet orbiting this particularly small and cool red dwarf star, officially known as GJ 3512, is at least half the mass of Jupiter. Scientists are unable to measure its dimensions, but models indicate it may be comparable to Jupiter in size, according to Morales.
Using observatories in Spain, the researchers repeatedly studied the star’s wobbling motion to disclose the planet in its lopsided orbit, rather than rely on the transit method in which a brief, periodic dimming of starlight indicates a planet passing in front of its star.
The star is so faint it almost didn’t make it into the group’s survey. Scientists needed more small stars for sampling and so added a few at the last minute.
“We were lucky to do so because otherwise we would have never made this discovery,” Ignasi Ribas, director of the Catalonia space studies institute, said in a statement.
Morales and his colleagues continue to search for a second planet orbiting this dwarf star. There may have been a third planet that was ejected from the system long ago, they noted.
The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content. | 0.907318 | 3.594649 |
Dec. 6, 2011 -- NASA's Kepler space telescope has found a new planet -- the most Earth-like yet -- circling a yellow star similar to Earth's sun and 600 light-years away, according to the space agency.
The most promising thing about this world, called Kepler-22b for now, is that it's in the so-called Goldilocks zone around its host star. Its surface temperature is estimated at an average of 72 degrees, which means liquid water -- considered essential for life as we know it -- would be possible there.
"We are certain that it is in the habitable zone and if it has a surface, it ought to have a nice temperature," said Bill Borucki, the Kepler principal investigator at NASA's Ames Research Center.
But just how realistic are the prospects for life on that distant world? Even in their excitement, the researchers caution that they have found no proof that we are not alone.
The Kepler team has done a prodigious job of detection and mathematical calculation, but Kepler has not actually seen the planet or taken any chemical measurements. They know its host star is slightly smaller and cooler than the sun, and they found that its light dims ever so slightly once every 290 Earth days. That means the dot of the planet is passing in front of it. It's a little closer to its sun than we are to our sun.
From there, they can extrapolate. For the planet to be in a nice, nearly circular orbit, not too hot and not too cold, they figured out that it's probably 2.4 times the diameter of Earth.
That makes it among the smallest planets yet found orbiting other stars, but it's a smidgen larger than an ideal candidate for extraterrestrial life would be.
"That smidgen makes all the difference," said Geoff Marcy of the University of California, Berkeley, who is one of the pioneers of planet-hunting outside Earth's solar system, and a member of the Kepler team.
Scientists know, from looking at Earth's solar system, that rocky worlds like the Earth's are a precious commodity. If a world is too small (think of Mercury or Earth's moon), any atmosphere will escape into space before life could possibly form. If a world is too large (think of Jupiter or Neptune) it's likely to be all atmosphere, a giant ball of gas or slush that thickens quickly as you plunge beneath its cloud tops, but probably has no solid surface where living things could thrive.
Kepler-22b might be the right temperature, but it is probably closer in mass to icy Neptune than to Earth. "I would bet my telescope that there is no hard, rocky surface to walk on," Marcy told the Associated Press.
Alan Boss of the Carnegie Institution for Science, a colleague of Marcy's, wrote in an email to ABC News, "We know the star is sun-like, and we know the orbit is Earth-like, but the size is super-Earth-like. As Meatloaf sings, two out of three ain't bad."
Still, the discovery sets scientists' minds racing.
"In less than 20 years, we have gone from not knowing if any other planets exist in the universe, to being able to look out at the night sky and realize that essentially any star we can see has at least one planet, and a good number of those are likely to be habitable," said Alan Boss. "That is a revelation that has not yet dawned on the general public, and even astronomers are having their minds blown when they think about it."
"This discovery shows that we Homo sapiens are straining our reach into the universe to find planets that remind us of home," Marcy said. "We are almost there."
The Associated Press contributed to this report. | 0.856775 | 3.799198 |
Astronomers have recognized various ways that stars can collapse to undergo a supernova. In one situation, an iron core collapses. The second involves a lower mass star with oxygen, neon, and magnesium in the core which suddenly captures electrons when the conditions are just right, removing them as a support mechanism and causing the star to collapse. While these two mechanisms make good physical sense, there has never been any observational support showing that both types occur. Until now that is. Astronomers led yb Christian Knigge and Malcolm Coe at the University of Southampton in the UK announced that they have detected two distinct sub populations in the neutron stars that result from these supernova.
To make the discovery, the team studied a large number of a specific sub-class of neutron stars known as Be X-ray binaries (BeXs). These objects are a pair of stars formed by a hot B spectral class stars with hydrogen emission in their spectrum in a binary orbit with a neutron star. The neutron star orbits the more massive B star in an elliptical orbit, siphoning off material as it makes close approaches. As the accreted material strikes the neutron star’s surface it glows brightly in the X-rays, becoming, for a time, an X-ray pulsar allowing astronomers to measure the spin period of the neutron star.
Such systems are common in the Small Magellanic Cloud which appears to have a burst of star forming activity about 60 million years ago, allowing for the massive B stars to be in the prime of their stellar lives. It is estimated that the Small Magellanic Cloud alone has as many BeXs as the entire Milky Way galaxy, despite being 100 times smaller. By studying these systems as well the Large Magellanic Cloud and Milky Way, the team found that there are two overlapping but distinct populations of BeX neutron stars. The first had a short period, averaging around 10 seconds. A second group had an average of around 5 minutes. The team surmises that the two populations are a result of the different supernova formation mechanisms.
The two different formation mechanisms should also lead to another difference. The explosion is expected to give the star a “kick” that can change the orbital characteristics. The electron-captured supernovae are expected to give a kick velocity of less than 50 km/sec whereas the iron core collapse supernovae should be over 200 km/sec. This would mean the iron core collapse stars should have preferentially longer and more eccentric orbits. The team attempted to discern whether this too was supported by their evidence, but only a small fraction of the stars they examined had determined eccentricities. Although there was a small difference, it is too early to determine whether or not it was due to chance.
According to Knigge, “These findings take us back to the most fundamental processes of stellar evolution and lead us to question how supernovae actually work. This opens up numerous new research areas, both on the observational and theoretical fronts. | 0.867391 | 4.078374 |
At present, scientists can only look for planets beyond our Solar System using indirect means. Depending on the method, this will involve looking for signs of transits in front of a star (Transit Photometry), measuring a star for signs of wobble (Doppler Spectroscopy), looking for light reflected from a planet’s atmosphere (Direct Imaging), and a slew of other methods.
