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The stars life sequence, ending with the formation of a black hole. Image credit: Nicolle Rager Fuller/NSF Click to enlarge
Just a few hundred millions years after the Big Bang, a massive star exhausted its fuel, collapsed as a black hole, and exploded as a gamma ray burst. The radiation from this catastrophic event has only now reached Earth, and astronomers are using it to peer back to the earliest moments of the Universe. The burst, named GRB 050904, was observed by NASA’s Swift satellite on September 4, 2005. One unusual thing about this burst is that it lasted for 500 seconds – most are over in a fraction of that time.
It came from the edge of the visible universe, the most distant explosion ever detected.
In this week’s issue of Nature, scientists at Penn State University and their U.S. and European colleagues discuss how this explosion, detected on 4 September 2005, was the result of a massive star collapsing into a black hole.
The explosion, called a gamma-ray burst, comes from an era soon after stars and galaxies first formed, about 500 million to 1 billion years after the Big Bang. The universe is now 13.7 billion years old, so the September burst serves as a probe to study the conditions of the early universe.
“This was a massive star that lived fast and died young,” said David Burrows, senior scientist and professor of astronomy and astrophysics at Penn State, a co-author on one of the three reports about this explosion published this week in Nature. “This star was probably quite different from the kind we see today, the type that only could have existed in the early universe.”
The burst, named GRB 050904 after the date it was spotted, was detected by NASA’s Swift satellite, which is operated by Penn State. Swift provided the burst coordinates so that other satellites and ground-based telescopes could observe the burst. Bursts typically last only 10 seconds, but the afterglow will linger for a few days.
GRB 050904 originated 13 billion light years from Earth, which means it occurred 13 billion years ago, for it took that long for the light to reach us. Scientists have detected only a few objects more than 12 billion light years away, so the burst is extremely important in understanding the universe beyond the reach of the largest telescopes.
“Because the burst was brighter than a billion suns, many telescopes could study it even from such a huge distance,” said Burrows, whose analysis focuses mainly on Swift data from its three telescopes, covering a range of gamma-rays, X-rays, and ultraviolet/optical wavelengths, respectively. Burrows is the lead scientist for Swift’s X-ray telescope.
The Swift team found several unique features in GRB 050904. The burst was long–lasting about 500 seconds–and the tail end of the burst exhibited multiple flares. These characteristics imply that the newly created black hole didn’t form instantly, as some scientists have thought, but rather it was a longer, chaotic event.
Closer gamma-ray bursts do not have as much flaring, implying that the earliest black holes may have formed differently from ones in the modern era, Burrows said. The difference could be because the first stars were more massive than modern stars. Or, it could be the result of the environment of the early universe when the first stars began to convert hydrogen and helium (created in the Big Bang) into heavier elements.
GRB 050904, in fact, shows hints of newly minted heavier elements, according to data from ground-based telescopes. This discovery is the subject of a second Nature article by a Japanese group led by Nobuyuki Kawai at the Tokyo Institute of Technology.
GRB 050904 also exhibited time dilation, a result of the vast expansion of the universe during the 13 billion years that it took the light to reach us on Earth. This dilation results in the light appearing much redder than when it was emitted in the burst, and it also alters our perception of time as compared to the burst’s internal clock.
These factors worked in the scientists’ favor. The Penn State team turned Swift’s instruments onto the burst about 2 minutes after the event began. The burst, however, was evolving as if it were in slow motion and was only about 23 seconds into the bursting. So scientists could see the burst at a very early stage.
Only one other object–a quasar–has been discovered at a greater distance. Yet, whereas quasars are supermassive black holes containing the mass of billions of stars, this burst comes from a single star. The detection of GRB 050904 confirms that massive stars mingled with the oldest quasars. It also confirms that even more explosions of distant stars–perhaps from the first stars, theorists say–can be studied through a combination of observations with Swift and other world-class telescopes.
“We designed Swift to look for faint bursts coming from the edge of the universe,” said Neil Gehrels of NASA Goddard Space Flight Center in Greenbelt, Maryland, Swift’s principal investigator. “Now we’ve got one and it’s fascinating. For the first, time we can learn about individual stars from near the beginning of time. There are surely many more out there.”
Swift was launched in November 2004 and was fully operational by January 2005. Swift carries three main instruments: the Burst Alert Telescope, the X-ray Telescope, and the Ultraviolet/Optical Telescope. Swift’s gamma-ray detector, the Burst Alert Telescope, provides the rapid initial location, was built primarily by the NASA Goddard Space Flight Center in Greenbelt and Los Alamos National Laboratory, and was constructed at GSFC. Swift’s X-Ray Telescope and UV/Optical Telescope were developed and built by international teams led by Penn State and drew heavily on each institution’s experience with previous space missions. The X-ray Telescope resulted from Penn State’s collaboration with the University of Leicester in England and the Brera Astronomical Observatory in Italy. The Ultraviolet/Optical Telescope resulted from Penn State’s collaboration with the Mullard Space Science Laboratory of the University College-London. These three telescopes give Swift the ability to do almost immediate follow-up observations of most gamma-ray bursts because Swift can rotate so quickly to point toward the source of the gamma-ray signal.
Original Source: PSU News Release | 0.83404 | 3.977565 |
It astonishes me how much we seem to know about aliens. They build technology-driven civilisations and pilot spaceships across the galaxy. They create energy-harvesting structures around their stars. They beam interstellar greetings to us. We cannot be sure that, when our own broadcasts reach them in some future era, they will breathlessly await the arrival of the next episode of Glee – but it seems a fair bet.
How do we know all this? Not by science’s usual method of finding out stuff, which is by observing. We know it because it stands to reason. Because we’ve seen it at the movies. Because it’s what we would do. Which is to say: when we start speculating about what advanced extraterrestrials are like, we are really just talking about ourselves.
The impulse to cast life on other worlds in our own image goes back all the way to the proto-science fiction of the 17th century, such as the novel The Comical History of the States and Empires of the Worlds of the Moon and Sun (1657) by the French writer Cyrano de Bergerac. Cyrano pictured a lunar landscape inhabited by gigantic man-animals who somehow managed to create a very European courtly society where they debated Aristotle and Christian theology. So it has been, mostly, ever since. The galactic empires of Isaac Asimov’s Foundation novels (1942-1993) and the Star Wars and Star Trek franchises are peopled by creatures modelled on robustly late-20th-century humans in psychology and motive, no matter how much fur or how many forehead ridges they possess.
Such self-reflexive assumptions about alien civilisations leapt from the movie screen to the science journals last September when the astronomer Tabetha Boyajian of Yale University and her coworkers, using the Kepler space telescope, reported that the light coming from a star called KIC 8462852 exhibits intense, rapid brightness fluctuations that can’t easily be explained by any known natural process. Boyajian suggested that a circling horde of comets might be blocking the star’s light, but Jason Wright, an astronomer at Pennsylvania State University, and his colleagues added a provocative, albeit unlikely, alternative: the flickering of KIC 8462852 could be the passing shadow of a gigantic structure built by alien engineers.
The concept of such a star-circling structure was proposed in the 1960s by the British-born physicist Freeman Dyson. He argued that any civilisation with sufficient technical capability would construct a vast solar array in space to feed its enormous energy demand. Wright’s comment about a possible real-life ‘Dyson sphere’ around KIC 8462852 was made with all due caution, but you can’t speculate quietly about the detection of aliens. Soon, the idea was shouted from headlines worldwide. Further raising the volume, other researchers began listening for messages coming from KIC 8462852. Those searches focused on radio waves and laser pulses, just like the signals we use, highlighting the abiding narcissism of the effort.
For as long as scientists have looked for alien life, they have conceived them in our own image. The quest arguably began with a 1959 Nature paper by the physicists Giuseppe Cocconi and Philip Morrison, who argued that ‘near some star rather like the Sun there are civilisations with scientific interests and with technical possibilities much greater than those now available to us’. The two scientists further posited that such aliens would have ‘established a channel of communication that would one day become known to us’. Such alien signals would most likely take the form of shortwave radio, which is ubiquitous through the Universe, and would contain an obviously artificial message such as ‘a sequence of small prime numbers of pulses, or simple arithmetical sums’.
Nothing in this suggestion was unreasonable, but it’s self-evidently the result of two smart scientists asking: ‘What would we do?’ Cocconi and Morrison’s proposal to look for familiar types of signals, coming from familiar types of technology, has heavily conditioned the search for extraterrestrial intelligence (SETI) ever since. Today, the Harvard astronomer Avi Loeb thinks it might be good to look for spectroscopic signatures of chlorofluorocarbons (CFCs) in the atmospheres of alien planets, apparently in the conviction that aliens have fridges like ours (or perhaps they’re just crazy about hairspray). Other scientists have proposed finding aliens by looking for their light-polluting cities; their starship Enterprise-style antimatter drives; or the radiation flashes from extraterrestrial nuclear war. It all sounds dreadfully… human.
The obvious defence is that, if you’re going to bother with SETI at all, you have to start somewhere. That we have the urge to search for life elsewhere probably owes something to our natural instincts to explore our environment and to propagate our kind. If – and this does seem rather likely – all complex life in the Universe originated through a competitive Darwinian evolutionary process, isn’t it reasonable to imagine that it will have evolved to be curious and expansionist? Then again, not all human societies seem intent on spreading beyond the village, and whether Darwinian selection will continue to be the predominant shaping force on humanity over the next millennium (never mind a million years) is anyone’s guess.
The problem with basing SETI on projections of our own impulses and inventions is that it constrains our thinking along a very narrow path. Those curbs were going up even before Morrison and Cocconi laid the foundations of SETI. In 1950 the Italian physicist Enrico Fermi was musing with some colleagues about the existence of intelligent aliens who explore the cosmos. If other beings are capable of travel between the stars, surely they’d have spotted us and come to take a look by now, he reasoned, so ‘Where is everybody?’ Fermi’s ‘paradox’ is still cited as an argument for why intelligent life must be rare in the Universe. Among the possible resolutions offered by the SETI Institute, whose name advertises its goals, is: ‘Aliens have done cost-benefit analyses that show interstellar travel to be too costly or too dangerous.’ Maybe ‘the Galaxy is urbanised [but] we’re in a dullsville suburb’. Or perhaps Earth is being preserved in isolation as ‘an exhibit for alien tourists or sociologists’.
It’s funny – I almost feel I know these aliens.
Do these failures of imagination mean that we should shut up about what alien civilisations might or might not do? Not at all. I reckon that speculating in this fashion is one of the perks our species has earned for having made a modicum of sense out of this perplexing cosmos. But how can we move beyond solipsism and tired Hollywood tropes?
One tip is not to be too distracted by science fiction. Some of it is fabulous, but let’s not forget that it’s storytelling, which means that it needs characters and plots with which we can identify. And so those classics, from Frank Herbert’s Dune (1965) and Arthur C Clarke’s Childhood’s End (1953) to the elaborate futures of Kim Stanley Robinson and Iain M Banks, have overlords and dictators, heroes and heroines, spaceship fleets and empires. The Dyson sphere was itself prefigured in, and explicitly inspired by, Olaf Stapledon’s novel Star Maker (1937). When we apply human-centric narratives to SETI, we need to remind ourselves that we’re merely looking into a distorted mirror. Such a warning could prod us to be more daring and imaginative in thinking about alien life, as well as to ponder whether there might be a more rigorous way to explore the range of possibilities.
Dig a little, and it’s possible to find more creative ideas about how intelligent aliens might exist yet not be detectable to us. Maybe super-advanced beings will relinquish the physical world, dwelling in the nooks and crannies of extra dimensions. Maybe they will disintegrate into a disembodied swarm intelligence, like the Black Cloud in the 1957 sci-fi novel of that name by English astronomer Fred Hoyle – a rare example of a scientist being truly inventive in fiction. Maybe the life of a hyper-intelligent alien will look to us incomprehensibly boring or complicated.
Or perhaps they will revert to a simpler lifestyle, like the small-brained, seal-like descendants of humans that lounge on rocks in Kurt Vonnegut’s novel Galápagos (1985). They still find farts amusing, though, so even they aren’t so very different from us. | 0.914132 | 3.180018 |
Rotation and Orbit2.6 - Be able to use the rotation and revolution (orbital) periods of the Moon
2.7 - Understand the synchronous nature of the Moon’s orbit
4.10 - Understand the difference between sidereal and synodic (solar) months
The Earth rotates in less than 24 hours and travels around the Sun over 365 days.
The Moon orbits the Earth in 27.3 Earth days. A day on the Moon is also 27.3 Earth days long.
The orbit and rotation period of the Moon are identical - 27.3 days.
The Moon has a synchronous (or captured) rotation which means it keeps the same side or face towards the body it orbits. This means that from Earth only one side or hemisphere can be seen.
The Moon has a day and night and receives sunlight on every area of its surface; an exception to this are deep craters at the poles which remain in permanent darkness.
Sidereal and Synodic (solar) months
A sidereal month is the time the Moon orbits the Earth as respect to the background stars.
A synodic month is the period between the same phase (e.g. Full Moon to Full Moon). This is longer because the Earth (and Moon) is also orbiting the Sun. We see two full Moons 29.5 days apart.
The Moon was closer to the Earth (it is now moving away from us at 4cm a year) and spun on its axis more quickly. Tidal forces slowed down the Moon's rotation. Tidal friction performs as a brake on the Earth's rotation and eventually in billions of years the Earth day will be 55 of our present days long and so will the Moon's. The Moon will appear to hang in the same position in the sky. When this happens, the Moon will be said to have a synchronous orbit as well as synchronous rotation.
- What is the name given to the type of rotation of the Moon around the Earth?
- Why can we only see one side of the Moon?
- How long is a day on the Moon?
Did you know?
The Moon orbits Earth in 27 Earth days, 7 Hours, 43 minutes and 7 seconds. | 0.823641 | 3.453773 |
Mining of Kepler space mission data reveals “supernova’s shockwave” in visible light
Space news (massive supernovae) – 1.2 billion light-years from Earth –
An international team of scientists at the University of Notre Dame in Indiana mining three years of Kepler Space Telescope data for massive supernovae discovered something never seen during the human journey to the beginning of space and time. Buried in the Kepler data Peter Garnavich and team observed for the first time the brilliant flash of a massive supernova’s shockwave in visible light as it reached the surface of the exploding star.
“In order to see something that happens on timescales of minutes, like a shock breakout, you want to have a camera continuously monitoring the sky,” said Garnavich. “You don’t know when a supernova is going to go off, and Kepler’s vigilance allowed us to be a witness as the explosion began.”
Garnavich’s the leader of the Kepler Extragalactic Survey (KEGS) research team, which is currently mining NASA’s Kepler K2 mission data looking for massive supernovae. NASA’s repurposed planet hunter is expected to detect around a dozen more events during its mission to capture the light from hundreds of distant galaxies and trillions of stars.
Astronomers call the brilliant flash of a supernova’s shockwave “a shock breakout”. This event only lasts around twenty minutes in the cases observed, so catching the flash as it happens is truly a milestone for astronomers studying supernovae. By piecing together individual moments of a supernova astronomers hope to learn more about the history of chemical complexity and the evolution of life.
“All heavy elements in the universe come from supernova explosions. For example, all the silver, nickel, and copper in the earth and even in our bodies came from the explosive death throes of stars,” said Steve Howell, project scientist for NASA’s Kepler and K2 missions at NASA’s Ames Research Center in California’s Silicon Valley. “Life exists because of supernovae.”
Massive supernovae and their less energetic brothers are the seeds of chemical complexity in the cosmos, spreading the elements of creation across the breadth of the universe. Understanding the physics behind these titanic events can help tell us how these elements of creation were spread across the universe.
Kepler observes two massive supernovae
The Kepler Space Telescope observed a type II supernova shockwave in visible light as it broke the surface of the star for the first time in history as supermassive red giant KSN 2011d went supernova in 2011. Containing roughly 500 times the mass of Sol, this supermassive star at the moment the shockwave from the supernova reached its surface was 130,000,000 times brighter than the Sun. Continuing to explode and grow, the star eventually reached a maximum brightness over 1 billion times greater than Sol 14 days later.
The Kepler Space Telescope also observed a second type II supernova in 2011. Red super massive star KSN 2011a contains 300 times as much mass as Sol and occupies a volume of space that would easily engulf the orbit of Earth around the Sun. Only 700 million light-years from Earth, astronomers weren’t able to observe a shock breakout in the data for this supernova, but they think it might be due to gas masking the shockwave as it reached the surface of the star.
“That is the puzzle of these results,” said Garnavich. “You look at two supernovae and see two different things. That’s maximum diversity.”
“While Kepler cracked the door open on observing the development of these spectacular events, K2 will push it wide open observing dozens more supernovae,” said Tom Barclay, senior research scientist and director of the Kepler and K2 guest observer office at Ames. “These results are a tantalizing preamble to what’s to come from K2!”
Watch this YouTube video on this event here.
Learn more about K2.
Discover what the Kepler Extragalactic Survey has told us here.
Take the voyage of the Kepler Space Telescope.
Learn more about type II supernovas here.
Learn more about astronomy at the University of Notre Dame here.
Learn more about the prominent emission lines in young stars.
Read about two merging black holes astronomers are watching. | 0.856905 | 3.700752 |
Gamma-ray bursts (GRBs) are already the most energetic events we know of in the universe, and now, astronomers have detected the most powerful gamma ray burst ever. The competition isn’t even close, either – this event is almost a thousand times more powerful than your average GRB.
Such an intensely powerful signal can only come from some of the most energetic events in the cosmos. GRBs are produced when stars go supernova and collapse into either neutron stars or black holes, ejecting massive amounts of plasma at close to the speed of light and throwing out more energy in seconds than the Sun will in its lifetime.
The energy of these bursts is measured in electron volts (eV), where one electron volt is the amount of energy gained by a single electron when accelerated by one volt. For most GRBs, the afterglow is measured in a few dozen giga-electronvolts (GeV), which are billions of electron volts. But this latest detection far outshines that – it registered up to 1 tera-electronvolt (TeV), or a trillion electron volts.
“High-energy GRBs with energies in the region of tera-electron-volts were theoretically predicted,” says Masahiro Teshima, an author of the study. “Astronomers have searched for such powerful bursts for 15 years. My international team and I are proud to announce the discovery of the first gamma-ray burst with observed energies up to 1 tera-electronvolt, by far the highest-energy photons ever detected from a GRB.”
The event in question is named GRB190114C, and it was observed on January 14 this year. It was first spotted by two satellites designed to detect gamma-ray bursts – the Swift Observatory and the Fermi Gamma-ray Space Telescope – and to them, it looked like any other GRB. That’s because the short-lived initial burst is usually weaker, on the order of a few mega-electronvolts (MeV).
But it’s the afterglow, which shines brighter, that’s of particular interest. To watch for that, whenever these instruments detect GRBs they immediately signal to other facilities which can follow up observations. More than 20 other telescopes and observatories around the world focused their attention onto the spot to watch the celestial fireworks.
The afterglow began about a minute after the initial burst, and lasted about 20 minutes total. For the first 30 seconds or so, the glow was over 100 times stronger than the Crab Nebula, which is the brightest known gamma ray source in the galaxy. Its energy peaked at 1 TeV, but it lingered for a while down to 0.3 TeV, which is still very strong.
One of the observatories that peered at GRB190114C was Hubble. Although it can’t detect gamma rays, the space telescope was able to help determine how far away the event was, and what kind of conditions may have contributed to its extreme energy. It turns out that the burst came from a galaxy that’s currently colliding with another.
“Hubble’s observations suggest that this particular burst was sitting in a very dense environment, right in the middle of a bright galaxy 5 billion light years away,” says Andrew Levan, a lead author of the study. “This is really unusual, and suggests that this concentrated location might be why it produced this exceptionally powerful light.”
The research was published in the journal Nature.
(For the source of this, and many other equally interesting articles, please visit: https://newatlas.com/space/most-powerful-gamma-ray-burst/) | 0.897628 | 4.079204 |
As the Voyager 1 spacecraft was about to leave the Solar System in 1990, the American astronomer Carl Sagan asked that spacecraft’s cameras be turned towards its home planet some 3 billion kilometres away.
The resulting photograph is called the Pale Blue Dot and shows Earth as a tiny bluish-white speck against the vast emptiness of space. Sagan later used this phrase for the title of a book about his vision of humanity’s future in space.
Given Earth’s distinctive colour, an interesting question is what colour an alien Earth orbiting another star might be. Today, we get an answer of sorts from Siddharth Hegde at the Max Planck Institute for Astronomy in Germany and Lisa Kaltenegger at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.
They point out that Earth’s colour is intimately linked to its habitability and, in particular, to the colour of water which covers 70 per cent of the Earth’s surface. However, the colour is also influenced by other environments such as desert, snow, lichen-covered rock and the 60 per cent of land covered by vegetation.
The vegetation, in particular, gives rise to the famous “red edge” that an alien viewer should see as the Earth rotates. It is the result of the increased absorption of red light by photosynthesis as an ocean disappears from view and is replaced by tree-covered land.
If an exoplanet is anything like Earth, particularly in the amount of liquid water at the surface, then its colour should be an important clue, say Hegde and Kaltenegger. Assuming a clear atmosphere that gives a view of the surface, these guys estimate the colour of alien Earths based on the percentage of surface covered in water, tree-like vegetation, bacterial mats, endoliths, which live inside rocks, and so on.
They conclude that it ought to be possible to assess the habitability of exoplanets that can be directly viewed in this way, a process that should help to focus interest on important exoplanets.
Bluish dots, for example, would gain priority over Mars-like red dots, since the red planet is entirely devoid of life as far as we can tell.
That could well turn out to be a handy technique. Today, the number of alien Earths stands at three–Gliese 581d, HD 85512b and Gliese 667Cc. But that number is set to grow dramatically in the coming months and years as observaotries such as NASA’s Kepler spacecraft provide more data. So a way of filtering the most interesting exoplanets will surely be of much use.
Ref: arxiv.org/abs/1209.4098: Colors Of Extreme exoEarth Environments | 0.900574 | 3.919423 |
A space rock bigger than four African Bush Elephants – the largest of the elephants – is shooting towards Earth, with it set to arrive while 2020 is still fresh. The asteroid, which has a diameter of 13 metres, has been dubbed 2019 AE3 and it is making its way through the solar system at a staggering 8.2 kilometres per second (5MPS), or 29,520 kilometres per hour. At that speed, the asteroid would be able to make it from London to New York in around six minutes.
For reference, the Lockheed SR-71 Blackbird, the fastest jet ever built, could not even reach New York from London in an hour.
Asteroid AE3 will be at its closest to Earth on January 2 when it is just 0.013 AU (astronomical unit) away from our planet.
One AU is the distance between the Earth and the Sun (149,598,000 km), so AE3 will be just 19,44,772 kilometres from Earth.
While this may seem like a sizeable distance, it is close enough for NASA to sit up and take notice.
The US-based space agency have classed 2019 AE3 as a Near Earth Object (NEO) and allow the space agency to study the history of our solar system.
NASA set on its Jet Propulsion Laboratory (JPL) website: “NEOs are comets and asteroids that have been nudged by the gravitational attraction of nearby planets into orbits that allow them to enter the Earth’s neighbourhood.
“The scientific interest in comets and asteroids is due largely to their status as the relatively unchanged remnant debris from the solar system formation process some 4.6 billion years ago.
“The giant outer planets (Jupiter, Saturn, Uranus, and Neptune) formed from an agglomeration of billions of comets and the left over bits and pieces from this formation process are the comets we see today.
“Likewise, today’s asteroids are the bits and pieces left over from the initial agglomeration of the inner planets that include Mercury, Venus, Earth, and Mars.”
While this specific asteroid poses no threat to Earth, NASA experts have warned there is a “100 percent” chance an asteroid will hit our world.
Greg Leonard, a senior research specialist at Catalina Sky Survey – a NASA funded project supported by the Near Earth Object Observation Program (NEOO) – told Bryan Walsh for the latter’s new book End Times: “I know the chances of me dying in an asteroid impact is less than dying from a lightning strike.
“But I also know that if we do nothing, sooner or later, there’s a one hundred percent chance that one will get us. So I feel privileged to be doing something.” | 0.833058 | 3.273859 |
LAWRENCE — During its nuclear fusion processes, a burning star does not make the element lithium. Rather, over time, stars consume their lithium supply that was originally created during the Big Bang that gave birth to our universe.
Now, scientists from the University of Kansas are using lithium measurements to better understand stars and star clusters in the Milky Way.
“Lithium is very, very cool as an element for a lot of reasons,” said Barbara Anthony-Twarog, professor of physics and astronomy at KU. “In the Big Bang, hydrogen and helium were created when the universe was about three minutes old, along with some other light elements like lithium, beryllium and boron. Everything else gets made inside stars. But lithium doesn’t get made further inside stars. It gets chewed up, burned or destroyed. We have this cosmological marker of how much lithium was made long ago. But is it still there inside a star? If not, why not?”
Working with her husband, Bruce Twarog, professor of physics and astronomy at KU, and Con Deliyannis of Indiana University, Anthony-Twarog utilizes a 3.5-meter telescope at the Kitt Peak National Observatory in Arizona and a 4-meter telescope at Cerro Tololo Observatory in Chile. With a spectrograph, the researchers look carefully at wavelengths of light from stars and star clusters within our galaxy to discover how much lithium is present.
“A spectrograph takes light and spreads it out like a prism — but much more spread out — so that we’re looking at a very small range of wavelength for features that are kind of like a bar code on a star’s spectrum,” Anthony-Twarog said. “If you look at the Sun’s light through a prism, there are some darker regions. It doesn’t look continuous like you think a rainbow should. And those dark regions are evidence of atoms in the star’s atmosphere pulling light out of the spectrum that we would otherwise see. So we quantify that subtraction and associate that with a number of lithium atoms or calcium atoms or hydrogen atoms in the star’s atmosphere.”
But such analysis of stellar wavelengths not only reveals the chemical makeup of the surface of a star, it presents a history of that star going back to its birth and also gives information about the interior of a star.
“Lithium is a diagnostic marker of what’s been going on inside a star basically from the time it formed,” said Anthony-Twarog. “The more a star has churned itself up inside, the less lithium we see on its surface. It’s kind of an integrated marker of how much disruption the star has internalized and mixed to the surface.”
Star clusters — groupings of thousands of stars — are particularly useful for analyzing lithium content because the stars that make them up are close to each other in age and distance from Earth.
“The advantage of looking at thousands of stars simultaneously in a cluster is that they all formed under the same conditions,” said Anthony-Twarog. “So there are some things we know in common about them. They’re about the same distance from us. We believe they formed out of the same kind of gas. So they should have the same chemical properties. If they’re a little different in mass, some of them will be a little further along in their evolution than others.”
The National Science Foundation supports Anthony-Twarog’s research quantifying lithium in stars. | 0.860542 | 3.985606 |
Stellar Magnetic Fields, Activity, and Exoplanets
Stars and exoplanets from space (Activity & planets - FFG funded through ASAP11): The study of magnetic fields is a cornerstone in present astrophysics, as magnetic fields play a key role in essentially all physical processes in space, in stellar and planetary formation and in the structure and evolution of planets and stars. Many aspects of magnetic fields and exoplanets ideally make use of observations from space; ESA has set up a sophisticated plan to advance the field, complemented by existing or recent missions providing comprehensive data archives, and in conjunction with ground-based observatories.
Within our research project, we study magnetic field morphologies in relation to stellar age, mass, and interior dynamics and the potential influence of these fields on the habitability of orbiting exoplanets. We focus on the central and cool regions of the Hertzsprung-Russel Diagram (HRD) covering young (pre-main sequence) stars, main sequence M-dwarfs, and solar-like stars from G- to mid F- and early A-spectral types as these presently are the most interesting and promising regions for the search for exoplanets. Magnetic fields significantly change their manifestation with stellar mass or stellar temperature. For example, the fields of M dwarfs are rather diverse, changing from simple, large-scale structures in fully convective mid-M dwarfs to more complex fields in earlier-type (more massive) M dwarfs; altogether, magnetic activity and the corresponding energetic radiation of M dwarfs decline much slower in time than in solar-type stars. The latter, of spectral type G and late-F, exhibit complex fields, variable on short time-scales, originating from a dynamo mechanism, while still slightly hotter F- (and A) stars either reveal globally structured, stable magnetic fields, or no (to date measurable) fields at all. These changing faces of stellar magnetism and the triggered activity phenomena most likely also cause a huge variety of conditions for - or against - the emergence of life on the surface of exoplanets - a centerpiece of present-day exoplanet research and key to upcoming exoplanet missions such as CHEOPS and PLATO.
Magnetic field studies are now benefiting from the enormous, combined progress of observational data quality and numerical simulations. Thus, we can apply sophisticated analysis techniques such as Bayesian photometric imaging (BPI) and Zeeman Doppler imaging (ZDI), and exploit excellent observational data obtained in space by, for example, the CoRoT and BRITE-C satellites, and data observed from ground with dedicated novel instrumentation such as ESPaDOnS, NARVAL, and HARPSpol.
This way we aim to significantly contribute to the explanation of theorigin, the evolution, and the pivotal role of magnetism in | 0.822986 | 4.014079 |
If E.T. is out there, it may be a lot easier to find him than we thought mostly because there are a lot more places for him to live. Scientists looking for life (or at least earthlike life) have always obeyed a simple rule: follow the water. Biology is a wet process, after all and generally the wetter the better. Now, the Herschel Space Observatory has spotted an infant solar system 175 million light years from Earth that seems fairly awash in primordial water. The finding suggests many more such systems may be out there and offers tantalizing clues about how our own biologically rich world began as well.
Herschel, which was launched by the European Space Agency in 2009, hovers in space 930,000 miles (1.5 million km) from Earth at what's known as a Lagrange point, a gravitationally quirky spot where the pull of the planet Earth and the sun balance out. This allows a spacecraft placed just so to remain locked in place on the far side of the planet, shielded from solar interference. In the case of Herschel, that's important, because the readings it takes are exquisitely precise, scanning the skies in the far infrared and submillimeter wavelengths.
Turning its gaze toward a star known as TW Hydrae a comparatively cool orange dwarf just 10 million years old the telescope recently found a vast disk of dusty material moving in a solar orbit about 200 times as far from the star as Earth is from our own sun. Dust is just dust in the visible spectrum, but operating in the extreme infrared, Herschel was able to spot the surprising signal of water lots and lots of water created as ultraviolet light from the star knocked individual water molecules free from the traces of ice that cling to the dust grains.
"These are the most sensitive [infrared] observations to date," said NASA project scientist Paul Goldsmith, who collaborates with the European investigators in analyzing Herschel findings. "It is a testament to the instrument builders that such weak signals can be detected."
What struck Goldsmith and the others was not just the vast quantity of water ice surrounding TW Hydrae, but also its location. Water halos have been found in the warm inner reaches of young solar systems before, but the proximity of the solar fires usually blasts the vapor farther into space where it gets locked up as ice in outer planets and moons. That's what happened in our own solar system, and helps explain why Mercury, Venus and Mars are so dry and the distant gas giants are so icy.
What that model doesn't explain, of course, is how Earth got so wet. One of the prevailing theories has long been that incoming comets crashed into our planet, carrying water ice with them. That scenario became even more plausible as a result of two studies earlier this month one that found that comets in our solar system carry the same chemical signature as the water in Earth's oceans; and another that discovered what amounts to a hailstorm of comets striking a planet circling the Eta Corvi, a bright star visible in our northern hemisphere. What's happening out there could have easily happened here.
The new findings push the knowledge frontier further since the colder region where the TW Hydrae vapor disk was found is exactly where comets could more easily form, but where the raw materials for that to happen had not been seen until now. Says Herschel astronomer Michiel Hogerheijde of the Leiden Observatory in the Netherlands: "Our observations of this cold vapor indicate enough water exists in the disk to fill thousands of Earth's oceans."
None of this means that TW Hydrae will necessarily give rise to a garden spot like Earth. Water is a necessary ingredient for life as we know it, and comets are handy couriers, but a lot of other tumblers have to fall just right for biology to take hold. Still, if astronomical history not to mention simple arithmetic suggests one thing, it's that what happens in one spot in the cosmos has a pretty fair chance of being repeated at least a few times in the infinitely vast spaces beyond. The possibility that that kind of repetition includes life is beginning to seem more compelling than ever. | 0.82396 | 3.887391 |
Hunting for Earth 2.0: NASA finds 715 new planets
- 26 February, 2014 21:08
NASA today announced the discovery of 715 planets orbiting 305 stars, revealing multi-planet systems much like our own solar system.
Four of these newly verified planets are in their sun's habitable zone, a distance from a star where the temperature is conducive to the planet's having water in liquid form. With water, it's possible these four planets could potentially hold life.
"This is the largest windfall of planets that's ever been announced at one time," said Douglas Hudgins, NASA's exoplanet exploration program scientist. "Planetary systems, with planets orbiting a star like our own, are in fact common. There are an abundance of habitable Earth-sized planets. Our goal is to find Earth 2.0 -- an Earth-like planet that could hold life."
Echoing the scientists around him during a press conference, Hudgins added, "These are really exciting times."
Prior to this discovery, scientists knew about 1,000 exoplanets, which are planets outside our own solar system.
The 715 planets were spotted and verified by NASA's Kepler Space Telescope, which began its work on May 12, 2009.
The discoveries came from the first two years of data that Kepler sent back to Earth. Scientists said they are now beginning to study the data from the second two years of Kepler's planet-hunting mission and expect to find hundreds of other planets.
The space telescope had two broken wheels that caused it to spin out of control. It could not be repaired well enough to return it to its initial work.
Scientists received enough data from Kepler to determine not only the size of a planet but whether it has a solid surface and its potential to have water in liquid form, which is considered crucial to the formation of life.
While the space telescope was still working, it observed 150,000 stars and hundreds that potentially are orbited by multiple planets. Through a careful study of this sample, scientists verified the 715 new planets.
According to NASA, nearly 95% of these planets are smaller than Neptune, which is almost four times the size of Earth. All of them are in multi-planet systems and have flat and circular orbits -- much like our own solar system, placing our outer-space neighborhood in context.
The discovery marks a significant increase in the number of known smaller planets that are more similar to Earth than previously identified exoplanets.
"We've been able to open the bottleneck and access the mother lode and announce more than 20 times as many planets as has ever been found at one time," said Jack Lissauer, a planetary scientist with NASA. "It's a veritable exoplanet bonanza."
Sara Seager, a professor of physics and planetary science at MIT, said Kepler has revolutionized the study of exoplanets. "Kepler is the gift that keeps on giving," she said.
Scientists said Kepler's discoveries will be advanced when the James Webb Space Telescope, which the space agency calls the next great observatory, is launched in 2018.
The new space telescope is geared to be the successor to the Hubble Space Telescope, and will search for the first galaxies that formed in the early universe and hopefully givie scientists information about the Big Bang and the Milky Way. It also should shine new light on these hundreds of exoplanets.
Sharon Gaudin covers the Internet and Web 2.0, emerging technologies, and desktop and laptop chips for Computerworld. Follow Sharon on Twitter at @sgaudin, on Google+ or subscribe to Sharon's RSS feed. Her email address is [email protected].
Read more about government/industries in Computerworld's Government/Industries Topic Center. | 0.888611 | 3.209112 |
Approximately half of the solar abundances of nuclei heavier than iron are created in the deep layers of asymptotic giant branch (AGB) stars via slow neutron captures (the s process). Freshly made heavy elements, such as Zr, Ba, and Pb, are carried to the stellar surface by recurrent mixing episodes and shed into the interstellar medium via strong stellar winds, thus contributing to the chemical evolution of galaxies. In the past few years several new modelling tools and observational constraints have added to our understanding of how the s process operates in AGB stars of different initial masses and metallicities. For AGB stars of low masses (≥4 M⊙), the 13C(α n)16O reaction is the main neutron source. The exact mixing mechanism leading to the formation of 13C is still unknown and multidimensional hydrodynamic models are needed to address this point. Recent stellar population modelling including s-process nucleosynthesis indicate that the spread in the efficiency of the 13C neutron source is limited to a factor of two of the value obtained when reasonable basic assumptions are applied to the mixing mechanism. This is confirmed by new refined measurements of the isotopic composition of heavy elements in meteoritic silicon carbide grains. On the other hand, observations of the Rb and Zr abundances in massive AGB stars (>4 M⊙) indicate that the main neutron source in these stars is the 22Ne(α n) 25Mg reaction. The increasing number of observations becoming available for the abundances of heavy elements in post-AGB stars and planetary nebulae, the progeny of AGB stars, can also be used to test the ideas above. At low metallicity, the main constraints for the s process come from observations of s-process-enriched carbon-enhanced metal-poor (CEMP) stars. In particular, the origin of CEMP stars enriched in both slow and rapid neutron-capture elements represent a challenge to our understanding of the origin of heavy elements.
|Journal||Proceedings of Science|
|Publication status||Published - 1 Dec 2008|
|Event||International Symposium on Nuclei in the Cosmos 2008 - Mackinac Island, United States of America|
Duration: 27 Jul 2008 → 1 Aug 2008
Conference number: 10th | 0.816862 | 3.99992 |
Image: Artist’s impressions of the TRAPPIST-1 planetary system.