Based on certain parameters, astronomers are then able to determine whether a planet is potentially-habitable or not. However, a team of astronomers from the Netherlands recently released a study in which they describe a novel approach for exoplanet-hunting: looking for signs of aurorae. As these are the result of interaction between a planet’s magnetic field and a star, this method could be a shortcut to finding life!
For decades, scientists have held that the Earth-Moon system formed as a result of a collision between Earth and a Mars-sized object roughly 4.5 billion years ago. Known as the Giant Impact Hypothesis, this theory explains why Earth and the Moon are similar in structure and composition. Interestingly enough, scientists have also determined that during its early history, the Moon had a magnetosphere – much like Earth does today.
However, a new study led by researchers at MIT (with support provided by NASA) indicates that at one time, the Moon’s magnetic field may have actually been stronger than Earth’s. They were also able to place tighter constraints on when this field petered out, claiming it would have happened about 1 billion years ago. These findings have helped resolve the mystery of what mechanism powered the Moon’s magnetic field over time.
Space is a hostile environment in so many ways. But one of its worst features is the various kinds of radiation you can find. When astronauts go back beyond the protective environment of the Earth’s magnetosphere, what are the various kinds of radiation they’ll encounter. And is there anything we’ll be able to do about it?
It’s easy to imagine the excitement NASA personnel must have felt when an amateur astronomer contacted NASA to tell them that he might have found their missing IMAGE satellite. After all, the satellite had been missing for 10 years.
IMAGE, which stands for Imager for Magnetopause-to-Aurora Global Exploration, was launched on March 25th, 2000. In Dec. 2005 the satellite failed to make routine contact, and in 2007 it failed to reboot. After that, the mission was declared over.
It’s astonishing that after 10 years, the satellite has been found. It’s even more astonishing that it was an amateur who found it. As if the story couldn’t get any more interesting, the amateur astronomer who found it—Scott Tilly of British Columbia, Canada—was actually looking for a different missing satellite: the secret ZUMA spy satellite launched by the US government on January 7, 2018. (If you’re prone to wearing a tin foil hat, now might be a good time to reach for one.)
After Tilly contacted NASA, they hurried to confirm that it was indeed IMAGE that had been found. To do that, NASA employed 5 separate antennae to seek out any radio signals from the satellite. As of Monday, Jan. 29, signals received from all five sites were consistent with the radio frequency characteristics expected of IMAGE.
In a press release, NASA said, “Specifically, the radio frequency showed a spike at the expected center frequency, as well as side bands where they should be for IMAGE. Oscillation of the signal was also consistent with the last known spin rate for IMAGE.”
“…the radio frequency showed a spike at the expected center frequency…” – NASA Press Release confirming the discovery of IMAGE
Then, on January 30, the Johns Hopkins Applied Physics Lab (JHUAPL) reported that they had successfully collected telemetry data from the satellite. In that signal was the ID code 166, the code for IMAGE. There were probably some pretty happy people at NASA.
So, now what?
NASA’s next step is to confirm without a doubt that this is indeed IMAGE. That means capturing and analyzing the data in the signal. That will be a technical challenge, because the types of hardware and operating systems used in the IMAGE Mission Operations Center no longer exist. According to NASA, “other systems have been updated several versions beyond what they were at the time, requiring significant reverse-engineering.” But that should be no problem for NASA. After all, they got Apollo 13 home safely, didn’t they?
If NASA is successful at decoding the data in the signal, the next step is to attempt to turn on IMAGE’s science payload. NASA has yet to decide how to proceed if they’re successful.
IMAGE was the first spacecraft designed to “see the invisible,” as they put it back then. Prior to IMAGE, spacecraft examined Earth’s magnetosphere by detecting particles and fields they encountered as they passed through them. But this method had limited success. The magnetosphere is enormous, and simply sampling a small path—while better than nothing—did not give us an accurate understanding of it.
IMAGE was going to do things differently. It used 3-dimensional imaging techniques to measure simultaneously the densities, energies and masses of charged particles throughout the inner magnetosphere. To do this, IMAGE carried a payload of 7 instruments:
High Energy Neutral Atom (HENA) imager
Medium Energy Neutral Atom (MENA) imager
Low Energy Neutral Atom (LENA) imager
Extreme Ultraviolet (EUV) imager
Far Ultraviolet (FUV) imager
Radio Plasma Imager (RPI)
Central Instrument Data Processor (CIDP)
These instruments allowed IMAGE to not only do great science, and to capture great images, but also to create some stunning never-seen-before movies of auroral activity.
This is a fascinating story, and it’ll be interesting to see if NASA can establish meaningful contact with IMAGE. Will it have a treasure trove of unexplored data on-board? Can it be re-booted and brought back into service? We’ll have to wait and see.
This story is also interesting culturally. IMAGE was in service at a time when the internet wasn’t as refined as it is currently. NASA has mastered the internet and public communications now, but back then? Not so much. For example, to build up interest around the mission, NASA gave IMAGE its own theme song, titled “To See The Invisible.” Yes, seriously.
But that’s just a side-note. IMAGE was all about great science, and it accomplished a lot. You can read all about IMAGE’s science achievements here.
For many reasons, Venus is sometimes referred to as “Earth’s Twin” (or “Sister Planet”, depending on who you ask). Like Earth, it is terrestrial (i.e. rocky) in nature, composed of silicate minerals and metals that are differentiated between an iron-nickel core and silicate mantle and crust. But when it comes to their respective atmospheres and magnetic fields, our two planets could not be more different.
For some time, astronomers have struggled to answer why Earth has a magnetic field (which allows it to retain a thick atmosphere) and Venus do not. According to a new study conducted by an international team of scientists, it may have something to do with a massive impact that occurred in the past. Since Venus appears to have never suffered such an impact, its never developed the dynamo needed to generate a magnetic field.
The study, titled “Formation, stratification, and mixing of the cores of Earth and Venus“, recently appeared in the scientific journal Earth and Science Planetary Letters. The study was led by Seth A. Jacobson of Northwestern University, and included members from the Observatory de la Côte d’Azur, the University of Bayreuth, the Tokyo Institute of Technology, and the Carnegie Institution of Washington.
For the sake of their study, Jacobson and his colleagues began considering how terrestrial planets form in the first place. According to the most widely-accepted models of planet formation, terrestrial planets are not formed in a single stage, but from a series of accretion events characterized by collisions with planetesimals and planetary embryos – most of which have cores of their own.
Recent studies on high-pressure mineral physics and on orbital dynamics have also indicated that planetary cores develop a stratified structure as they accrete. The reason for this has to do with how a higher abundance of light elements are incorporated in with liquid metal during the process, which would then sink to form the core of the planet as temperatures and pressure increased.
Such a stratified core would be incapable of convection, which is believed to be what allows for Earth’s magnetic field. What’s more, such models are incompatible with seismological studies that indicate that Earth’s core consists mostly of iron and nickel, while approximately 10% of its weight is made up of light elements – such as silicon, oxygen, sulfur, and others. It’s outer core is similarly homogeneous, and composed of much the same elements.
As Dr. Jacobson explained to Universe Today via email:
“The terrestrial planets grew from a sequence of accretionary (impact) events, so the core also grew in a multi-stage fashion. Multi-stage core formation creates a layered stably stratified density structure in the core because light elements are increasingly incorporated in later core additions. Light elements like O, Si, and S increasingly partition into core forming liquids during core formation when pressures and temperatures are higher, so later core forming events incorporate more of these elements into the core because the Earth is bigger and pressures and temperatures are therefore higher.
“This establishes a stable stratification which prevents a long-lasting geodynamo and a planetary magnetic field. This is our hypothesis for Venus. In the case of Earth, we think the Moon-forming impact was violent enough to mechanically mix the core of the Earth and allow a long-lasting geodynamo to generate today’s planetary magnetic field.”
To add to this state of confusion, paleomagnetic studies have been conducted that indicate that Earth’s magnetic field has existed for at least 4.2 billion years (roughly 340 million years after it formed). As such, the question naturally arises as to what could account for the current state of convection and how it came about. For the sake of their study, Jacobson and his team considering the possibility that a massive impact could account for this. As Jacobson indicated:
“Energetic impacts mechanically mix the core and so can destroy stable stratification. Stable stratification prevents convection which inhibits a geodynamo. Removing the stratification allows the dynamo to operate.”
Basically, the energy of this impact would have shaken up the core, creating a single homogeneous region within which a long-lasting geodynamo could operate. Given the age of Earth’s magnetic field, this is consistent with the Theia impact theory, where a Mars-sized object is believed to have collided with Earth 4.51 billion years ago and led to the formation of the Earth-Moon system.
This impact could have caused Earth’s core to go from being stratified to homogeneous, and over the course of the next 300 million years, pressure and temperature conditions could have caused it to differentiate between a solid inner core and liquid outer core. Thanks to rotation in the outer core, the result was a dynamo effect that protected our atmosphere as it formed.
The seeds of this theory were presented last year at the 47th Lunar and Planetary Science Conference in The Woodlands, Texas. During a presentation titled “Dynamical Mixing of Planetary Cores by Giant Impacts“, Dr. Miki Nakajima of Caltech – one of the co-authors on this latest study – and David J. Stevenson of the Carnegie Institution of Washington. At the time, they indicated that the stratification of Earth’s core may have been reset by the same impact that formed the Moon.
It was Nakajima and Stevenson’s study that showed how the most violent impacts could stir the core of planets late in their accretion. Building on this, Jacobson and the other co-authors applied models of how Earth and Venus accreted from a disk of solids and gas about a proto-Sun. They also applied calculations of how Earth and Venus grew, based on the chemistry of the mantle and core of each planet through each accretion event.
The significance of this study, in terms of how it relates to the evolution of Earth and the emergence of life, cannot be understated. If Earth’s magnetosphere is the result of a late energetic impact, then such impacts could very well be the difference between our planet being habitable or being either too cold and arid (like Mars) or too hot and hellish (like Venus). As Jacobson concluded:
“Planetary magnetic fields shield planets and life on the planet from harmful cosmic radiation. If a late, violent and giant impact is necessary for a planetary magnetic field then such an impact may be necessary for life.”
Looking beyond our Solar System, this paper also has implications in the study of extra-solar planets. Here too, the difference between a planet being habitable or not may come down to high-energy impacts being a part of the system’s early history. In the future, when studying extra-solar planets and looking for signs of habitability, scientists may very well be forced to ask one simple question: “Was it hit hard enough?”
Human beings have known for quite some time that our behavior has a significant influence on our planet. In fact, during the 20th century, humanity’s impact on the natural environment and climate has become so profound that some geologists began to refer to the modern era as the “Anthropocene”. In this age, human agency is the most deterministic force on the planet.
But according to a comprehensive new study by an Anglo-American team of researchers, human beings might be shaping the near-space environment as well. According to the study, radio communications, EM radiation from nuclear testing and other human actions have led to the creation of a barrier around Earth that is shielding it against high-energy space radiation.
The study, which was published in the journal Space Science Reviews under the title “Anthropogenic Space Weather“, was conducted by a team of scientists from the US and Imperial College, London. Led by Dr. Tamas Gombosi, a professor at the University of Michigan and the director at the Center for Space Modelling, the team reviewed the impact anthropogenic processes have on Earth’s near-space environment.
These processes include VLF and radio-frequency (RF) radio communications, which began in earnest during the 19th century and grew considerably during the 20th century. Things became more intense during the 1960s when the United States and the Soviet Union began conducting high-altitude nuclear tests, which resulted in massive electromagnetic pulses (EMP) in Earth’s atmosphere.
To top it off, the creation of large-scale power grids has also had an impact on the near-space environment. As they state in their study:
“The permanent existence, and growth, of power grids and of VLF transmitters around the globe means that it is unlikely that Earth’s present-day space environment is entirely “natural” – that is, that the environment today is the environment that existed at the onset of the 19th century. This can be concluded even though there continue to exist major uncertainties as to the nature of the physical processes that operate under the influence of both the natural environment and the anthropogenically-produced waves.”