A new study has found that the seven planets orbiting the nearby ultra-cool dwarf star TRAPPIST-1 are all made mostly of rock, and some could potentially hold more water than Earth. The planets’ densities, now known much more precisely than before, suggest that some of them could have up to 5 percent of their mass in the form of water — about 250 times more than Earth’s oceans. The hotter planets closest to their parent star are likely to have dense steamy atmospheres and the more distant ones probably have icy surfaces. In terms of size, density and the amount of radiation it receives from its star, the fourth planet out is the most similar to Earth. It seems to be the rockiest planet of the seven, and has the potential to host liquid water.
SulutPos.com, Garching bei München, Germany – Planets around the faint red star TRAPPIST-1, just 40 light-years from Earth, were first detected by the TRAPPIST-South telescope at ESO’s La Silla Observatory in 2016. In the following year further observations from ground-based telescopes, including ESO’s Very Large Telescope and NASA’s Spitzer Space Telescope, revealed that there were no fewer than seven planets in the system, each roughly the same size as the Earth. They are named TRAPPIST-1b,c,d,e,f,g and h, with increasing distance from the central star .
Further observations have now been made, both from telescopes on the ground, including the nearly-complete SPECULOOS facility at ESO’s Paranal Observatory, and from NASA’s Spitzer Space Telescope and the Kepler Space Telescope. A team of scientists led by Simon Grimm at the University of Bern in Switzerland have now applied very complex computer modelling methods to all the available data and have determined the planets’ densities with much better precision than was possible before .
Simon Grimm explains how the masses are found: “The TRAPPIST-1 planets are so close together that they interfere with each other gravitationally, so the times when they pass in front of the star shift slightly. These shifts depend on the planets’ masses, their distances and other orbital parameters. With a computer model, we simulate the planets’ orbits until the calculated transits agree with the observed values, and hence derive the planetary masses.”
Team member Eric Agol comments on the significance: “A goal of exoplanet studies for some time has been to probe the composition of planets that are Earth-like in size and temperature. The discovery of TRAPPIST-1 and the capabilities of ESO’s facilities in Chile and the NASA Spitzer Space Telescope in orbit have made this possible — giving us our first glimpse of what Earth-sized exoplanets are made of!”
The measurements of the densities, when combined with models of the planets’ compositions, strongly suggest that the seven TRAPPIST-1 planets are not barren rocky worlds. They seem to contain significant amounts of volatile material, probably water , amounting to up to 5% the planet’s mass in some cases — a huge amount; by comparison the Earth has only about 0.02% water by mass!
“Densities, while important clues to the planets’ compositions, do not say anything about habitability. However, our study is an important step forward as we continue to explore whether these planets could support life,” said Brice-Olivier Demory, co-author at the University of Bern.
TRAPPIST-1b and c, the innermost planets, are likely to have rocky cores and be surrounded by atmospheres much thicker than Earth’s. TRAPPIST-1d, meanwhile, is the lightest of the planets at about 30 percent the mass of Earth. Scientists are uncertain whether it has a large atmosphere, an ocean or an ice layer.
Scientists were surprised that TRAPPIST-1e is the only planet in the system slightly denser than Earth, suggesting that it may have a denser iron core and that it does not necessarily have a thick atmosphere, ocean or ice layer. It is mysterious that TRAPPIST-1e appears to be so much rockier in its composition than the rest of the planets. In terms of size, density and the amount of radiation it receives from its star, this is the planet that is most similar to Earth.
TRAPPIST-1f, g and h are far enough from the host star that water could be frozen into ice across their surfaces. If they have thin atmospheres, they would be unlikely to contain the heavy molecules that we find on Earth, such as carbon dioxide.
“It is interesting that the densest planets are not the ones that are the closest to the star, and that the colder planets cannot harbour thick atmospheres,” notes Caroline Dorn, study co-author based at the University of Zurich, Switzerland.
The TRAPPIST-1 system will continue to be a focus for intense scrutiny in the future with many facilities on the ground and in space, including ESO’s Extremely Large Telescope and the NASA/ESA/CSA James Webb Space Telescope.
Astronomers are also working hard to search for further planets around faint red stars like TRAPPIST-1. As team member Michaël Gillon explains : “This result highlights the huge interest of exploring nearby ultracool dwarf stars — like TRAPPIST-1 — for transiting terrestrial planets. This is exactly the goal of SPECULOOS, our new exoplanet search that is about to start operations at ESO’s Paranal Observatory in Chile.”
ESOcast 150 Light: Planets around TRAPPIST-1 Probably Rich in Water
The planets were discovered using the ground-based TRAPPIST-South at ESO’s La Silla Observatory in Chile; TRAPPIST-North in Morocco; the orbiting NASA Spitzer Space Telescope; ESO’s HAWK-I instrument on the Very Large Telescope at the Paranal Observatory in Chile; the 3.8-metre UKIRT in Hawaii; the 2-metre Liverpool and 4-metre William Herschel telescopes on La Palma in the Canary Islands; and the 1-metre SAAO telescope in South Africa.
Measuring the densities of exoplanets is not easy. You need to find out both the size of the planet and its mass. The TRAPPIST-1 planets were found using the transit method — by searching for small dips in the brightness of the star as a planet passes across its disc and blocks some light. This gives a good estimate of the planet’s size. However, measuring a planet’s mass is harder — if no other effects are present planets with different masses have the same orbits and there is no direct way to tell them apart. But there is a way in a multi-planet system — more massive planets disturb the orbits of the other planets more than lighter ones. This in turn affects the timing of transits. The team led by Simon Grimm have used these complicated and very subtle effects to estimate the most likely masses for all seven planets, based on a large body of timing data and very sophisticated data analysis and modelling.
The models used also consider alternative volatiles, such as carbon dioxide. However, they favour water, as vapour, liquid or ice, as the most likely largest component of the planets’ surface material as water is the most abundant source of volatiles for solar abundance protoplanetary discs.
The SPECULOOS survey telescopes facility is nearly complete at ESO’s Paranal Observatory.
This research was presented in a paper entitled “The nature of the TRAPPIST-1 exoplanets”, by S. Grimm et al., to appear in the journal Astronomy & Astrophysics.
The team is composed of Simon L. Grimm (University of Bern, Center for Space and Habitability, Bern, Switzerland) , Brice-Olivier Demory (University of Bern, Center for Space and Habitability, Bern, Switzerland), Michaël Gillon (Space Sciences, Technologies and Astrophysics Research Institute, Université de Liège, Liège, Belgium), Caroline Dorn (University of Bern, Center for Space and Habitability, Bern, Switzerland; University of Zurich, Institute of Computational Sciences, Zurich, Switzerland), Eric Agol (University of Washington, Seattle, Washington, USA; NASA Astrobiology Institute’s Virtual Planetary Laboratory, Seattle, Washington, USA; Institut d’Astrophysique de Paris, Paris, France), Artem Burdanov (Space Sciences, Technologies and Astrophysics Research Institute, Université de Liège, Liège, Belgium), Laetitia Delrez (Cavendish Laboratory, Cambridge, UK; Space Sciences, Technologies and Astrophysics Research Institute, Université de Liège, Liège, Belgium), Marko Sestovic (University of Bern, Center for Space and Habitability, Bern, Switzerland), Amaury H.M.J. Triaud (Institute of Astronomy, Cambridge, UK; University of Birmingham, Birmingham, UK), Martin Turbet (Laboratoire de Météorologie Dynamique, IPSL, Sorbonne Universités, UPMC Univ Paris 06, CNRS, Paris, France), Émeline Bolmont (Université Paris Diderot, AIM, Sorbonne Paris Cité, CEA, CNRS, Gif-sur-Yvette, France), Anthony Caldas (Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, Pessac, France), Julien de Wit (Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA), Emmanuël Jehin (Space Sciences, Technologies and Astrophysics Research Institute, Université de Liège, Liège, Belgium), Jérémy Leconte (Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, Pessac, France), Sean N. Raymond (Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, Pessac, France), Valérie Van Grootel (Space Sciences, Technologies and Astrophysics Research Institute, Université de Liège, Liège, Belgium), Adam J. Burgasser (Center for Astrophysics and Space Science, University of California San Diego, La Jolla, California, USA), Sean Carey (IPAC, Calif. Inst. of Technology, Pasadena, California, USA), Daniel Fabrycky (Department of Astronomy and Astrophysics, Univ. of Chicago, Chicago, Illinois, USA), Kevin Heng (University of Bern, Center for Space and Habitability, Bern, Switzerland), David M. Hernandez (Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA), James G. Ingalls (IPAC, Calif. Inst. of Technology, Pasadena, California, USA), Susan Lederer (NASA Johnson Space Center, Houston, Texas, USA), Franck Selsis (Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, Pessac, France) and Didier Queloz (Cavendish Laboratory, Cambridge, UK).
ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile and by Australia as a strategic partner. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research.
ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. ESO is also a major partner in two facilities on Chajnantor, APEX and ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become “the world’s biggest eye on the sky”.
ESO Science Release | 0.831035 | 3.881182 |
For almost a decade, thanks to an increased effort in exoplanet hunting such as NASA's Kepler mission, astronomers have identified a lot of Earth-like planets outside our solar system. However, they had a problem explaining why a significant number of these exoplanets, usually in pairs, have unstable orbits. There seemed to be an invisible force pushing them apart from each other.
A team of Yale researchers thinks they might have found an answer to that mystery: according to their calculation, the pole of these planets could be over-tilted.
In astronomy obliquity, also known as axial tilt, describes the angle between a body's rotational axis and its orbital axis. All planets exhibit axial tilt to a certain degree. Currently, Earth has an axial tilt about 23°, while the one of Mars is 25°. An oddball in the solar system, Uranus has an axis tilts of 82°, making it look like a tipped-over barrel that rotates on its side.
Related reading: Why Uranus is so tilted?
Scientists had previously suspected that the tides on these planets, caused by their host star, could nudging them out of the regular orbits by draining their orbital energy. But the problem is that later calculation revealed the tides aren't strong enough to pull off such a feat.
Sarah Millholland and professor Gregory Laughlin, the Yale astronomers behind the latest study, added their ingenious tweak to the original theory: they proposed that if these exoplanets have a substantial obliquity, similar to the case of Uranus, then the tides would have sufficient kinetic energy to affect their orbit.
In a press release, Millholland explained their idea: "When planets such as these have large axial tilts, as opposed to little or no tilt, their tides are exceedingly more efficient at draining orbital energy into heat in the planets. This vigorous tidal dissipation pries the orbits apart."
The probable over-tilting feature of these exoplanets will have board implications in the planet's physical characters, such as their climate and atmosphere.
Earth's current obliquity allows our planet to have a gradual switch between distinct seasons. Hypothetically, if a planet has a perfect 90° tilt angle, it would always be summer and day time at one pole, and winter and night time at the other.
And also thanks to the Moon, which has a stabilizing effect on Earth's obliquity, our poles only oscillate in a small range (22°-24°) in the past 5 million years. Otherwise, scientists suspect that Earth's obliquity might reach near 90° over several billion years.
For their next step, the astronomy duo will be looking into the effect of substantial obliquity on planets' structures over time.
Their study was recently published in the journal Nature Astronomy.
What Knocked Over Uranus? And Two Other Mysteries (SciShow Space)
Source: Science Daily | 0.888126 | 3.895873 |
According to Einstein’s general theory of relativity, first published in 1915, the phenomenon we experience as gravitation can be interpreted purely geometrically. Objects moving in the absence of external forces travel along “geodesics”, curves generalizing straight lines. However, in the presence of matter, the geometry of space-time is not Euclidean. Instead, nearby geodesics move closer together, similarly to longitude lines on the surface of the earth as one walks toward the north or south pole. Bodies moving along converging geodesics are, perforce, attracted to each other.
Among the predictions of general relativity is the bending of light by gravitation. In May 1919, Arthur Eddington led an expedition to the Isle of Principe in the Gulf of Guinea, West Africa. A companion expedition was sent to Sobral, in northern Brazil. A rare and timely astronomical coincidence was due to occur: a total solar eclipse as the sun passed through the Hyades, “an exceptional field of bright stars” in Eddington’s words. The expeditions’ goal was to photograph the deflection of starlight by the sun’s gravitational field. Newton’s law of gravitation also predicted deflection, but by an amount only half as great as Einstein’s prediction. The plates from Sobral showed, within bounds of experimental uncertainty, a greater deflection than predicted by Newtonian gravitation. Both sets of plates were entirely consistent with Einstein’s prediction. This initial experimental confirmation of general relativity catapulted Einstein to international fame.
Written in 1920, Eddington’s “Space, Time and Gravitation” is one of the first popular accounts of general relativity. The book begins with an imaginary conversation between a classical physicist, a pure mathematician, and a relativistic physicist who challenges the classical physicist (and therefore the reader) to reconsider the static, Galilean concepts of space and time. Chapter by chapter, using little more than the Pythagorean theorem, Eddington builds an ever-stronger case for the relativistic thesis: Space and time are not independent absolutes, but together comprise a single physical entity in which disparate physical ideas become unified.
The decades bracketing 1920 saw a dramatic shift in cosmology. In 1917, Einstein used general relativity to model the entire universe, introducing a “cosmological constant” in his field equations in order to obtain a static solution. In 1922, Alexander Friedmann found expanding solutions to Einstein’s original field equations (without a cosmological constant). By 1929, Edwin Hubble had discovered that distant galaxies were moving away from the earth at speeds proportional to their distance, an experimental suggestion that Friedmann’s model was closer to reality than Einstein’s. Eddington’s book predates these foundational discoveries, and even contains cosmological speculations that seem naive in retrospect. Despite this, the book remains a lively, accessible, and literate introduction to the rich geometric background underlying Einstein’s general theory of relativity.
This review was contributed by DP-volunteer adhere. | 0.837486 | 4.141841 |
In case you missed it, here is video footage of the 2012 Venus transit from the Solar Dynamics Observatory.
Launched on Feb. 11, 2010, the Solar Dynamics Observatory, or SDO, is the most advanced spacecraft ever designed to study the sun. During its five-year mission, it will examine the sun’s atmosphere, magnetic field and also provide a better understanding of the role the sun plays in Earth’s atmospheric chemistry and climate. SDO provides images with resolution 8 times better than high-definition television and returns more than a terabyte of data each day.
On June 5 2012, SDO collected images of the rarest predictable solar event–the transit of Venus across the face of the sun. This event happens in pairs eight years apart that are separated from each other by 105 or 121 years. The last transit was in 2004 and the next will not happen until 2117.
The videos and images displayed here are constructed from several wavelengths of extreme ultraviolet light and a portion of the visible spectrum. The red colored sun is the 304 angstrom ultraviolet, the golden colored sun is 171 angstrom, the magenta sun is 1700 angstrom, and the orange sun is filtered visible light. 304 and 171 show the atmosphere of the sun, which does not appear in the visible part of the spectrum.
Video: NASA Goddard Space Flight Center | 0.808605 | 3.231199 |
The planet I'm working with has two different moons, both around the same size (3/4ths that of the main planet). Is it possible for the planet to support the orbit of these moons, especially with these proportions?
Yes, it's possible
However, you may have to widen your definition of "orbit" somewhat!
Usually it's relatively safe to say "the moon orbits around the planet", which leads most people to visualize orbits like this:
Fig 1. (As with most diagrams like this, it's not to scale; the moon would be much farther away! But then it'd be very small on the diagram.)
The light blue arc is the planet's orbit around the star. The pink circle is the moon's orbit around the planet.
With Earth's moon, the above diagram would tell the tale (more or less), because our moon is much less massive than the Earth.
However, with a moon that is about half the mass of the planet, the gravitational pull of the moon on the planet becomes significant, and this is what you would see instead:
Fig 2. While the "planet" and "moon" are (still) not to scale, the inner/outer orbit circles are approximately to scale! That means the planet would be heavily "yanked" around by the moon. The planet and moon orbit a common center point known as the "barycenter", and they both then orbit the star (light blue line, as before).
This is known as a double body system, but for our discussion, I'll stick with "planet" (or "primary") and "moons" (or "satellites").
Fig #2 is the most basic way to arrange the orbit. As with any system, the orbits could be elliptical, and/or eccentric (where the ellipses overlap each other, like my 2nd diagram in this question about binary stars, which follow the same basic rules.)
I assumed size = volume, which means the moon has about 42% of the mass of the planet. If you instead take size = mass, so the moon has 75% of the mass, it makes the planet's orbit even wider, but the overall shape is the same.
Adding in the second moon
So far I've only addressed the question of one massive moon. Pretty much everything I've said above applies equally to the 2nd moon. But the orbits get more complicated, as the 3rd moon can start interfering with the orbits of the other two objects (or vice-versa). The orbits get even more complicated if they are eccentric (see above).
For example, the objects can now pull each other into higher orbits or even eject one object from the system, sending it out of its (satellite) orbit and (likely) into its own orbit around the star.
Collisions aren't out of the question, although they're rather unlikely.
How would they form?
One of a few possibilities:
- Leftover swirling "dust" from the creation of the solar system forms the moon.
- Large proto-planet (mass nearly as big as the planet) collides with the planet and knocks a huge mass of debris into orbit that is then pulled together by gravity into a round moon.
- The moon could be a rogue planetoid, captured by the gravity of the planet
Play Simulation Time!
If you'd like to see something like this in action and have a chance to play with the parameters, try UNL's eclipsing binary simulator. It's made for binary star systems, but the principles work just as well for planets and moons. I don't know of any online orbital simulators which can handle more than two bodies (to anyone reading: please leave a comment if you know of one!), however even this two-body simulator could be quite instructive!
Your question asked about the "required proportions" to make this work. Hopefully this question has already answered that, but I realized I didn't actually address the point directly. As long as you don't have the objects so close that their atmospheres (or surfaces...) collide, the only thing you have to worry about are potentially strong tides (not only liquid ocean tides (if you have oceans), but the same tidal forces could cause seismic tremors if the planetoids are rather close together).
Someone may happen by and mention the Roche limit, which is the radius within which one of your moons could actually be ripped apart by tidal forces. You would have to design quite an extreme system indeed to have to worry about the Roche limit, assuming your planetoids are all of a typical solid, rocky construction.
So, back to the question of "required proportions": as long as you keep the objects reasonably distant (say, on the order of the Earth-Moon distance of about 385,000 km), with Earth-like masses, you should be OK. I'd suggest you use the above simulator to help you visualize what your parameters might look like.
The only examples that we have of multi moon systems is where either the multiple moons are very small relative to the planet or where a smaller moon is a much greater distance away than the larger moon. Two large moons would likely perturb each other enough to kick at least one of them out. It is very unlikely that they would chance into any of the very few (if any) stable systems.
Now if one large moon orbited close and the other orbited far enough away to treat the planet and inner moon as a single gravitational source, it might work as well.
In any case, if you have a moon that is 3/4 the size of its planet, you pretty much have a binary planet. | 0.807352 | 3.836982 |
Sure, space-based X-ray telescopes have been in service since the Einstein Observatory launched back way back in 1978. But the NuSTAR Project is different: It promises to illuminate at the heavens above as never before.
The NuSTAR observatory, part of NASA’s Small Explorer satellite program (SMEX-11), will provide scientists with the first focusing telescope that observes the high-energy X-ray (6-79keV) spectrum. Until now, orbiting X-ray satellites have relied on coded apertures rather than optics that actually focus. This feature will provide 10 to 100 times the clarity of existing ground-based systems and detect otherwise unseen high-energy cosmic X-ray emissions.
To make these observations, the NuSTAR relies an advanced optics system mounted on the end of an extendable boom that focuses the incoming X-rays for a pair of CZT detecting units. The optics system aboard the NuSTAR relies on the Wolter Type I lens, which was developed in 1952 by German scientist Hans Wolter. While his optics were initially built for use in an X-ray microscope, they have since been scaled up to the macro level — 400m long with a 15-inch diameter, and 10m focal length. The optics themselves are constructed from the same flexible glass sheets used in laptop and mobile phone screens, bonded together with epoxy and shaped over precision polished cylindrical quartz forms.
These optics sit at the end of a an articulated 10m long mast, built by ATK-Goleta. The mast is extendable — which minimises space requirements during launch — but provides a stable, movable platform to mount the optics. An adjustment mechanism will help ensure proper alignment between the optics and detectors once the mast is initially deployed and extended. The NuSTAR also uses a dual laser metrology system to correct for image blur.
At the other end of the mast are a pair of detection units made of 32×32 pixel Cadmium-Zinc-Tellurium detectors. These devices convert X-rays to electrons more efficiently than other detector technologies. Each detector images independently, transmits the images via a data downlink to a ground station located in Malindi, Kenya where they are recombined for study.
The NuSTAR is expected to launch in mid-June for an initial two-year mission. It will be charged with generating a census of collapsed stars and black holes around the centre of the Milky Way galaxy as well as their ejecting particle jets, observing the beyond the galactic boundary, illustrating the conditions that create supernovae. In addition, if any new supernovae or gamma-ray bursts are discovered, the NuSTAR will be able to provide some truly unprescedented images. [NuSTAR – NuSTAR PDF – Wikipedia – NASA] | 0.859397 | 3.81824 |
Gibbous ♓ Pisces
Moon phase on 26 June 2013 Wednesday is Waning Gibbous, 18 days old Moon is in Aquarius.Share this page: twitter facebook linkedin
Previous main lunar phase is the Full Moon before 3 days on 23 June 2013 at 11:32.
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 ∠18° of ♒ Aquarius tropical zodiac sector.
Lunar disc appears visually 2.9% wider than solar disc. Moon and Sun apparent angular diameters are ∠1943" and ∠1887".
Next Full Moon is the Buck Moon of July 2013 after 26 days on 22 July 2013 at 18:15.
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 18 days old. Earth's natural satellite is moving from the middle to the last part of current synodic month. This is lunation 166 of Meeus index or 1119 from Brown series.
Length of current 166 lunation is 29 days, 15 hours and 18 minutes. It is 42 minutes longer than next lunation 167 length.
Length of current synodic month is 2 hours and 34 minutes longer than the mean length of synodic month, but it is still 4 hours and 29 minutes shorter, compared to 21st century longest.
This lunation true anomaly is ∠168.8°. At the beginning of next synodic month true anomaly will be ∠191.6°. The length of upcoming synodic months will keep decreasing since the true anomaly gets closer to the value of New Moon at point of perigee (∠0° or ∠360°).
3 days after point of perigee on 23 June 2013 at 11:09 in ♑ Capricorn. The lunar orbit is getting wider, while the Moon is moving outward the Earth. It will keep this direction for the next 10 days, until it get to the point of next apogee on 7 July 2013 at 00:36 in ♋ Cancer.
Moon is 368 869 km (229 205 mi) away from Earth on this date. Moon moves farther next 10 days until apogee, when Earth-Moon distance will reach 406 493 km (252 583 mi).
6 days after its ascending node on 20 June 2013 at 09:51 in ♏ Scorpio, the Moon is following the northern part of its orbit for the next 6 days, until it will cross the ecliptic from North to South in descending node on 3 July 2013 at 04:15 in ♉ Taurus.
6 days after beginning of current draconic month in ♏ Scorpio, the Moon is moving from the beginning to the first part of it.
3 days after previous South standstill on 22 June 2013 at 16:11 in ♐ Sagittarius, when Moon has reached southern declination of ∠-20.186°. Next 9 days the lunar orbit moves northward to face North declination of ∠20.170° in the next northern standstill on 6 July 2013 at 02:09 in ♊ Gemini.
After 11 days on 8 July 2013 at 07:14 in ♋ Cancer, the Moon will be in New Moon geocentric conjunction with the Sun and this alignment forms next Sun-Moon-Earth syzygy. | 0.848363 | 3.098175 |
Crescent ♈ Aries
Moon phase on 13 May 2072 Friday is Waning Crescent, 25 days old Moon is in Aries.Share this page: twitter facebook linkedin
Previous main lunar phase is the Last Quarter before 3 days on 10 May 2072 at 03:17.
Moon rises after midnight to early morning and sets in the afternoon. It is visible in the early morning low to the east.
Moon is passing first ∠0° of ♈ Aries tropical zodiac sector.
Lunar disc appears visually 6.2% narrower than solar disc. Moon and Sun apparent angular diameters are ∠1784" and ∠1898".
Next Full Moon is the Flower Moon of May 2072 after 18 days on 31 May 2072 at 22:18.
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 25 days old. Earth's natural satellite is moving from the second to the final part of current synodic month. This is lunation 894 of Meeus index or 1847 from Brown series.
Length of current 894 lunation is 29 days, 12 hours and 22 minutes. It is 2 hours and 43 minutes longer than next lunation 895 length.
Length of current synodic month is 22 minutes shorter than the mean length of synodic month, but it is still 5 hours and 47 minutes longer, compared to 21st century shortest.
This lunation true anomaly is ∠250.1°. At the beginning of next synodic month true anomaly will be ∠285°. The length of upcoming synodic months will keep decreasing since the true anomaly gets closer to the value of New Moon at point of perigee (∠0° or ∠360°).
2 days after point of apogee on 10 May 2072 at 17:48 in ♒ Aquarius. The lunar orbit is getting closer, while the Moon is moving inward the Earth. It will keep this direction for the next 10 days, until it get to the point of next perigee on 23 May 2072 at 23:46 in ♌ Leo.
Moon is 401 844 km (249 694 mi) away from Earth on this date. Moon moves closer next 10 days until perigee, when Earth-Moon distance will reach 369 656 km (229 694 mi).
1 day after its descending node on 12 May 2072 at 08:23 in ♓ Pisces, the Moon is following the southern part of its orbit for the next 12 days, until it will cross the ecliptic from South to North in ascending node on 25 May 2072 at 15:57 in ♍ Virgo.
14 days after beginning of current draconic month in ♍ Virgo, the Moon is moving from the second to the final part of it.
7 days after previous South standstill on 6 May 2072 at 07:01 in ♑ Capricorn, when Moon has reached southern declination of ∠-18.526°. Next 7 days the lunar orbit moves northward to face North declination of ∠18.609° in the next northern standstill on 20 May 2072 at 14:55 in ♊ Gemini.
After 4 days on 18 May 2072 at 00:18 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 | 3.169669 |
Distant object at edge of Solar System is an ancient relic from 4.5 billion years ago
It's a rather uninspiring object, with no moons, rings or dust clouds in orbit around it; nor is there any evidence of an atmosphere. But this distant space rock at the far edge of our Solar System is actually an ancient relic that's remained largely untouched – even by the heat of the Sun – since its formation roughly 4.5 billion years ago, a new study said. The unassuming, 20-mile-long object, which looks like a snowman that's been flattened like a pancake, is informally known as "Ultima Thule." Thus, it preserves clues about the early history of the Solar System.
NASA drops insane map of 4000 planets discovered outside our solar system # Nasa # Planets # discovered #latestnews Please Subscribe My Channel Thanks For
NASA 's Hubble and Spitzer discover 'Super Earth' planet in a distant solar system has a rich atmosphere and could unlock mystery of how planets are formed. Experts at the University of Montreal in Canada used a pair of NASA telescopes - Hubble and Spritzer - to conduct their study of a planet
NASA believes exoplanets like TRAPPIST-1f could have the right conditions for liquid water, meaning they could support life.
It seems insane now, but it wasn't long ago we had no hard evidence of planets existing outside our solar system. Known as "exoplanets", the first definitive discovery of one didn't come until 1992. For many years after that, a trickle of distant worlds were added to the known exoplanet catalog.
Only in the last decade, with the help of the recently retired Kepler Space Telescope, has the pace of discovery really increased exponentially. In June, the 4,000th exoplanet was confirmed.
NASA’s Kepler just spotted 18 new Earth-sized planets, but only one is worth dreaming about
NASA's Kepler Space Telescope may be dead, but that doesn't mean that the wealth of data it gathered doesn't still hold some untold surprises. A new research paper from scientists at the Max Planck Institute, Georg August University, and the Sonneberg Observatory is a great reminder of that, and it reveals the existence of 18 (!) completely new exoplanets that were previously unknown to astronomers.
Exploring Planets Outside the Solar System - In Search of Alien Planets in the Universe Documentary Space & The Universe HD 4 962 зрителя. What has NASA 's Juno discovered around Jupiter so far?
NASA just dropped an astonishingly elaborate map of more than 4,000 exoplanets known to exist outside our Solar System , which takes the form of a video that shows how many It’s an impressive visualization of the exponential rate at which we’re discovering outside worlds many light-years away.
Requiem for Kepler? NASA's pioneering planet-finder (pictures)
Since its 2009 launch, NASA's Kepler space telescope has chalked up an impressive list of firsts and logged a tidy tally of newly discovered exoplanets (planets outside our solar system): 132 confirmed, plus another 2,740 unconfirmed "candidates." Perhaps most impressive, the craft has helped make a household notion of the idea that there may in fact be oodles of Earth-like, potentially life-supporting planets tucked among the many stars of the Milky Way. With NASA announcing this week that an equipment malfunction might mean an end to Kepler's mission, we thought we'd pay homage to the craft and take a look back at its life and work. The image above is an artist's rendition of Kepler on the job, gazing intently into the cosmos. Click through the rest of the slideshow to refresh your memory of the mission, watch the craft come into being, and check out some of Kepler's mind-expanding, and imagination-fueling, discoveries.
NASA has described the Kepler mission as "a search for habitable planets," that is, Earth-size planets that orbit their star in the "habitable zone," a temperate realm hospitable to H20, and thus, possibly, to the carbon-based life we're familiar with. "The habitable zone is where we think water will be," Kepler principal investigator Bill Borucki has explained . "If you can find liquid water on the surface, we think we may very well find life there. So that zone is not too close to the star, because it's too hot and water boils, and not too far away where the water is condensed...a planet covered with glaciers. It's the Goldilocks zone -- not too hot, not too cold, just right for life." The planets also need to be Earth-size. If they're too small, they don't have enough gravity to hold air molecules and create a life-friendly atmosphere. If they're too big, they hold hydrogen and helium and turn into gas giants like Jupiter and Saturn. Here we see Borucki discussing the plans for the Kepler mission during a meeting at the SETI Institute in Mountain View, Calif., two years before the craft's launch. At that time he said, "We are trying to find man's place in the universe. The first step in doing that is finding Earth-like planets."
The way Kepler has discovered all those "new" planets and their characteristics is by staring at stars. When a planet orbits and passes in front of its star (in what's known as a "transit"), it naturally blocks some of the light being emitted by that star. The brightness of that star, then, drops. And, under certain conditions, Kepler's instruments can register that drop. As NASA puts it: "By measuring the depth of the dip in brightness and knowing the size of the star, scientists can determine the size or radius of the planet. The orbital period of the planet can be determined by measuring the elapsed time between transits. Once the orbital period is known, [Johannes] Kepler's Third Law of Planetary Motion can be applied to determine the average distance of the planet from its star." And this, along with the probable temperature of the star, can be used to determine the likely temperature on the planet. Earth-based instruments have used a similar technique -- involving a planet's gravitational pull on its star, as opposed to changes in the star's brightness -- to spot new planets. In fact, in 2010, astronomers working with a spectrometer and this " wobble method " at Hawaii's Keck Observatory announced they'd discovered the first real example of a potentially life-friendly exoplanet . But the brightness-based "transit method" of planet-finding provides information the wobble method doesn't -- perhaps most importantly, a planet's size. And Earthbound tools can't use the transit method; Earth's orbit and the changing night sky prevent constant monitoring of the same stars, and atmospheric conditions interfere. Since it sits comfortably out in space, Kepler avoids these issues (and it has special characteristics that a space telescope like Hubble doesn't). Its data can be combined with info gleaned by Earthbound and other instruments to create profiles of planets.
So what is Kepler? In simple terms, it's a giant light meter, made up of a telescope, a "camera," and various electronics, that stands on a spacecraft base while nestled in a wraparound solar array (which powers the setup). Here's a model of Kepler, from the 2007 SETI meeting mentioned in slide number two. Note the foil-wrapped light meter (or "photometer"), the putty-colored spacecraft base, and the wraparound solar array.
And here's a more detailed artist's rendering, sans foil. Note the two black, spool-like structures at the far left, sticking out of the side of the craft's base, below the solar array -- they look a bit like auto rims without tires. Those are two of the four "reaction wheels" on Kepler. In order for the craft to reliably establish the existence of a planet, it's had to track that potential planet's transit across a star several times, not just once. And that's meant Kepler has had to maintain a precise field of view over time. (It would, of course, take an Earth-size planet in an Earth-like position about a year to circle its star a single time.) The reaction wheels have been keeping Kepler focused on the stars it's been monitoring. At least, they had been doing that. Read on...
A closer look at two of Kepler's four reaction wheels, during the craft's assembly at Ball Aerospace & Technologies. The reaction wheels are, as NASA has said , "special electric motors mounted on the spacecraft that act like specialized gyroscopes. Changes in the motor spin rates result in changes in the spacecraft orientation in different directions without resorting to firing rockets or jets." The wheels were designed to keep Kepler's light meter constantly pointed at the same stars: "The motor spin rates are controlled electronically by computer and are essential for altering spacecraft orientation by very small amounts, as needed for keeping the Kepler telescope pointed precisely at its designated sky target area." They've also been rolling Kepler 90 degrees every three months to keep the solar panels pointed at the sun. However...
...it looks like one too many of the reaction wheels may be dead or dying. Kepler needs only three wheels in order to stay properly positioned, and NASA provided four just in case. But one failed earlier, so now we're down to two. Hence, Kepler's gaze is drifting. NASA isn't ready to call the mission over just yet; Earthbound technicians are trying to jump-start the misbehaving wheel (at 42.4 million miles from Earth, Kepler is too far away for a Hubble-like, astronaut repair job ). But in any case, the errant wheel lasted about eight and a half months beyond the originally planned three-and-a-half-year duration of the Kepler mission. So with its payload of other sophisticated equipment, Kepler has accomplished quite a lot.
Here's what is perhaps the centerpiece of Kepler's collection of gear: the focal plane assembly, also known as the biggest camera NASA has ever flown in space. The 21 purplish-blue squares you see here are each made up of two rectangular, 2,200x1,024-pixel "charged coupled devices," or CCDs, which have been measuring the light from Kepler's targeted stars. This camera, rated at a whopping 95 megapixels, hasn't been taking the sort of pictures you're used to, however. It's been collecting data on brightness and sending it to an onboard computer, which in turn has been beaming the data to Earth once a month. Remember that pattern of squares -- you'll see it again very soon.
Voila. This is the view that's been enjoyed by the focal plane assembly for more than four years now: "an expansive star-rich patch of sky in the constellations Cygnus and Lyra," as NASA describes it. The view encompasses more than 100,000 stars. Kepler was designed to observe so many because only a small percentage of the stars might actually show a planet's transit in front of them. That's because in order for a transit to be visible, a star's planetary system has to be perfectly aligned with our line of sight. Create a fist with one hand and call that a star. Then create a planet with the tip of your other index finger and orbit it around your fist at different distances and angles. You'll begin to understand the alignment issue. NASA says that "for Earth-size planets around sunlike stars, the chances of randomly oriented orbital planes being in the correct orientation for Kepler to see a transit is about 0.5 percent." Remember those low odds -- they'll be used to make a rather breathtaking point in an upcoming caption. (By the way, the detailed areas called out in this image show a cluster of stars, called NGC 6791, and a star with a known planet called TrES-2 [circled in blue].)
Here, we've zoomed out a little, to show the region of the Milky Way that's home to the Cygnus and Lyra constellations. Some of the stars Kepler has been staring at are as many as 3,000 light-years away.
Now let's take a very quick trip back through time to watch Kepler grow into a fully formed adult, ready to leave the nest. Here's the focal plane assembly that we saw earlier being prepared for mounting inside of Kepler's telescope.
And here, it's being guided into the telescope's lower housing.
This diagram shows the focal plane assembly's eventual placement inside the telescope, between the mirror, at the bottom, and the Schmidt corrector lens, which corrects for the mirror's curvature, at the top. The image of the stars is, of course, bounced off the superhigh-tech mirror onto the focal plane assembly and its equally high-tech CCDs. Together, all this gear forms Kepler's giant light meter, or photometer.
Here's the back side of the primary mirror assembly. The honeycomb structure keeps the mirror very light -- it's just one-seventh the weight of a solid mirror with the same thickness and diameter.
The lower housing is guided onto the primary mirror assembly. (You can see the head of one of the technicians reflected in the curved mirror.)
The assembled photometer. (That's some light meter, eh?)
And here's the gold-wrapped photometer being lowered onto its spacecraft base.