The existence of radiation belts (or “toroids”) around Earth has been a well-known fact since the late 1950s. These belts were found to be the result of charged particles coming from the Sun (i.e. “solar wind”) that were captured by and held around Earth by it’s magnetic field. They were named Van Allen Radiation Belts after their discover, the American space scientist James Van Allen.
The extent of these belts, their energy distribution and particle makeup has been the subject of multiple space missions since then. Similarly, studies began to be mounted around the same time to discover how human-generated charged particles, which would interact with Earth’s magnetic fields once they reached near-space, could contribute to artificial radiation belts.
However, it has been with the deployment of orbital missions like the Van Allen Probes (formerly the Radiation Belt Storm Probes) that scientists have been truly able to study these belts. In addition to the aforementioned Van Allen Belts, they have also taken note of the VLF bubble that radio transmissions have surrounded Earth with. As Phil Erickson, the assistant director at the MIT Haystack Observatory, said in a NASA press release:
“A number of experiments and observations have figured out that, under the right conditions, radio communications signals in the VLF frequency range can in fact affect the properties of the high-energy radiation environment around the Earth.”
One thing that the probes have noticed was the interesting way that the outward extent of the VLF bubble corresponds almost exactly to the inner and outer Van Allen radiation belts. What’s more, comparisons between the modern extent of the radiations belts from the Van Allen Probe data shows that the inner boundary is much farther away than it appeared to be during the 1960s (when VLF transmissions were lower).
What this could mean is that the VLF bubble we humans have been creating for over a century and half has been removing excess radiation from the near-Earth environment. This could be good news for us, since the effects of charged particles on electronics and human health is well-documented. And during periods of intense space weather – aka. solar flares – the effects can be downright devastating.
Given the opportunity for further study, we may find ways to predictably and reliably use VLF transmissions to make the near-Earth environment more human and electronics-friendly. And with companies like SpaceX planning on bringing internet access to the world through broadband internet-providing satellites, and even larger plans for the commercialization of Near-Earth Orbit, anything that can mitigate the risk posed by radiation is welcome.
And be sure to check this video that illustrates the Van Allen Probes findings, courtesy of NASA:
In the past few decades, astronomers and geophysicists have benefited immensely from the study of planetary magnetic fields. Dedicated to mapping patterns of magnetism on other astronomical bodies, this field has grown thanks to missions ranging from the Voyager probes to the more recent Mars Atmosphere and Volatile EvolutioN (MAVEN) mission.
Looking ahead, it is clear that this field of study will play a vital role in the exploration of the Solar System and beyond. As Jared Espley of NASA’s Goddard Space Flight Center outlined during a presentation at NASA’s Planetary Science Vision 2050 Workshop, these goals include advancing human exploration of the cosmos and the search for extraterrestrial life.
This week, NASA’s Planetary Science Division (PSD) hosted a community workshop at their headquarters in Washington, DC. Known as the “Planetary Science Vision 2050 Workshop“, this event ran from February 27th to March 1st, and saw scientists and researchers from all over the world descend on the capitol to attend panel discussions, presentations, and talks about the future of space exploration.
One of the more intriguing presentations took place on Wednesday, March 1st, where the exploration of Mars by human astronauts was discussed. In the course of the talk, which was titled “A Future Mars Environment for Science and Exploration“, Director Jim Green discussed how deploying a magnetic shield could enhance Mars’ atmosphere and facilitate crewed missions there in the future.
The current scientific consensus is that, like Earth, Mars once had a magnetic field that protected its atmosphere. Roughly 4.2 billion years ago, this planet’s magnetic field suddenly disappeared, which caused Mars’ atmosphere to slowly be lost to space. Over the course of the next 500 million years, Mars went from being a warmer, wetter environment to the cold, uninhabitable place we know today.
This theory has been confirmed in recent years by orbiters like the ESA’s Mars Express and NASA’s Mars Atmosphere and Volatile EvolutioN Mission (MAVEN), which have been studying the Martian atmosphere since 2004 and 2014, respectively. In addition to determining that solar wind was responsible for depleting Mars’ atmosphere, these probes have also been measuring the rate at which it is still being lost today.
Without this atmosphere, Mars will continue to be a cold, dry place where life cannot flourish. In addition to that, future crewed mission – which NASA hopes to mount by the 2030s – will also have to deal with some severe hazards. Foremost among these will be exposure to radiation and the danger of asphyxiation, which will pose an even greater danger to colonists (should any attempts at colonization be made).
In answer to this challenge, Dr. Jim Green – the Director of NASA’s Planetary Science Division – and a panel of researchers presented an ambitious idea. In essence, they suggested that by positioning a magnetic dipole shield at the Mars L1 Lagrange Point, an artificial magnetosphere could be formed that would encompass the entire planet, thus shielding it from solar wind and radiation.
Naturally, Green and his colleagues acknowledged that the idea might sounds a bit “fanciful”. However, they were quick to emphasize how new research into miniature magnetospheres (for the sake of protecting crews and spacecraft) supports this concept:
“This new research is coming about due to the application of full plasma physics codes and laboratory experiments. In the future it is quite possible that an inflatable structure(s) can generate a magnetic dipole field at a level of perhaps 1 or 2 Tesla (or 10,000 to 20,000 Gauss) as an active shield against the solar wind.”
In addition, the positioning of this magnetic shield would ensure that the two regions where most of Mars’ atmosphere is lost would be shielded. In the course of the presentation, Green and the panel indicated that these the major escape channels are located, “over the northern polar cap involving higher energy ionospheric material, and 2) in the equatorial zone involving a seasonal low energy component with as much as 0.1 kg/s escape of oxygen ions.”
To test this idea, the research team – which included scientists from Ames Research Center, the Goddard Space Flight Center, the University of Colorado, Princeton University, and the Rutherford Appleton Laboratory – conducted a series of simulations using their proposed artificial magnetosphere. These were run at the Coordinated Community Modeling Center (CCMC), which specializes in space weather research, to see what the net effect would be.
What they found was that a dipole field positioned at Mars L1 Lagrange Point would be able to counteract solar wind, such that Mars’ atmosphere would achieve a new balance. At present, atmospheric loss on Mars is balanced to some degree by volcanic outpassing from Mars interior and crust. This contributes to a surface atmosphere that is about 6 mbar in air pressure (less than 1% that at sea level on Earth).
As a result, Mars atmosphere would naturally thicken over time, which lead to many new possibilities for human exploration and colonization. According to Green and his colleagues, these would include an average increase of about 4 °C (~7 °F), which would be enough to melt the carbon dioxide ice in the northern polar ice cap. This would trigger a greenhouse effect, warming the atmosphere further and causing the water ice in the polar caps to melt.
By their calculations, Green and his colleagues estimated that this could lead to 1/7th of Mars’ oceans – the ones that covered it billions of years ago – to be restored. If this is beginning to sound a bit like a lecture on how to terraform Mars, it is probably because these same ideas have been raised by people who advocating that very thing. But in the meantime, these changes would facilitate human exploration between now and mid-century.
“A greatly enhanced Martian atmosphere, in both pressure and temperature, that would be enough to allow significant surface liquid water would also have a number of benefits for science and human exploration in the 2040s and beyond,” said Green. “Much like Earth, an enhanced atmosphere would: allow larger landed mass of equipment to the surface, shield against most cosmic and solar particle radiation, extend the ability for oxygen extraction, and provide “open air” greenhouses to exist for plant production, just to name a few.”
These conditions, said Green and his colleagues, would also allow for human explorers to study the planet in much greater detail. It would also help them to determine the habitability of the planet, since many of the signs that pointed towards it being habitable in the past (i.e. liquid water) would slowly seep back into the landscape. And if this could be achieved within the space of few decades, it would certainly help pave the way for colonization.
In the meantime, Green and his colleagues plan to review the results of these simulations so they can produce a more accurate assessment of how long these projected changes would take. It also might not hurt to conduct some cost-assessments of this magnetic shield. While it might seem like something out of science fiction, it doesn’t hurt to crunch the numbers!
Stay tuned for more stories from the Planetary Science Vision 2050 Workshop!
Whether or not a planet has a magnetic field goes a long way towards determining whether or not it is habitable. Whereas Earth has a strong magnetosphere that protects life from harmful radiation and keeps solar wind from stripping away its atmosphere, planet’s like Mars no longer do. Hence why it went from being a world with a thicker atmosphere and liquid water on its surface to the cold, desiccated place it is today.
For this reason, scientists have long sought to understand what powers Earth’s magnetic field. Until now, the consensus has been that it was the dynamo effect created by Earth’s liquid outer core spinning in the opposite direction of Earth’s rotation. However, new research from the Tokyo Institute of Technology suggests that it may actually be due to the presence of crystallization in the Earth’s core.
Of particular concern for the research team was the rate of which Earth’s core cools over geological time – which has been the subject of debate for some time. And for Dr. Kei Hirose – the director of the Earth-Life Science Institute and lead author on the paper – it has been something of a lifelong pursuit. In a 2013 study, he shared research findings that indicated how the Earth’s core may have cooled more significantly than previously thought.
He and his team concluded that since the Earth’s formation (4.5 billion years ago), the core may have cooled by as much as 1,000 °C (1,832 °F). These findings were rather surprising to the Earth sciences community – leading to what one scientists referred to as the “New Core Heat Paradox“. In short, this rate of core cooling would mean that some other source of energy would be required to sustain the Earth’s geomagnetic field.
On top of this, and related to the issue of core-cooling, were some unresolved questions about the chemical composition of the core. As Dr. Kei Hirose said in a Tokyo Tech press release:
“The core is mostly iron and some nickel, but also contains about 10% of light alloys such as silicon, oxygen, sulfur, carbon, hydrogen, and other compounds. We think that many alloys are simultaneously present, but we don’t know the proportion of each candidate element.”
In order to resolve this, Hirose and his colleagues at ELSI conducted a series of experiments where various alloys were subjected to heat and pressure conditions similar to that in the Earth’s interior. This consisted of using a diamond anvil to squeeze dust-sized alloy samples to simulate high pressure conditions, and then heating them with a laser beam until they reached extreme temperatures.
In the past, research into iron alloys in the core have focused predominantly on either iron-silicon alloys or iron-oxide at high pressures. But for the sake of their experiments, Hirose and his colleagues decided to focus on the combination of silicon and oxygen – which are believed to exist in the outer core – and examining the results with an electron microscope.
What the researchers found was that under conditions of extreme pressure and heat, samples of silicon and oxygen combined to form silicon dioxide crystals – which were similar in composition to mineral quartz found in the Earth’s crust. Ergo, the study showed that the crystallization of silicon dioxide in the outer core would have released enough buoyancy to power core convection and a dynamo effect from as early on as the Hadean eon onward.
As John Hernlund, also a member of ELSI and a co-author of the study, explained:
“This result proved important for understanding the energetics and evolution of the core. We were excited because our calculations showed that crystallization of silicon dioxide crystals from the core could provide an immense new energy source for powering the Earth’s magnetic field.”
This study not only provides evidence to help resolve the so-called “New Core Heat Paradox”, it also may help advance our understanding of what conditions were like during the formation of Earth and the early Solar System. Basically, if silicon and oxygen form crystal of silicon dioxide in the outer core over time, then sooner or later, the process will stop once the core runs out of these elements.
When that happens, we can expect Earth’s magnetic field will suffer, which will have drastic implications for life on Earth. It also helps to put constraints on the concentrations of silicon and oxygen that were present in the core when the Earth first formed, which could go a long way towards informing our theories about Solar System formation.
What’s more, this research may help geophysicists to determine how and when other planets (like Mars, Venus and Mercury) still had magnetic fields (and possibly lead to ideas of how they could be powered up again). It could even help exoplanet-hunting science teams determine which exoplanets have magnetospheres, which would allow us to find out which extra-solar worlds could be habitable.
Jupiter may be the largest planet in the Solar System with a diameter 11 times that of Earth, but it pales in comparison to its own magnetosphere. The planet’s magnetic domain extends sunward at least 3 million miles (5 million km) and on the back side all the way to Saturn for a total of 407 million miles or more than 400 times the size of the Sun.
If we had eyes adapted to see the Jovian magnetosphere at night, its teardrop-like shape would easily extend across several degrees of sky! No surprise then that Jove’s magnetic aura has been called one of the largest structures in the Solar System.