Last but not least, the solar array was added. (And the little white elves finally got to take a sandwich break.)
So what do you do with millions of dollars' worth of custom-built, highly sensitive instrumentation? You set it atop a huge amount of highly flammable liquid and light a match. On March 6, 2009, Kepler leaped toward the stars on top of a Delta II rocket, on the way to making its historic discoveries...
On January 4, 2010, NASA announced Kepler's first modest discovery: five exoplanets -- "hot jupiters," with high masses, extreme temperatures, and large sizes (from about the size of Neptune to larger than Jupiter -- both of which are far larger than the planet we call home). So, nothing habitable. But since then, the industrious floating photometer has gone on to discover more than one orb in the habitable zone, along with a few tantalizing space oddities. The beautiful blue-green ball you see here, in a NASA artist's rendition of course, is Kepler-22b, the first planet Kepler confirmed (on December 5, 2011) as orbiting in a star's habitable zone. The planet grabbed headlines as a potential doppelganger for Earth (despite it being two and a half times larger). But scientists aren't sure if it has a predominantly rocky, gaseous, or liquid composition. Still, Douglas Hudgins, Kepler program scientist at NASA Headquarters in Washington, said at the time of the discovery, "This is a major milestone on the road to finding Earth's twin." And it presumably made a lot of people sit up and pay attention.
About three months prior to the discovery of Kepler 22-b, NASA announced , on August 26, 2010, Kepler's discovery of the first confirmed planetary system with more than one planet crossing in front of the same star. Here, we see the star, Kepler-9, being circled by its two planets, Kepler-9b, on the right, and Kepler 9c. Both planets are close in size to Saturn. Another super-Earth-size planet was later spotted in the same system. And still later, on February 2, 2011, Kepler confirmed a system with six planets circling their star, Kepler-11. NASA has called this Kepler-11 system "the fullest, most compact planetary system yet discovered beyond our own."
One of the oddities spied by Kepler is this possible "evaporating planet," discovered on May 18, 2012. Analyzing data beamed back by Kepler, researchers identified a strange light pattern coming from a star called KIC 12557548. This led them, as NASA puts it , to: "hypothesize that the star-facing side of the potentially rocky inferno is an ocean of seething magma. The surface melts and evaporates at such high temperatures that the energy from the resulting wind is enough to allow dust and gas to escape into space. This dusty effluence trails behind the doomed companion as it disintegrates around the star." The doomed companion has not yet been confirmed as a planet, however.
NASA announced the discovery of this system, Kepler-47, on August 28, 2012. Here, we see it compared to part of our own solar system. There's an intriguing little detail in this diagram. Can you spot it? Read on...
If you spotted the Kepler-47 system's two suns, consider yourself an honorary member of Kepler's focal plane assembly. Kepler-47 was the first instance the space telescope found of multiple transiting planets orbiting a pair of stars. Earlier, on September 15, 2011, Kepler had spotted its first confirmed single planet orbiting two stars: Kepler-16b. And on January 11, 2012, it discovered two more double-sun planets: Kepler-34b and Kepler-35b. (We'll be quizzing you on these planet names, so we hope you're taking notes.) But if two stars aren't enough for you, how about four? On October 15, 2012, a joint effort between scientists and amateur astronomers with the Planet Hunters project tapped data from Kepler to discover PH1, the first known planet orbiting a double-star that itself is orbited by a distant pair of stars. But let's not get greedy. In the above image, we see Kepler-47c in the foreground and Kepler 47b in the distance, with their two suns glowing in the middle. The foreground planet is a gaseous giant, inhospitable to life, but just for the sake of discussion, let's ask the following question: If future generations of humans were to somehow colonize Kepler-47c, would they go for an evening stroll and see...
...this? And if they did, would they recall their history books -- er, data sets -- and fondly remember Kepler? (This, of course, is a memorable scene from 1977's "Star Wars," depicting Luke Skywalker on his home planet of Tatooine.)
Kepler 62f was one of the first exoplanets found by the space telescope beginning to approach the size of Earth. Four years later, it's still among the best candidates that could be a sister planet to our own.
And here's a size comparison of habitable-zone planets discovered by Kepler to date, alongside Earth. From left to right: Kepler-22b, Kepler-69c, Kepler-62e, Kepler-62f, and Earth. (They're all artist's renderings, except for Earth.)
And here's the Kepler-62 system alongside a part of our solar system. At a glance it looks pretty similar, doesn't it? (Of course, there are differences. For one thing, the Kepler-62 system's "sun" is two-thirds the size of our sun and only one-fifth as bright.) Clearly, Kepler has yet to find a dead ringer for Earth. Still, as John Grunsfeld, associate administrator of the Science Mission Directorate at NASA Headquarters in Washington, was quoted as saying, in the space agency's announcement about the Kepler 62 system: "The discovery of these rocky planets in the habitable zone brings us a bit closer to finding a place like home. It is only a matter of time before we know if the galaxy is home to a multitude of planets like Earth, or if we are a rarity." Unfortunately, unless NASA's technicians can get Kepler's troubled reaction wheel spinning again, time may have run out for Kepler itself. But check out the last two slides...
Remember this one? Let's zoom out again...
OK, here we've zoomed out a lot, to show the entire Milky Way, along with the area Kepler has been looking at and through. Remember that low probability we mentioned back at slide nine? Of Kepler spotting the transit of a planet across a given star? You'll recall that a transit can be seen only with the proper orientation of a planet's orbit to our line of sight, and that the probability of Kepler spying a transit among its 100,000 stars has been about 0.5 percent. NASA says that "statistically, we can infer that every planet Kepler detects represents hundreds more planets that are out there but not detectable due to inopportune orbital orientation." As mentioned before, Kepler has spotted 132 confirmed planets, plus 2,740 potential planets. And it's been looking at a relatively miniscule patch of the galaxy. How many hundreds, or thousands, or millions of Earth-like planets might there be? Or here's another way of thinking about it. Kepler has discovered a fascinating variety of planetary systems, which suggest further, perhaps infinite, varieties. Given those differences, how many solar systems exactly like ours, or even all that similar to ours, might there not be? This is perhaps Kepler's main achievement: the tweak it's given to our perception of the universe and, as principal investigator Borucki put it, our "place in it." Maybe life is far more abundant than we ever imagined, and thus, perhaps, that much more amazing. Or maybe it's rarer, more unique, than we might've thought -- and that much more precious.
That's a big leap in a single lifetime, and to mark just how far we've come in refining our view of the universe, NASA created the above video visualizing when and where in the night sky all the known exoplanets were discovered. Note how quickly the pace of the finds picks up once Kepler starts making its contribution in 2010.
NASA is going to fire an atomic clock into space so astronauts know where they’re going
As NASA and other organizations begin to lay the groundwork for crewed missions to places other than an orbiting space station or even the Moon.
map of 4,000 planets outside our solar system :O In just a few decades, we've gone from knowing of no planets Two Earth-like planets just discovered in the habitable zone near Teegarden's star, 12 The planets resemble the inner planets of our solar system , may have water, and are slightly
It seems insane now, but it was not long before we had no hard evidence of planets outside our solar system . Known as "exoplanets", the first definitive discovery of one This is a great leap in a single lifetime, and to mark just how far we have come to refine our view of the universe, NASA created the
Kepler went to sleep permanently in 2018, but its legacy has been picked up by other observatories like the Transiting Exoplanet Survey Satellite (TESS), which has already found over 700 new planet candidates in its first year in space.
Next up, the European Characterizing Exoplanets Satellite (CHEOPS) is set to launch by the end of the year and NASA's James Webb Space Telescope is set to blast off in 2021. Both space telescopes will be able to do more than just spot exoplanets -- they could help determine if conditions exist to support life upon their surfaces.
Best places in space to search for alien life
The deeper we look into space, the more places we come across that seem like maybe, just maybe, could host life. From our neighboring planets to distant galaxies sending out weird signals, the list of spots in space worth checking out just continues to grow. The closest world we should check for signs of life is one we've already been to, or at least our robots have . There's increasing evidence that Mars was once a lot more like Earth , with oceans on its surface. Today it's more harsh, but it's not out of the question that we could find some sort of microbes in Martian soil.
Dwarf planet Ceres in the asteroid belt is full of surprises. It started with those big bright spots that turned out to be salt deposits, and there's also a huge, strange pyramid-shaped mountain , plenty of water beneath the surface and even the building blocks of life . Some people already believe this huge rock is actually an alien ship. The evidence isn't there to support that theory, but the place does seem worth a closer look.
We don't think of the largest gas giant planet around as a place to look for life, but science fiction author Ben Bova has other ideas. "It's got all the ingredients, enough room and lots of energy," he said in 2016 . Bova briefly explained his notion of life-forms that might be able to live in the air or in water underneath Jupiter's dense deck of clouds. He referred me to a few of the novels from his "Grand Tour" series , including " Jupiter " and " Leviathans of Jupiter ." The storyline of the novels revolves around the existence of massive, city-size life-forms called Leviathans living in gigantic oceans that have condensed beneath the clouds of Jupiter. Um, sure. Why not?
Saturn's satellite Titan is the rare moon in our solar system with an atmosphere, weather, seas and rivers. It sure looks like home, except it's freezing and the lakes are flammable. Whatever life could survive there would be awfully weird, but scientists would still love to send a submarine to see for themselves.
Like Europa, Saturnian moon Enceladus has an icy shell with plumes shooting into space. In 2015, the Cassini spacecraft actually flew through one of the plumes and found large amounts of hydrogen present in its hidden ocean. This suggests the watery world has just about all the ingredients required to support life.
Jupiter moon Europa not only hides a subsurface ocean beneath its icy shell, but geysers have also been spotted there , hinting that some sort of hydrothermal activity might be able to support marine life.
Jupiter's moon Callisto is another world that harbors an unseen ocean. Checking it for microbes or any other exotic life forms might be tough, though, because it would require drilling through its huge, rocky exterior.
Ganymede, Jupiter's largest moon, has long been suspected of harboring a subsurface ocean. In 2015, scientists said they could confirm a salty ocean beneath its frozen crust . It also has a thin oxygen atmosphere, adding to its intrigue.
Yes our nearest planetary neighbor is supposed to be a horrible, hot and toxic hellscape, but that's just below the clouds. Higher in the atmosphere it could be quite nice . The planet wasn't always so inhospitable , so perhaps something managed to adapt? Scary to imagine what might have managed that, but you know you want to see it.
This former planet is very cold, but it's also more interesting than we used to think , with hints of active geology, lots of ice and perhaps some hidden oceans of its own. Definitely worth adding to the life-prospecting itinerary.
A potentially habitable planet around the nearest star to the sun, Proxima b is a no-brainer for closer examination. In fact, some told stories about alien civilizations there before the planet was even discovered. Plans are already underway to send tiny craft there to see if anyone is about.
The TRAPPIST-1 system is just 40 light-years away and hosts up to seven Earth-sized planets, all very close to each other and perfect for the space-faring civilization of our sci-fi dreams.
Wolf 1061 c is a "super-Earth" just 14 light-years away, making it one of the top five closest potentially habitable planets orbiting another star. We've known about it for a few years, and scientists have already started checking it for alien transmissions .
Mysterious signals known as "fast radio bursts" have baffled astronomers for a decade. The only such signal that repeats has been traced to a tiny galaxy in this image in the constellation Auriga. Is it E.T. phoning home?
Something weird is going on around the distant star KIC 8462852, also known as Boyajian's Star . After a few years of research, no one knows for sure what's happening, but one explanation that's yet to be completely ruled out is the far-out notion that a highly advanced society is building insanely huge megastructures in space that obstruct the star. Gulp.
Kepler 186f was one of the first confirmed Earth-like, potentially habitable exoplanets. But at 500 light years away, it no longer receives quite as much attention as targets closer to home.
Kepler-283c was discovered as part of a huge data dump from Kepler that included over 700 newly confirmed exoplanets. It is about twice the size of Earth and orbits much closer to its home star, which is 1,743 light years from Earth.
Some of the strangest exoplanets can be found in the habitable zone of Gliese 667C , which is one of three suns in the triple-star Gliese 667 system. This probably makes for some interesting skyscapes from planets Gliese-667Ce and Gliese-667Cf, the two most likely planets in the system to harbor water (a third planet nearby is also in the habitable zone, but with slightly less favorable conditions for life.)
HD 40307g is another nearby super-Earth only 42 light years away that will be a top target for the next generation of telescopes.
Kepler 62f was one of the first exoplanets found by the space telescope beginning to approach the size of Earth. Four years later, it's still among the best candidates that could be a sister planet to our own.
Gliese 832c is a super-Earth just 16 light years away that could be potentially habitable but probably has some pretty extreme seasons. Perhaps we'll one day find it to be the true home of Westeros ?
Gliese 581d is a potentially habitable planet just 20 light-years away. In 20 years we could probably know if it delivers on that potential.
The exoplanet LHS 1140b , which orbits a red dwarf star 40 light-years from Earth and may be the new holder of the title "best place to look for signs of life beyond the solar system." This world is a little larger and much more massive than the Earth and has likely retained most of its atmosphere.
A very strange signal reportedly came from the direction of the star HD 164595 in the constellation Hercules, which has at least one confirmed planet, a Neptune-size world in close orbit that would seem unlikely to support life as we know it. Then again, there could be other planets there we haven't seen yet...
There's a number of other potentially habitable exoplanets out there that kind of blend together, most of them discovered by the Kepler Space Telescope. To keep from getting monotonous, we're not listing them all, but the Planetary Habitability Lab does here .
When some of us think of life on distant exoplanets, it's hard not to picture dusk on the home world of one young Luke Skywalker. Recently scientists have considered how real planets in binary star systems, just like Tatooine of "Star Wars" fame , might be able to support life. Their results were promising, partially validating a primary reason that at least one space nut hopes we continue looking everywhere for life: the hope that Yoda really is still out there somewhere.
Three Rocky Exoplanets Have Been Found Orbiting a Star Just 12 Light-Years Away.
Three new exoplanets have been found orbiting a nearby star, and one of them is ranked pretty highly for potential habitability. All three are rocky, and within the vicinity of Earth-sized - and the outermost is orbiting the star in the habitable zone, where temperatures are compatible with the possibility of liquid water on the surface. The star is Gliese 1061, at a distance of 3.67 parsecs - around 12 light-years away - making it the 20th closest star to the Solar System. And its three planets are Gliese 1016 b, Gliese 1016 c and Gliese 1016 d. | 0.843735 | 3.079463 |
Jun 11, 2013
In parts of the Amazonian rainforest, traditional costume included a headdress consisting of a circular arrangement of feathers. The ring of 36 feathers, most of which are white, lacks an obvious counterpart in the skies we see above us.
The above example was collected in c. 1910 from the Kayapó, a small nation living in central Brazil, and was locally known as an ȧkkȧpa-ri or a ‘footed feather headdress’.
In stark contrast to the modern world, traditional societies often used to derive their fashion standards from mythological or religious sources, looking backward rather than ahead for inspiration. Jolene Rickard and Gabrielle Tayac, of the Smithsonian Museum of the American Indian, explain that the ȧkkȧpa-ri ‘reflects the Kayapó view of the universe’. It is a cosmogram, representative of the sky, which is inserted in a beeswax hat known as a kutop, that signifies ‘the physical world’. The wooden stick running vertically through the opening is interpreted as ‘the rope that Kayapó descended to reach this earth’. In the latter, anthropologists readily recognise an expression of the axis mundi, a vertical connector between the spiritual realms above and the human world here below.
None of this would make any headlines were it not for the awkward fact that the ‘world’ or the ‘sky’ looks nothing like the Kayapó outfit. If the heavens are circular, no vertical ‘rope’ is seen to dangle down from the centre. Neither the central red feather on top nor the two orange feathers flanking the bottom strike one as familiar.
In the absence of any further clarification from Kayapó informants, a competition of scholars’ informed guesses is the best we can muster. Should the starburst pattern remind some of the rays of the sun, the sparse information culled from the Kayapó is already violated, for an image of the sun cannot at the same time represent the cosmos – whereas a conceptual link between the sun and an ancestral rope from heaven cannot be assumed without firmer evidence.
The earth is immersed in a sea of plasma, distributed across its ionosphere, its magnetosphere and the solar wind. While this may be over the heads of some people, an understanding of this plasma environment offers an unexpected and quite adventurous solution to the mystery of the Kayapó crown.
The familiar ‘curtains’ formed by the earth’s aurorae are the result of so-called diocotron instabilities, in which a hollow sheath of plasma breaks up into a cylindrical ring of discrete filaments. These typically number 112 or 56 at first and subsequently merge in pairs or groups of three as they revolve.
Plasma physicist Anthony Peratt proposed that one or more extreme solar storms transpiring in the early Holocene temporarily transformed the earth’s plasma environment into a single, collimated plasma tube – displaying a bewildering array of instabilities that included the diocotron type. Consequently, a structure very much like the Kayapó crown may have been visible in the sky at those times. Structural analogues to this formation can be found in medicine wheels and stone circles, maṇḍalas, Maypole-style dances, and various other aspects of traditional ‘sacred culture’.
A daring hypothesis it is, but could Peratt have been heading in the right direction? At the very least, an in-depth study of prehistoric fluctuations in the earth’s geomagnetic field would be a feather in the hat of any open-minded scientist.
Rens Van Der Sluijs
Books by Rens Van Der Sluijs:
Traditional Cosmology: The Global Mythology of Cosmic Creation and Destruction | 0.819673 | 3.275327 |
The innermost planet in the Solar System, Mercury, is unique in many ways. It is surprisingly dense, reflecting a massive metallic core that has 60% of the mass of the planet (versus less than 31% for Earth, Venus, and Mars). It has a highly eccentric orbit, approaching as close as 0.3236 AU to the Sun and retreating as far as 0.4506 AU on each orbit, covering the entire range in half an orbital period, 44 Earth days. The intensity of sunlight striking Mercury’s orbit drops off with the square of the distance from the Sun, so it varies by nearly a factor of two.
Even odder, the rotation of Mercury is locked onto its orbital period. Most examples of spin-orbit resonances in the Solar System are 1:1 (one rotation per orbit), which means that the smaller body always keeps the same side toward the larger body. Examples include Earth’s Moon and the large Galilean satellites of Jupiter. The most extreme example of a strong lock between rotation and orbit is Pluto and its satellite Charon: they are locked into a 1:1:1 spin-spin-orbit state, in which both Charon and Pluto always keep exactly the face toward each other. Mercury is noteworthy in that it has a 3:2 spin-orbit resonance: Mercury rotates exactly 3 times every 2 Mercury years, or 1 ½ times per year. Thus in consecutive closest approaches to the Sun (perihelion), opposite sides of the planet get baked. This situation is understandable if Mercury is elongated along one of its equatorial axes: the planet then points the ends of this long axis (the so-called tidal bulges) at the Sun alternatingly at each perihelion passage.
Mercury shows no trace having ever had a significant atmosphere or oceans. The faint wisp of gases surrounding Mercury today is in part due to solar wind gases from the Sun temporarily captured by Mercury’s gravity, and in part to atoms, such as sodium, baked out of the surface by the extreme heat and the impact of high-speed solar wind ions. Gases released from Mercury’s interior, such as argon-40 from the radioactive decay of potassium-40 in the crust and mantle, can easily be ionized by ultraviolet radiation from the Sun, entrapped in the magnetic field of the solar wind, and swept away.
How did Mercury get to be like this? The spin-orbit resonance is essentially unavoidable for a planet that orbits so close to a star. The absence of atmosphere and oceans is also unavoidable for a planet with such weak gravity in so hostile an environment. But the high density of Mercury is a continuing puzzle. The smaller bodies that accreted to form Mercury may have collided so violently that brittle silicates were preferentially crushed to dust, while tough grains of metal survived. Dissipation of the finest dust would then leave behind the ingredients of a metal-rich, dense planet. A second possibility is that the material in the zone where Mercury was to accrete was so strongly heated by the early superluminous Sun that the most volatile minerals were evaporated and lost from Mercury’s formation zone, leaving dense, involatile solids behind to form the planet. A third scenario is that Mercury formed normally with a composition similar to that of the other terrestrial planets, but that post-accretion impacts of comets and asteroids eroded away the crust and much of the mantle, blasting them off at high speeds and leaving behind a part of the lower mantle and the well-protected dense metallic core. Each of these three scenarios predicts different surface compositions for present-day Mercury. The goal of the MESSENGER spacecraft, which is due to enter orbit around Mercury in January, is to test these hypotheses by analyzing the crust by means of gamma-ray spectroscopy and probing the interior of the planet by means of measuring its gravitational and magnetic fields and the interaction of Mercury’s core with the magnetic field of the solar wind.
If all goes well, the answers to these puzzles will soon be in our hands. | 0.855621 | 4.0416 |
May is graduation month, and with it, school star party season is about to conclude. If you happen to be out this coming weekend showing the sky off to the public, keep an eye out for one of the top celestial sights that you won’t see at the eyepiece, as we’re in for a slew of good visible passes of the International Space Station worldwide.
Welcome to the start of what NASA refers to as “high beta angle season,” a time when the station enters a period of full illumination throughout the span of its orbit. This fortuitous circumstance is a direct result of the station’s orbit, inclined 51.6 degrees relative to the Earth’s equator. The station was deliberately placed in this orbit in order to make it accessible to international partners worldwide. This also makes the station visible to over 99 percent of humanity, from latitude 60 degrees north to 60 degrees south.
Full illumination for the ISS occurs near each solstice, with June favoring the northern hemisphere for multiple bright passes every evening and December favoring the southern. This week, the International Space Station exits the Earth’s shadow on May 17th at 18:42 Universal Time (UT)/2;42 PM EDT, and doesn’t hit the Earth’s shadow until briefly on May 20th at 17:55 UT/1:55 PM EDT. Passes over central Asia also favor seeing another unique event: seeing the ISS enter, then exit the Earth’s shadow on the same pass.
This is also about as early as high beta angle season can occur, over one month prior to the June 21st solstice. On this date, the north rotational pole of the Earth is tipped its farthest towards the Sun, and the station’s orbit along with it. Viewers in the United Kingdom, southern Canada and the northern United States along latitude 45 to 55 degrees north can expect to see multiple illuminated passes of the International Space Station in one night.
A friend of ours (@OzoneVibe on Twitter) has suggested that this phenomenon be known as a FISSION, for Four/Five International Space Station passes in One Night. Can you complete a FISSION in one all-night marathon session?
High Beta Angle season is a special time for NASA and the station, as well. During this period NASA generally ‘feathers’ the station’s huge solar panels, in order to create artificial shadow and avoid overheating key areas. Most exterior operations, such as scheduled extravehicular activities (EVAs) and arrivals and departures from the station are avoided if possible around this time as well.
When’s the next ISS pass near you? A multitude of apps and websites exist to track the station and other satellites; our favorite go to is the old standby, Heavens-Above. Moving at 17,100 mph (27,600 kph) and orbiting at an average of 250 miles (400 kilometers) above the Earth’s surface, it takes the station just over 92 minutes to orbit the Earth.
Observing the station is as simple as watching at the appointed time and waiting. The station will appear as a bright moving ‘star’. Unlike aircraft, the station shines by reflected sunlight and won’t blink, though it may flare up in brightness as the Sun glints off of a solar panel. The station can reach a brilliant magnitude -5.7 when it passes near the zenith, bright enough to cast a shadow. At 108.5-meters across, the International Space Station is the largest object in orbit ever constructed. You can even see structure in binoculars on a good pass. Depending how the station is oriented, it can look like anything from a miniature Star Wars TIE fighter, to a tiny box, to a flattened double star on a good pass.
You can also image the station by simply running a wide-field time exposure during a pass, and letting the ISS trail through the field. More challenging is to image the space station through a telescope. Several dedicated backyard observers employ sophisticated tracking and fine-guiding programs to image the ISS. We’ve gotten acceptable results by simply running video during a pass, roughly aiming the ‘scope and tracking the ISS, and seeing what turns up afterwards. Be sure to preset your focus and exposure time before the pass starts. A bright planet, star or passing aircraft make great targets to practice on beforehand.
Another technique is to aim at the Sun or Moon, and wait for the ISS to come to you. CALSky and Transit Finder are great resources to let you know when the next transit of the ISS across the Sun or Moon is occurring near you. These events are quick (often less than a second in duration) and often involve a bit of travel to get positioned at the precise location we’re they’ll occur.
Currently, there’s a full crew compliment of six humans aboard the ISS: three NASA astronauts, two Russian cosmonauts and one Canadian astronaut. The station has been continuously occupied since November 2nd, 2000. That’s right: we pass the 20 year mark for continuous human presence in space, late next year. A marvelous achievement worth noting as you watch the ISS pass overhead this weekend. | 0.840678 | 3.182776 |
Scientists have used data from NASA's Chandra X-ray Observatory and the NSF's Jansky Very Large Array to determine the likely trigger for the most recent supernova in the Milky Way, as described in our latest press release.
Astronomers had previously identified G1.9+0.3 as the remnant of the most recent supernova in our Galaxy. It is estimated to have occurred about 110 years ago from the vantage point of Earth, in a dusty region of the Galaxy that blocked visible light from reaching Earth. This Chandra image shows G1.9+0.3 where low-energy X-rays are colored red, medium-energy X-rays are green, and a higher-energy band of X-rays is blue.
G1.9+0.3 belongs to the Type Ia category, an important class of supernovas exhibiting reliable patterns in their brightness that make them valuable tools for measuring the rate at which the universe is expanding. Most scientists agree that Type Ia supernovas occur when white dwarfs, the dense remnants of Sun-like stars that have run out of fuel, explode. However, there has been a debate over what triggers these white dwarf explosions. Two primary ideas are the accumulation of material onto a white dwarf from a companion star or the violent merger of two white dwarfs.
The researchers in this latest study applied a new technique that could have implications for understanding other Type Ia supernovas. They used archival Chandra and VLA data to examine how the expanding supernova remnant G1.0+0.3 interacts with the gas and dust surrounding the explosion. The resulting radio and X-ray emission provide clues as to the cause of the explosion. In particular, an increase in X-ray and radio brightness of the supernova remnant with time is expected only if a white dwarf merger took place, according to theoretical work.
This result implies that Type Ia supernovas are either all caused by white dwarf collisions, or are caused by a mixture of white dwarf collisions and the mechanism where the white dwarf pulls material from a companion star. It is important to identify the trigger mechanism for Type Ia supernovas because if there is more than one cause then the contribution from each can change over time, affecting their use as "standard candles" in cosmology.
A paper describing these results appeared in the March 1st, 2016 issue of The Astrophysical Journal and is available online. The authors on the paper are Sayan Chakraborti, Francesca Childs, and Alicia Soderberg (Harvard). NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations. | 0.836198 | 4.054612 |
Classification of Meteorites
Since the beginnings of the science of meteoritics in the late 18th century, several schemes have been developed to categorize the various meteorites in our collections. The most popular of these classification schemes is based upon the primary composition of each major group, dividing all meteorites into three main classes: stony meteorites, stony-iron meteorites, and iron meteorites.
Several subgroups have been subsequently assigned to each of these classes, just to cope with the difficulties, and discrepancies that were brought about by this over-aged classification scheme - a scheme that is still widespread in the respective literature, scientific publications, as well as on most meteorite-related websites.
Modern meteoritics has a more sophisticated view, and provides us with new classification schemes based upon the formation history, origin, mineralogy, chemism, and also upon the more subtle isotopic compositions of each meteorite class, clan, and group.
According to these schemes, meteorites can be basically divided into two main categories: primitive meteorites, representing more or less primordial matter, and differentiated meteorites that have been processed and changed during time, similar to the rocks and minerals on our own planet that have been differentiated by igneous processing, and other forces. Have a look at our classification index for a brief overview.
Most primitive meteorites belong to a class called chondrites, and chondrites do not only represent the most common type of meteorite, but also some of the most primitive matter known. They are more or less undifferentiated, primordial matter that has remained nearly unchanged for the last 4.5 billion years.
The chondrites formed simultaneously with the central star of our system, the Sun. It is thought that small droplets of olivine and pyroxene condensed and crystallized from the hot primordial solar nebula in form of small spheres that we call chondrules. This process of solidification and crystallization is not completely understood, and different scientists suggest different theories for chondrule formation.
However, they all agree that those chondrules accreted with other material that condensed from the solar nebula forming a matrix, and of course, the larger parent bodies of those primitive meteorites, i.e., smaller and larger asteroids of chondritic composition.
In their chemical compositions, chondrites and other primitive meteorites, such as primitive achondrites, resemble the Sun, depleted of the most volatile elements like hydrogen and helium. However, the distribution of elements has not been uniform in the primordial solar nebula - elemental composition varied as did the conditions under which the chondritic parent bodies formed.
Different asteroids formed in various regions of the primordial solar nebula under different conditions. Those parent bodies were further subjected to different thermal and chemical processes as well as to impacts with other asteroids resulting in a variety of chondrites, and primitive achondrites which have been categorized into several clans, groups, and subgroups by modern meteoritics and cosmochemistry. We will elaborate on most of these clans and groups on the respective pages.
Primitive achondrites mark a borderline between primordial and differentiated matter as they retained the primitive chemical and isotopic patterns of their chondritic precursors while having changed their overall texture through partial melting and moderate igneous processing. Their respective parent bodies were probably just too small to amass the necessary amount of Al26, the radioctive element that has been responsible for the initial heating, melting, and processing of all asteroids, planetisemals, and planets in our solar system. They also lacked the mass to retain the initial heat, and cooled very quickly, leaving the primitive achondrites as a witness for an uncomplete differentiation.
Larger bodies with enough mass completed the process of heating, melting, and remelting to various degrees, leading to the separation of the more heavy elements, such as nickel and iron, to form a core, and the lighter elements, and minerals, mostly silicates, to form an outer mantel and crust.
The terrestrial planets, such as Mercury, Venus, and Mars, are the perfect examples of a completed differentiation process, but also our own Moon, and a few asteroids belong to the group of the differentiated parent bodies. Contempory research has proved that some classes of evolved achondrites actually represent the outer crust, and the mantle of the planet Mars, the Moon, or the asteroid Vesta, one of the largest asteroids in our solar system.
However, some worlds had to be destroyed to reveal their initial degree of differentiation. Samples of such worlds, disrupted by violent impact events, and cosmic collisions, are the siderites, subdivided into the stony-iron meteorites, and iron meteorites.
While stony-iron meteorites, such as the most intriguing pallasites, are thought to represent the core-mantle boundary where silicates and metal mixed in intriguing patterns, some iron meteorites are thought to actually represent core samples of differentiated asteroids that had been disrupted in the early days of the formation of our solar system. Have a look at the respective pages to learn more about the classes, clans, and groups of differentiated meteorites.
Meteorite Classification Index | 0.829815 | 3.614656 |
By Brendan Hesse3 hours ago
Looking up at the sky inspires deep moments of introspection and curiosity. It’s easy to feel small under a starry night sky, but in order to begin to grasp just how small we truly are, we must know what our relative size is compared to the larger celestial bodies of the Galaxy — and what makes a better point of comparison than a star? Enter UY Scuti, a bright red supergiant variable star that resides within the Scutum constellation and is currently believed to be the largest star in the Milky Way galaxy.
German astronomers originally discovered UY Scuti at the Bonn Observatory in 1860, but it wasn’t until astronomers observed UY Scuti through the Very Large Telescope in Chile’s Atacama Desert in 2012 that the star’s true size became well documented. Following this discovery, UY Scuti was officially named the largest known star in the galaxy, surpassing previous record holders such as Betelgeuse, VY Canis Majoris, and NML Cygni.
While there are stars that are brighter and denser than UY Scuti, it has the largest overall size of any star currently known, with a radius of 1,708 ± 192 R☉. That figure amounts to somewhere between 1,054,378,000 and 1,321,450,000 miles in size, which is about 1,700 times larger than our Sun’s radius and 21 billion times the volume. Wrapping one’s head around such number can be difficult, so let’s break this down a bit. For more click on link. | 0.82596 | 3.113168 |
The Moon and Jupiter will make a close approach, passing within 1°35' of each other. The Moon will be 8 days old.
From Fairfield, the pair will be visible in the evening sky, becoming accessible around 19:01 (EDT) as the dusk sky fades, 25° above your southern horizon. They will then reach its highest point in the sky at 19:48, 26° above your southern horizon. They will continue to be observable until around 23:30, when they sink below 7° above your south-western horizon.
The Moon will be at mag -12.1; and Jupiter will be at mag -2.4. Both objects will lie in the constellation Sagittarius.
They will be too widely separated to fit within the field of view of a telescope, but will be visible to the naked eye or through a pair of binoculars.
A graph of the angular separation between the Moon and Jupiter around the time of closest approach is available here.
The positions of the pair at the moment of closest approach will be as follows:
|Object||Right Ascension||Declination||Constellation||Magnitude||Angular Size|
The coordinates above are given in J2000.0. The pair will be at an angular separation of 104° from the Sun, which is in Virgo at this time of year.
|The sky on 25 September 2020|
8 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.
|14 Jul 2020||– Jupiter at opposition|
|28 Jan 2021||– Jupiter at solar conjunction|
|19 Aug 2021||– Jupiter at opposition|
|05 Mar 2022||– Jupiter at solar conjunction| | 0.895513 | 3.391177 |
In 2005, the first mission that planned to collect samples from an asteroid- the Hayabusa spacecraft launched by the Japanese- reached Itokawa, its target asteroid. Five years later Hayabusa has successfully returned to Earth along with a valuable cargo of samples. In the following years, scientists have been heard at work, analyzing the samples in order to understand the history of the asteroid and how it formed. The results were recently published in a per-reviewed journal in many interesting details have been learned.
Itokawa, which is held together by shield gravity, was revealed to be almost 4, 6 billion years old, on par with the age of the solar system. Originally, the asteroid was larger and more impressive but a direct collision with another asteroid 1, 5 billion ago reduced it to the state in which it is today. Itokawa has also orbited with the main asteroid belt until recently when it joined the Near Earth Asteroid orbit, which means that it may collide with Earth one day, unless it breaks apart before it gets too near.
More than 1,000 samples were collected from Itokawa. Some of them contain micro phosphate minerals which were used in tests along uranium to determine the exact age of the satellite at around 4.64 billion dollars with an error space of 180 million years. Further analysis of found isotopes confirms the collision but the exact date is harder to match in this case.
The mission was successful despite a few technical problems. A solar flare hit the spacecraft soon after launch but it continued its mission. A deployable lander disappeared and the spacecraft was forced to land in order to collect the sample. But the problems did not hinder the project and the mission was completed.
The Japanese space agency has sent Hayabusa2 to examine the Ryugu asteroid. It is hoped that it will bring back new samples that will further improve our understanding of asteroids. | 0.830227 | 3.29143 |
The Jovian Planets
Far past Earth and Mars lays enormous planets known as the Jovian planets. These planets get there name for being giant and Jupiter like. The four Jovian planets are (in order) Jupiter, Saturn, Uranus, and Neptune. The Jovian planets are unlike the rest of the terrestrial planets because of their size, structure and massive rotation structure. These planets are known as gas giants that contain several rings of ice, dust, and debris from outer space as well as many moons that surround each planet. The Jovian planets formed farther from the sun allowing their inner core to collect mass amounts of ice, rock, and metals which allowed the planet to grow rapidly in size. As these planets accumulated size their gravity eventually pulled in other space debris which created the structure of these giant planets. These planets are much too far for man to travel and explore up closely, however unmanned space craft have ventured out in exploration of these four giant planets.
The Jovian planets formation occurs outside of what astronomers and scientists call the ???frost line.??? Here hydrogen compounds form to ice which combines with rock and metal to form a cluster mixed with gasses. As these particles and elements cluster larger and larger they create what is known as a planetesimals. These planetesimals are the planets beginning to take shape into what they will become, a giant ball of gas, rock and ice which gain intense gravitational pull which collects even more particles and elements, gaining massive size. The leftover parts that occur during the break up of the solar nebula become moons and rings to these giant masses which explains why these planets have a large number of moons and many rings orbiting them. These planets are what we know today as the Jovian Planets.
As you would first set off to explore the Jovian planets you would come across Jupiter, the largest of the four Jovian planets. Jupiter??™s atmosphere is primarily made up of hydrogen and helium. Along Jupiter??™s outer atmosphere there are rings, but they are not clearly visible and has a total of 16 known moons, the larger four ( Io, Europa, Ganymede, and Callisto) can all be seen from earth Jupiter itself is slightly denser than water but gives off twice the amount of energy that the sun gives it due to the heat from the formation of the planet. Jupiter essentially has no surface as the clouds just get thicker and thicker down to the gasses which make up and surround the core. We know that Jupiter is essentially made of gas because of its differential rotation in which the equator spins faster than the north and south poles; this is only possible if the planet was made out of gas. Jupiter has a large notable spot on it known as ???The Great Red Spot??? which is made up of strong winds spinning in opposite directions forming a hurricane.