Io, Jupiter’s innermost of the planet’s four large moons, orbits deep within this giant bubble. Despite its small size — about 200 miles smaller than our own Moon — it doesn’t lack in superlatives. With an estimated 400 volcanoes, many of them still active, Io is the most volcanically active body in the Solar System. In the moon’s low gravity, volcanoes spew sulfur, sulfur dioxide gas and fragments of basaltic rock up to 310 miles (500 km) into space in beautiful, umbrella-shaped plumes.
Once aloft, electrons whipped around by Jupiter’s powerful magnetic field strike the neutral gases and ionize them (strips off their electrons). Ionized atoms and molecules (ions) are no longer neutral but possess a positive or negative electric charge. Astronomers refer to swarms of ionized atoms as plasma.
Jupiter rotates rapidly, spinning once every 9.8 hours, dragging the whole magnetosphere with it. As it spins past Io, those volcanic ions get caught up and dragged along for the ride, rotating around the planet in a ring called the Io plasma torus. You can picture it as a giant donut with Jupiter in the “hole” and the tasty, ~8,000-mile-thick ring centered on Io’s orbit.
That’s not all. Jupiter’s magnetic field also couples Io’s atmosphere to the planet’s polar regions, pumping Ionian ions through two “pipelines” to the magnetic poles and generating a powerful electric current known as the Io flux tube. Like firefighters on fire poles, the ions follow the planet’s magnetic field lines into the upper atmosphere, where they strike and excite atoms, spawning an ultraviolet-bright patch of aurora within the planet’s overall aurora. Astronomers call it Io’s magnetic footprint. The process works in reverse, too, spawning auroras in Io’s tenuous atmosphere.
Io is the main supplier of particles to Jupiter’s magnetosphere. Some of the same electrons stripped from sulfur and oxygen atoms during an earlier eruption return to strike atoms shot out by later blasts. Round and round they go in a great cycle of microscopic bombardment! The constant flow of high-speed, charged particles in Io’s vicinity make the region a lethal environment not only for humans but also for spacecraft electronics, the reason NASA’s Juno probe gets the heck outta there after each perijove or closest approach to Jupiter.
But there’s much to glean from those plasma streams. Astronomy PhD student Phillip Phipps and assistant professor of astronomy Paul Withers of Boston University have hatched a plan to use the Juno spacecraft to probe Io’s plasma torus to indirectly study the timing and flow of material from Io’s volcanoes into Jupiter’s magnetosphere. In a paper published on Jan. 25, they propose using changes in the radio signal sent by Juno as it passes through different regions of the torus to measure how much stuff is there and how its density changes over time.
The technique is called a radio occultation. Radio waves are a form of light just like white light. And like white light, they get bent or refracted when passing through a medium like air (or plasma in the case of Io). Blue light is slowed more and experiences the most bending; red light is slowed less and refracted least, the reason red fringes a rainbow’s outer edge and blue its inner. In radio occultations, refraction results in changes in frequency caused by variations in the density of plasma in Io’s torus.
The best spacecraft for the attempt is one with a polar orbit around Jupiter, where it cuts a clean cross-section through different parts of the torus during each orbit. Guess what? With its polar orbit, Juno’s the probe for the job! Its main mission is to map Jupiter’s gravitational and magnetic fields, so an occultation experiment jives well with mission goals. Previous missions have netted just two radio occultations of the torus, but Juno could potentially slam dunk 24.
Because the paper was intended to show that the method is a feasible one, it remains to be seen whether NASA will consider adding a little extra credit work to Juno’s homework. It seems a worthy and practical goal, one that will further enlighten our understanding of how volcanoes create aurorae in the bizarre electric and magnetic environment of the largest planet. | 0.886674 | 3.877492 |
Solstices, Vegetables, and Official Definitions
Summer officially began just a few days ago—at least that’s what the calendar says. June 20 was the summer solstice, the day when the northern hemisphere is most inclined towards the sun and consequently receives the most daylight. By this definition, summer lasts until the autumnal equinox, in late September, when days and nights are of equal length. But by other definitions, summer starts at the beginning of June and goes through August. Other less formal definitions may put the start of summer on Memorial Day or after the end of the school year (which for my children were the same this year).
For years I wondered why summer officially began so late into June. After all, shouldn’t the solstice, as the day when we receive the most sunlight, be the middle of summer rather than the start? But even though it receives the most sunlight, it’s not the hottest, thanks to something called seasonal lag. The oceans absorb a large amount of heat and continue to release that heat for quite some time after the solstice, so the hottest day may come a month or more after the day that receives the most solar energy. Summer officially starts later than it should to compensate for this lag.
But what does this have to do with language? It’s all about definitions, and definitions are arbitrary things. Laypeople may think of June 1 as the start of summer, but June 1 is a day of absolutely no meteorological or astronomical significance. So someone decided that the solstice would be the official start of summer, even though the period from June 20/21 to September 22/23 doesn’t completely encompass the hottest days of the year (at least not in most of the United States).
Sometimes the clash between common and scientific definitions engenders endless debate. Take the well-known argument about whether tomatoes are fruit. By the common culinary definition, tomatoes are vegetables, because they are used mostly in savory or salty dishes. Botanically, though, they’re fruit, because they’re formed from a plant’s ovaries and contain seeds. But tomatoes aren’t the only culinary vegetables that are botanical fruits: cucumbers, squashes, peas, beans, avocados, eggplants, and many other things commonly thought of as vegetables are actually fruits.
The question of whether a tomato is a fruit or a vegetable may have entered popular mythology following a Supreme Court case in 1893 that answered the question of whether imported tomatoes should be taxed as vegetables. The Supreme Court ruled that the law was written with the common definition in mind, so tomatoes got taxed, and people are still arguing about it over a century later.
Sometimes these definitional clashes even lead to strong emotions. Consider how many people got upset when the International Astronomical Union decided that Pluto wasn’t really a planet. People who probably hadn’t thought about planetary astronomy since elementary school passionately proclaimed that Pluto was always their favorite planet. Even some astronomers declared, “Pluto’s dead.” But nothing actually happened to Pluto, just to our definition of planet. Astronomers had discovered several other Pluto-like objects and suspect that there may be a hundred or more such objects in the outer reaches of the solar system.
Does it really make sense to call all of these objects planets? Should we expect students to learn the names of Eris, Sedna, Quaoar, Orcus, and whatever other bodies are discovered and named? Or is it perhaps more reasonable to use some agreed-upon criteria and draw a clear line between planets and other objects? After all, that’s part of what scientists do: try to increase our understanding of the natural world by describing features of and discovering relationships among different things. Sometimes the definitions are arbitrary, but they’re arbitrary in ways that are useful to scientists.
And this is the crux of the matter: sometimes definitions that are useful to scientists aren’t that useful to laypeople, just as common definitions aren’t always useful to scientists. These definitions are used by different people for different purposes, and so they continue to exist side by side. Scientific definitions have their place, but they’re not automatically or inherently more correct than common definitions. And there’s nothing wrong with this. After all, tomatoes may be fruit, but I don’t want them in my fruit salad. | 0.835684 | 3.248343 |
Scientists have uncovered clues to the source of Earth’s bountiful water. New research shows that water carried in comets may originate from the same source as water in the Earth’s oceans, suggesting that water could have been carried to our planet by comets millions of years ago.
Comets are small, icy bodies which melt and vaporize when they pass the Sun. This vaporization is what produces their famous tails. NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) observed a comet called Comet Wirtanen during its close approach to Earth in December 2018, and noted that it contained water similar to that found in our oceans.
The scientists looked at the ratio of water to heavy water (water with an extra neutron inside one of the hydrogen atoms) in both sources and found the comet’s water had the same ratio as ocean water.
But the members of the team were surprised when it compared the SOFIA data to older studies of comets, as they discovered that the amount of heavy water was not related to the origin of the comet as they had expected. Rather, the amount of heavy water was affected by whether water was mostly released from the halo of matter around the comet or from its surface.
“This is the first time we could relate the heavy-to-regular water ratio of all comets to a single factor,” Dominique Bockelée-Morvan, scientist at the Paris Observatory and the French National Center for Scientific Research and second author of the paper, said in a statement. “We may need to rethink how we study comets because water released from the ice grains appears to be a better indicator of the overall water ratio than the water released from surface ice.”
The data were collected by SOFIA, NASA’s laboratory aboard an airplane, which can fly above most of the water in Earth’s atmosphere. This water interferes with distant signals, so moving above it allows scientists to collect more accurate data and to see more distant cosmic events. These findings give weight to the idea that water arrived on Earth from elsewhere, but studies on more comets are required to confirm that.
“Water was crucial for the development of life as we know it,” Darek Lis, a scientist at NASA’s Jet Propulsion Laboratory and lead author of the study, said in the statement. “We not only want to understand how Earth’s water was delivered, but also if this process could work in other planetary systems.”
- How NASA’s Perseverance Rover will search for life on Mars
- See the surface of Jupiter’s icy moon Europa in unprecedented detail
- What the solar minimum really means for life on Earth
- A lucky dip into Jupiter’s clouds captures stunning image of the planet
- Hubble spots a wacky exoplanet with yellow skies and iron rain | 0.905829 | 3.918936 |
Billions of years ago, when microbial life first emerged on Earth, our planet would have appeared purple from space. Armed with this knowledge, scientists now say we should be on the lookout for exoplanets tinged in a similar purple hue — a possible sign of extraterrestrial life.
Back during the Archean era, some three billion years ago, one of the more widespread forms of life were purple bacteria — photosynthetic microorganisms that inhabited both aquatic and terrestrial environments. These conditions would have been similar to the one recently discovered by Australian scientists, an ecosystem dating back 3.5 billion years.
Related: Scientists find a pink planet.
A team of astrobiologists, curious to know if these signatures could be both visible and detectable from space, recently conducted an investigation to simulate the visible and near-infrared radiation reflected by Earth. Their radiative transfer model took several scenarios into account as they simulated an early version of Earth, including the possible distribution of purple bacteria as it would have appeared over continents and oceans, and in consideration of cloud cover.
Their results showed that purple bacteria would indeed have had a noticeable reflective spectrum and a strong reflectivity increase similar to the red edge of leafy plants, though shifted towards the color red. This would have produced a detectable signal in the visual spectra of our planet, though it would have depended on the amount of cloud cover and the concentration and distribution of the purple bacteria.
The next step, says team member Lisa Kaltenegger of the Max Planck Institute for Astronomy in Heidelberg, Germany, is to use multi-color photometric techniques to search for planets similar to an Archean Earth — a search that would look for large swaths of purple bacteria inhabiting vast extensions of an exoplanet. The same technique could be used to locate a planet with present-day Earth-like conditions, one that's covered by deserts, vegetation, and microbial mats. We could even start to look for life around non-traditional candidates, like white dwarfs. Realistically, this search could start in 2018 with the launch of the James Webb Space Telescope.
Read the entire study at the preprint archive arXiv: "Characterizing the purple Earth: Modelling the globally-integrated spectral variability of the Archean Earth." | 0.825077 | 3.686162 |
Crescent ♐ Sagittarius
Moon phase on 22 September 2001 Saturday is Waxing Crescent, 5 days young Moon is in Sagittarius.Share this page: twitter facebook linkedin
Previous main lunar phase is the New Moon before 5 days on 17 September 2001 at 10:27.
Moon rises in the morning and sets in the evening. It is visible toward the southwest in early evening.
Moon is passing about ∠7° of ♐ Sagittarius tropical zodiac sector.
Lunar disc appears visually 2.5% narrower than solar disc. Moon and Sun apparent angular diameters are ∠1864" and ∠1912".
Next Full Moon is the Hunter Moon of October 2001 after 10 days on 2 October 2001 at 13:49.
There is low ocean tide on this date. Sun and Moon gravitational forces are not aligned, but meet at big angle, so their combined tidal force is weak.
The Moon is 5 days young. Earth's natural satellite is moving from the beginning to the first part of current synodic month. This is lunation 21 of Meeus index or 974 from Brown series.
Length of current 21 lunation is 29 days, 8 hours and 56 minutes. It is 2 hours and 21 minutes shorter than next lunation 22 length.
Length of current synodic month is 3 hours and 48 minutes shorter than the mean length of synodic month, but it is still 2 hours and 21 minutes longer, compared to 21st century shortest.
This New Moon true anomaly is ∠13.2°. At beginning of next synodic month true anomaly will be ∠30.5°. 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°).