The next stop you move on to Saturn which is visible from Earth by only using binoculars at times. Saturn is best known for its large complex system of rings along its outer atmosphere. These rings are primarily composed of ice and rock and cover over 50,000 miles around Saturn and go 200 yards deep. Also along Saturn??™s atmosphere there are 33 known moons, the largest and most interesting one being Titan. Titan is slightly larger than Mercury and contains its own atmosphere which is denser than Earth??™s and made up of mostly nitrogen and small amounts of methane. This leads astronomers and scientists to believe that life could be found on Titan. Saturn is about three times smaller than Jupiter however is very similar to it with its composition and atmosphere.
As you move on farther out in our solar system you come across two ???ice giants??? the first being Uranus, which is named after the roman god of the sky. Uranus has an atmosphere composed of helium and methane which essentially gives it the bluish look and has a slight amount of rings. Uranus has a known 27 moons, the largest being Titania which was discovered by William Herschel in 1787. Uranus??™s are categorized in two groups, inner and outer moons. There are six larger moons that orbit far out from the planet as the inner ones tend to stay close with the rings more toward the planet itself. The way that Uranus??™s axis is tilted makes it different from any other planet in our solar system by having the majority of the planet being polar. Uranus would most likely have 42 years of darkness followed by 42 years of Light. This also would amount to Uranus??™s cold temperatures lows of around -200C and having a cool core unlike the other giants, making it the coldest of the planets.
The second of the ???ice giants??? is Neptune which is named after the roman god of the sea and was discovered by English and French astronomers. Neptune is similar to Uranus in size and has an atmosphere composed of helium and methane giving it the similar bluish look to that of Uranus. Neptune however has a fierce more atmosphere than Uranus??™s with much faster and stronger winds reaching up to 1000 miles per hour. Neptune??™s atmosphere is the coldest in the solar system; however its inner core is not nearly as cold as to that of Uranus??™s. Neptune has 13 known moons with the largest being Triton. Triton is similar to Saturn??™s Titan due to it having its own atmosphere; however its atmosphere is a lot thinner than that of Titans. In 1989 when Voyager 2 made its mission around Neptune it sent back pictures of a storm similar to that of the one on Jupiter. This storm came to be known as ???The Great Dark Spot.???
As astronomers and scientists continue to explore and gain knowledge about these four Jovian planets they have been aided by the success of space missions set up and sent out during ???flybys??? to gather information. Jupiter has had two main successful missions that of the Pioneer 10 in 1973 and Galileo providing good information from the pictures of Saturn and some of its moons. Saturn has been visited by the Pioneer 11 in 1979, Voyager 1 in 1980, and Voyager 2 in 1982. These missions also brought back pictures of Saturn??™s moon Titan. Uranus has been visited by Voyager 2 in 1986, the only mission that has visited the planet which captured visual of the planet and some of its nearby moons. Neptune, just like Uranus, has only had one visit, that coming from Voyager 2 in 1989 which captured images of the planet and its largest moon Triton.
Fortunately with today??™s technology all of these missions have brought astronomers and scientist closer to understanding the Jovian Planets and how they were formed. It is apparent that human travel is impossible for human landing on these planets due to none of them containing any surface are from being composed of gas, however it cannot be ruled out that human travel may someday be possible to these Jovian planets. The more information astronomers and scientists can gain about these planets only improves science theory??™s, technology, and history about these massive giant planets in our solar system.
American Association of Armature Scientists. The Jovian Planets. November 29th, 2009.
NASA/JPL University of Arizona. The Outer Planets. November 29th, 2009. | 0.87303 | 3.587978 |
The Hubble Space Telescope has discovered something truly unique – a pair of orbiting asteroids that are behaving like a comet.
A group of astronomers used the NASA/ESA telescope to observe the system known as 288P in September 2016, just before it made its closest approach to our Sun. To their surprise, 288P is not a single asteroid, as previously thought, but a pair of orbiting space rocks with very unusual characteristics.
The asteroids are orbiting at a distance of about 100km, much farther than any other known binary pair. But what’s also unusual is that they are exhibiting the features of a comet, including a bright coma and a long tail.
"We detected strong indications of the sublimation of water ice due to the increased solar heating – similar to how the tail of a comet is created," explained Jessica Agarwal of the Max Planck Institute for Solar System Research in Germany, the team leader and main author of the research paper published in Nature.
This strange behaviour makes 288P the first known binary asteroid that is also classified as a main-belt comet. There are other asteroids that orbit each other and those that are releasing vapour, but this is the first time astronomers have seen both characteristics at once.
Astronomers take every chance they can get to study asteroids up close because these space rocks hold vital clues as to how certain planets, like Earth, end up with water, while others get none. The composition of asteroids in the asteroid belt of our Solar System has remained virtually the same since the planets were formed, telling us a lot about the materials that went into making those planets and how they may have been formed.
But asteroids are very difficult to examine because, in cosmic terms, they’re pretty small and dim. Having one pass close by is a great opportunity for study and the fact that these two orbit each other allows the researchers to gather more information, including calculating their masses. The fact that the system is trailing water also proves that it hasn’t been in this binary situation for long.
"Surface ice cannot survive in the asteroid belt for the age of the Solar System but can be protected for billions of years by a refractory dust mantle, only a few metres thick,” said Agarwal.
288P has probably only existed as an orbiting pair for about 5000 years. It probably started as one asteroid that broke up because of how fast it was rotating and then the two large orbiting fragments were pushed further away from each other by the gases and dust they are ejecting.
It may just be a coincidence that such an unusual pairing presented for study, it could be quite a unique system. But it nonetheless will be an extremely important system for future studies.
Asteroids are a ripe field for further study, with some citizen projects hoping to be able to mine their riches and agencies like NASA funding further research into them. NASA’s Osiris-Rex mission is currently travelling through space to a nearby asteroid in the hopes of taking a sample from it and returning it to Earth. | 0.902157 | 3.982144 |
What are the seasons?
The seasons are a result of the 23.5 degree inclination of Earth's rotational axis in relation to the plane around which it orbits the Sun. This tilt means that throughout Earth's orbit around the sun (our calendar year) certain areas of the globe are tilted towards the Sun, while other areas are tilted away from it.
This creates a difference in the amount of solar radiation (or sunlight) that reaches different parts of the Earth and thus creates the global cycle of fluctuations that we know as the seasons.
This can be seen in the diagram where the northern hemisphere is leaning towards the Sun, while the southern hemisphere is leaning away - this is summer in the northern hemisphere and winter in the southern hemisphere.
This point represents the summer solstice in the northern hemisphere (20/21 June) when every point north of the arctic circle faces the sun for a full 24 hours and is the longest day for the northern hemisphere.
The exact opposite is true for the winter solstice (21/22 December) when every point north of the arctic circle is in total darkness for a full 24 hours and the northern hemisphere experiences its shortest day.
In between the two solstices we experience the equinoxes which mark the beginning of spring and autumn. At equinox, the plane of Earth's equator passes the exact centre of the sun. This means that the Earth is neither tilted towards or away from the Sun.
When this occurs on 20/21 March in the northern hemisphere it marks the point at which the northern hemisphere begins to tilt towards the Sun and consequently the beginning of the astronomical spring. Similarly on 22/23 September, the equinox occurs again this time marking the point at which the northern hemisphere begins to tilt away from the Sun and consequently the beginning of the astronomical autumn.
Another notable attribute of equinox is that the night and the day are of roughly equal length. The word 'equinox' is derived from the Latin aequus (meaning 'equal') and nox (meaning 'night').
All all information From the met office | 0.819144 | 3.724983 |
Plasma: the negatively charged electrons (yellow) are freely
streaming through the positively charged ions (blue).
The Plasma State
Plasma is known as the fourth state of matter (the first three states being solid, liquid and gas).
Matter in ordinary conditions on Earth has electrons that orbit around the atomic nucleus. The electrons are bound to the nucleus by the mutual, electrostatic attractive force. If the temperature is high enough, the electrons
(at least those of the outermost orbits) acquire enough kinetic energy
to escape the atom's potential (similar to a spacecraft that escapes the Earth's gravitational pull). In this situation the electrons are no longer trapped in orbits around the nucleus. This is the plasma state, where a gas becomes a collection of negatively charged electrons which have escaped the pull of the nucleus and ions which are positively charged because they have lost one or more electrons.
The majority of the matter in the universe is actually found in the plasma state. This is because stars are made up of material in the plasma state.
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It's back! After a winter sabbatical of sorts, hiding out of sight since the beginning of December, Venus — by far the most brilliant of the naked-eye planets — is back in view. After spending much of 2017 as a morning object, Venus is about to settle in as a prominent "evening star" for the next eight months, becoming a fixture of the western sky.
Our nearest planetary neighbor travels in a nearly perfect circle, orbiting the sun 13 times in eight Earth years, so that, as seen from Earth, it appears to make five circuits around the sky. Each of the eight years in this Venus cycle (known and important to ancient civilizations such as the Maya and Babylonians) has its own particular pattern, so 2018 repeats (within about two or three days of the same date) the phenomena of 2010.
Venus passed superior conjunction, appearing to go behind the sun as seen from Earth, back on Jan. 9. Until recently, it has been invisible, mired deep in the brilliant glare of the sun. Nonetheless, with each passing day, it has been moving on a slow course toward the east and pulling slowly away from the sun's general vicinity. [When, Where and How to See the Planets in the 2018 Night Sky]
On Feb. 5, Larry Gerstman, a member of the Amateur Observers' Society of New York, spotted Venus from Long Beach, New York. He wrote:
"I decided to watch the sunset and then hunt for Venus with my 12x40 handheld binoculars with Venus' being less than 5 degrees above the horizon. After watching the last bead of sunset I immediately aimed my binoculars, with a 5.5 degree field of view, up and slightly to the left and there was Venus, easy to see in the binoculars just seconds after sunset at 5:18 PM. I could not see Venus [with my] naked eye, but five minutes later it became even more obvious in the binoculars and I followed it to within a half a degree above the horizon at 5:44 PM."
During this upcoming week, Venus should become more evident even without optical aid, very low in the western twilight. On the evening of Saturday, Feb. 24, it sets 8 degrees south of due west about 50 minutes after sunset, and by March 1, this will have improved slightly to an hour after sunset, giving less-experienced skywatchers an excellent chance to get their first glimpse of it.
Keeping company with Mercury (and Uranus)
As a bonus for Venus watchers, for the first three weeks of March, the planet will be within 5 degrees of another bright world: the so-called "elusive planet," Mercury. On the evening of March 4, the two planets are separated by just 1.1 degrees. Mercury shines at magnitude -1.2, making it nearly as brilliant as the brightest star in the sky, Sirius. Yet, this is only one-twelfth as bright as dazzling Venus, which will glow at magnitude -3.9. (Smaller magnitudes denote brighter objects.) Mercury will then be situated to the upper right of Venus. Search for them low above the western horizon a half-hour after sunset. While both will be evident to the naked eye, binoculars will certainly enhance their visibility against the bright twilight.
Continuing to swing east of the sun during March, Venus will soon become plainly visible in the western evening sky even to the most casual of observers. The planet will appear as a brilliant, white "star" shining with a steady glow, and it will set 80 minutes after the sun by St. Patrick's Day.
On March 28, you can use Venus as a "pointer" to locate the planet Uranus. On that evening, Venus passes only 4 minutes of arc (0.066 degree) south of Uranus. Venus will be resplendent at magnitude -3.9 compared to sixth magnitude Uranus; this close approach will serve as a convenient opportunity for identifying Uranus in a small telescope or binoculars without the need to consult a sky map. Wait until about an hour after sundown to look for them, but be aware that by that time, the planetary duo will be very low — only about 6 degrees above the western horizon.
With each passing week, Venus rises higher each evening to adorn the western evening sky during the upcoming spring and summer. [Learn to View the Night Sky with 'See It with a Small Telescope']
A slow rise to prominence, then a rapid exit
By the beginning of June, Venus will stand nearly 30 degrees above the sunset horizon and set as late as 2 hours and 40 minutes after the sun. Interestingly, the planet's greatest altitude at sunset will also be occurring at this time, when the ecliptic (the apparent path of the sun, moon and planets throughout the year) becomes nearly vertical with respect to the western horizon for observers in northern latitudes.
On July 9, Venus passes 1 degree to the north of bluish Regulus, the brightest star in the constellation Leo, the lion. Six days later, on July 15, Venus and a slender (12-percent illuminated) crescent moon will make for an eye-catching sight in the western sky.
Venus reaches its greatest elongation — its greatest angular distance from the sun — 46 degrees to the east of the sun — on Aug. 17, though it will actually appear about 10 degrees lower compared with where it was during late spring. It is brightest at the very end of summer as it heads back down toward the sun, reaching its greatest illuminated extent (greatest brilliancy) for this apparition on the evening of Sept. 21, at an eye-popping magnitude of -4.8. By then, however, it will be only 10 degrees high at sunset and will be setting just over an hour after the sun does.
Venus then drops rapidly back toward the sun, vanishing from view within the first few days of October, and passes inferior conjunction on Oct. 26.
Through a telescope
Between now and October, repeated observation of Venus with a small telescope will show its complete range of phases and disk sizes. Currently, the planet will appear practically full (98-percent sunlit), as a tiny, dazzling gibbous disk. It will start becoming noticeably less gibbous by July 20. In mid-August, Venus reaches dichotomy (displaying a "half-moon" shape). Then, for the rest of the year, it will appear as a large crescent as it swings near to Earth. Indeed, skywatchers using telescopes will note that, while the Earth-Venus distance is lessening, the apparent size of Venus' disk will be growing, doubling from its present size by July 29. When it has doubled again in size on Sept. 21, its large crescent shape should be easily discernable even in steadily held seven-power binoculars. During the last week of September, as Venus rapidly sinks lower each night, it will appear as a relatively large and slender crescent. It will disappear from the evening sky within the first few days of October.
In November, Venus sprouts up into the predawn eastern sky, to reach an even greater maximum height in the morning skies of December. And Christmas 2018 will see Venus mimicking a modern-day Star of Bethlehem, appearing as a glorious "star in the east" before sunrise.
Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmer's Almanac and other publications, and he is also an on-camera meteorologist for Fios1 News in Rye Brook, New York. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com. | 0.873135 | 3.469452 |
The most distant supernova ever detected has been confirmed by an international team of astronomers led by the University of Southampton, UK.
The celestial event is a huge cosmic explosion that took place 10.5 billion years ago, or three-quarters the age of the Universe itself.
The exploding star, named DES16C2nm, was detected by the Dark Energy Survey (DES), an international collaboration to map several hundred million galaxies in order to find out more about dark energy – the mysterious force believed to be causing the accelerated expansion of the Universe.
DES16C2nm is classified as a superluminous supernova (SLSN), the brightest and rarest class of supernovae, first discovered ten years ago, thought to be caused by material falling onto the densest object in the Universe – a rapidly rotating neutron star newly formed in the explosion of a massive star.
Light from the event has taken 10.5 billion years to reach Earth, making it the oldest supernova ever discovered and studied. The Universe itself is thought to be 13.8 billion years old.
“It’s thrilling to be part of the survey that has discovered the oldest known supernova. DES16C2nm is extremely distant, extremely bright, and extremely rare – not the sort of thing you stumble across every day as an astronomer,” lead author of the study Dr Mathew Smith, of the University of Southampton, said in a press release.
“As well as being a very exciting discovery in its own right, the extreme distance of DES16C2nm gives us a unique insight into the nature of SLSN. “The ultraviolet light from SLSN informs us of the amount of metal produced in the explosion and the temperature of the explosion itself, both of which are key to understanding what causes and drives these cosmic explosions.”
DES16C2nm was first detected in August 2016, and its distance and extreme brightness confirmed in October that year using three of the world’s most powerful telescopes – the Very Large Telescope and the Magellan, in Chile, and the Keck Observatory, in Hawaii.
Over five years (2013-2018), the DES collaboration is using 525 nights of observation to carry out a deep, wide-area survey to record information from 300 million galaxies that are billions of light-years from Earth.
A new study published in The Astrophysical Journal. | 0.863326 | 3.831925 |
After fulfilling the main purpose of our trip—to build relationships with universities in Santiago, the capital city of Chile—we headed north to the Atacama Desert, the driest non-polar desert in the world. The small town of San Pedro de Atacama serves as a starting point for adventure travelers looking to experience all this beautiful landscape has to offer. It is also the closest town to the Atacama Large Millimeter/submillimeter Array (ALMA)—a multi-national space observatory that seeks to understand our cosmic origins.
My colleagues and I boarded a public tour bus to the ALMA operations center. The on-board safety video once again put physiology front and center as it discussed a reality that locals here deal with every day: the effects of altitude on the human body.
San Pedro, and most of the Atacama Desert, is located at around 8,000 feet above sea level. The ALMA control center sits above the town at around 10,000 feet. Most impressively, the radio telescopes that make the observations are located on a plateau at 16,000 feet high. For comparison, Mount Whitney, the highest mountain in the continental U.S., is 14,505 feet above sea level.
Spending time at high altitudes can have an impact on the cardiovascular and respiratory systems. The increased ultraviolet exposure is significant, and ALMA visitors (even just to the control center) are cautioned against spending prolonged periods in the sun and are advised to wear sunscreen and protective clothing. The extremely arid Atacama Desert also challenges the body’s ability to maintain proper hydration, so water is frequently provided to visitors.
The safety video explained that at 10,000 feet, the control center is considered “moderate” altitude that most people can tolerate well. However, we learned that any visitors to the actual telescopes—which the general public is not allowed to visit—must go through a medical screening that includes taking vital signs (heart rate, blood pressure, blood oxygenation) and assessing signs and symptoms of altitude sickness (dizziness, headaches, nausea). Telescope visitors must also spend a minimum of one night getting used to the high elevation (acclimatizing) in Calama (the town where the nearest airport is) or San Pedro to prepare the body for this challenging environment. They are also given supplemental oxygen to help prevent any altitude-related issues and to allow them to perform physical tasks that might otherwise be too difficult.
All of these physiological challenges of visiting and working at ALMA ultimately are what makes it perfectly suited for its main purpose, observing our skies. Dryness, high altitude, no clouds and minimal light or radio pollution from nearby sparsely populated towns (it’s not easy to live in the Atacama!) are perfect conditions for the ALMA scientists to try to solve important astronomical mysteries.
This post is part two of a three-part series by physiologist Anne Crecelius, PhD, chronicling her summer of research and travels through South America. (Read part one here.) Crecelius is assistant professor at the University of Dayton. | 0.817583 | 3.145304 |
How a California Teen Is Helping Scientists Look for Aliens
David Lipman was a junior in high school when he caught wind of strange light patterns coming from Tabby’s Star, which later became known as “the most mysterious star in the universe.”
Sometimes the light from the distant star was bright, sometimes it was dim — almost like there was something blocking it. In 2015, astronomer Jason Wright, Ph.D., from Penn State’s Department of Astronomy, even floated a theory that the strange patterns might be caused by a “alien megastructure” used to capture the star’s energy.
“When I first heard about Tabby’s Star and the potential megastructure around it, it was pretty fascinating,” Lipman tells Inverse. “It sounded like something out of a sci-fi movie.”
So, during a summer internship at the Berkeley SETI Research Center, he built an algorithm that could comb through the light that data telescopes captured from Tabby’s Star, and flag images that might be signals of artificial activity. Specifically, his algorithm searches for laser activity, which could be an indicator that there was some type of extraterrestrial activity happening around the star.
"Sadly, no alien signals."
“I was already sort of involved with SETI building my algorithm, so I thought maybe applying it to Tabby’s Star would be a very useful application, and it was a hot topic at the time,” Lipman, now a Freshman at Princeton University, tells Inverse. “After going through the spectra, we flagged a few candidates, all of which appeared to be atmospheric airglow — so sadly, no alien signals.”
For his work, Lipman was listed as the first author on a paper published in Publications of the Astron Society of the Pacific, an academic journal — a prestigious accomplishment for a high school intern. The paper was published in December.
The weird goings-on around KIC 8462852, an object about 1,500 light years away from Earth, had amateur astronomers and space scientists speculating as early as 2011.
Some floated the idea that the star was surrounded by comets, dust, or aliens trying to harvest its energy.
Lipman has been fascinated by the sky for as long has he can remember. Lipman’s father is also an amateur astronomer, and the two would sometimes drive up into the hills around Palo Alto, California in the evenings to look through their telescope. During those evening visits, Lipman hadn’t actually seen the weird light patterns coming from Tabby’s Star, but other astronomers, both amateur and professional, had.
During his research that summer at Berkeley, he ran his analysis several times, double checking the images his algorithm had flagged, Lipman eventually pulled out five of the strongest candidate images that could have represented basically, alien lasers.
"“I just think that probabilistically there has to be something else out there."
All the light images ended up all being natural phenomena after all, and in January 2018, scientists announced they were fairly certain that it was dust causing all the strange dimming — not an megastructure built by an advanced alien race (cool as that scenario might be.)
Now, he adds, it will hopefully still be used at SETI, as the institute refines the algorithm and continues to scan the stars for signs of extraterrestrial life.
On January 4, SETI released the data used in Lipman’s paper, hoping that it might spark someone else to come up with a way to mine it for information.
“His thorough analysis of this one object will form the groundwork for the analysis of the hundreds of other targets that we’ve observed as part of the Breakthrough Listen program at APF,” writes Steve Croft, a scientist at Berkeley-SETI.
His Plans For the Future
Lipman is now trying to get involved in new research; he’s a part of Princeton’s Sports Analytics Club, and he’s playing intramural soccer and basketball. “I’m very big into sports, I’m a big Golden State Warriors fan,” he adds. “I’m worried that Kevin Durant is leaving this summer, though. That’s on my mind right now.”
Looking back at his project, Lipman admits that a small part of him was disappointed when his results came back negative for alien laser activity. The scientist in Lipman knew that finding extraterrestrial activity was a long shot, but still, he had held out a small amount of hope. He’s looking to add some machine learning capability and to help decrease the rate of false positives. The next time his algorithm flags something, hopefully it will be the real thing:
“As for my hopes to detect signals one day, I am fairly confident that extraterrestrials are out there,” Lipman says. “I just think that probabilistically there has to be something else out there, and I think we have the capabilities of finding it.”
The quest for extraterrestrial life is ongoing, but KD’s days at Oracle Arena might be numbered. | 0.808569 | 3.181534 |
JUICE (Jupiter Icy Moons Explorer)
JUICE is the first large-class mission in ESA's Cosmic Vision 2015-2025 program. Planned for launch in 2022 and arrival at Jupiter in 2029, it will spend at least three years making detailed observations of the giant gaseous planet Jupiter and three of its largest moons, Ganymede, Callisto and Europa. 1) 2)
Science objectives: The focus of JUICE is to characterize the conditions that may have led to the emergence of habitable environments among the Jovian icy satellites, with special emphasis on the three ocean-bearing worlds, Ganymede, Europa, and Callisto. Ganymede is identified for detailed investigation since it provides a natural laboratory for analysis of the nature, evolution and potential habitability of icy worlds in general, but also because of the role it plays within the system of Galilean satellites, and its unique magnetic and plasma interactions with the surrounding Jovian environment. JUICE will determine the characteristics of liquid-water oceans below the icy surfaces of the moons. This will lead to an understanding of the possible sources and cycling of chemical and thermal energy, allow an investigation of the evolution and chemical composition of the surfaces and of the subsurface oceans, and enable an evaluation of the processes that have affected the satellites and their environments through time. The study of the diversity of the satellite system will be enhanced with additional information gathered remotely on Io and the smaller moons. The mission will also characterize the diversity of processes in the Jupiter system that may be required in order to provide a stable environment at the icy moons on geologic time scales, including gravitational coupling between the Galilean satellites and their long term tidal influence on the system as a whole. JUICE will carry out extensive new studies of Jupiter’s atmosphere, magnetosphere and their interaction with the satellites to further enhance our understanding of the evolution and dynamics of the Jovian system. 3) 4) 5)
In 2012, ESA selected the JUICE mission over two other candidates: NGO (New Gravitational wave Observatory), to hunt for gravitational waves, and ATHENA (Advanced Telescope for High-Energy Astrophysics). 6)
Jupiter’s diverse Galilean moons – volcanic Io, icy Europa and rock-ice Ganymede and Callisto – make the Jovian system a miniature Solar System in its own right. With Europa, Ganymede and Callisto all thought to host internal oceans, the mission will study the moons as potential habitats for life, addressing two key themes of Cosmic Vision: what are the conditions for planet formation and the emergence of life, and how does the Solar System work? JUICE will continuously observe Jupiter’s atmosphere and magnetosphere, and the interaction of the Galilean moons with the gas giant planet.
JUICE will visit Callisto, the most heavily cratered object in the Solar System, and will twice fly by Europa. JUICE will make the first measurements of the thickness of Europa’s icy crust and will identify candidate sites for future in situ exploration.
The spacecraft will finally enter orbit around Ganymede in 2032, where it will study the icy surface and internal structure of the moon, including its subsurface ocean. Ganymede is the only moon in the Solar System known to generate its own magnetic field, and JUICE will observe the unique magnetic and plasma interactions with Jupiter’s magnetosphere in detail.
Today’s announcement is the culmination of a process started in 2004 when ESA consulted the wider scientific community to set Europe’s goals for space exploration in the coming decade.
The planned journey of JUICE
• May 12, 2020: Jupiter’s moon Europa is a fascinating world. On its surface, the moon appears to be scratched and scored with reddish-brown scars, which rake across the surface in a crisscrossing pattern. These ‘scars’ are etched into a layer of water ice, which is thought to be at least several kilometers thick and covering a vast – and potentially habitable – subsurface ocean. 7)
Figure 1: The scars seen in this view of the moon (Europa) from the archives of NASA’s Galileo mission – based on images taken by the spacecraft in the 1990s – are a series of long cracks in its icy surface, thought to arise as Jupiter tugs at Europa and breaks the ice apart. The colors visible across the moon’s surface are representative of the surface composition and size of the ice grains: reddish-brown areas, for instance, contain high proportions of non-ice substances, while blue-white areas are relatively pure (image credit: NASA/JPL-Caltech/SETI Institute)
Scientists are keen to explore beneath Europa’s thick blanket of ice, and they can do so indirectly by hunting for evidence of activity emanating from below. A new study, led by ESA research fellow Hans Huybrighs and published in Geophysical Research Letters, did exactly this. Building on previous magnetic field studies by Galileo, the simulation-based study aimed to understand why fewer than expected fast-moving protons – which are subatomic particles with a positive charge – were recorded in the vicinity of the moon during one of the flybys of the moon performed by the Galileo probe in the year 2000. 8)
Researchers initially put this down to Europa obscuring the detector and preventing these usually abundant charged particles from being measured. However, Hans and colleagues found that some of this proton depletion was due to a plume of water vapor shooting out into space. This plume disrupted Europa’s thin, tenuous atmosphere and perturbed the magnetic fields in the region, altering the behavior and prevalence of nearby energetic protons.
Scientists have suspected the existence of plumes at Europa already since the times of the Galileo mission, however indirect evidence for their existence has only been found in the last decade. Excitingly, if such plumes are indeed present, breaking through the moon’s icy shell, they would offer a possible way to access and characterize the contents of its subsurface ocean, which would otherwise be hugely challenging to explore.
These prospects are of great interests to ESA’s upcoming Juice mission, planned for launch in 2022 to investigate Jupiter and its icy moons. Juice will carry the equipment needed to directly sample particles within the moon’s water vapor plumes and also to detect them remotely, aiming to reveal the secrets of its vast, mysterious ocean.
Scheduled to arrive in the Jupiter system in 2029, the mission will study the potential habitability and the underground oceans of three of the giant planet’s moons – Ganymede, Callisto and Europa. As this new study demonstrates, tracing the energetic charged and neutral particles in Europa’s vicinity offers huge promise in efforts to probe the moon’s atmosphere and wider cosmic environment – and this is precisely what Juice plans to do.
Olivier Witasse, ESA’s Juice project scientist, is also a co-author on the study, along with a number of ESA research fellows, including former Science Directorate fellows Lina Hadid and Olivier Lomax, Mika Holmberg, a research fellow in the Technology, Engineering and Quality Directorate.
The new study is based on data collected by Galileo during a flyby of Europa in 2000. The image comprises data acquired by the Galileo Solid-State Imaging (SSI) experiment on the spacecraft's first and fourteenth orbits through the Jupiter system, in 1995 and 1998, respectively, and was recently re-processed in 2014. The image scale is 1.6 km/pixel, and the north pole of the moon is to the right.
Main requirements of the spacecraft design (Ref. 2)
Radiation mitigation: The radiation environment is dominated by the bound electrons in the Jupiter magnetosphere. Their fluence is dominating over the solar proton contribution by several orders of magnitude. The electron spectrum also has a high energy component, which extends to higher energies than exposed to in geo-stationary. At low energies of the electron spectrum, the expected total mission fluence is actually lower than a typical exposure for 10–15 year geostationary mission. Such electrons are predominantly absorbed at the surface, and therefore heritage is available of materials withstanding such doses. For the surfaces of the spacecraft, standard mitigation strategies for geostationary applications will be used, such as coating with conductive layers.
For the considerations of shielding the benefit of units shielding each other has been considered and evaluated with detailed radiation transport simulations. The required radiation tolerance was set at 50 krad at the outside of each unit.
Power: The other main mission drivers are related to the large distance from the Sun, and the requirements that the mission generate power by solar cells. The worst case solar intensity is 46 W/m2. Together with detailed analysis of all critical mission phases, the requirements on the power generation were obtained resulting in a solar array area of close to100 m2. This solar array size can only be obtained when eclipses in the final phases of the mission around Ganymede were excluded. Furthermore, when in Ganymede’s orbit, the normal incidence of the sunlight onto the solar arrays will be maintained through one-axis solar array drive mechanisms combined with a rotation of the spacecraft around the nadir axis. It is however foreseen that this yaw steering could be paused for a limited period of time, e.g. in support of high resolution imaging.
Thermal: The entire spacecraft will be optimized for operations in the cold environment at Jupiter and will be covered by MLI (Multi-Layer Insulation). The albedo heating from the Jupiter moons is negligible. During the Venus gravity assist, the high gain antenna will be used as sun-shield, so as to avoid forcing the spacecraft design to also accommodate for this hot case in full. Passive thermal control will be achieved with radiators; only electrical heating will be provided.
Propulsion: The orbit insertions at Jupiter and Ganymede, the reductions of the altitude of the orbit around Ganymede, and the large number of gravity assists and flyby maneuvers (>25) lead to a high Δv requirement, and consequently to a high wet/dry mass ratio (about 2.6:1). The spacecraft architecture will therefore need to include large volume of propellant tanks.
Communications: The large distance to Earth results in a signal round trip time of up to 1h 46 minutes requiring careful pre-planning and autonomous execution of operations by the spacecraft. Additionally, a high gain antenna is required for data downlink. The data downlink system is sized for an average daily data volume of at least 1.4 Gbit, assuming maximum telecommunication pass of 8 h/day.
AOCS (Attitude and Orbit Control Subsystem): The AOCS is driven by the need for maintaining nadir pointing of the spacecraft during flybys for observations with the scientific instruments. In addition the spacecraft has a large angular inertia mainly due to the large area of the solar panels. The remaining deployable appendices (sub-surface radar antenna and magnetometer boom) add constraints on the pointing stability.
The attitude will be provided through the use of momentum wheels, supported by a propulsion system for off-loading. Off-loading will be scheduled outside science observation windows.
Avionics: The avionics subsystem provides for sufficient command storage to enable the required autonomy of operations. A storage for several days of science data will be included to provide sufficient flexibility such that the spacecraft can be pointed according to the needs of the science instrumentation, and buffer the data for downlink later.
Mechanisms: Mechanisms include the solar panels, the solar array drive mechanisms, the sub-surface radar boom, the magnetometer boom and the RPWI antennae. The appendices will be accommodated such that their deployment can be performed independently, and that they do not infringe the field-of-view of the optical and particle instruments, including stray light avoidance cones.
Launcher: The baseline launcher is Ariane 5 ECA from Kourou.
The mission will include a limited number of flybys of Callisto, Ganymede and Europa, and will then finally go into orbit around Ganymede and will be disposed on Ganymede’s surface. The highest Planetary Protection Category targets are Europa and Ganymede.
Europa is a Planetary Protection Category III target (“chemical evolution and/or origin of life interest or for which scientific opinion provides a significant chance of contamination which could jeopardize a future biological experiment”). The mission therefore either needs to demonstrate that the likelihood of collision with Europa is <10–4, or undergo active bioburden reduction to meet the requirement that the probability of inadvertent contamination of the Europa ocean is <10–4. The first option was taken as the baseline for proceeding. The risk of collision with Europa is limited to the period up to the Europa flybys. After this period the spacecraft has a perijove higher than Europa’s orbit and a lower apocenter, such that collisions are sufficiently unlikely within the timeframe of concern (several 100 years). A dedicated study was performed analyzing the likelihoods of impact, in case of spacecraft failures after each maneuver. Depending on the time and location of the maneuver, this ranges from below 5% to 40% (only for the case of the Europa flyby) for the duration during which it was estimated that the spacecraft would be sterilized by radiation (200 years). Consequently an allocation for the reliability of the spacecraft against total loss was allocated including a margin of at least a factor of two. A preliminary bottom-up assessment of spacecraft’s subsystem reliabilities taking into considerations the lifetime and the exposure to the environment indicated that the overall allocated spacecraft reliability can be met. As for short term failures, i.e. loss of spacecraft control during approach for the Europa flyby, a re-targeting strategy will be performed: the spacecraft trajectory will be implemented such that Europa always remains outside the 3σ uncertainty, and small correction maneuvers be performed during the approach (step-in procedure).
Ganymede is a Planetary Protection Category II target (“significant interest relative to the process of chemical evolution and the origin of life, but only a remote chance that contamination by spacecraft could compromise future investigations”). For Ganymede the bio-burden brought to it shall be controlled and limited such that the likelihood of one active organism reaching the Ganymede subsurface ocean shall be <10–4. For the calculation of the likelihood of bringing a surviving organism to the Ganymede subsurface ocean, the recommendations in [D-3] are followed, and it is largely reduced by the assumption of the low probability of the burial mechanism (10–4) and by the low likelihood of landing in an active region (2 x 10–3). Further factors, such as the estimated cruise survival fraction (10–1), sterilization through radiation (10–1), and probability of survival during transport on the surface (10–2), bring the total likelihood to 2 x 10–11. Assuming a typical bioburden at launch around 106 based on the assumption of equipment exposure to a standard clean room environment, the requirement of 10–4 would be met by a factor of 5.
Consequently, apportionment and monitoring of the bioburden will be required during the mission implementation, by break down and allocation of allowed budgets to each hardware supplier, including payload. Monitoring will be achieved through essays taken at regular intervals.
Furthermore, collateral probability of contamination of alternative critical bodies, such as Mars by any part of the flight segment, including any part of the launch vehicle within 50 years shall be smaller than 10–2. Some launch opportunities consider Mars gravity assists, and it will be demonstrated for these that neither the spacecraft nor any part of the launcher will impact Mars within this timescale. Early assessment confirmed this assumption.
Ground segment and operations
The JUICE mission will be planned and operated by ESA. The ground segment will consist of the Mission Operation Center (MOC) and the Science Operation Center (SOC). The JUICE Science Ground Segment (SGS) is made of the SOC and of the PI instrument teams and will be implemented according to the guidelines described in the Science Management Plan.
The S/C will be operated by an off-line monitoring and control approach. A pre-scheduled timeline (planned sequences of operations, defining S/C or instrument activities) will be uploaded by the MOC at regular intervals and stored on-board. During the nominal science operations, the ground station contact will happen daily, and will be used to upload new S/C and instrument commands, as well as to retrieve the scientific data together with the housekeeping data (for the S/C and instruments). No routine science operations are foreseen in the mission baseline scenario during the cruise phase.
The JUICE SGS is responsible for performing the science operations related to the implementation of the high-level science activities designed by the SWT (Science Working Plan).
Science operations encompass two main groups of activities, called hereafter the Uplink or Downlink side of Science Operations.
The Uplink activities are related to the generation of an instrument operations timeline to be uplinked to the Spacecraft. The SOC and the PI teams will consolidate and validate the science operations requests from individual instrument teams into an instrument operation timeline delivered to the MOC before being uplinked onboard the spacecraft.
In case of non-routine operations (reference measurements during the Earth and Venus flybys during the cruise phase) the SOC will assist the instrument teams in generating Pointing Timeline Request (PTR) files and delivering the instrument commanding directly to the MOC.
Figure 2: Top-level overview of the JUICE operations planning activities. Schematic timeline, workflow and interfaces of the different science planning levels, from the top level science activity plan to the uplink of instrument commands. The blue, semi-transparent box indicates all science planning related to SGS activities (PI teams and SOC).
The nominal science operation planning will be divided in three steps. The first step is the Long Term Planning (LTP) covering 6 months of mission, addressing in more details the top-level planning with a refined knowledge of the S/C resources and constraints. The next step is the MTP (Medium Term Planning) performed on a monthly basis. The main goal of the MTP phase is the finalization of the integration of the observations pointings as well as the validation of the associated instrument modes against the latest knowledge of S/C available resources, constraints and flight rules. The output of this phase is a frozen PTR (Pointing Timeline Request) file. The last step is the STP (Short Term Planning), performed on a monthly basis, whose main goal is the finalization of the instrument commanding.
Downlink activities encompass all data handling and archiving tasks, from retrieval of instrument telemetry and auxiliary data from the DDS (Data Disposition System) under MOC responsibility and all subsequent processing to higher data levels, as well as quick look checks of the performed observations. Data archiving is performed at different levels of the data processing chain.
The SOC will process the telemetry data and distribute the resulting raw data to the instrument teams and to the archive. The raw data processing (telemetry into uncalibrated science data) is centralized at the SOC. Raw data product will be made available to the instrument teams about 4 hours after the telemetry packets are available on the DDS. Immediately after the data becomes available in the DDS, SOC retrieves, verifies and processes all spacecraft and instrument related telemetry (house-keeping and science data) obtained from the DDS. Telemetry integrity (science packets) will be checked by SOC. In addition, SOC retrieves any auxiliary data needed for science data processing, in particular the data from Flight dynamics: reconstructed spacecraft trajectory and attitude.
The instrument teams have the responsibility to generate their calibrated data and distribute them to the archive and follow the general requirements for science data archive format (PDS4). All calibration products (software, procedures and calibration files) must be delivered by the PI teams to the SOC and archived as PDS4 products. The SOC works closely with the instrument teams to facilitate the generation of these products in PDS compliant formats, thereby minimizing the additional effort required for this activity.
Airbus is developing and building JUICE (JUpiter ICy moons Explorer) spacecraft for the European Space Agency, which will study Jupiter and its icy moons. In July 2015, the company was selected by ESA (European Space Agency) as prime contractor for the design, development, production, and testing of a new spacecraft named ‘JUICE’. As prime contractor, Airbus will employ 150 people and lead a consortium of more than 60 companies during the course of the project. 9)
In May 2022, JUICE will begin a 7.6 year cruise to Jupiter to spend three and a half years in the Jovian system. Its main mission will be to explore the huge planet’s three largest icy moons in the hope of determining whether life is possible on these dwarf planets. What if extra-terrestrial life does exist? For centuries, this question – which both fascinates and frightens mankind – has remained unanswered. But by the year 2030, answers to the questions: how do planets form? how does life emerge? how does the solar system work? may well have been found.
It will take JUICE seven and a half years to travel the almost 600 million kilometers to the gas giant. Once the spacecraft enters Jupiter’s gravitational field, the first two and a half years of its three-and-a-half-year mission will be spent making about 30 observation overflights of the three moons, observing examining gravity and magnetic interactions, amongst other things. The last year will be spent in orbit around Ganymede to observe this moon in much greater detail.
The challenges are enormous. JUICE must deal with very low and very high temperatures as it will circle Earth, Mars and Venus for gravity assist maneuvers to build up enough speed to reach Jupiter’s orbit. Jupiter’s cold environment also makes it hard to collect energy. "The goal is to investigate whether there are liquid oceans under these icy crusts which might harbor organic components or even life" says Vincent Poinsignon, JUICE project manager.
Figure 3: In July 2019, Airbus has completed the first step in the construction of the inner structure of ESA's JUICE satellite. The inner structure or SSTS (Structure, Shielding and Thermal control Subsystem), built at the Madrid-Barajas site of Airbus, is carbon fibre and is composed of the central load carrying cylinder, shear panels, two equipment protecting Vaults, the TCS (Thermal Control System) which includes a heat pipes network and multilayer insulation, and secondary elements such as 13 additive manufacturing brackets. This key element weighs 580 kg and will support the satellite’s weight of 5,300 kg (of which about 3,000kg is chemical propellant). Jupiter’s distance from the Sun will make it challenging to generate energy. For this reason the spacecraft is equipped with solar arrays with a total surface of 85 m2, the largest ever built for any interplanetary spacecraft (image credit: Airbus DS) 10)
The JUICE spacecraft is a 3-axis stabilized platform that will accommodate 10 instruments. The power subsystem consists in a solar array with two wings of five panels each for a total surface of 97 m2 providing ~820 W at Jupiter (end of life conditions), and a Li-ion battery. 11)
A 2.5 m diameter High Gain Antenna, using X- and Ka- bands, will ensure telemetry/telecommand links for routine operations, safe-mode, and radio science related investigations. At least, 1.4 Gbits of scientific data will be downloaded every day.
Figure 4: Artist's impression of JUICE (image credit: Spacecraft: ESA/ATG medialab; Jupiter: NASA/ESA/J. Nichols; Ganymede: NASA/JPL; Io: NASA/JPL/University of Arizona; Callisto and Europa: NASA/JPL/DLR) 12)
The propulsion system is a bi-propellant main engine plus a set of 10 thrusters. The two main mission maneuvers are the Jupiter and Ganymede orbit insertions. Two vaults will provide to some electronics a shielding against the harsh Jupiter radiation environment, as well as adequate thermal conditions.
The spacecraft includes deployable appendices such as a 10.6 m boom supporting J-MAG (JUICE Magnetometer) and RPWI (Radio and Plasma Wave Instrument) sensors, a 16 m radar antenna, and a steerable medium gain antenna used for communication and radio-science investigations.
PVA (Photovoltaic Assembly) for JUICE: The PVA design, development and verification (DD&V) foresee a thorough development, design verification and qualification activities along with associated test samples. 13)
The development of the JUICE PVA is progressing. A number of issues have been identified and recovery / alternative plans put in place to identify solutions. A robust baseline design is under final consolidation and will be available by the third quarter of 2018 allowing the release of all qualification campaigns.
• April 23, 2020: ESA's upcoming JUICE spacecraft arrives at the satellite integration center of the project’s prime contractor Airbus in Friedrichshafen, Germany, in April 2020, to undergo final integration. 14)
- Expected to set out for its seven-year cruise to Jupiter in 2022, JUICE will carry 10 scientific instruments for detailed inspection of the largest planet of the Solar System and its moons, including Ganymede, Europa and Callisto, which are believed to host oceans of water. During its planned three-year mission, the spacecraft is expected to answer the question whether the oceans of the icy moons host any forms of life.
- A result of cooperation of more than 80 companies from all over Europe, JUICE was built and assembled in Airbus’ facilities in Madrid. The spacecraft was then fitted with a propulsion system at ArianeGroup’s site in Lampoldshausen, Germany, to form the spacecraft body, and transported to Friedrichshafen inside a special secured container on board of an oversized transporter.
Figure 5: The 5.2-ton spacecraft will be fitted with remaining components such as power electronics, an on-board computer, communication systems and navigation sensors, before continuing its journey to ESTEC (ESA Space Technology and Research Center) in the Netherlands for testing (image credit: Airbus)
• February 25, 2020: The first instrument to fly on ESA’s JUICE ( Jupiter Icy Moon Explorer) has been delivered for integration onto the spacecraft this month. The UVS (Ultraviolet Spectrograph), pictured in this photo while being prepared before shipping, was designed and built by Southwest Research Institute in San Antonio, TX, US. 15)
- Juice is the first large-class mission in ESA's Cosmic Vision 2015–2025 program. With launch scheduled in 2022, it will arrive at Jupiter in 2029 to perform detailed observations of the giant planet and three of its largest moons: Ganymede, Callisto and Europa.
- The mission, which is being developed by Airbus Defence and Space as prime contractor, comprises 10 state-of-the-art instruments to investigate the Jupiter system plus one experiment that uses the spacecraft telecommunication system jointly with ground-based radio observations (Very Long Baseline Interferometry). The 10 instruments will perform in situ measurements of Jupiter's atmosphere and plasma environment as well as remote observations of the surface and interior of the three icy moons.
- As part of Juice’s comprehensive suite of instruments, UVS will get close-up views of Europa, Ganymede and Callisto, which are all thought to host underground oceans beneath their icy surfaces. By recording the ultraviolet light emitted, transmitted and reflected by the moons, the instrument will reveal the composition of their surfaces and atmospheres, and enable investigations of how these icy bodies interact with Jupiter and its giant magnetosphere.
- UVS will cover the wavelength range between 55 and 210 nm with spectral resolution better than 0.6 nm. It will achieve a spatial resolution of 0.5 km at Ganymede and up to 250 km at Jupiter.
- The instrument is now at the premises of Airbus Defence & Space GmbH in Friedrichshafen, Germany, where it will be integrated on the spacecraft. The other nine instruments are being integrated and tested by the respective instrument teams and will be delivered for integration over the course of 2020.
- The UVS instrument represents NASA’s contribution to the mission. The instrument team, led by scientists at Southwest Research Institute, includes additional scientists from University of Colorado Boulder and SETI institute in the US, as well as University of Leicester and Imperial College London (UK), University of Liège (Belgium) and Laboratoire Atmosphères, Milieux, Observations Spatiales (France). NASA’s New Frontiers Program at Marshall Space Flight Center (MSFC) oversees the UVS contribution to ESA.
Figure 6: Photo of the UVS instrument (image credit: SwRI)
• November 19, 2019: For the solar array of ESA's JUICE mission to Jupiter, Airborne delivered the last 4 out of 10 XL substrate panels to Airbus Defence and Space Netherlands. As timing is critical for the interplanetary spacecraft to be put on the right trajectory enabling gravity-assist flybys after its launch in 2022, the delivery of the XL panels is crucial in order for the solar array to be readied according to schedule. Given extreme distance from the Sun, the JUICE spacecraft asked for an exceptionally large solar array in order to generate sufficient power. 16)
- As market leader in the manufacturing of solar array substrate panels in Europe, Airborne was selected by Airbus Defence and Space Netherlands to develop and manufacture the XL substrate panels for JUICE's solar array. With a total surface area of 85 m2 the satellite will be equipped with the largest solar array ever flown on an interplanetary mission.
- Airborne's specific expertise was required to produce the substrate panels for the solar panels with a surface area of almost 9 m2 per panel - the largest units manufactured by Airborne to date. To enable production Airborne modified the manufacturing equipment, including extending the maximum inside diameter of the autoclave from 2.6 to 2.9 meters. Combined with a length of 13 meters, the extended autoclave enables Airborne to produce more XL size panels for aerospace customers.
- JUICE's solar array is built with the new ARA (Advanced Rigid Array) Mk4 technology, which has been developed and qualified by Airbus Defence and Space Netherlands in close cooperation with Airborne. Airbus' ARA Mk4 technology allows for 20 percent cost reduction and increases the robustness of the solar array by expanding the temperature range and adding stiffness. As the satellite will be exposed to extreme conditions during the full length of the mission, the panels need to withstand temperatures as low as -240º Celsius, as well as space radiation.
- The extreme temperatures to which the satellite will be exposed near Jupiter made additional qualification necessary on the panel design and its interfaces. Airborne manufactured 160 qualification test samples and two full-size panels which were delivered in January 2017. After an intensive testing campaign by Airbus Defence and Space Netherland, Airborne manufactured a total of 10 substrate panels. The last 4 panels were completed in October 2019 - on time for the next step in the manufacturing process of JUICE's solar array.
- Arno van Mourik, CEO of Airborne says: "JUICE is a great example of what we can do in terms of state-of-the-art substrate panel technology for solar arrays of extremely demanding space missions. Building on this position we are determined to move forward in the domain of affordable space panels for new space. Combining our knowledge on high end substrates with our capabilities in the domain of industrialization of composites will allow us to provide the new space market with high performance, yet radically affordable solutions in high volumes."
- After its launch in 2022 and a journey that will last seven and a half years, the JUICE (JUpiter ICy moons Explorer) satellite of the European Space Agency will spend three and a half years making detailed observations of the giant gaseous planet Jupiter and three of its largest moons. ESA selected Airbus as prime contractor for the design, development, production, and testing of spacecraft JUICE.
• November 4, 2019: In a decade’s time, an exciting new visitor will enter the Jovian system: ESA’s JUICE (Jupiter Icy Moons Explorer) mission. As its name suggests, the mission will explore Jupiter and three of its largest moons – Ganymede, Callisto and Europa – to investigate the giant planet’s cosmic family and gas giant planets in general. 17)
- JUICE is planned for launch in 2022, and its instruments are currently being perfected and calibrated so they are ready to start work once in space. This image shows one of the many elements involved in this calibration process: a miniature gold-plated metallic model of JUICE used to test the spacecraft’s antennas.
Figure 7: This model of JUICE was built by the Technical University of Dresden, Germany, and the tests were performed by the Austrian Academy of Sciences’ Space Research Institute in Graz, Austria, as part of a project financed by the Austrian Research Promotion Agency (FFG). The lead scientist for the calibration effort was Georg Fischer of the Space Research Institute, also using computer simulations performed by Mykhaylo Panchenko (image credit: G. Fischer/IWF Graz)
- JUICE will carry multiple antennas to detect radio waves in the Jupiter system. These antennas will measure the characteristics of the incoming waves, including the direction in which they are moving and their degree of polarization, and then use this information to trace the waves back to their sources. In order to do this, the antennas must work well regardless of their orientation to any incoming waves – and so scientists must figure out and correct for the antennas’ so-called ‘directional dependence’.
- This shiny model was used to perform a set of tests on JUICE’s Radio and Plasma Wave Instrument (RPWI) last year. It was submerged in a tank filled with water; an even electric field was then applied to the tank, and the model was moved and rotated with respect to this field. The results revealed how the antennas will receive radio waves that stream in from different directions and orientations with respect to the spacecraft, and will enable the instrument to be calibrated to be as effective as possible in its measurements of Jupiter and its moons.
- Similar tests, which are technically referred to as rheometry, were conducted in the past for spacecraft including the NASA/ESA/ASI Cassini-Huygens mission to Saturn (which operated at Saturn between 2004 and 2017), NASA’s Juno spacecraft (currently in orbit around Jupiter), and ESA’s Solar Orbiter (scheduled for launch in early 2020 to investigate the Sun up close).
- The test performed for Juice posed a few additional hurdles – the model’s antennas were especially small and needed to be fixed accurately onto the model’s boom, which required scientists to create a special device to adjust not only the antennas, but also the boom itself.
- The model was produced at a 1:40 scale, making each antenna 62.5 mm long from tip to tip; scaled up, the antennas will be 2.5 m long on JUICE. The main spacecraft parts modelled here include the body of the probe itself, its solar panels, and its antennas and booms. The model has an overall ‘wingspan’ of 75 cm across its solar panels. The photo also shows a spacecraft stand, which extends out of the bottom of the frame. The gold coating ensured that the model had excellent electric conducting properties, and reacted minimally with the surrounding water and air during the measurements.
- Meanwhile, the assembly of the JUICE flight model has started in September, with the delivery of the spacecraft's primary structure, followed by integration of the propulsion system.
• October 23, 2019: The assembly of the flight model of ESA's JUICE spacecraft began in September, with the delivery of the spacecraft's primary structure, followed by integration of the propulsion system that will enable the mission to reach and study Jupiter and its moons. 18)
- The primary structure of the spacecraft features a central tube – the main load bearing element – with vertical shear panels located radially around the tube, and horizontal floor panels. This will be completed later with the optical bench and external closing panels that will form the outer walls and will be added when all the internal equipment has been integrated.
- The structure is part of the SSTS ( Structure, Shielding and Thermal Subsystem), built under the responsibility of Airbus Defence & Space in Madrid, Spain, with participation by RUAG Space Switzerland and RUAG Space Austria.
- One of the features of the JUICE SSTS is that the some of the vertical panels and parts of the closing walls of the structure are lined with a thin layer of lead, which provides shielding to protect the spacecraft's electronic systems from damage by the severe radiation environment at Jupiter.
- One of the features of the JUICE SSTS is that the some of the vertical panels and parts of the closing walls of the structure are lined with a thin layer of lead, which provides shielding to protect the spacecraft's electronic systems from damage by the severe radiation environment at Jupiter.
- Over the coming months, five companies will be working almost simultaneously on the SSTS in order to ensure that JUICE can proceed to the assembly and integration phase that will take place in Airbus facilities in Friedrichshafen, Germany, so that it will be completed and ready for launch in 2022.
- One of the main tasks at Lampoldshausen will be to integrate the propulsion system. This includes two identical propellant tanks that have been newly developed for EuroStar Neo, ESA's new generation of platforms for geostationary telecommunications satellites. JUICE will be the first space mission to actually utilize them.
- The first titanium tank, capable of holding 1600 liters of oxidant (mixed oxides of nitrogen, or MON), was carefully lowered inside the spacecraft's central cylinder on 7 September. The second tank, which will contain monomethyl hydrazine (MMH) fuel, is scheduled for installation at the end of October.
- "JUICE will need to carry more than 3000 kg of propellant in these tanks," said Daniel Escolar, ESA's Mechanical, Thermal & Propulsion System Engineer for the mission. ”Such a large load will be essential for JUICE to arrive in orbit around Jupiter and complete its scientific tour with multiple flybys of the Galilean moons, before eventually becoming the first spacecraft ever to enter orbit around Ganymede."
Figure 8: The unpacking of the primary spacecraft structure of ESA's JUICE mission in the airlock at the Arianegroup facility in Lampoldshausen, Germany on 5 September 2019. The delivery marked the beginning of the flight model assembly, with the integration of the propulsion system that will enable the mission to reach and study Jupiter and its moons (image credit: Airbus and ArianeGroup)
- The integration of the spacecraft's propulsion system will, however, involve much more than installing two propellant tanks. Eventually, three fairly small tanks, each filled with helium pressurant, will be affixed around the exterior of the central cylinder, together with all the necessary plumbing. Some 130 meters of titanium piping will also have to be installed and welded in the SSTS.
- Other hardware to be added during installation of the propulsion system will include pressure regulators, valves, filters and thrusters. In addition to its single 400-newton main engine that will be used for the larger orbital maneuvers, JUICE will carry eight 22-newton thrusters for smaller maneuvers and as a backup system, along with twelve 10-newton thrusters for attitude control.
- Meanwhile, engineers are busy carrying out other essential tasks that can only be completed whilst the external panels are not fitted, enabling easy access to the spacecraft's interior. These include placing single layer insulation around the central cylinder, adding thermocouples to measure temperatures, and attaching support fixtures for the harness that will eventually be required to carry around 10 km of electrical cable.
- According to the current schedule, the JUICE flight model will be moved to Friedrichshafen around March next year for integration and testing of its electrical systems.
- In the meantime, development of the JUICE scientific payload is continuing, and the magnetometer boom for the flight model has recently been delivered to ESA/ESTEC (Space Research and Technology Center) in Noordwijk, the Netherlands, for three weeks of vibration and deployment tests.
• August 28, 2019: The test facility at CERN, the European Organization for Nuclear Research, was used to simulate the high-radiation environment surrounding Jupiter to prepare for ESA’s JUICE mission to the largest planet in our Solar System. 19)
- All candidate hardware to be flown in space first needs to be tested against radiation: space is riddled with charged particles from the Sun and further out in the cosmos. An agreement with CERN gives access to the most intense beam radiation beams available – short of travelling into orbit.
- Initial testing of candidate components for ESA’s JUpiter ICy moons Explorer, JUICE, took place last year using CERN’s VESPER (Very energetic Electron facility for Space Planetary Exploration missions in harsh Radiative environments) facility.
- VESPER’s high energy electron beamline simulated conditions within Jupiter’s massive magnetic field, which has a million times greater volume than Earth’s own magnetosphere, trapping highly energetic charged particles within it to form intense radiation belts.
- Due to launch in 2022, JUICE needs to endure this harsh radiation environment in order to explore Callisto, Europa and Ganymede – moons of Jupiter theorized to hide liquid water oceans beneath their icy surfaces. JUICE is being built by Airbus for ESA, with construction of its spacecraft flight model due to begin next month.
- Last month ESA and CERN signed a new implementing protocol, building upon their existing cooperation ties.
- Signed by Franco Ongaro, ESA’s Director of Technology, Engineering and Quality, and Eckhard Elsen, CERN Director for Research and Computing, this new agreement identifies seven specific high-priority projects: high-energy electron tests; high-penetration heavy-ion tests; assessment of commercial off-the-shelf components and modules; in-orbit technology demonstration; ‘radiation-hard’ and ‘radiation-tolerant’ components and modules; radiation detectors monitors; and dosimeters and simulation tools for radiation effects.
- “The radiation environment that CERN is working with within its tunnels and experimental areas is very close to what we have in space,” explains Véronique Ferlet-Cavrois, Head of ESA’s Power Systems, EMC & Space Environment Division.
- “The underlying physics of the interaction between particles and components is the same, so it makes sense to share knowledge of components, design rules and simulation tools. Plus access to CERN facilities allows us to simulate the kind of high-energy electrons and cosmic rays found in space. At the same time we are collaborating on flying CERN-developed components for testing in space.”
- Petteri Nieminen, heading ESA’s Space Environments and Effects section adds: “Along with JUICE, CERN heavy-energy radiation testing will also be useful for our proposed Ice Giants mission to Neptune and Uranus. The spacecraft may have to be pass through Jupiter’s vast magnetic field on the way to these outer planets, and both worlds have radiation belts of their own.
- “And the ability to simulate cosmic rays benefits a huge number of missions, especially those venturing beyond Earth orbit, including Athena and LISA as well as JUICE. It is also a huge interest for human spaceflight and exploration to study radiobiology effects of heavy ion cosmic rays on astronaut DNA. Not to mention that radiation simulations developed in collaboration with CERN help set space environment specifications for all ESA missions.”
Figure 9: Technology image of the week: this CERN test facility was used to recreate the highly radioactive environment surrounding Jupiter for ESA’s JUICE mission (image credit: CERN)
• August 22, 2019: As part of preparations for the launch of ESA’s Jupiter Icy Moons Explorer, its navigation camera has been given a unique test: imaging its destination from Earth. 20)
Figure 10: Annotated image of Jupiter system captured in JUICE NavCam test from Earth (image credit: Airbus DS)
- The NavCam has been specifically designed to be resistant to the harsh radiations environment around Jupiter and to acquire images of the planet, moon and background stars. Importantly, NavCam measurements will allow the spacecraft to be in the optimal trajectory and to consume as little fuel as possible during the grand tour of Jupiter, and to improve the pointing accuracy during these fast and close rendezvous approaches. The close encounters will bring the spacecraft between about 200 and 400 km to the moons.
- In June, a team of engineers took to the roof of the Airbus Defence and Space site in Toulouse to test the NavCam engineering model in real sky conditions. The purpose was to validate hardware and software interfaces, and to prepare the image processing and onboard navigation software that will be used in-flight to acquire images.
- In addition to observing Earth’s Moon and other objects, the instrument was pointed towards an obvious target in the night sky: Jupiter. The camera used the ‘Imaging mode’ and ‘Stars Centroiding Mode’ to test parameter settings which in turn will be used to fine-tune the image processing software at attitude control and navigation levels.
- “Unsurprisingly, some 640 million km away, the moons of Jupiter are seen only as a mere pixel or two, and Jupiter itself appears saturated in the long exposure images needed to capture both the moons and background stars, but these images are useful to fine-tune our image processing software that will run autonomously onboard the spacecraft,” says Gregory Jonniaux, Vision-Based Navigation expert at Airbus Defence and Space. “It felt particularly meaningful to conduct our tests already on our destination!”
- During the flybys themselves it will be possible to see surface features on these very different moons. In a separate test, the NavCam was optically fed with simulated views of the moons to process more realistic images of what can be expected once in the Jupiter system.
Figure 11: Simulated NavCam views of the Jupiter moons. Impressions of how the Jupiter Icy Moons Explorer will see moons Europa (left), Ganymede (middle) and Callisto (right) with its Navigation Camera (NavCam). To generate these images, the NavCam was fed simulated views – based on existing images of the moons – to process realistic views of what can be expected once in the Jupiter system (image credit: Airbus DS)
- Meanwhile the test navigation camera will be further improved with a full flight representative performance optics assembly by the end of the year, and will subsequently be used to support onboard software tests of the complete JUICE spacecraft. After launch, the test camera will be used at ESA’s operations center to support the mission operations throughout its mission.
• June 17, 2019: JUICE, will ride into space on an Ariane launch vehicle, Arianespace and ESA confirmed today at the International Paris Air Show. 21)
- JUICE is the first large-class mission in ESA's Cosmic Vision 2015–2025 program. Its mission is devoted to complete a unique tour of the Jupiter system.
- JUICE will spend at least three years making detailed observations of the giant gaseous planet Jupiter and in-depth studies of three of its largest moons and potentially ocean-bearing satellites, Ganymede, Europa and Callisto.
- The launch period for JUICE will start in mid-2022 aboard an Ariane 5 or an Ariane 64 launch vehicle – depending on the final launch slot from from Europe’s Spaceport in French Guiana, South America.
• April 3, 2019: ESA's JUpiter ICy moons Explorer, JUICE, has been given the green light for full development after its CDR (Critical Design Review) was successfully concluded on 4 March. This major milestone marks the beginning of the qualification and production phase, taking this flagship mission one key step closer to starting its long journey to Jupiter in 2022. 22)
• March 20, 2019: A test version of the 10.5 m long magnetometer boom built for ESA’s mission to Jupiter, developed by SENER in Spain, seen being tested at ESA’s Test Center in the Netherlands, its mass borne by balloons. 23)
- The flight model will be mounted on the JUICE (Jupiter Icy Moons Explorer) spacecraft, due to launch in 2022, arriving at Jupiter in 2029. The mission will spend at least three years making detailed observations of the giant gaseous planet Jupiter and three of its largest moons: Ganymede, Callisto and Europa.
- The Juice spacecraft will carry the most powerful remote sensing, geophysical, and in situ payload complement ever flown to the outer Solar System. Its payload consists of 10 state-of-the-art instruments.
- This includes a magnetometer instrument that the boom will project clear of the main body of the spacecraft, allowing it to make measurements clear of any magnetic interference. Its goal is to measure Jupiter’s magnetic field, its interaction with the internal magnetic field of Ganymede, and to study subsurface oceans of the icy moons.
- The deployment of this qualification model boom has been performed before and after simulated launch vibration on the Test Center shaker tables to ensure it will deploy correctly in space. Since the boom will deploy in weightlessness, three helium balloons were used to help bear its weight in terrestrial gravity.
Figure 12: A test version of the 10.5 m long magnetometer boom built for ESA’s mission to Jupiter, developed by SENER in Spain, seen being tested at ESA’s Test Center in the Netherlands, its weight borne by balloons (image credit: ESA–G. Porter, CC BY-SA 3.0 IGO)
• December 11, 2018: The JUICE engineering model spacecraft test readiness review was completed successfully on 2 October, and the first engineering model instruments are now being delivered and tested. 24)
Figure 13: The engineering model of ESA's JUICE at the facilities of prime contractor Airbus Defence and Space in Toulouse, France. The central cylinder of the spacecraft is well visible in this view, along with the electrical harness (image credit: Airbus DS)
- A major step in the development of ESA's upcoming JUICE mission to the Jupiter system is the start of integration and testing of the spacecraft engineering model at the facilities of prime contractor Airbus Defence and Space in Toulouse, France.
- Following the JUICE flight model spacecraft test readiness review, in October 2019, the engineering model will be used to test procedures and study functional issues that may arise during the development testing of the flight model. The engineering model will also be used, on ground, in support of the actual spacecraft operations after launch.
• November 12, 2018: JUICE is ESA's future mission to explore the most massive planet in Solar System and its large moons Ganymede, Europa and Callisto. Planned for launch in June 2022, it will embark on a seven-year cruise that will make use of several flybys – of Earth, Venus, Earth, Mars, and Earth again – before leaving the inner Solar System en route to Jupiter. 25)
- All three moons are thought to have oceans of liquid water beneath their icy crusts, and the Radar for Icy Moons Exploration (RIME) instrument on Juice will be used to probe their subsurface structure. Emitted by a 16-m long antenna, the radar signals will penetrate the icy surfaces of Jupiter’s moons down to a depth of 9 km.
- RIME will be the first instrument of its kind capable of performing direct subsurface measurements of worlds in the outer Solar System, and it should provide key clues on the potential for such bodies to harbor habitable environments.
- Once in space, the instrument’s performance will be influenced by several factors, including the radiation pattern of the antenna. To evaluate these effects, a series of tests were carried out at ESA’s Hertz facility in September, using a 1:18 scale model of the RIME antenna – shrunk to a length of about 80 cm and mounted on a simplified, scaled-down model of the spacecraft.
Figure 14: A miniaturized model of the Juice spacecraft during electromagnetic tests at ESA's technical heart in the Netherlands (image credit: ESA–M. Cowan)
• June 7, 2018: One of the major challenges facing ESA's JUICE (JUpiter Icy Moon Explorer) will be the extreme temperatures that the spacecraft and its suite of instruments will have to endure. 26)
In order to ensure that the orbiter survives the voyage to Jupiter and the cold, hostile environment of the Solar System's largest planet, the spacecraft will have to pass a series of challenging tests during its lengthy development process. The first of these – known as a TDM (Thermal Development Model) test – was recently completed.
The objective of the test, which took place between 5 and 10 May at ESA/ESTEC in The Netherlands, was to verify that the spacecraft's thermal control system could protect the spacecraft from extreme temperatures during its complex mission.
After launch, JUICE will embark on an 88-month cruise that will make use of several flybys – of Earth, Venus, Earth, Mars, and again Earth – before leaving the inner Solar System on its way to Jupiter.
En route, the spacecraft will have to endure the effects of solar heating, particularly during the flyby of Venus. Eventually, it will have to operate in an extremely cold environment where some of its external surfaces will experience temperatures below -200º Celsius after arrival at Jupiter, with even colder conditions during solar eclipses, when the spacecraft will be in the planet's shadow.
The JUICE thermal control system is designed to minimize the impact of the external environment on the spacecraft through the use of high efficiency MLI (Multi-Layer Insulation). The material that is used to blanket the spacecraft's exterior is known as StaMet coated black kapton 160XC.
The MLI will moderate the external temperature during the spacecraft's closest approach to the Sun. It must also limit heat leakage in the cold Jupiter environment in order to minimize demand for power from the spacecraft's heaters, especially when its instruments are operating during the science and communication phases.
The power demand will be a crucial factor during operations given the limited power generated by the spacecraft's solar panels at Jupiter's distance from the Sun, where the amount of incoming solar energy is 25 times lower than on Earth.
Efficient passive thermal insulation also minimizes hardware mass – always a major concern for spacecraft designers – by reducing the need for radiators and heaters.
Thermal verification test: The thermal verification test was required to check the passive heat loss properties of the spacecraft in both cold and hot environments. It used a full scale model, the TDM, which comprised a simplified version of the JUICE flight model structure.
The spacecraft's central cylinder was replaced by a basic hexagonal structure and the HGA (High Gain Antenna) was simulated by a simple, white-painted aluminum disc with the same diameter as the HGA flight model. This was relevant for the test, because the HGA will be used as an umbrella shielding the structure when the spacecraft will be at its closest to the Sun.
Figure 15: The JUICE TDM inside the Large Space Simulator (image credit: ESA–M. Cowan)
There were no other protruding instruments or appendages on the TDM, but heat dissipation from the platform and internal instruments was simulated by adding test heaters.
The TDM itself, wrapped in MLI, was placed in the LSS (Large Space Simulator) at ESA/ESTEC (European Space Research & Technology Centre) in Noordwijk, the Netherlands. Operated by European Test Services, the LSS is the largest space simulation facility in Europe, enabling a wide variety of tests to be performed on spacecraft.
Engineers began pumping the air out of the 9.4-m diameter chamber on 5 May, in order to create a vacuum comparable to the airless environment of deep space. This vacuum was maintained throughout the test.
Figure 16: The JUICE TDM inside the Large Space Simulator, before (left) and after (right) closing the 5 m diameter side door (image credit: ESA–M. Cowan)
• April 14, 2017: NASA’s partnership in a future ESA (European Space Agency) mission to Jupiter and its moons has cleared a key milestone, moving from preliminary instrument design to implementation phase. 27)
- Designed to investigate the emergence of habitable worlds around gas giants, JUICE is scheduled to launch in five years, arriving at Jupiter in October 2029. JUICE will spend almost four years studying Jupiter’s giant magnetosphere, turbulent atmosphere, and its icy Galilean moons—Callisto, Ganymede and Europa.
- The April 6 milestone, known as Key Decision Point C (KDP-C), is the agency-level approval for the project to enter building phase. It also provides a baseline for the mission’s schedule and budget. NASA’s total cost for the project is $114.4 million. The next milestone for the NASA contributions will be the Critical Design Review (CDR), which will take place in about one year. The CDR for the overall ESA JUICE mission is planned in spring 2019.
- JUICE is a large-class mission—the first in ESA’s Cosmic Vision 2015-2025 program carrying a suite of 10 science instruments. NASA will provide the UVS (Ultraviolet Spectrograph), and also will provide subsystems and components for two additional instruments: the PEP (Particle Environment Package) and the RIME (Radar for Icy Moon Exploration) experiment.
- The UVS was selected to observe the dynamics and atmospheric chemistry of the Jovian system, including its icy satellites and volcanic moon Io. With the planet Jupiter itself, the instrument team hopes to learn more about the vertical structure of its stratosphere and determine the relationship between changing magnetospheric conditions to observed auroral structures. The instrument is provided by the Southwest Research Institute (SwRI), at a cost of $41.2 million.
- The PEP is a suite of six sensors led by the Swedish Institute of Space Physics (IRF), capable of providing a 3-D map of the plasma system that surrounds Jupiter. One of the six sensors, known as PEP-Hi, is provided by the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, and is comprised of two separate components known as JoEE and JENI. While JoEE is focused primarily on studying the magnetosphere of Ganymede, JENI observations will reveal the structure and dynamics of the donut-shaped cloud of gas and plasma that surrounds Europa. The total cost of the NASA contribution to the PEP instrument package is $42.4 million.
- The Radar for Icy Moon Exploration (RIME) experiment, an ice penetrating radar, which is a key instrument for achieving groundbreaking science on the geology, is led by the Italian Space Agency (ASI). NASA’s Jet Propulsion Laboratory (JPL), in Pasadena, California, is providing key subsystems to the instrument, which is designed to penetrate the surface of Jupiter's icy moons to learn more about their subsurface structure. The instrument will focus on Callisto, Ganymede, and Europa, to determine the formation mechanisms and interior processes that occur to produce bodies of subsurface water. On Europa, the instrument also will search for thin areas of ice and locations with the most geological activity, such as plumes. The total cost of the NASA contribution is $30.8 million.
• March 15, 2017: Demanding electric, magnetic and power requirements, harsh radiation, and strict planetary protection rules are some of the critical issues that had to be tackled in order to move ESA's JUICE (Jupiter Icy Moons Explorer) from the drawing board and into construction. The PDR (Preliminary Design Review) is completed. 28)
• December 9, 2015: The mission was selected in May 2012 as the first Large-class mission within ESA's Cosmic Vision 2015–25 program, and is planned for launch in 2022 to arrive at the giant planet in 2030. 29)
- For three and a half years, JUICE will sweep around Jupiter, exploring its turbulent atmosphere, enormous magnetosphere and tenuous set of dark rings, as well as studying the icy moons Ganymede, Europa and Callisto. It will eventually go into orbit around Ganymede, a first in Solar System exploration.
- All three of these planet-sized satellites are thought to have oceans of liquid water beneath their icy crusts and should provide clues on the potential for such moons to offer habitable environments.
- Airbus Defence & Space SAS in France was announced as the prime contractor in July when ESA approved the €350 million contract.
- The contract covers the design, development, integration, test, launch campaign and in-space commissioning of the spacecraft. The Ariane 5 launch is not included and will be procured later from Arianespace.
- The 10 state-of-the-art instruments were approved by ESA in February 2013 and are being developed by teams spanning 16 European countries, the USA and Japan, under national funding.
- The spacecraft will be assembled at Airbus Defence and Space GmbH in Friedrichshafen, Germany.
• In July 2015, Airbus DS was selected by ESA (European Space Agency) as prime contractor for the design, development, production, and testing of a new spacecraft named ‘JUICE’. As its name implies (Jupiter Icy Moons Explorer), the mission will be to explore the Jovian system, focusing on three of Jupiter’s huge Galilean moons: Europa, Ganymede and Callisto, which are as large as dwarf planets and covered by an icy crust (Ref. 9).