5 days after point of perigee on 16 September 2001 at 15:50 in ♍ Virgo. The lunar orbit is getting wider, while the Moon is moving outward the Earth. It will keep this direction for the next 6 days, until it get to the point of next apogee on 29 September 2001 at 05:33 in ♒ Aquarius.
Moon is 384 510 km (238 923 mi) away from Earth on this date. Moon moves farther next 6 days until apogee, when Earth-Moon distance will reach 405 791 km (252 147 mi).
10 days after its ascending node on 11 September 2001 at 21:36 in ♊ Gemini, the Moon is following the northern part of its orbit for the next day, until it will cross the ecliptic from North to South in descending node on 24 September 2001 at 10:28 in ♑ Capricorn.
10 days after beginning of current draconic month in ♊ Gemini, the Moon is moving from the beginning to the first part of it.
9 days after previous North standstill on 12 September 2001 at 12:19 in ♋ Cancer, when Moon has reached northern declination of ∠23.677°. Next 2 days the lunar orbit moves southward to face South declination of ∠-23.780° in the next southern standstill on 25 September 2001 at 05:14 in ♑ Capricorn.
After 10 days on 2 October 2001 at 13:49 in ♈ Aries, the Moon will be in Full Moon geocentric opposition with the Sun and this alignment forms next Sun-Earth-Moon syzygy. | 0.848363 | 3.08862 |
Archaeologists have discovered a 9th-century Mayan house with astronomical tables inscribed on the walls. The tables suggest that the Mesoamerican civilisation had advanced astronomy for over 1000 years, and that the information was widely available in Mayan society.
Until now our main evidence of Mayan astronomical knowledge came from books produced centuries after their society declined. The most famous is the Dresden Codex, which dates from the 11th or 12th century. “The Dresden Codex was the summit – artistically, calligraphically, and intellectually,” says Stephen Houston of Brown University in Providence, Rhode Island.
But the Maya civilisation reached its height centuries before that. The Classic period spanned AD 250-900 and saw the rise of major cities – including Tikal in what is now Guatemala – and the construction of vast stepped pyramids.
No Classic astronomical texts survive, because Mayan books were made of plaster and bark paper that have rotted away, says William Saturno of Boston University in Massachusetts.
Dig for astronomy
In 2010 Saturno and colleagues were excavating Mayan ruins at Xultún, also in Guatemala. One house had been partially looted, exposing a mural on one wall. Intrigued, Saturno excavated the rest of the building.
The walls were covered with pictures of Mayan people. In the gaps between the drawings, and sometimes drawn over the top of them, were glyphs: Mayan writing. Two sets looked like Dresden Codex glyphs, and contained astronomical information.
The first is a table describing lunar cycles: the 29.5 days it takes for the moon to go through all of its phases. The Maya believed in six gods of the moon, each ruling its own lunar cycle. By knowing which god was in charge of the moon at any given time, Mayan rulers could plan their actions accordingly. “The Maya doubtless started with a presumption of meaning in such movements,” explains Houston.
Mayan society was dominated by the idea that time is cyclic. “The Maya conceived of time as a series of cycles that all interplay and all repeat,” Saturno says. By understanding these repetitions, including astronomical cycles, they picked the most auspicious dates for events, such as coronations.
The second set of glyphs is more obscure. Saturno thinks it relates to two Mayan calendars: a ritual calendar lasting 260 days and the solar calendar, lasting 365 days. The two calendars only show the same date once every 18,980 days – the so-called Calendar Round.
All the numbers in the second set are multiples of 18,980, suggesting they are anniversaries. They are also multiples of other astronomical cycles. But Saturno doesn’t know what they represent.
“It seems obvious that the Maya were making almanacs, major calculations, and Dresden Codex-like astronomical tables for over 1000 years,” says Joyce Marcus of the University of Michigan in Ann Arbor.
The house probably belonged to a senior figure but not a royal. That suggests astronomical information was broadly available in Mayan society, says Gary Feinman of the Field Museum in Chicago, Illinois.
Journal reference: Science, DOI: 10.1126/science.1221444
More on these topics: | 0.824478 | 3.186574 |
Crowdsourced astronomy is an area of growing interest. On this blog, we’ve looked at a number of crowdsourced projects, such as one that mapped the asteroid Tercidina as it passed in front of a star in 2002 and another that determined the orbit of Comet 17P/Holmes using photographs posted on the web.
Now Hugh Hudson at the Space Sciences Laboratory, UC Berkeley, and a group of chums have announced the most ambitious crowdsourced project so far. These guys want to make a megamovie of a solar eclipse using stills taken by amateur photographers.
Their chosen eclipse is theone that will cross the continental US on 21 August 2017. “If 10,000 observers each obtained 100 frames, then we would have a million-frame movie; at standard frame rate this would take 12 hours to show, and would thus be a slow-motion representation of coronal evolution,” they say. That’ll be fun to make, not so much to watch.
But it could also be useful to solar scientists. Total eclipses on Earth give a particularly good view of the low corona, a region that is difficult for space-based coronagraphs to see. The megamovie should also show the deflection of starlight due to gravity, the same effect that Arthur Eddington reported in 1919 that finally confirmed Einstein’s theory of general relativity.
This experiment has never been repeated in the visual part of the experiment and there is some debate now about the veracity of original result. So using crowdsourced astronomy to repeat it now would something of a feat.
During the 2017 eclipse, the Sun will be close to Regulus, the brightest star in the constellation of Leo. Its starlight will be deflected by 0.74 seconds of arc, an amount that ought to be easy to spot in a high-resolution megamovie.
Hudson and co point out some potential challenges for their project. One is the large amount of data it would generate; another is the problem of accurately registering each photograph against the background starfield. None of these seem particularly serious impediments.
A more serious problem is that these guys will be scooped. Crowdsourcing allows the very rapid development of some impressive projects.
Hudson and co have given themselves 6 years. It’s more likely that we’ll see a solar eclipse megamovie long before this, perhaps next year after the eclipse in northern Australia on 13 November 2012.
Ref: arxiv.org/abs/1108.3486: The U.S. Eclipse Megamovie In 2017: A White Paper On A Unique Outreach Event | 0.861569 | 3.256694 |
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