Launch: In May 2022, Ariane 5 will lift Juice into space from Europe’s Spaceport in Kourou. A series of gravity-assist flybys at Earth (3), Venus (1) and Mars (1) will set the spacecraft on course for its October 2029 rendezvous in the Jovian system. 30) 31)
Figure 17: This animation depicts the journey to Jupiter and the highlights from its foreseen tour of the giant planet and its large ocean-bearing moons (video credit: ESA)
- The satellite will have a mass at liftoff of approximately six tons and will be placed in an Earth escape orbit in a direction to Jupiter starting a journey of 600 million kilometers. After a 7.5-year cruise, which includes gravitational assists from Earth, Venus and Mars, the spacecraft will enter orbit around the giant planet in October 2029.
- "JUICE is the first 'large-class' mission in our Cosmic Vision program and of prime importance for investigating the habitability potential of ocean-worlds beyond our own," said Günther Hasinger, ESA's Director of Science. "We're delighted to confirm it will have a flying start with an Ariane launch vehicle, setting it on course to fulfil its scientific goals in the Jupiter system."
- Stéphane Israël, Chief Executive Officer of Arianespace, added: "Arianespace is honored to be awarded this new scientific mission from ESA, which will advance our understanding of the Universe. Less than a year after the launch of BepiColombo to Mercury, we have won the launch contract for the JUICE mission to Jupiter's moons, further confirmation of Arianespace's ability to ensure Europe's independent access to space for all types of missions. We are once again marshaling all of our strengths and capabilities to support Europe's spaceborne ventures, with a launch services offering based on Ariane 5 and Ariane 6 so we can deliver the availability and flexibility needed by ESA for its latest emblematic mission."
Sensor complement (3GM, Gala, JANUS, J-MAG, MAJIS, PEP, PRIDE, RIME, RPWI, SWI, UVS)
The payload consists of 10 state-of-the-art instruments plus one experiment that uses the spacecraft telecommunication system with ground-based instruments. This payload is capable of addressing all of the mission's science goals, from in situ measurements of Jupiter's atmosphere and plasma environment, to remote observations of the surface and interior of the three icy moons, Ganymede, Europa and Callisto.
Figure 18: Overview of JUICE instruments (image credit: ESA/ATG medialab)
3GM (Gravity & Geophysics of Jupiter and Galilean Moons)
The instrument is a radio package comprising the KaT (Ka-Transponder), USO (ultrastable oscillator) and HAA (High Accuracy Accelerometer). The experiment will study the gravity field at Ganymede, the extent of the internal oceans on the icy moons, and the structure of the neutral atmosphere and ionosphere of Jupiter (0.1 - 800 mbar) and its moons.
PI: L. Iess, Università di Roma "La Sapienza", Italy. Lead funding agency: ASI.
GALA (GAnymede Laser Altimeter)
GALA will study the tidal deformation of Ganymede and the topography of the surfaces of the icy moons. GALA will have a 20 m spot size and 0.1 m vertical resolution at 200 km.
PI: H. Hussmann, DLR, Institut für Planetenforschung, Germany. Lead funding agency: DLR.
JANUS (optical camera system)
JANUS will study global, regional and local features and processes on the moon, as well as map the clouds of Jupiter. It will have 13 filters, a FOV of 1.3º, and spatial a resolution up to 2.4 m on Ganymede and about 10 km at Jupiter.
PI: P. Palumbo, Università degli Studi di Napoli "Parthenope", Italy. Lead funding agency: ASI.
J-MAG (JUICE Magnetometer)
J-MAG is equipped with sensors to characterize the Jovian magnetic field and its interaction with that of Ganymede, and to study the subsurface oceans of the icy moons. The instrument will use fluxgates (inbound and outbound) sensors mounted on a boom.
PI: M. Dougherty, Imperial College London, United Kingdom. Lead funding agency: UKSA, United Kingdom.
MAJIS (Moons and Jupiter Imaging Spectrometer)
MAJIS will observe cloud features and atmospheric constituents on Jupiter, and will characterize ices and minerals on the icy moon surfaces. MAJIS will cover the visible and infrared wavelengths from 0.4 to 5.7 µm, with spectral resolution of 3-7 nm. The spatial resolution will be up to 25 m on Ganymede and about 100 km on Jupiter.
PI: Y. Langevin, Institut d'Astrophysique Spatiale, France. Lead funding agency: CNES.
PEP (Particle Environment Package)
PEP comprises a package of sensors to characterize the plasma environment of the Jovian system. PEP will measure density and fluxes of positive and negative ions, electrons, exospheric neutral gas, thermal plasma and energetic neutral atoms in the energy range from <0.001 eV to >1 MeV with full angular coverage. The composition of the moons' exospheres will be measured with a resolving power of more than 1000.
PI: S. Barabash, Swedish Institute of Space Physics (Institutet för rymdfysik, IRF), Kiruna, Sweden. Lead funding agency: SNSB, Sweden.
PRIDE (Planetary Radio Interferometer & Doppler Experiment)
PRIDE will use the standard telecommunication system of the spacecraft, together with radio telescopes on Earth, VLBIs (Very Long Baseline Interferometry systems), to perform precise measurements of the spacecraft position and velocity to investigate the gravity fields of Jupiter and the icy moons.
PI: L. Gurvits, Joint Institute for VLBI in Europe, The Netherlands. Lead funding agency: NWO (Dutch Research Council) and NSO (Netherlands Space Office), The Netherlands.
RIME (Radar for Icy Moons Exploration)
RIME is an ice-penetrating radar to study the subsurface structure of the icy moons down to a depth of around nine kilometers with vertical resolution of up to 30 m in ice. RIME will work at a central frequency of 9 MHz (1 and 3 MHz bandwidth) and will use a 16 m antenna.
PI: L. Bruzzone, Università degli Studi di Trento, Italy. Lead funding agency: ASI.
RPWI (Radio and Plasma Wave Investigation)
The instrument will characterize the radio emission and plasma environment of Jupiter and its icy moons using a suite of sensors and probes.
RPWI will be based on four experiments, GANDALF, MIME, FRODO, and JENRAGE. It will use a set of sensors, including two Langmuir probes to measure DC electric field vectors up to a frequency of 1.6 MHz and to characterize thermal plasma and medium- and high-frequency receivers, and antennas to measure electric and magnetic fields in radio emission in the frequency range 80 kHz- 45 MHz.
PI: J.-E. Wahlund, Swedish Institute of Space Physics (Institutet för rymdfysik, IRF), Uppsala, Sweden. Lead funding agency: SNSB, Sweden.
SWI (Sub-millimeter Wave Instrument)
The objective of SWI is to investigate the temperature structure, composition and dynamics of Jupiter’s atmosphere, and the exospheres and surfaces of the icy moons. SWI is a heterodyne spectrometer using a 30 cm antenna and working in two spectral ranges 1080-1275 GHz and 530-601 GHz with spectral resolving power of ~107.
PI: P. Hartogh, Max-Planck-Institut für Sonnensystemforschung, Germany. Lead funding agency: DLR, Germany.
UVS (UV imaging Spectrograph)
The aim of UVS is to characterize the composition and dynamics of the exospheres of the icy moons, to study the Jovian aurorae, and to investigate the composition and structure of the planet’s upper atmosphere. The instrument will perform both nadir observations and solar and stellar occultation sounding.
UVS will cover the wavelength range 55-210 nm with a spectral resolution of <0.6 nm. The spatial resolution will reach 0.5 km at Ganymede and up to 250 km at Jupiter.
PI: R. Gladstone, SwRI (Southwest Research Institute), USA. Lead funding agency: NASA.
2) ”JUICE definition study report (Red Book),” ESA/SRE(2014)1, Issue 1, September 2014, URL: https://sci.esa.int/documents/33960/35865/1567260128466-JUICE_Red_Book_i1.0.pdf
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5) Pablo Hermosín, Javier Martín, Simone Centuori, Eric Ecale, Arnaud Boutonnet, Christian Erd, ”JUICE planetary protection analysis,” Proceedings of the 70th IAC (International Astronautical Congress), Washington DC, USA, 21-25 October 2019, paper: IAC-19,A3,5,4, URL: https://iafastro.directory/iac/proceedings/IAC-19/IAC-19/A3/5/manuscripts/IAC-19,A3,5,4,x52942.pdf
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The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: ”Observation of the Earth and Its Environment: Survey of Missions and Sensors” (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates ([email protected]). | 0.867215 | 3.898868 |
The Giant Radio Array for Neutrino Detection (GRAND) is a planned large-scale observatory of ultra-high-energy (UHE) cosmic particles, with energies exceeding 108 GeV. Its goal is to solve the long-standing mystery of the origin of UHE cosmic rays. To do this, GRAND will detect an unprecedented number of UHE cosmic rays and search for the undiscovered UHE neutrinos and gamma rays associated to them with unmatched sensitivity. GRAND will use large arrays of antennas to detect the radio emission coming from extensive air showers initiated by UHE particles in the atmosphere. Its design is modular: 20 separate, independent sub-arrays, each of 10000 radio antennas deployed over 10000 km2. A staged construction plan will validate key detection techniques while achieving important science goals early. Here we present the science goals, detection strategy, preliminary design, performance goals, and construction plans for GRAND.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all) | 0.824185 | 3.069785 |
The Moon is home to one of the largest known impact craters in the Solar System. At 2,500 kilometres (1,550 miles) across, the South Pole-Aitken Basin on the Moon's far side covers nearly a quarter of the lunar surface - and there's something massive buried beneath it.
We can't see it from here on Earth, but detailed readings made using lunar orbiters indicate there is something huge enough under that crater to be causing a significant gravitational anomaly.
"Imagine taking a pile of metal five times larger than the Big Island of Hawaii and burying it underground," said geophysicist Peter James of Baylor University.
"That's roughly how much unexpected mass we detected."
The anomaly was discovered in two sets of data. The first was from NASA's GRAIL mission, a pair of orbiting spacecraft that mapped the Moon's gravitational field in 2011 and 2012 to try to shed some light on its interior structure.
This data had already indicated a gravitational anomaly, and that the basin had higher-than-average density compared to the rest of the lunar surface; the team attributed this to its iron-rich surface composition.
But when the team compared these findings with the lunar topography data collected by NASA's Lunar Reconnaissance Orbiter, the results showed something else: a mass of about 2.18 quintillion kilograms (that's a number with 18 zeroes), extending more than 300 kilometres (184 miles) below the surface.
This mass, the researchers believe, is weighing the floor of the basin downward by more than 800 metres, around 10 percent of its total depth, explaining a depression in the bottom of the basin previously attributed to contraction.
"One of the explanations of this extra mass," James said, "is that the metal from the asteroid that formed this crater is still embedded in the Moon's mantle."
According to computer simulations, if conditions are just right, the iron-nickel core of an impacting asteroid can be dispersed into the upper mantle, between the Moon's crust and core.
This is what could have happened 4 billion years ago, when the object that created the basin slammed into the Moon.
"We did the maths and showed that a sufficiently dispersed core of the asteroid that made the impact could remain suspended in the Moon's mantle until the present day, rather than sinking to the Moon's core," James said.
Another possible explanation has to do with volcanism, of which the Moon was once a hotbed. There is a high concentration of titanium oxides in the lunar mantle, thought to have been produced by the cooling and solidification of oceans of lunar magma.
These oxides have a great deal of mass, which somehow could have been concentrated beneath the South Pole-Aitken Basin (although that 'somehow' is yet to be explored).
Whatever the explanation, the mass reveals some interesting things about the Moon's interior. For instance, we know that it's not molten enough for the mass to sink to the centre.
If the mass is from around the same time as the impact that made the basin, this implies an upper temperature limit of around 1,480 degrees Celsius for the latter half of the Moon's lifespan, consistent with estimates based on seismology.
This also implies that the Moon has lost a whole lot of thermal energy across its lifespan, the team said. Maybe China's Yutu2 rover, currently crawling across the South Pole-Aitken Basin, can shed more light on the matter.
The research has been published in Geophysical Research Letters. | 0.852202 | 4.032166 |
The Earth's Moon
The Earth's one natural satellite, the Moon, is more than one quarter
the size of Earth itself (3,474 km diameter). Because of its smaller
size, the Moon's gravity is one-sixth of the Earth's gravity, as we
saw demonstrated by the giant leaps of the Apollo astronauts.
While there are only two basic types of
regions on the Moon's surface, there are many interesting surface
features such as craters, mountain ranges, rilles, and lava plains.
The structure of the Moon's interior is more difficult to study. The
Moon's top layer is a rocky solid, perhaps 800 km thick. Beneath
this layer is a partially molten zone. Although it is not known for
certain, many lunar geologists believe the Moon may have a small iron
core, even though the Moon has no magnetic field. By studying the
Moon's surface and interior, geologists can learn about the Moon's geological history and its formation.
The footprints left by Apollo astronauts will last for centuries
because there is no wind on the Moon. The Moon does not possess any
atmosphere, so there is no weather as we are used to on Earth. Because
there is no atmosphere to trap heat, the temperatures on the Moon are
extreme, ranging from 100° C at noon to -173° C at night.
The Moon doesn't produce its own light, but looks bright because it
reflects light from the Sun. Think of the Sun as a light bulb, and
the Moon as a mirror, reflecting light from the light bulb. The lunar phase changes as the
Moon orbits the Earth and
different portions of its surface are illuminated by the Sun.
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Radar images of the Moon's surface taken by American Defense Departments's Clementine lunar probe have pointed to the possibility of finding water on the Moon. The images of the Moon's south pole region...more | 0.802221 | 3.499243 |
The comet of the year for 2010 seems to be Hartley 2. Although this comet is receding from Earth now (its closest approach was in the latter half of October) and growing fainter, it seems to have left us with one last hurrah: The spawning a brief meteor shower.
Although other comets, such as 2009 R1 (McNaught) and 2P/Encke have passed earlier this year, none has presented an especially tempting target for amateur astronomers (both McNaught and Encke were too close to the Sun during perihelion to be easily observed). Additionally, Hartley is the target of a flyby of the Deep Impact probe bringing it further attention.
Meanwhile, observationally, the comet has been somewhat difficult to observe. I went out on October 17th to hunt for it with a 4″ telescope, but despite my best efforts, couldn’t find it. Although the comet was predicted to reach 5th magnitude, the growing nucleus has apparently become so diffuse, reaching over 1° in the sky, that it’s hard to spot. Undeterred, I attempted again this past weekend with my 8″ SCT. Again, my attempts were frustrated. Even a 15 second exposure with my camera barely brought out more than a smudge.
Yet that night we observed several bright meteors radiating from near Cassiopeia which is where Hartley had been a few weeks prior. We checked to ensure there weren’t any other annual meteor showers from that region. Sure enough, there weren’t, and we wondered if there might be a connection between Hartley’s passing and the meteors we witnessed.
Sure enough, just such a shower was a predicted possibility. Whether or not the shower would occur would depend on just how much dust Hartley had given off in the past and how diffuse the cloud had grown (on this pass and others) since its closest approach to Earth was still 12 million km. Although the meteors my friends and I witnessed were notable (around 2nd to 3rd magnitude) they came from the wrong direction. Meteors spawning from Hartley should have a radiant in Cygnus, the swan. But while ours may not have caught these “Hartley-ids”, others have been witnessing a far grander show in the past few nights that seem to come from the right direction.
In Seascape California, Helga Cabral caught a bright fireball. “I saw a bright white ball and tail, arcing towards the ocean. It was quite beautiful and it looked like it was headed out to sea and so picture perfect it could have been a movie!” A similar fireball was reported the same night near Boston, Massachusetts by Teresa Witham. The predicted peak of this shower occurs tonight so if you have a chance and clear skies, go out and look. As with most showers, there may be some stragglers just before and after so you may be able to catch some for the next few nights if conditions tonight aren’t favorable.
Meteors from Hartley 2 will have a relatively low velocity upon entering our atmosphere since the comet is traveling roughly in the same direction. As such, the expected velocity as it hits our planet is a mere 7 miles a second. The result of this is that they will likely travel slowly across the sky, taking perhaps as much as a few seconds. In contrast, the Leonid showers coming later this month have a relative velocity of 45 miles per second, which causes the meteors to streak across the entire sky in less than a second. The lower velocity for the Hartley-ids will also mean they won’t undergo as much frictional heating and will likely glow fainter shades of reds and yellows. | 0.809543 | 3.706367 |
Astronomers uncover new clues to the star that wouldn't die
What happens when a star behaves like it exploded, but it's still there?
About 170 years ago, astronomers witnessed a major outburst by Eta Carinae, one of the brightest known stars in the Milky Way galaxy. The blast unleashed almost as much energy as a standard supernova explosion.
Yet Eta Carinae survived.
An explanation for the eruption has eluded astrophysicists. They can't take a time machine back to the mid-1800s to observe the outburst with modern technology.
However, astronomers can use nature's own "time machine," courtesy of the fact that light travels at a finite speed through space. Rather than heading straight toward Earth, some of the light from the outburst rebounded or "echoed" off of interstellar dust, and is just now arriving at Earth. This effect is called a light echo. The light is behaving like a postcard that got lost in the mail and is only arriving 170 years later.
By performing modern astronomical forensics of the delayed light with ground-based telescopes, astronomers uncovered a surprise. The new measurements of the 1840s eruption reveal material expanding with record-breaking speeds up to 20 times faster than astronomers expected. The observed velocities are more like the fastest material ejected by the blast wave in a supernova explosion, rather than the relatively slow and gentle winds expected from massive stars before they die.
Based on this data, researchers suggest that the eruption may have been triggered by a prolonged stellar brawl among three rowdy sibling stars, which destroyed one star and left the other two in a binary system. This tussle may have culminated with a violent explosion when Eta Carinae devoured one of its two companions, rocketing more than 10 times the mass of our Sun into space. The ejected mass created gigantic bipolar lobes resembling the dumbbell shape seen in present-day images.
The results are reported in a pair of papers by a team led by Nathan Smith of the University of Arizona in Tucson, Arizona, and Armin Rest of the Space Telescope Science Institute in Baltimore, Maryland.
The light echoes were detected in visible-light images obtained since 2003 with moderate-sized telescopes at the Cerro Tololo Inter-American Observatory in Chile. Using larger telescopes at the Magellan Observatory and the Gemini South Observatory, both also located in Chile, the team then used spectroscopy to dissect the light, allowing them to measure theejecta's expansion speeds. They clocked material zipping along at more than 20 million miles per hour (fast enough to travel from Earth to Pluto in a few days).
The observations offer new clues to the mystery surrounding the titanic convulsion that, at the time, made Eta Carinae the second-brightest nighttime star seen in the sky from Earth between 1837 and 1858. The data hint at how it may have come to be the most luminous and massive star in the Milky Way galaxy.
"We see these really high velocities in a star that seems to have had a powerful explosion, but somehow the star survived," Smith explained. "The easiest way to do this is with a shock wave that exits the star and accelerates material to very high speeds."
Massive stars normally meet their final demise in shock-driven events when their cores collapse to make a neutron star or black hole. Astronomers see this phenomenon in supernova explosions where the star is obliterated. So how do you have a star explode with a shock-driven event, but it isn't enough to completely blow itself apart? Some violent event must have dumped just the right amount of energy onto the star, causing it to eject its outer layers. But the energy wasn't enough to completely annihilate the star.
One possibility for just such an event is a merger between two stars, but it has been hard to find a scenario that could work and match all the data on Eta Carinae.
The researchers suggest that the most straightforward way to explain a wide range of observed facts surrounding the eruption is with an interaction of three stars, where the objects exchange mass.
If that's the case, then the present-day remnant binary system must have started out as a triple system. "The reason why we suggest that members of a crazy triple system interact with each other is because this is the best explanation for how the present-day companion quickly lost its outer layers before its more massive sibling," Smith said.
In the team's proposed scenario, two hefty stars are orbiting closely and a third companion is orbiting farther away. When the most massive of the close binary stars nears the end of its life, it begins to expand and dumps most of its material onto its slightly smaller sibling.
The sibling has now bulked up to about 100 times the mass of our Sun and is extremely bright. The donor star, now only about 30 solar masses, has been stripped of its hydrogen layers, exposing its hot helium core.
Hot helium core stars are known to represent an advanced stage of evolution in the lives of massive stars. "From stellar evolution, there's a pretty firm understanding that more massive stars live their lives more quickly and less massive stars have longer lifetimes," Rest explained. "So the hot companion star seems to be further along in its evolution, even though it is now a much less massive star than the one it is orbiting. That doesn't make sense without a transfer of mass."
The mass transfer alters the gravitational balance of the system, and the helium-core star moves farther away from its monster sibling. The star travels so far away that it gravitationally interacts with the outermost third star, kicking it inward. After making a few close passes, the star merges with its heavyweight partner, producing an outflow of material.
In the merger's initial stages, the ejecta is dense and expanding relatively slowly as the two stars spiral closer and closer. Later, an explosive event occurs when the two inner stars finally join together, blasting off material moving 100 times faster. This material eventually catches up with the slow ejecta and rams into it like a snowplow, heating the material and making it glow. This glowing material is the light source of the main historical eruption seen by astronomers a century and a half ago.
Meanwhile, the smaller helium-core star settles into an elliptical orbit, passing through the giant star's outer layers every 5.5 years. This interaction generates X-ray emitting shock waves.
A better understanding of the physics of Eta Carinae's eruption may help to shed light on the complicated interactions of binary and multiple stars, which are critical for understanding the evolution and death of massive stars.
The Eta Carinae system resides 7,500 light-years away inside the Carina nebula, a vast star-forming region seen in the southern sky.
The team published its findings in two papers, which appear online Aug. 2 in The Monthly Notices of the Royal Astronomical Society. | 0.931747 | 4.031008 |
Luna spacecraft with Lunokhod payload
|Mission type||Planetary Science|
|Mission duration||8 days (day of launch to day of landing)|
|Launch mass||5,950 kg (13,120 lb)|
|Dry mass||4,850 kg (10,690 lb)|
|Start of mission|
|Launch date||06:55:38, 8 January 1973 (UTC)|
|Rocket||Proton 8K82K with Blok D upper stage|
|Launch site||Baikonur Cosmodrome|
|Orbital insertion||12 January 1973|
|Periselene altitude||90 km (56 mi)|
|Aposelene altitude||100 km (62 mi)|
|Landing date||22:35, 15 January 1973|
|Spacecraft component||Lunokhod 2|
|Landing date||01:14, 16 January 1973|
|Distance covered||42 km (26 mi)|
Luna 21 (Ye-8 series) was an unmanned space mission, and its spacecraft, of the Luna program, also called Lunik 21, in 1973. The spacecraft landed on the Moon and deployed the second Soviet lunar rover, Lunokhod 2. The primary objectives of the mission were to collect images of the lunar surface, examine ambient light levels to determine the feasibility of astronomical observations from the Moon, perform laser ranging experiments from Earth, observe solar X-rays, measure local magnetic fields, and study mechanical properties of the lunar surface material.
Luna 21 carried the second successful Soviet lunar rover, Lunokhod 2, and was launched less than a month after the last Apollo lunar landing. The Proton-K/D launcher put the spacecraft into Earth parking orbit followed by translunar injection. On 12 January 1973, Luna 21 was braked into a 90 × 100 km orbit about the Moon, at a 60° inclination. On 13 and 14 January, the perilune was lowered to 16 km altitude. On 15 January after 40 orbits, the braking rocket was fired at 16 km altitude, and the craft went into free fall. At an altitude of 750 meters the main thrusters began firing, slowing the fall until a height of 22 meters was reached. At this point the main thrusters shut down and the secondary thrusters ignited, slowing the fall until the lander was 1.5 meters above the surface, where the engine was cut off. Landing occurred at 23:35 UT in Le Monnier crater at 25.85° N, 30.45° E, between Mare Serenitatis ("Sea of Serenity") and the Taurus Mountains. The lander carried a bas-relief of Vladimir Lenin and the Soviet coat-of-arms.
Less than three hours later, at 01:14 UT on 16 January, the rover disembarked onto the lunar surface. The 840 kilogram Lunokhod 2 was an improved version of its predecessor and was equipped with a third TV camera, an improved eight-wheel traction system, and additional scientific instrumentation. By the end of its first lunar day, Lunokhod 2 had already traveled further than Lunokhod 1 in its entire operational life. On 9 May, the rover inadvertently rolled into a crater and dust covered its solar panels and radiators, disrupting temperatures in the vehicle. Attempts to save the rover failed, and on 3 June, the Soviet news agency announced that its mission was over. Before last contact, the rover took 80,000 TV pictures and 86 panoramic photos and had performed hundreds of mechanical and chemical surveys of the soil. The Soviets later revealed that during a conference on planetary exploration in Moscow, 29 January to 2 February 1973 (that is, after the landing of Luna 21), an American scientist had given photos of the lunar surface around the Luna 21 landing site to a Soviet engineer in charge of the Lunokhod 2 mission. These photos, taken prior to the Apollo 17 landing, were later used by the "driver team" to navigate the new rover on its mission on the Moon.
- Launch Date/Time: 1973-01-08 at 06:55:38 UTC
- On-orbit dry mass: 4850 kg
- Lunokhod 2
- Lunokhod programme
- Timeline of artificial satellites and space probes
- List of artificial objects on the Moon
|Luna programme||Succeeded by|
- "NASA NSSDC Master Catalog - Luna 21/Lunokhod 2". Retrieved 1 January 2011.
- Zarya - Luna 21 chronology | 0.828446 | 3.431954 |
What is Radio Astronomy?
Astronomers around the world use radio telescopes to observe the naturally occurring radiowaves that come from stars, planets, galaxies, clouds of dust, and molecules of gas. Most of us are familiar with visible-light astronomy and what it reveals about these objects. Visible ” light — also known as optical light — is what we see with our eyes, however, visible lightVisible LightThe wavelengths of electromagnetic radiation that are visible to the naked eye. doesn’t tell the whole story about an object. To get a complete understanding of a distant quasarQuasarAn apparently small (at least to observers on Earth) yet immensely powerful cosmic object. Some quasars (quasi-stellar objects, or QSOs) are strong radio sources. Radio-emitting quasars were the first to be discovered. These are some of the most distant objects in the Universe, and are believed to be fueled by supermassive black holes residing in ancient galaxies. or a planet, for example, astronomers study it in as many wavelengths as possible, including the radio range.
There’s a hidden universe out there, radiating at wavelengths and frequencies we can’t see with our eyes. Each object in the cosmos gives off unique patterns of radio emissions that allow astronomers to get the whole picture of a distant object. Radio astronomers study emissions from gas giant planets, blasts from the hearts of galaxies, or even precisely ticking signals from a dying star.
Today, radio astronomy is a major branch of astronomy and reveals otherwise-hidden characteristics of everything in the universe.
What ARE Radio Waves?
Our eyes are built to see the cosmos in visible light. However, objects in the universe radiate many other types of light, across what’s called the “electromagnetic spectrum”. Light travels through space in waves, like ripples in a pond. Each ripple has a peak and a trough, which is called a cycle. An object emitting radio waves gives off many cycles in a very short period of time. During each cycle, the wave moves a short distance, which is called its wavelength.
Radio Frequencies and Astronomy by the Numbers
For radio waves of all kinds, the number of cycles per second is called a frequencyFrequencyA measure of wave vibrations per unit time. Typically measured in hertz, or cycles per second. In radio astronomy, high frequency corresponds to shorter wavelengths, like submillimeter waves detected by ALMA. Lower frequency refer to longer waves, like centimeter waves detected by the VLA. . One cycle per second is called one hertzHertzA unit of measurement of a wave's frequency. Hertz are measured by the number of oscillations that occur per second. 1 Hertz (Hz) = 1 cycle or oscillation/second.. A thousand cycles per second is a kilohertz; a gigahertz is a billion cycles per second. Radio astronomers are most interested in objects that emit in the frequency range between 3 kilohertz and about 900 gigahertz. It’s easier to think of these in terms of wavelengths, however, which range from a very large 100-kilometer radio wave to those less than a millimeter in length.
Doing Radio Astronomy
The radio portion of the electromagnetic spectrum can come from energetic objects and processes in the universe as well as cold, dark objects that emit no visible light. Because different wavelengths are given off by different objects, radio astronomers use a variety of methods and instruments to detect them. One type of instrument is a large antenna that looks similar to a satellite TV dish. It’s called a radio telescope. While single-dish radio telescopes are essential, NRAO’s telescopes consist of many dishes linked together in giant arrays to gather detailed radio images of distant objects.
Since humans are a visual species, seeing or “imaging” is an important part of all astronomy, regardless of the type of light being studied. While radio telescopes don’t take pictures in the same way that visible-light telescopes do, the radio signals they detect are converted into data that can be used to make images. Radio astronomy data streams are brought together and processed in a supercomputer. The output can be turned into images that are colored in different ways to show characteristics of the object such as its temperature, “clumpiness”, or the strength of radio emissions from different regions. The resulting images let scientists and the public see the otherwise invisible radio objects. | 0.803422 | 4.084883 |
The ‘word’ planet is sourced from the Greek word ‘planētēs’ which means ‘a wanderer’. In ancient times the cosmic bodies which were seen to wander relative to the backdrop of the fixed stars, which we now understood to include galaxies and other celestial phenomena, were the planets of our solar system. They were known as ‘wandering stars’ ……. points of light which appeared to move relative to the other lights which did not seem to move. Astrologers have also traditionally used the word ‘planet’ to include ‘the luminaries’, which are the Sun and the Moon. The luminaries are also referred to as ‘the lights’. The Sun lights up the day sky and the Moon lights up the night sky.
In modern astronomy ‘the planets’ have come to represent a distinct category which excludes the lights. However in current astrological practise the traditional meaning of the word ‘planets’ has not changed, and is still meant to include the lights. This distinction must be clearly understood by those who wish to participate in any discussion of astrology.
Sun at the Centre
Astrologers in the 21st century do of course understand that the Sun is actually a star generating enormous amounts of energy fuelled by nuclear reactions at its core, and that the Moon is actually a satellite of the Earth. The understanding that the Sun is actually at the centre of the solar system has been known to astrologers for many centuries, and is reflected in the ancient Chaldean order of the planets (sometimes referred to as the ‘Ptolemaic’ order of the planets) which places the Sun at the centre: Saturn Jupiter Mars Sun Venus Mercury Moon.
The ancient astrological cosmological order extends this model further by adding the stars at the highest level and the earth at the lowest level. It is interesting to observe that the modern ephemeris lists the planets beginning with the Sun and the Moon and then in order of orbital speed out to Pluto. As Andrew McMahon points out in the Introduction of his publication of Lilly’s Starting Astrology,
“…the mid-point of the sequence, lies between Mars and Jupiter, where appropriately enough, we find the asteroid belt. The fragmentation of the asteroid belt is too apt a metaphor as the esoteric centre of our modern world to require further discussion.”
Earth at the Centre of the Horoscope
Because astrology is focused on the study of the relationship between the cosmos and our lives here on Earth, the Earth is always placed at the centre of the horoscope, encircled by the symbols representing the luminaries and planets. This geocentric arrangement is in no way meant to deny the structure of the solar system. Rather it is meant to reflect the actual focus of astrological study, and our position relative to our immediate cosmic environment.
This geocentric model, which is the horoscope, is also meant to convey meanings other than those which are strictly physical. In this modern age our awareness is predominantly focused on the material and physical aspects of life, to the exclusion of other dimensions of life, which are mostly either ignored or forgotten. These other levels of human life revealed by the horoscope include the spiritual, social, psychological and deeply personal aspects of life.
The Classical Planets
Until the discovery of Uranus, there were only seven known planets: Saturn, Jupiter, Mars, Sun, Venus, Mercury and the Moon. These are usually referred to as the ‘classical planets’ or the ‘visible’ planets.
From an astrological perspective the classical planets represent everything that exists within physical manifestation. From the more ancient perspective, when life was viewed within the context of a universe created by God, these seven planets represented everything within divine creation.
When it is understood that these seven planets represent everything that exists within physical form, then their meaning becomes more apparent. For example because Saturn is the outermost planet visible to the naked eye, it represents the edge and structure of everything, including boundaries, fences, the skin and the internal skeleton, and the edge of life itself: death. Saturn is seen as the gateway between manifest creation and that which is not manifest. It represents the doorway between the material and the immaterial.
In the interpretation of temperament for example, Saturn represents coldness, hardness, heaviness and all things gloomy and depressed. It’s more positive associations include responsibility, duty, and authority. For those beginning the study of astrology it is most helpful to first understand the meaning of the classical planets, before studying the astrological significance of the ‘modern’ planets.
The Modern Planets
Astrologers categorise planets other than the visible ‘classical planets’ described above as the ‘modern planets’. These include Uranus, Neptune and Pluto. Some also include Ceres and Chiron in this category.
The more recently discovered cosmic bodies in the Kuiper and Oort belts, whose definition as planets or dwarf planets has been the subject of debate within the IAU (International Astronomical Union), may also be included within the list of ‘modern planets’.
The astrological meaning of the modern planets (most of which are now categorised as ‘dwarf planets’ by the IAU) beyond the orbit of Saturn has to do with the unconscious realm of the human psyche. This is also reflected by the names assigned to them by astronomers. The further from Earth they are placed, the more their meaning is associated with deeper levels of the unconscious psyche.
Because the classical planets rule everything on this Earth, the modern planets are secondary in importance. However their importance in astrological interpretation is elevated if they are placed on an angle or in close proximity to an important significators.
Modern astrologers describe the modern outer planets as ‘transcendental’ which suggests that they cannot rule the signs or mundane houses. Only the classical planets can rule signs and houses. The modern planets DO NOT rule any signs and they have no association with any of the signs.
The Primary Importance of the Luminaries and the Planets
In any astrological analysis the first and most important layer of study is the luminaries and planets. They are like the actors on a stage and contain the essential energies that reveal the make-up of whatever subject is the focus of study. Together they constitute ‘the engine’ of the horoscope. Without them astrology is nothing.
Next in order of importance are the zodiacal signs in which the cosmic bodies are placed, and thirdly, the houses in which they are placed. The zodiacal signs describe how the luminaries and planets function, and the houses pinpoint the area of life in which their energy manifests.
Any basic appraisal of the luminaries and planets is incomplete without an assessment of their condition in the horoscope being studied. Their condition, which describes their ability to express their nature, includes the aspects between them, plus their essential and accidental dignities. The planets have natural rulerships and ‘accidental’ rulerships. | 0.923541 | 3.203109 |
Wow – what an image! Michael Jaeger’s photo of Comet C/2011 L4 PANSTARRS on March 19 resembles those taken by the orbiting Stereo-B spacecraft. Check out this video (and the one below) to see what I mean. Most observers using binoculars and telescopes are seeing the comet’s head, bright false nucleus and a single plume-like tail.
Careful photography like Jaeger’s reveals so much more – two bright, broad dust tails and three shorter spikes. One of the dust tails peels off to the left of the comet’s head, the other extends upward feather-like before splitting into two separate streamers. There are also several narrow, spike-like tails due to various excited elements and gas emissions from the comet’s icy nucleus.
Video of Comet PANSTARRS made from pictures taken by NASA’s STEREO-B spacecraft on March 13, one of two spacecraft that orbit ahead and behind Earth monitoring solar activity on the sun’s farside.
Michael Jaeger of Austria has been shooting pictures of comets since 1982. His images always reveal details that entice visual observers to go out and look for more than what first meets the eye. Last night I got my first look at the comet through a telescope and was delighted at the sight of its smooth, luminous tail and brilliant yellow false-nucleus. The false nucleus is the bright spot visible in the center of the PANSTARRS’ head; in 10×50 binoculars it looks like a star. Through a telescope it’s a fuzzy, yellow pea. Buried deep within the false nucleus is the icy comet nucleus itself, vaporizing in the sun’s heat and shrouded by its own dust.
The comet has faded in the past week or two from 1st magnitude – equal to some of the brightest stars – to about magnitude 2.5 or somewhat fainter than the stars of the Big Dipper. In very clear skies, it was still dimly visible with the naked eye about 40 minutes after sunset low in the northwestern sky. I only knew where to look after first finding the comet in 10×50 binoculars. The tail points straight up and stretches nearly 2 degrees in length once the sky gets dark enough to increase contrast and before PANSTARRS sinks too low. I kept it in view for nearly an hour from a wind-whipped location north of Duluth, Minn.
Through the telescope the nucleus blazed yellow from sunlit dust. Set inside the comet’s sleek, smooth head it reminded me of a lighthouse beacon shining through the mist. Gorgeous! The tail trailed bent back to the northeast with a slight arc. I highly recommend setting up your telescope for a look at PANSTARRS, if for no other reason than to see the beauty of the false-nucleus within the finger-like tail.
You can use the chart to help you find the comet for the remainder of the month. It shows the comet’s position every 3 days now through March 31 from mid-northern latitudes, specially 42 degrees north (Chicago, Ill.). If you live in the northern U.S., the comet will be in approximately the same positions but slightly higher in the sky; in the southern U.S. it will be a little lower. Notice the “15 degree” altitude line. If you set the bottom of your fist flat on the horizon, the 15 degree line is a fist and a half above that level.
Time lapse video made by Patrick Cullis showing Comet PANSTARRS setting behind the Flatirons of Boulder, Col. on March 19. As you watch, notice how the comet appears against the sky background and the direction it moves toward the horizon – both clues to help you find it.
The map compensates for the sun rising later each night and shows the comet’s height above the horizon when the sun is 7.5 degrees below the horizon. 7.5 degrees corresponds to about 30 minutes after sunset. Notice that the sun moves northward (to the right) just like the comet does over the next couple weeks but more slowly.
See those yellow numbers along the map’s horizon? Those are compass bearings called azimuths. If you have a compass, dig it out and give it a look. Every compass is marked in degrees of azimuth. 270 degrees is due west, 285 degrees is a fist and a half to the right of due west, 315 degrees is exactly halfway between due west and due north. North can be either 360 degrees or 0 degrees. Azimuths are simple way to subdivide directions to make them more precise.
The next time it’s clear, bring your binoculars and a compass (if needed) and find a location with a great view of the western sky preferably down to the horizon. Use the map along with the compass bearings to guide your eyes in the right direction. You can also use the sun’s position below the horizon to point you to the comet by angling up from the lingering glow at the sunset point. Remember to first focus your binoculars on the moon, cloud bank or star before attempting to find PANSTARRS. There’s nothing more frustrating than sweeping for a fuzzy comet with an out-of-focus instrument. | 0.831788 | 3.550044 |
We’ve got two new podcasts from the Astronomy Cast team of Dr. Pamela Gay and Fraser Cain: Ep. 313: Precession, and Episode 314: Acceleration.
The Earth is wobbling on its axis like a top. You can’t feel it, but it’s happening. And over long periods of time, these wobbles shift our calendars around, move the stars from where they’re supposed to be, and maybe even mess with our climate. Thank you very much Precession.
Put that pedal to the metal and accelerate! It’s not just velocity, but a change in velocity. Let’s take a look at acceleration, how you measure it, and how Einstein changed our understanding of this exciting activity.
In our previous episode, week we explored the various ways spacecraft can die. But this week, we explore the spacecraft (and the scientists) who never give up, snatching victory from the jaws of defeat. We’ll look at clever solutions to potential spacecraft catastrophes.
So many of the forces in space depend on equilibrium, that point where forces perfectly balance out. It defines the shape of stars, the orbits of planets, even the forces at the cores of galaxies. Let’s take a look at how parts of the Universe are in perfect balance.
In the end, everything dies, even plucky space robots. Today we examine the last days of a series of missions. How do spacecraft tend to die, and what did in such heroes as Kepler, Spirit, and Galileo (the missions… not the people).
Even the ancient astronomers knew there was something different about the planets. Unlike the rest of the stars, the planets move across the sky, backwards and forwards, round and round. It wasn’t until Copernicus that we finally had a modern notion of what exactly is going on.
Sometimes a trilogy needs four parts! The Astronomy Cast team of Fraser Cain and Pamela Gay have taken a look at the history and modern era of space stations, as well as peering into the future at some space station concepts still in the works. You can listen to this four-part series at the Astronomy Cast website, or at the links below:
And the podcast is also available as a video, as Fraser and Pamela now record Astronomy Cast as part of a Google+ Hangout. You can see their latest Hangouts at the Astronomy Cast YouTube page. They record most Mondays at 18:00 UTC (3:00 PM EDT, 12:00 PDT) at Google+.
The mighty Arecibo Radio Observatory is one of the most powerful radio telescopes ever built – it’s certainly the larger single aperture radio telescope on Earth, nestled into a natural sinkhole in Puerto Rico. We’re celebrating the 50th anniversary of the construction of the observatory with a special episode of Astronomy Cast.
Astronomy Cast has recently uploaded several new podcasts, and while we normally post them separately here on Universe Today, since there are a number of them arriving at once, here’s a list of the new ones:
We’ve recently had a ‘changing of the guard’ at Astronomy Cast as far as getting things posted to the AC website and getting podcasts loaded to the feed, and are now getting caught up. But as you probably know, Fraser and Pamela now record Astronomy Cast as part of Google+ Hangouts. You can watch them record live at Google+ (they usually record on Mondays at 12 noon Pacific time) or at the AstrosphereVids You Tube channel (where you can watch past Hangouts as well).
Spring, Summer, Autumn and Winter. These are the seasons we experience here on Earth as our planet completes an orbit around the Sun. But what’s going on? Why do we experience such different temperatures and weather over the course of 365 days? Do other planets experience the seasons like we do?
We’ve all seen the classic science fiction space explosions, full of flames and loud sounds. Beautiful on the screen but, totally lacking in any kind of… science. What’s wrong with science fiction? What would chemical and nuclear explosions really look like? What would we hear? And what are some natural explosions that nature detonates in space? | 0.84709 | 3.278018 |
In the next decade, astronomers have powerful telescopes that analyse the atmospheres of exoplanets, the thousands of millions of worlds that are in the orbit of the stars of the Milky Way. Thanks to that, you will be able to study their nature and to suggest which ones could harbor life as we know it (of which we know nothing, we have nothing to say). This is more important than it seems: if we had a twin of the Earth to the extent, our present-day instruments would be unable to study its atmosphere; it could be a world with oceans and the beings living there "to the side" and we would not be aware of it.
despite the limitations of the existing instruments, a team of researchers has just discovered water in a world that has the right temperatures to support life.
For the first time, have detected water vapor in the atmosphere of a world rocky , in addition, it is to be in the zone of habitability of its star, the region in which a planet can have liquid water on the surface. This is K2-18b, a supertierra eight times more massive than our planet and located 110 light years and that has become the exoplanet most promising in the search for habitable planets. The discovery has been published in Nature Astronomy. Another team from the university of Montreal (Canada) has made the same observations, which has been published in arXiv.
"This is the first detection of water vapor in the atmosphere of a planet that is not a gas giant," explained Angelos Tsiaras, first author of the study and researcher at the University College of London (Uk). "It is a planet that is within the habitable zone of its star, which means you can have liquid water. So, right now, is the only planet outside the solar system that has the right temperature to support liquid water, which has an atmosphere and that, effectively, has water vapor."
Since it was discovered in 2015, K2-18b became one of the exoplanets most promising to search for traces of water in an atmosphere, but this new discovery places him as a priority target for further observations with powerful telescopes.Another representation of K2-18b - Alex Boersma
in Addition have detected water vapor in its astmósfera, whose concentration, according to the researchers going from one to 50%, the authors have concluded that K2-18b get as much radiation from its star as the Earth from the Sun , so you might have water on the surface. The authors consider that it is very likely that this exoplanet has clouds. However, they have clarified that without more data you cannot place a bet if K2-18b is a ocean world or if you have a surface dry.Not an "Earth 2.0"
despite this, K2-18b is very far from being a brother of the Earth . It is twice as big and has eight times its mass, which makes him a supertierra. In addition, it is very close to its star, so that it takes only 33 days to complete a lap around it. Your "sun" is a red dwarf, a star that is half the size of the Sun, which is red and which bombards the surface of K2-18b with large doses of ultraviolet rays. In other places, these stars raze their planets with countless flares, stellar, although on this occasion this seems not to be the case, according to the researchers.
"K2-18b is not an "Earth 2.0", because it is significantly heavier and has an atmospheric composition different", has had the effect of Tsiaras. "However, helps us to answer a fundamental question: what Is the Earth unique? ".The three atmospheres of the supertierra
The researchers used data collected by the Hubble space telescope between 2016 and 2017 and were processed with a program designed for the occasion. So, they analyzed the footprint left by the atmosphere of the exoplanet when it was crossed by the light of his star during the transits, the "eclipses" in which the planet comes between the Earth and the star. With this information, scientists developed a series of computer models according to which K2-18b can have three different atmospheres.
"There are three chemical weather possible", explained Ingo Waldmann, a co-author of the study. "A very dominated by water, with some hydrogen. Another dominated by a gas transparent, possibly nitrogen, and another in which there are clouds," he said. "All of them fit equally well with the data available now, but all indicate a high abundance of water ".Uncertainty surrounding K2-18b
And still there are more important mysteries to unravel. The data collected by the scientists suggest that K2-18b could be a world rocky with an extensive atmosphere, but, as has been pointed out to ABC Enric Pallé, a scientist at the Institute of Astrophysics of Canarias (IAC) an expert in atmospheres, "K2-18b is a supertierra on tenterhooks" .
As has been said, is very close to the upper limit after which it begins to be considered an exoplanet, not as a land of gigantic, a supertierra, but as a small gaseous planet, a minineptuno. "You could have a wrapped gas very important. I would not be considered as a candidate exoplanet is habitable, although it is only my opinion and depends on the physical properties that really have".
In any case, the authors have explained that the calculated density for this world closer to a world rocky world of a gas. In fact, according to their calculations, the density of K2-18b is similar to that of the Moon and Mars.In search of the atmosphere of a living planet
Be that as it may, it seems that these puzzles cannot be resolved, for the time being.
The Hubble space telescope, launched in 1996, has reached its limit . Has revealed countless secrets of the Universe and provided amazing images of the solar system, but is unable to seek the footprint that it would leave in the atmospheres molecules such as nitrogen or methane.
In fact, as explained Pallé, to find an atmosphere compatible with the presence of life would have to "find an atmosphere in disequilibrium, generated by the life, with the presence of oxygen, water and methane.
the authors of The study have highlighted the need to observe K2-18b with new instruments to be able to go beyond and know what is the chemistry and the structure of its atmosphere, which is fundamental to understanding the nature of the surface of this exoplanet.
Instruments like the space telescope James Webb , which NASA will launch in 2021, or the mission ARIEL, of the ESA that will analyze hundreds of planetary atmospheres beginning in 2028, will be critical. In addition, the new generation of observatories giant land , as the "Extremely Large Telescope", that is being built in Chile, or the "Thirty Meter Telescope", to be built in Hawaii, if the protests of some local permitting, will also be revolutionary.What lies ahead
In connection with K2-18b, Waldmann has pointed out that, "given that we expect to discover many supertierras in the next two decades, it is likely that this is the first discovery of many potentially habitable planets". And not only because the supertierras are among the planets most abundant of the galaxy, but because the sun that enlightens K2-18b, a red dwarf, is the type of star most common in the galaxy.
According to Giovanna Tinetti, co-author of the study and principal investigator of the mission ARIEL, of the THAT: "Our discovery makes K2-18b one of the most interesting for future studies . Have been detected around 4,000 exoplanets, but we do not know much about their nature or composition. But, by observing a large sample of planets, we hope to reveal the secrets of their chemistry, formation and evolution".
that's why, according to Tsiaras, K2-18b is crucial to our understanding of the worlds habitable beyond the solar system, and, finally, to "put the Earth, our only home, in the image of the cosmos." Time will tell what is also the site it occupies K2-18b, but for the moment, it is the world that most requirements meets to be a world habitable.
Updated Date: 23 September 2019, 20:01 | 0.909608 | 3.887283 |
Imagine that it is possible to make multiple copies of the Earth and then place them at random in circular orbits around the stars of one's choice. Presuming further that we wish to have liquid water available on the surface of each new Earth, the question is, given the parent stars luminosity, what range of orbital radii will satisfy the surface water existence condition? This question has, in fact, long ago been addressed by James Kasting (Pennsylvania State University) and co-workers, and the term ''habitable zone'' has been coined to describe the region in which liquid water might exist on the surface of an Earth-like planet.
The width of the habitable zone is bounded according to the distances at which water boils (the inner boundary) and freezes (the outer boundary), and these distances will change according to the star's luminosity.3 The lower the luminosity, the closer the habitability zone resides to the parent star; the higher the luminosity, the further it is away.
Kasting and co-workers have refined the determination of the habitability zone by studying detailed climate models. The inner edge of the habitability zone in such detailed models is set according to the rapid loss of water vapor (actually, its constituent hydrogen atoms) by photodissociation in the upper atmosphere. The outer edge is set according to the formation of CO2 clouds that, being highly reflective, dramatically increases the albedo and the planet is thereby cooled off. The variation of the width and radial location of the habitable zone, according to the calculations of Kasting and co-workers, is illustrated in Figure 5.9.
As one would expect for our Solar System (Figure 5.9), the Earth is situated within the habitability zone for a solar-mass star of age 4.5 billion years. Similar such diagrams for different-mass stars of other ages can also be constructed to gauge the location of the habitability zones for exoplanet-supporting stars (a topic we return to in Chapter 8). For the present, however, we note that terraform-ing might, in some sense, be described as the vertical shifting of a planet within the habitability zone diagram. The present orbit occupied by Venus, for example, would fall within the habitability
zone if it orbited a 0.75 M© star. Likewise, the current orbit of Mars would place it in the habitability zone if it orbited a 1.5 M© star.
Although not necessarily beyond the realms of possibility, we are not advocating changing the Sun's mass in order to make the planets Venus or Mars habitable (there are easier ways of achieving the same ends), but as the Sun ages there are, in fact, sound reasons for attempting to reduce its mass, as briefly described at the end of Chapter 4.
Was this article helpful? | 0.857889 | 4.017396 |
What exactly is a galaxy? In simple words, a galaxy is a system of stars, stellar remnants, and other celestial objects, bound together by gravitational force. Galaxies can differ in shape, size and each revolve around their center of mass.
Our Knowledge about the galaxies (including that of the Milky War), has evolved from the philosophical thinking of Aristotle in the 5th century B.C., to Edwin Hubble’s groundbreaking discoveries in the early 1920s to major scientific findings in the late 20th and 21st century.
There are an estimated two trillion galaxies or more in the observable universe. Most of the discovered galaxies to date have distinct features and vary largely in shapes and sizes.
To categorize different galaxies, astronomers and researchers use a morphological classification known as Hubble Sequence (developed by Edwin Hubble), which helps them to study individual galaxies precisely.
Hubble’s method was later modified by French astronomer Gérard de Vaucouleurs in 1959. Based on these classifications and a few other characteristics, we have discussed different types of galaxies below. So, space nerds, let’s begin.
Hubble Classification scheme for galaxies
In 1926, Edwin Hubble put forward the first-ever morphological classification scheme for galaxies; the Hubble’s classification. It recognizes three major types of galaxies; Elliptical, Spiral, and Lenticular. These broad categories of galaxies are subdivided to form a system called tuning fork diagram.
Elliptical galaxies are generally smooth and featureless. Hubble’s classification scheme, separate these galaxies based on their rate of ellipticity, E0, being almost spherical to E7, a highly elongated galaxy.
One of the most noteworthy features of elliptical galaxies is they have a very low number of open clusters (a group of few thousand stars) and a low rate of star formation. These galaxies generally consist of older, more evolved stars.
The largest galaxies in the observable universe are ellipticals. Many of them are more than 700,000 light-years across and have a mass near 100000000000000 solar masses, that’s 10^13 solar masses.
Examples of elliptical galaxies: Messier 87, IC 1101, and Maffei 1 (closest elliptical galaxy).
NGC 7793, a spiral galaxy Image Courtesy: NASA/JPL-Caltech/R. Kennicutt
The spiral galaxies are recognized by their bright spiral arms (mostly two) and a central bulge, inhabited chiefly by older stars. In Hubble’s classification, spiral galaxies are denoted by the English letter ‘S’ followed by a, b, or c, which indicates the stretch of spiral arms (‘a’ being close armed).
The arms of a spiral galaxy are distinctively visible due to the presence of young, still-forming stars in abundance.
Barred Spiral Galaxies
A barred spiral galaxy is, basically, a spiral galaxy with a bar-like structure at the center, which extends outward from its either sides. More than half of all spiral galaxies observed to date are, in fact, barred spiral galaxies. Hubble designates them as S.B., followed by small English letters a, b, and c, similar to the one in normal spiral galaxies.
These galactic bars are assumed to be temporary (they decay over time) and are caused either by an outward release of energy from the core, or due powerful tidal interaction with a neighbor galaxy.
The Milky Way, which contains two billion stars (one of which is the Sun), was once classified as a spiral galaxy but is now confirmed as a barred spiral galaxy.
Examples of (Barred) Spiral Galaxies: Milky Way, Andromeda Galaxy, and Whirlpool Galaxy.
At the very center of Hubble’s system, where two branches of spiral galaxies bifurcate, you can see an intermediate galaxy(s) attributed by the symbol S0.
These types of galaxies are known as lenticular galaxies. They have a bright bulge at their core and are elliptical in appearance. However, unlike spiral galaxies, they lack spiral arms and are not producing new stars at significant rates.
Examples of Lenticular Galaxies: Cartwheel Galaxy, NGC 2787
De Vaucouleurs Classification
Diagram of Hubble-de Vancouleurs Galaxy Morphology
Based on the Hubble’s sequence, French astronomer de Vaucouleurs developed an extension of galaxy morphological classification. He argued that Hubble’s classification is incomplete and doesn’t describe them to their full extent.
While the De Vaucouleurs system maintains the primary classification of galaxies, ellipticals, spirals, lenticulars, and irregulars, it introduces a more detailed categorization of galaxies, which focuses on their rings, bars, and spiral arms.
Some Other Types of Galaxies Based on their Morphology
Peculiar Galaxy: A Peculiar galaxy, as its name suggests, is a galaxy of strange shape, size and has an unknown composition. Only a small percentage of all discovered galaxies are categorized as peculiar galaxies. AGNs (Active Galactic nuclei) and interacting galaxies are currently the two types of peculiar galaxies identified by astronomers.
These types of galaxies are believed to be a result of a gravitational tug-of-war between two galaxies when they come extremely close to each other. The two affected parties develop peculiar visual properties due to massive tidal interaction.
Hoag’s object; a ring Galaxy | Image Courtesy: NASA and The Hubble Heritage Team
Ring Galaxy: A ring galaxy contains many massive, young, and bright stars, encircling around a relatively less bright nucleus. The Hoag’s object is the perfect example of the ring galaxies located in the Serpens Caput, about 612 mega light-years away.
One leading theory regarding their formation is the gravitational disruption caused by a near pass-by of a smaller galaxy near the core of a larger one.
Irregular Galaxies: Those galaxies which can neither be classified as elliptical nor as spiral are known as Irregular galaxies. They have a chaotic appearance and are without any spiral arm or a central bulge. Irregular galaxies can be divided into three subcategories; Irr-I galaxy, lrr-II galaxy, and dI-galaxy, none of which cleanly aligns with Hubble’s scheme.
In the above section, we have discussed galaxies based on their morphology or their appearance. But if a galaxy, irrespective of its shape, contains an active galactic nucleus, then it can also be classified as an active galaxy.
What is an active galactic nucleus you ask, well it’s a compact region near the center of a galaxy that has more than usual luminosity over almost the entire electromagnetic spectrum.
Active galaxies are divided into two categories; radio-quiet AGNs and Radio-loud AGNs. Radio-quiet AGNs like Seyfert galaxies show narrow and sometimes broad emission-lines, infrequent strong X-ray emission, and weak radio jet. Other types of radio-quiet AGNs are LINERs, Quasar 2s, and Radio-quiet quasars.
The Image captured by Hubble telescope shows the ejected jet of matter from Messier 87, an active galaxy traveling nearly at the speed of light.
On the other hand, “Blazars,” a type of radio-loud A.G. Ns, are distinguished by high X-ray and radio emissions, jets and are highly variable. Other types of radio-loud AGNs are optically violent variable quasar and radio galaxies.
Starburst galaxies are known to generate new stars at an exceptionally high rate. This rate is so high that these galaxies are bound to use their entire star-forming gas reservoir much faster than any other type of galaxy. Most of the observable starburst galaxies are either going through a galactic merger or are about to encounter one.
Over the years, astronomers marginally classified starburst galaxies based on their distinct apparent characteristics. They are Blue compact galaxies, Luminous infrared galaxies, and Wolf-Rayet galaxies. One of them is described below.
Luminous infrared galaxy: Infrared galaxies are most probably single, gaseous spirals, which get their infrared luminosity either from large numbers of stars packed in a compact region or from an active galactic nucleus. LIRGs are believed to have brightness more than 100 billion times that of the Sun.
It is generally considered that some luminous infrared galaxies create nearly 100 new stars compared to only 7 stars by the Milky Way each year, in this way they maintain their extremely high luminosity levels.
On the left is an actual Lyman-alpha emitter and on the right is an artist impression of the galaxy Image Courtesy: Chandra Observatory
Lyman-alpha emitter or LAE are galaxy types that emit a continuous spectrum of hydrogen known as Lyman-alpha radiation. These galaxies, located in the far reaches of the universe, are young and have typically low mass (10^8 solar masses).
Other characteristics include the highest specific star formation rate that strongly suggests these galaxies are incredibly valuable to study the evolution of much older and evolved galaxies like our Milky Way itself.
Low Activity Galaxies
Ultra diffuse galaxies (UDG): UDGs are extremely-low density galaxies found in different galaxy clusters. Most of the Ultra diffuse galaxies are about the same size as the Milky Way but have as low as 1% of its visible star count. UDGs are largely inhabited by older stars due to the lack of star-forming gas.
Low-surface-brightness galaxy: These type galaxies are mostly dwarf, and most of their matter is in gaseous hydrogen form rather than stars. They are extremely faint due to the lack of star formation. | 0.837502 | 4.063817 |
Best Stargazing Events for 2017
Download a 5-minute podcast discussing the Best 5 Stargazing events for 2017 (5.5-Meg MP3 file).
#1 -- The Evening Star: A celestial beacon shining brilliantly in the evening twilight is a great way to start the year, which is exactly what we're gifted with in 2017. Venus is radiant in the west after sunset, visible each evening from January until early March, earning it the nick-name "Evening Star". Adding to the picturesque scene is the crescent Moon, which lies near Venus at dusk on January 01 & 02, January 31 & February 01, and on March 01. After March, Venus moves into the morning sky where it can be enjoyed as the "Morning Star". During July, the tiny and rapidly-moving planet Mercury stands in as Evening Star; July is the best time this year to glimpse the little planet. On the evenings of July 24, 25, and 26, the crescent Moon joins Mercury at dusk.
#2 -- Eclipse of the Sun: A solar eclipse - when the Moon lies between us and the Sun - shows off the dynamic nature of our solar system. On the afternoon of February 26, as seen from southern Africa and southern South America, the Moon partially obscures the Sun. The eclipse begins at 14:10 and ends at 19:36. Safe methods for viewing an eclipse - which if done incorrectly will damage your eyes - are described on the ASSA website.
Sometimes, the Earth's shadow falls on the Moon, and a lunar eclipse can be witnessed. There is one such eclipse during 2017, on the evening of August 07, but it won't be particularly striking since the Moon just skims the edge of the Earth's shadow and the subsequent darkening is only slight.
#3 -- The Full Moon, big and small: When the Earth is located between the Sun and the Moon, we see the Moon fully illuminated with sunlight, hence a "full" Moon. On the day of a Full Moon, as the Sun sets behind the western horizon, the Moon is just rising above the eastern horizon. As the twilight deepens into night, the Moon seems to loom above the eastern horizon, and is a great opportunity to have a good howl. For an even better view, look the day before Full Moon: the almost-full Moon will then be above the horizon as twilight falls, presenting an excellent photo opportunity with enough light to capture terrestrial subjects with the Moon in the background. But be aware of the "moon illusion"! This sneaky optical illusion fools the mind into thinking the Moon is much larger than it really is. Your camera, however, isn't fooled at all, and on a typical photograph of the Full Moon low on the horizon, the Moon appears much smaller than expected. To recreate the massive Moon effect with a camera, use a powerful zoom lens and include a distant object in the frame next to the Moon: voila!
As the Moon orbits the Earth, it follows an elliptical path, meaning that the distance to the Moon is constantly changing. It takes the Moon about 27 days and 8 hours to complete a single orbit. Also, as the position of the Moon and Sun as seen from Earth changes, the Moon appears to go through a cycle of shadow phases, from New to Full and back again. From one phase to the next is about 29 days and 13 hours. This combination of orbital period and cycle of phases - close but not exact - means that Full Moons don't always happen at the same distance from the Earth. Sometimes the Full Moon is nearer to us than at other times. During 2017, the largest Full Moon is on December 03 and the smallest Full Moon is on June 09.
Don't be confused by the "moon illusion" - this effect only happens in your mind. The real size of the Moon depends on how far away it is. Here's an experiment: take a photograph of the Full Moon on June 09, and use the same camera settings on December 03 and take a second photograph, and compare them for yourself.
#4 -- The Big 5 of the African Sky: The best examples of each celestial object type - star clusters, nebulae (gas clouds) and galaxies - visible from Africa are known as the Big 5 of the African Sky. These exotic and gorgeous specimens are the Southern Pleiades, omega Centauri, the eta Carinae Nebula, the Coal Sack, and the southern Milky Way. They can all be seen with the naked eye from a dark site, are outstanding when seen using binoculars, and mind-blowing when observed through a telescope. All five of the Big 5 can be seen in the morning sky during April, at midnight during June, and in the evening sky during August.
Find out more: Big5 page on the ASSA website
#5 -- Star parties: Long dark nights under the stars, surrounded by telescopes, star gazers, and the beautiful cosmos, is what star parties are all about. Astronomy enthusiasts, from beginners to experts, gather at several times in different places to observe the sky, discuss astronomical subjects, and share in the camaraderie of their fellow star gazers. During 2017 you can look forward to the Summer Southern Star Party (February 22 – 27, Leeuwenboschfontein, Cape), the Karoo Star Party (April 24 – 28, near Britstown), the Free State Star Party (June 23 – 25, near Brandfort), the MSP Star Party (July 21 – 23, near Rustenburg) and the Spring Southern Star Party (October 18 – 23, near Bonnievale, Western Cape).
nothing more to see. please move along. | 0.841052 | 3.175893 |
Where do meteorites come from?
Most meteorites are believed to originate in the asteroid belt between Mars and Jupiter, and were formed early in the history of the Solar System ~4.56 billion years ago. These fragments of asteroids were either knocked out of their orbit of the Sun, and into Earth-crossing orbits, through collisions with other objects, or through the interaction of gravitational forces exerted by the Sun and Jupiter.
Image credit: NASA/JPL-Caltech
How do we know meteorites come from space?
Meteorites that come from the asteroid belt are about the same age as the solar system, approximately 4.5 billion years old. No Earth rocks are this old, because they have all been repeatedly broken down and reformed by terrestrial geological processes such as erosion and plate tectonics.
Which asteroids do they come from?
While it is difficult to pinpoint specific asteroids as parent bodies of specific meteorite types, comparison of meteorite data with data from asteroids from Earth-based observations and spacecraft can help to define likely sources of some meteorite types. For example, data collected by NASA’s Dawn spacecraft has strengthened the theory that the HED (Howardites, Eucrites and Diogenites) group of achondrites formed in the crust of asteroid 4-Vesta (This mosaic synthesizes some of the best views the Dawn spacecraft had of the giant asteroid Vesta. Image credit: NASA/JPL-Caltech/UCAL/MPS/DLR/IDA)
Meteorites from a tracked asteroid
The small asteroid 2008 TC3 was first discovered October 6th, 2008, by an automated telescope at Mount Lemmon in Tucson, Arizona. The asteroid was tracked closely as it entered Earth's atmosphere and exploded approximately 37 km above northern Sudan’s Nubian Desert early the following morning.
The meteorites recovered from this fall, named Almahata Sitta, are extremely interesting, as the specimens exhibit multiple distinct lithologies, ranging from ordinary chondrite to bencubinnite. The stones from this unprecedented event continue to provide key information about the composition of asteroids.
Do we have meteorites from other planets?
Some meteorites come from the Moon and Mars. These lunar or martian crustal rocks were ejected into space when another (asteroidal or cometary) object collided with the Moon or Mars with enough force to launch some of the impact-produced debris into Earth-crossing orbits.
How do we know they’re from Mars?
Martian meteorites are distinguished from Earth rocks and other meteorite types by their chemical and mineral composition, as well as their age. Moreover, gases trapped in shock glass in martian meteorites have been matched to measurements of the martian atmosphere taken by the NASA Viking mission in 1976.
Nakhla, martian achondrite. Image ⓒ ASU/CMS
How do we know they’re from the Moon?
Because we’ve been there! Lunar meteorites are identified by their unique chemical and mineral characteristics indicative of their origin on the Moon, mainly based on comparison to lunar rocks returned to Earth by the Apollo and Luna missions.
Did you know that the first ever carbon analysis of lunar rocks was done at the ASU Center for Meteorite Studies? Learn more about it here!
Do we have any confirmed meteorites from Venus or Mercury?
Not yet, but there could be pieces of both planets in existing meteorite collections, waiting to be identified. Data from NASA’s MESSENGER mission could help to identify potential mercurian meteorites, while venusian meteorites might be distinguished using data from the Vega 1 and 2 landers, and the Magellan spacecraft.
Venus. Image credit: SSV, MIPL, Magellan Team, NASA | 0.866364 | 3.826506 |
When NASA’s Juno spacecraft flew past Earth in October of this year, it focused some of its cameras on the Earth-Moon system. Immediately after the flyby, images taken by the Junocam were released, but today, NASA released an amazing video taken by the Advanced Stellar Compass (ASC) camera, a low-light camera that is primarily used as a star tracking a navigation tool. Over the course of three days, it captured the orbital ballet-like dance between the Earth and Moon.
“This is profound, and I think our movie does the same thing as “Pale Blue Dot” image from Voyager, except it’s a movie instead of an image,” said Scott Bolton, Juno principal investigator, speaking during a press briefing from the American Geophysical Union conference today in San Fransisco. “Like Carl Sagan said, everything we know is on this dot. To me this says, ‘we’re all in this together.’”
The Oct. 9 flyby was a gravity assist, accelerating Juno out of the inner solar system and toward Jupiter’s orbit. The probe is expected to arrive at Jupiter on July 4, 2016.
The movie begins at 2:00 UTC on Oct. 6, more than four days before Juno’s closest approach, when the spacecraft was approximately 2.1 million miles (3.3 million kilometers) from Earth. Earth’s moon is seen transiting in front of our planet, and then moves out of frame toward the right as Juno enters the space inside the orbit of our natural satellite. As Juno gets closer to Earth, hints of clouds and continents are visible before the planet’s brightness overwhelms the cameras, which were not designed to image so bright an object. The sequence ends as Earth passes out of view, which corresponds to approximately 17:35 UTC Oct. 9 when Juno was at an altitude of about 47,000 miles (76,000 kilometers) above Earth’s surface.
“From a half-million kilometers out, the Moon is dark as charcoal and but Earth way brighter, as a shiny blue dot,” said John Joergensen, who lead the team that designed the star tracking cameras. “It’s amazing to think that all of humanity being scanned in this movie, and to see how small the Moon is relative to Earth.”
The cameras that took the images for the movie are located near the pointed tip of one of the spacecraft’s three solar-array arms. They are part of Juno’s Magnetic Field Investigation (MAG) and are normally used to determine the orientation of the magnetic sensors. These cameras look away from the sunlit side of the solar array, so as the spacecraft approached, the system’s four cameras pointed toward Earth. Earth and the moon came into view when Juno was about 600,000 miles (966,000 kilometers) away — about three times the Earth-moon separation.
During the flyby, timing was everything. Juno was traveling about twice as fast as a typical satellite, and the spacecraft itself was spinning at 2 rpm. To assemble a movie that wouldn’t make viewers dizzy, the star tracker had to capture a frame each time the camera was facing Earth at exactly the right instant. The frames were sent to Earth, where they were processed into video format.
As Juno is a spinning spacecraft, the images were aligned to remove their apparent rotation. The original ASC images are monochrome; faint coloration has been added by converting the measured grayscale values into false colors matching a true color image of Earth. | 0.843092 | 3.255821 |
Infographic: Astronomy highlights in winter 2018/2019
The new 3-month night sky calendar at a glance. The astronomical infographic ’Highlights of the Winter Sky 2018/2019’ shows you what will be happening in the night sky. Descriptions of the individual events are below:
05.12. The Moon near Mercury
Early in the morning, the Moon can be observed near Mercury. They are separated by about only 7 degrees – making them suitable for observing with a pair of wide-angle binoculars.
07.12. Mars near Neptune
A fantastic spectacle – a very close encounter between Mars and Neptune. Only about 4 arcminutes away from Neptune, Mars passes north of Neptune from around 18:00. You will need a pair of binoculars or, even better, a telescope to observe them.
If the night sky is clear in the evening, then it is best to observe facing south, as the ‘Geminids’ meteor shower will seem to come from the constellation of the ‘twins’ – more precisely, from a point two degrees above the star Pollux. Between 21:00 and 6:00 is the best time to observe. With around 120 meteors per hour, the Geminids is one of the most intense showers. However, the full Moon will diminish the view this year. Even so, you really shouldn’t miss this event.
15.12. Moon near Mars
The 42% illuminated and waxing moon can be observed near Mars today, separated by a distance of about 5 degrees.
16.12. Comet 46P/Wirtanen
The December Comet – finally, we have a bright comet again, which can be observed with binoculars and small telescopes. Comet 46P/Wirtanen reaches its closest proximity to the Earth on the 16th and can be observed near the Pleiades (M45) open star cluster at only 3 degrees away. A beautiful ‘constellation‘ through binoculars. Wirtanen is a rare comet, which could attain a strong brightness and hence become an impressive object for beginners. If everything progresses well, it could reach a brightness of up to magnitude 4 by the end of the year and so even become visible to the naked eye. Without the disturbing presence of the Moon, the comet can be found easily in the evening sky after Christmas.
28.12. Hebe in opposition
The asteroid 6 HEBE comes into opposition on December 28, attaining a brightness of about magnitude 8.5. It can best be seen around midnight in the constellation of Monoceros or in the constellation of Orion. You will need a mid-size telescope to observe it. Its current position can be found at any time, by using the Stellarium planetarium program for example.
01.01. Planet chain Moon, Venus, Jupiter, Mercury
Just in time for New Year’s Eve, the New Year welcomes us with a pretty chain of planets. In the morning sky just before sunrise, you can see, from the top right to the bottom left to the horizon: the Moon, a bright Venus, Jupiter and even a shy Mercury close to the horizon. Tip: A great opportunity to take a beautiful photo.
The next meteor shower is here – the Quadrantids. This shower comes from the constellation of Bootes, with the number of meteors observed across the sky potentially reaching a maximum of 120 per hour. Observing in the early morning will give you the best chance of successful observing.
05.01. Comet Wirtanen circumpolar
The Christmas Comet will also delight us in the new year – while the comet was only seen in the evening or in the morning sky before, it has now become circumpolar, wandering through the constellation of the Ursus Major. You can now observe it over the entire night.
06.01. Venus at greatest western elongation
The best view of Venus is now here. The ‘morning star’ shines brightly (magnitude -4.5). At 47 degrees angular separation, it is at greatest western elongation and can be seen half illuminated. The planet will first peep over the horizon at about 4:30 CET, and can be observed for about three hours before disappearing in the sunlight.
12.01. Moon near Mars
From dusk on, you can observe the Moon in the south with Mars above it. They are separated by about 7 degrees.
15.01. μ Cet occulted by the Moon (evening)
The Moon will occult the 4.1 mag star μ Cet in the very early evening. The Moon approaches the star with its dark side and finally occults it at 17:44 CET. An occultation from the Moon’s dark side is always fascinating to observe – it appears as though the star has suddenly been ‘switched off’. It will take almost an hour for the star to then reappear on the illuminated side of the Moon.
21.01. Total lunar eclipse
Everyone probably still remembers the Total Lunar Eclipse in 2018, when the Moon offered us a summer spectacle at a still-comfortable time of night. This time around the show is on the 21st of January, at a rather unfavourable time with temperatures that are too cold to be considered ‘T-shirt weather’.
Entry into the penumbra: 3:36 CET
Entry into the umbra: 4:33 CET
Beginning of totality: 5:40 CET
End of totality: 6:43 CET
Exits umbra: 7:50 CET
Exits penumbra: 8:48 CET
22.01. Venus near Jupiter
Jupiter and Venus can be observed together before sunrise. We can observe both planets shining in the southeast at a separation of only about 2 degrees. Venus is at magnitude -4.3, with Jupiter significantly weaker at magnitude -1.9. They provide a beautiful sight through binoculars, where you can admire them both in the same field of view.
31.01. Moon near Jupiter and Venus
On January 22nd the Moon joins the two planets, inserting itself in the middle between Venus and Jupiter.
02.02. Moon near Saturn (occulting in Germany and Austria)
The Moon is a waning ‘sickle’ and only 6% illuminated, so it is not visible until early in the morning. At 6.30 CET both astronomical bodies can be seen close to the horizon. The Moon can be seen to actually occult Saturn in both Germany and Austria – the ringed planet disappears behind the illuminated crescent moon at 6:37 CET, reappearing an hour later at the dark, north-eastern edge.
10.02. Moon near Mars
You can observe the crescent Moon and Mars together this evening in the same field of view in binoculars having a field of view of at least 7 degrees.
13.02. Mars near Uranus
Tonight, Mars will be less than 1.5 degrees away from the distant gas giant Uranus. The difference in brightness is significant – the red planet shines brightly at magnitude 1, whereas Uranus is only at a dim magnitude 5.8. Both objects can be observed using binoculars or a telescope. But it is definitely worthwhile – you can even see them together in the same field of view in a low magnification, wide-angle eyepiece.
27.02. Mercury at greatest eastern elongation (and half-full)
Because Mercury orbits so fast and so close to the Sun we cannot always observe it. But now Mercury is once again at a greater angular distance – of 18°- from the Sun. It’s not a huge separation, but it allows us to observe it for sufficient time during its half-full phase. Mercury can now be seen in the evening sky shortly after sunset. Be sure to wait until the sun has completely set before observing through any optics. You will then find Mercury just above the western horizon. | 0.895713 | 3.441191 |
The late twentieth and early twenty-first centuries have been a great age of exploration. While the tools for past discoveries were ships, compasses and sextants, the tools of the current age have been rockets, satellites and telescopes.
Satellites such as Hipparcos and networks of radio telescopes such as the Very Long Baseline Array have determined precise distance estimates for parts of the Milky Way, and this work will be tremendously enhanced by the GAIA project expected to begin at the end of 2011. Infrared space telescopes such as IRAS, MSX, and Spitzer have pierced through the vast clouds of dust that block our view of much of the Milky Way and have given us stunning views of the mysterious and unknown starscapes that lie beyond. Microwave and millimetre radio dishes have worked tirelessly year after year to map out the giant molecular clouds that form the birthplace of our galaxy's great star associations.
The world's astronomers have worked together to make their research available to all on the Internet, through the huge collection of scientific abstracts and papers at the Astrophysics Data System, the more than seven thousand data catalogs at VizieR, the great directory of almost five million astronomical objects at Simbad and the trillions of bytes of observational data available through the Virtual Observatory.
The results of this exciting research are summarised in four different ways within this website.
The Milky Way Explorer gives you direct access to many of the large sky surveys and shows you the sky as it would appear if you had super sensitive eyes that could detect infrared, microwave and radio frequencies. The Google Map interface makes it easy to navigate across the Milky Way, zooming in to see one nebula or zooming out to view hydrogen loops or huge regions like the Orion or Ophiuchus molecular clouds.
The face-on maps shows the estimated positions of thousands of nebulae, bright stars, clusters, molecular clouds and more as they would appear from a starship hovering above and outside the galaxy.
Our Galactic Region is the first draft of a book about the Milky Way, with a special focus on the region of the galaxy within about 10 thousand parsecs (over 30 thousand light years). It includes the stories of some of the key scientists mapping the Milky Way, a Commentary on the Galactic Plane and a commentary on the whole sky as seen in hydrogen-alpha, the frequency of ionised hydrogen gas.
Finally, images and descriptions of several hundred optically visible HII regions, supernova remnants and other prominent nebulae are available and can be accessed either through the object descriptions available by clicking on the maps, or through image gallery pages. There are five image galleries available. A general gallery shows all of the nebulae described on this website. Special galleries show objects in the Sharpless, Gum and RCW catalogs. You can also view a growing gallery of larger unusual and often beautiful images, Strange New Worlds.
You can read my blog to find out about major changes to the site or important new Milky Way research. | 0.865156 | 3.698468 |
The ancient mollusk, from an extinct and wildly diverse group referred to as rudist clams, grew fast, laying down daily growth rings. The new study used lasers to sample minute slices of shell and count the expansion rings more accurately than human researchers with microscopes.
The growth rings allowed the researchers to work out the number of days during a year and more accurately calculate the length of each day 70 million years ago. The new measurement informs models of how the Moon formed and the way on the brink of Earth it’s been over the 4.5-billion-year history of the Earth-Moon gravitational dance.
The new study also found evidence that the mollusks harbored photosynthetic symbionts which will have fueled reef-building on the size of modern-day corals.
The high resolution obtained within the new study combined with the fast rate of growth of the traditional bivalves revealed unprecedented detail about how the animal lived and therefore the water conditions it grew in, right down to a fraction of each day.
“We have about four to 5 data points per day, and this is often something that you simply almost never get in geological history. we will basically check out each day 70 million years ago. It’s pretty amazing,” said Niels de Winter, an analytical geochemist at Vrije Universiteit Brussel and therefore the lead author of the new study.
Climate reconstructions of the deep past typically describe future changes that occur on the size of tens of thousands of years. Studies like this one provide a glimpse of change on the timescale of living things and have the potential to bridge the gap between climate and weather models.
Chemical analysis of the shell indicates ocean temperatures were warmer within the Late Cretaceous than previously appreciated, reaching 40 degrees Celsius (104 degrees Fahrenheit) in summer and exceeding 30 degrees Celsius (86 degrees Fahrenheit) in winter. The summer high temperatures likely approached the physiological limits for mollusks, de Winter said.
“The hi-fi of this data-set has allowed the authors to draw two particularly interesting inferences that help to sharpen our understanding of both Cretaceous astrochronology and rudist palaeobiology,” said Peter Skelton, a retired lecturer of palaeobiology at The Open University and a rudist expert unaffiliated with the new study.
The new study analyzed one person who lived for over nine years during a shallow seabed within the tropics — a location which is now, 70-million-years later, land within the mountains of Oman.
Torreites sanchezi mollusks appear as if tall pint glasses with lids shaped like bear claw pastries. the traditional mollusks had two shells, or valves, that met during a hinge, like asymmetrical clams, and grew in dense reefs, like modern oysters. They thrived in water several degrees warmer worldwide than modern oceans.
In the late Cretaceous, rudists like T. sanchezi dominated the reef-building niche in tropical waters around the world, filling the role held by corals today. They disappeared within the same event that killed the non-avian dinosaurs 66 million years ago.
“Rudists are quite special bivalves. There’s nothing love it living today,” de Winter said. “In the late Cretaceous especially, worldwide most of the reef builders are these bivalves. in order that they really took on the ecosystem building role that the corals have nowadays.”
The new method focused a laser on small bits of shell, making holes 10 micrometers in diameter, or about as wide as a red blood corpuscle . Trace elements in these tiny samples reveal information about the temperature and chemistry of the water at the time the shell formed. The analysis provided accurate measurements of the width and number of daily growth rings also as seasonal patterns. The researchers used differences due to the season within the fossilized shell to spot years.
The new study found the composition of the shell changed more over the course of each day than over seasons, or with the cycles of ocean tides. The fine-scale resolution of the daily layers shows the shell grew much faster during the day than in the dark
“This bivalve had a really strong dependence on this daily cycle, which suggests that it had photosymbionts,” de Winter said. “You have the day-night rhythm of the sunshine being recorded within the shell.”
This result suggests daylight was more important to the life-style of the traditional mollusk than could be expected if it fed itself primarily by filtering food from the water, like modern-day clams and oysters, consistent with the authors. De Winter said the mollusks likely had a relationship with an indwelling symbiotic species that ate up sunlight, almost like living giant clams, which harbor symbiotic algae.
“Until now, all published arguments for photosymbiosis in rudists are essentially speculative, supported merely suggestive morphological traits, and in some cases were demonstrably erroneous. This paper is that the first to supply convincing evidence in favor of the hypothesis,” Skelton said, but cautioned that the new study’s conclusion was specific to Torreites and will not be generalized to other rudists.
De Winter’s careful count of the amount of daily layers found 372 for every yearly interval. This wasn’t a surprise, because scientists know days were shorter within the past. The result’s , however, the foremost accurate now available for the late Cretaceous, and features a surprising application to modeling the evolution of the Earth-Moon system.
The length of a year has been constant over Earth’s history, because Earth’s orbit round the Sun doesn’t change. But the amount of days within a year has been shortening over time because days are growing longer. The length of each day has been growing steadily longer as friction from ocean tides, caused by the Moon’s gravity, slows Earth’s rotation. | 0.822768 | 3.2214 |
Aristarchus (310 BC - circa 230 BC) was a Greek astronomer and mathematician, born in Samos, Greece. He is the first recorded person to propose a heliocentric model of the solar system, placing the Sun, not the Earth, at the center of the known universe (hence he is sometimes known as the Greek Copernicus). His astronomical ideas were not well-received and were subordinated to those of Aristotle and Ptolemy, until they were successfully revived and developed by Copernicus nearly 2000 years later.
The only work of Aristarchus which has survived to the present time, On the Sizes and Distances of the Sun and Moon, is based on a geocentric worldview. We know through citations, however, that Aristarchus wrote another book in which he advanced an alternative hypothesis of the heliocentric model. Archimedes wrote:
- "You King Gelon are aware the 'universe' is the name given by most astronomers to the sphere the centre of which is the center of the Earth, while its radius is equal to the straight line between the center of the Sun and the center of the Earth. This is the common account as you have heard from astronomers. But Aristarchus has brought out a book consisting of certain hypotheses, wherein it appears, as a consequence of the assumptions made, that the universe is many times greater than the 'universe' just mentioned. His hypotheses are that the fixed stars and the Sun remain unmoved, that the Earth revolves about the Sun on the circumference of a circle, the Sun lying in the middle of the orbit, and that the sphere of fixed stars, situated about the same center as the Sun, is so great that the circle in which he supposes the Earth to revolve bears such a proportion to the distance of the fixed stars as the center of the sphere bears to its surface."
Aristarchus thus believed the stars to be infinitely far away, and saw this as the reason why there was no visible parallax, that is, an observed movement of the stars relative to each other as the Earth moved around the Sun. The stars are in fact much farther away than was assumed in ancient times, which is why stellar parallax is only detectable with telescopes. But the geocentric model was assumed to be a simpler, better explanation for the lack of parallax. The rejection of the heliocentric view was apparently quite strong, as the following passage from Plutarch suggests (On the Apparent Face in the Orb of the Moon):
- "[Cleanthes, a contemporary of Aristarchus] thought it was the duty of the Greeks to indict Aristarchus of Samos on the charge of impiety for putting in motion the Hearth of the universe [i.e. the earth], . . . supposing the heaven to remain at rest and the earth to revolve in an oblique circle, while it rotates, at the same time, about its own axis."
Size of the Moon
Aristarchus observed the Moon moving through the Earth's shadow during a lunar eclipse. He estimated that the diameter of the Earth was 3 times the Moon's diameter. Using Eratosthenes' calculation that the Earth was 42,000 km in circumference, he concluded that the Moon was 14,000 km in circumference. The Moon has a circumference of about 10,916 km.
Distance to the Sun
Aristarchus argued that the Sun, Moon, and Earth form a near right triangle at the moment of first or last quarter moon. He estimated that the angle was 87°. Using correct geometry, but inaccurate observational data, Aristarchus concluded that the Sun was 20 times farther away than the Moon. The Sun is actually about 390 times farther away. He pointed out that the Moon and Sun have nearly equal apparent angular sizes and therefore their diameters must be in proportion to their distances from Earth. He thus concluded that the Sun was 20 times larger than the Moon. This is also incorrect, although logical. | 0.846848 | 3.921489 |
Scientists looking at Earthshine reflected from the moon have concluded that, indeed, there is life on our planet. Though the result may be obvious, the findings can help in the search for life on other worlds.
This is not the first time that researchers have tried to see what the Earth would look like when viewed remotely. For example, the Voyager 1 spacecraft's famous Pale Blue Dot image shows the Earth from nearly 4 billion miles away, giving a rough idea of what extraterrestrial telescopes looking at our planet would observe.
The recent study tried to get an outsider perspective from slightly closer to home. The sun's rays hit the surface of the Earth and are reflected through the atmosphere. Most of that light escapes into the blackness of space but some of it bounces off the moon.
"Essentially, we use the moon as a giant mirror to look back at the Earth," said astronomer Michael Sterzik of the European Southern Observatory in Chile, who co-authored the new paper out in Nature on Feb. 29.
This light contains a great deal of information. Break the light from a distant star into a spectrum and you can determine what elements are present.
One day, when scientists can directly detect light from an Earth-like planet, they may be able to check if its atmosphere contains things like oxygen, nitrogen, and methane. If present, these gases may represent biosignatures for distant life.
In addition to checking the Earthshine's color, Sterzik and his team looked at the polarization, or direction, of the light waves bouncing off the moon. They were able to match the polarized light to different models, where our planet's surface contained potential percentages of things like oceans, continents, and vegetation.
The model that best fit the polarized light contained a combination of these elements that looked exactly like, well, Earth. Though it may seem trivial at first glance, the finding has profound implications in the search for extraterrestrial life, said astronomer Darren Williams at Penn State Erie, The Behrend College, who was not involved with the study.
"It's a demonstration that we have a fighting chance of learning what the surface of a distant planet is like," he said.
While information about Earth's biomes is useful, distant life could potentially be very exotic. Does it make sense to assume that life on other worlds will be very much like our own?
"Earth is the only example we have of a life-bearing planet," said Sterzik. "If it is typically characteristic, we don't know. But it's not absurd to assume that life evolved along the same principles elsewhere."
Image: ESO/B. Tafreshi/TWAN | 0.852891 | 3.74622 |
Currently roaming our solar system are what astrophysicists call “small bodies,” which include asteroids, trans-Neptunian objects, comets, and a category simply described as “transitional objects.” Those small bodies can be mere meters across, but some are thousands of kilometers wide—and about once a year an object the size of a washing machine enters the Earth’s atmosphere. Understanding that an asteroid did once wipe out about 95 percent of our species, and also noting that late physicist Stephen Hawking considered an asteroid collision to be earth’s biggest threat, it seems important, as a planet, to be aware.
Fortunately, we’re not going about it blindly. The Florida Space Institute (FSI), a research facility created by the State University System of Florida and the University of Central Florida, is on the case. And since the arrival of Ramon “Ray” Lugo III in 2013 as the FSI director, the grants the Institute has secured for a variety of research and educational programs—as well as the study of small bodies—have quadrupled.
Lugo came to FSI with a made-for-this-job resume. He had previously served as director at the Glenn Research Center, charged with overall management and operations of the National Aeronautics and Space Administration (NASA) facility. He has engineering and engineering management degrees, and he understands how to navigate the universe of government and university grant funding.
Because stopping those rogue chunks of space rocks is going to take some money and foresight. That’s what Lugo’s job is about, and he’s pretty clear that means recruiting the best and the brightest to make it happen.
“The idea is to create a research effort focused on space and space-related topics that are broader than what NASA does,” he says. The work of FSI goes far beyond the asteroid threat. It includes identifying commercial opportunities, the role of space in national defense, and being part of a consortium—with the University of Central Florida—that manages the Arecibo Observatory in Puerto Rico. Arecibo, built by Cornell University in the 1960s, is the largest fully operational radio telescope in the world.
“I decided I wanted to create something that would last beyond my tenure. Something that would help scientists, that would contribute to our understanding of science and space.”
On the way to becoming the leader at FSI, Lugo had gone into something of a retirement mind-set. He was initially in conversation with the Institute’s governance committee about an advisory board position, but becoming the director began to make more sense.
“We were only lightly funded at the time and there were no students on site,” he says. “I decided I wanted to create something that would last beyond my tenure. Something that would help scientists, that would contribute to our understanding of science and space.”
Lugo’s first steps were to bring in PhDs and postdoctoral scientists to attract grant funding. FSI receives $800,000 annually from the Florida state legislature for seed funding, but currently has more than $10 million from external sources happy to recognize the value of what the Institute’s scientists are doing.
That includes the development and actual manufacturing of regolith—the dust, rocks, and soil that are found on extraterrestrial bodies, including the moon. FSI is a repository of the physical and chemical makeup of this “moon dust” (and that of Mars, Jupiter, asteroids, etc), and with more than two hundred companies for customers, it is able to recover costs involved in producing it. Lugo says that government space agencies and corporations use the mineral composition to conduct research on how and why space exploration and mining will unfold in the future.
“The idea is to create a research effort focused on space and space-related topics that are broader than what NASA does.”
That regolith contributes to understanding how the universe formed billions of years ago. But in partnership with Microsoft, FSI is mining data from the past four decades that was gathered but never analyzed at the Arecibo Observatory. “Arecibo found the first pulsar ever identified,” he says. “But we have three to four petabytes [equal to three to four million gigabytes] gathered by the observatory that has never been analyzed. We now have the heuristics to understand this—and we might identify other, older pulsars.”
This is the kind of thing that excites students, both at the collegiate and postgraduate levels, but also those in high school. That includes two hundred students from Puerto Rico in the STAR (STEAM Teaching at Arecibo) Space & Planetary Sciences program who compete to visit the Institute as part of their studies.
FSI also intentionally endeavors to have one of the largest groups of female space scientists in the world. Already there are thirty women, about a third of the total, working in various capacities and programs. For example, one is a medical doctor teamed with a medical student, also female, to work on health issues associated with long-duration space flight.
So while some of the work Lugo’s people conduct at FSI includes looking out for rocks hurtling toward the earth, much more of what they do is about earthlings hurtling out to space—which is something that wouldn’t happen but for the funding and the organization to support it.
What’s the Dirt?
Space regolith—dust and loose detritus found on the moon, Mars, and other planets—might one day play a role in extraterrestrial agriculture. This is why the Exolith Lab, a wholly owned partner of the Florida Space Institute, develops facsimile regolith for experimentation sold to commercial and educational institutions.
Growing food on other moons and planets might one day enable better, healthier space exploration. The natural soil on those planets will likely need supplementation and figuring out how to do that starts with understanding what is there to begin with.
FSI’s Ray Lugo says Exolith has developed more than one hundred varieties of regolith simulants to meet specific requirements of locations. | 0.883749 | 3.231299 |
The list of Pluto's neighbors just got considerably longer, potentially boosting scientists' odds of finding the putative Planet Nine.
Astronomers have discovered 139 more "minor planets" small bodies circling the sun that are neither official planets nor comets in the dark, frigid depths beyond Neptune's orbit, a new study reports. The new additions represent nearly 5% of the current trans-Neptunian object (TNO) tally, which stands at about 3,000, the researchers said.
The scientists pored over data gathered by the Dark Energy Survey (DES) during its first four years of operation, from 2013 to 2017. The DES studies the heavens using the 520-megapixel Dark Energy Camera, which is mounted on the Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory in Chile.
Related: Trans-Neptunian objects in the outer solar system (infographic)
As the project's name implies, the main goal of the DES involves shedding light on dark energy, the mysterious force thought to be behind the universe's accelerating expansion. But the high-resolution DES imagery has a number of other applications, including the discovery of small objects in our own solar system, as the new study shows.
The researchers started out with 7 billion DES-detected dots, which they whittled down to 22 million "transients" after ruling out objects such as galaxies that appeared in roughly the same spot on multiple nights. Those 22 million were further culled to 400 TNO candidates, whose movements the team was able to track over at least six different nights.
After months of vetting by analysis and observation, the team verified 316 of the small bodies as bona fide TNOs. These cataloged objects lie between 30 and 90 astronomical units (AU) from the sun, and 139 of them are new to science, the researchers said. (1 AU is the Earth-sun distance, which is about 93 million miles, or 150 million kilometers.)
The techniques the researchers developed could aid future TNO searches, including those potentially conducted by the Vera C. Rubin Observatory, which is scheduled to come online in the early 2020s, study team members said.
"Many of the programs we've developed can be easily applied to any other large datasets, such as what the Rubin Observatory will produce," lead author Pedro Bernardinelli, a physics and astronomy graduate student at the University of Pennsylvania, said in a statement.
The team members are also now running their analyses on the DES' entire six-year data set, an effort that could yield an additional 500 or so newfound TNOs. (The DES' initial run wrapped up in 2019.) Such new additions could end up being bread crumbs that lead to Planet Nine, the hypothesized world that some scientists think lurks undiscovered in the far outer solar system, hundreds of AU from the sun.
Planet Nine's existence, after all, is inferred from weird clustering in the orbits of certain TNOs.
"There are lots of ideas about giant planets that used to be in the solar system and aren't there anymore, or planets that are far away and massive but too faint for us to have noticed yet," study co-author Gary Bernstein, an astronomy and astrophysics professor at the University of Pennsylvania, said in the same statement.
"Making the catalog is the fun discovery part," Bernstein added. "Then, when you create this resource, you can compare what you did find to what somebody's theory said you should find."
The new study was published this week in The Astrophysical Journal Supplement Series. You can read a preprint of it for free at arXiv.org.
Mike Wall is the author of "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.
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- I'd like to boldly go where everyone ought to be headed by now, by Susie Reing - The Keene Sentinel - February 1st, 2020
- Is there a 2nd planet orbiting Proxima Centauri? - EarthSky - February 1st, 2020 | 0.902078 | 3.706568 |
Planetoid 3753 Cruithne – Discovered in 1986
Planetoid 3753 Cruithne – Discovered in 1986. Its the so-called quasi-moon. Its orbit is irregular and resembles a horseshoe shape. The full trajectory lasts 770 years. In less than 3000 years, the asteroid may collide with Earth. He approaches our planet for a minimum distance of about 15 million. km. The last such approximation took place in 1900, the next one will be in 2285. If this does not happen, Cruithne is in danger of collision with Venus in 8,000 years. In the vicinity of Earth there are also two other quasi-moons named 2006 FV35 and 2010 SO16. Humanity has not come up with an effective way to prevent the possible collision of asteroids with Earth.
Measuring asteroids – Shape and size
Measuring asteroids – Shape and size – French scientists from the Observatoire de la Cote d’Azur have developed a new way of measuring the shape and size of asteroids. They used an interferometer constructed of 2 VLT telescopes, with diameters of 8.2 m. To measure the asteroid Barbara. The results indicate that the asteroid is composed of two parts with a diameter of 37 and 21 km. Apart from each other 24 km.
Space probe Galileo Jupiter
Space probe Galileo Jupiter – In October, 1989. Space shuttle Atlantis took into space probe Galileo. Did not move out of orbit straight to Jupiter, but first flew in the direction of Venus, which was used to assist gravity. In the same order twice used the Earth and finally moved toward the gas giant. Along the way, the first probe approached asteroid, specifically Gaspra, a distance of 1600 km.
Galileo probe to Jupiter was heard after 7 years and accompanied him the next 8. It became his artificial satellite. Among other things, sent into the atmosphere of Jupiter measuring instrument, which in hellish conditions lasted almost an hour. Several times flew near the Galilean moons: Io, Ganymede, Europa and Callisto. Discovered that beneath the surface of the last three is salty ocean water.
Due to the good operation of the systems, the probe mission was extended several times (the last time – at the end of April 2001.). Made a total of 34 laps around Jupiter. At that time, 7 times visited Io, Callisto 8 times, as many times Ganymede, 11 times Europe.
Phobos – One of the two moons of Mars
Phobos – One of the two moons of Mars resembles its shape potato cratered. Red Planet caught the flying asteroid and made it their satellite. Phobos looks like it went through a herd of worms, because the inside is full of holes. The object awaits the sad fate of Mars, Phobos still draws closer and for approx. 50 million years, tidal forces of Mars moon tear to shreds. Thanks to the Red Planet will become a decoration in the form of a ring. | 0.800355 | 3.507001 |
The ground begins to tremble. Massive engines roar to life, billowing clouds of exhaust. And in a blinding pillar of fire, a mighty voyager leaves the Earth behind to explore the vast universe among the stars.
Launching a rocket into space is one of humankind's crowning achievements. Although they come in many different shapes and sizes, all rockets are propelled by engines that produce thrust.
The rockets that launch into space are made up of four major systems based on function.
The structural system makes up the frame that holds a rocket together, and consists of the cylindrical body, nose cone, and fins.
Next, the propulsion system takes up the most amount of space, and includes the rocket engine, fuel, and oxidizer.
The payload system depends on each mission and consists of anything a rocket is carrying into space, like a spacecraft, satellite, or human being.
Lastly, the guidance system is made up of radars and computers that provide stability for the rocket and control maneuvers in flight.
In order to launch into space, all four of these rocket systems must work together to overcome the forces of gravity.
The launch begins when the rocket's propulsion system starts to generate a massive amount of thrust.
Thrust is the force produced by burning fuel as exhaust gases escape through the engine.
Once the rocket generates more thrust than its own weight, it lifts into the air to begin its powered ascent.
During this phase of the flight, the weight of the rocket will constantly change as fuel continues to burn off.
As a result, most space-bound rockets use a technique called "staging" to reduce dead weight and increase efficiency.
The method involves breaking up a large rocket into two or three smaller rockets that fall away at different stages of the launch.
As the rocket continues into orbit, its sophisticated guidance system maintains balance and steers to keep the flight trajectory on track.
At the correct altitude and speed, the upper stage engine cuts off—completing the rocket's journey from Earth's surface into orbit.
Long before blasting into space, rockets were used here on Earth as early as the 13th century.
The first known rockets were introduced by the Chinese in 1232 AD. These "fire arrows" were used to fight against invading armies and were made by attaching fireworks packed with gunpowder to long arrows.
By the 16th century, the use of rockets for amusement had spread from Asia to Europe, where they gained popularity in elaborate firework displays at celebrations and festivities.
During the following centuries, the work of scientists like Isaac Newton and his laws of motion began to greatly increase knowledge into the forces behind rocketry and how to control them.
And by the end of the 18th century, military forces around the world began to apply these new scientific understandings to the battlefield—transforming the earlier crude rockets into powerful weapons of war.
However, the true dawn of modern rocketry began in the early 20th century, thanks to massive technological improvements in rocketry and aeronautics.
By the 1950s, the stage was set for the modern Space Age and development began on sophisticated launch vehicle systems like: the Atlas rocket family, which launched America's first astronaut into orbit; the Titan rockets, which were behind the pivotal Gemini missions during the Space Race; and the Saturn rocket family, which includes the largest and most powerful rocket ever successfully launched—the mighty Saturn V.
Standing as high as a 36-story building and weighing more than 3,000 tons, this behemoth was used to launch the Apollo missions to the moon.
Since the beginning of human history, adventurers have looked to the skies and dreamed of touching the stars.
And today, innovations in rocketry are opening up possibilities to launch astronauts farther into space than ever before.
Whether our sights are set on the Moon, Mars, or beyond, the future of rocketry in space exploration is only just blasting off. | 0.818721 | 3.836598 |
Mysterious worlds with icy, dense cores surrounded by clouds of gas, or rocky planets like our own — the conditions in our solar system are astoundingly different, but there are fascinating similarities between its worlds. Jovian planets were formed outside the frost line, while the terrestrial planets were bathed in warm sun rays. Vastly different conditions led to the creation of worlds that would float on water and worlds suitable for manned missions; nonetheless, they share some striking likenesses.
Terrestrial and Jovian Planets
Each planet orbiting our sun is unique. Yet the four inner planets have much in common. Mercury, Venus, Earth and Mars are terrestrial or telluric planets. They are rocky with a dense metal core consisting mostly of iron. Planetary scientists theorize that Mars and Venus may once have had conditions like Earth's, favorable to life. The name "terrestrial" comes from the Latin word "terra," which means land. There are at least four Jovian or gas planets in our solar system. Jovian planets such as Jupiter, Saturn, Uranus and Neptune are large planets that are composed of light materials such as hydrogen and helium. The name "Jovian" comes from the planets' resemblance to Jupiter. The moniker "gas planet" is slightly misleading, since the interior of these frigid planets is gas supercooled to a liquid state.
Our solar system is part of a larger solar nebula. A solar nebula consists of a cloud of gas and dust left after a sun has formed. The discovery of extrasolar planets has introduced problems into our understanding of solar system formation. For now, the nebula theory of planet formation is the most popular explanation. That theory holds that all the planets in our solar system were formed from the same material. The natural elements present on the planets today were present in that solar nebula. Our sun and the Jovian planets consist mainly of hydrogen and helium, while the inner rocky planet consists mainly of silicon, iron and copper. All planets in our system are spherical. Yet the poles on terrestrial planets are less flat. Terrestrial planets spin slower and this affects their overall shape.
Most of the planets in our solar system have a nearly circular orbit around our sun. The astronomer Johannes Kepler discovered that the orbits are actually ellipses. The only planet that has a different orbit is Mercury. A planet’s orbit is described by referring to earth’s orbital angle. Mercury’s orbit is inclined by 7 degrees to Earth’s orbital plane, while Jupiter’s is just over 1 degree. Thus, there are similarities between terrestrial and Jovian planets when you describe their orbits around our sun.
Core and Atmosphere
The planets in our solar system have similar interiors composed of a core and a mantle. Terrestrial planets also have a crust or a solid outer shell. The core of terrestrial planets consists mainly of iron, wrapped in a silicate mantle. Computer models suggest that Jovian planets have a core consisting of rock, metal and hydrogen. A gaseous atmosphere surrounds both types of planets. Jovian planets may consist of a gaseous "surface," but they still have separate atmospheres with cloud layers.
Weather and Magnetic Fields
Terrestrial and Jovian planets have weather. Photos of all the planets in our system show bands and spots indicating weather activity. That means storms and winds influence the conditions on the planets. Storms on Jovian planets are intense and can affect the clouds that surround the planets, which can be seen from Earth-based telescopes. Jovian planets have several layers of clouds of varying colors, with the top layers consisting of red clouds and the bottom of blue clouds. Intense storms move the layers of clouds around and the color of the area changes. Jupiter has a storm area that is the size of two Earths. NASA says the storms on Jupiter are so powerful that they drag material from beneath Jupiter's cloudtops and lift it to different cloud layers. Terrestrial planets also have clouds, but the effects of weather are less severe. A strong magnetic field is common on the Jovian planets, and several terrestrial planets have magnetic fields. Earth's magnetic field helps create the planet's auroras by deflecting the charged particles of the "solar wind."
- Ablestock.com/AbleStock.com/Getty Images | 0.858405 | 3.722134 |
The Snowflake Cluster is a young open cluster located in the constellation Monoceros. It is one of the objects found within the designation NGC 2264, along with the Cone Nebula, the Christmas Tree Cluster, and the Fox Fur Nebula, but not officially included. The cluster lies at an approximate distance of 2,400 light years from Earth.
The Snowflake Cluster is part of the larger Christmas Tree Cluster. It consists of a compact group of bright protostars that appear geometrically arranged in a pattern similar to that of a single crystal of snow. The young stars in the cluster seem to have formed in regularly spaced intervals in a structure that now resembles a snowflake or spokes of a wheel.
Snowflake Cluster. Image: NASA/JPL-Caltech/P.S. Teixeira (Center for Astrophysics)
The stars in the cluster are tightly packed and believed to be only 100,000 years old. They have not yet moved away from their stellar nursery. The snowflake pattern will dissipate when they eventually do.
Object type: Open cluster
Distance: 2,400 light years
Newborn stars, hidden behind thick dust, are revealed in this image of a section of the Christmas Tree Cluster from NASA’s Spitzer Space Telescope. The newly revealed infant stars appear as pink and red specks toward the center and appear to have formed in regularly spaced intervals along linear structures in a configuration that resembles the spokes of a wheel or the pattern of a snowflake. Hence, astronomers have nicknamed this the “Snowflake Cluster.” Star-forming clouds like this one are dynamic and evolving structures. Since the stars trace the straight line pattern of spokes of a wheel, scientists believe that these are newborn stars, or “protostars.” At a mere 100,000 years old, these infant structures have yet to “crawl” away from their location of birth. Over time, the natural drifting motions of each star will break this order, and the snowflake design will be no more. While most of the visible-light stars that give the Christmas Tree Cluster its name and triangular shape do not shine brightly in Spitzer’s infrared eyes, all of the stars forming from this dusty cloud are considered part of the cluster. Like a dusty cosmic finger pointing up to the newborn clusters, Spitzer also illuminates the optically dark and dense Cone Nebula, the tip of which can be seen towards the bottom left corner of the image. Image: NASA/JPL-Caltech/P.S. Teixeira (Center for Astrophysics) | 0.876423 | 3.835125 |
NASA's Hubble telescope has provided scientists with some of the most detailed and farthest views of the observable universe. Since launching in 1990, Hubble has made more than 1.4 million observations and scientists have published more than 17,000 scientific papers based on these observations.
When Hubble launched aboard the Space Shuttle Discovery, NASA said the mission kick-started a revolution in astronomy.
The US space agency said: "Developed as a partnership between the United States space program and the European Space Agency, Hubble orbits 340 miles above Earth’s surface.
"Its gaze outward lies beyond the distorting effects of the atmosphere, which blurs starlight and blocks some important wavelengths of light from reaching the ground.
"This vantage point allows Hubble to observe astronomical objects and phenomena more consistently and with better detail than generally attainable from ground-based observatories."
READ MORE: Alien technology discovered on Mars?
The Eagle Nebula (M16) - Pillars of Creation, 1995
This striking image of the Eagle Nebula is perhaps Hubble's best-known photo.
The picture features colossal columns of stellar gas and dust that have been dubbed the Pillars of Creation.
The tallest of the pillars measure approximately four light-years across - 23,514,501,000,000 miles.
NASA said: "As the pillars themselves are slowly eroded away by the ultraviolet light, small globules of even denser gas buried within the pillars are uncovered.
"Forming inside at least some of the globules are embryonic stars."
Omega Nebula (M17), 2003
Hubble orbits 340 miles above Earth’s surface
This beautiful collage of swirling colours "resembling the fury of a raging sea" is a large cloud of hydrogen, oxygen and sulfur.
Dubbed the Omega Nebula, the cloud is also known as the Swan Nebula or Messier 17 (M17).
NASA said: "The ultraviolet radiation is carving and heating the surfaces of cold hydrogen gas clouds.
"The warmed surfaces glow orange and red in this photograph."
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Jupiter and Its Moon Io, 1999
Nine years after Hubble was placed in orbit around Earth, the space telescope caught a glimpse of Jupiter and it's moon Io.
In the photo, you can see the moon dwarfed by the gas giant as it casts its shadow on Jupiter's surface.
NASA said: "While hunting for volcanic plumes on the volatile moon Io, the Hubble Space Telescope captured this image of Io sweeping across the giant face of Jupiter and casting its shadow below.
"The smallest details visible on Io and Jupiter measure 93 miles (150 kilometres) across, or about the size of Connecticut.
"The bright patches on Io are regions of sulfur dioxide frost."
Cone Nebula, 2002
In this image, NASA's Hubble photographed an ominous-looking column of gas officially known as NGC 2264.
The Cone Nebula sits within a turbulent region of space known for star formation.
NASA said: "Resembling a nightmarish beast rearing its head from a crimson sea, this monstrous object is actually an innocuous pillar of gas and dust."
The Nebula is about as long as 23 million trips to the Moon and back from Earth. | 0.855835 | 3.080489 |
Google has declared war on the independent media and has begun blocking emails from NaturalNews from getting to our readers. We recommend GoodGopher.com as a free, uncensored email receiving service, or ProtonMail.com as a free, encrypted email send and receive service.
06/05/2018 / By Edsel Cook
The mantles of Earth and Mars boast a lot of iron and “iron-loving” metals, more than what should be present from planetary formation. In a Space.com article, a new study suggests that these metallic bounties resulted from the impacts of giant space rocks in the distant past.
Planets start out as tiny grains of cosmic dust that accumulate to form planetesimals. These “minute planets” will keep bumping into each other until they are either hurled outside the star system, devoured by the star, or form a stable planet.
Even after reaching planethood, a celestial body continues to grow. The leftover planetary material fall on the surface of the young planets in a process called “late accretion.”
A joint research team from the Tokyo Institute of Technology (Tokyo Tech) and the University of Colorado, Boulder (CU) investigated a giant impact that took place during Mars’ late accretion. They believed this impact explains why the mantle of the Red Planet has large amounts of rare noble metals.
A similar impact supposedly accounts for the same reason why Earth’s mantle has so much resources. (Related: Study of microbes from extreme habitats may aid search for life on Mars.)
Once a proto-planet gets far enough into the accretion process, its core forms when certain metals start sinking into it. Iron and nickel are some of these metals, which is why Earth’s core is mostly nickel-iron. The same holds true for Mars.
The iron and nickel also drag down siderophiles, which are elements that easily bond with iron. Some examples of siderophiles are gold, iridium, and platinum.
The mantles of Earth and Mars, however, contain higher siderophiles than normal. Planetary expert Ramon Brasser of Tokyo Tech says those metals would have sunk through the mostly silicate mantle to get to the core.
Brasser believes the siderophiles in the mantle arrived after the core and mantle became distinct layers. In a different paper published in 2016, he showed that the abundance of siderophile elements on Earth came from a giant impact and not late accretion.
Furthermore, he showed that this same impact could have been the one that formed the Moon. A lunar-sized impactor would have been big enough to ensure the siderophile levels in Earth’s mantle.
Meteorites from Mars provide evidence that the Red Planet gained another 0.8 percent mass during late accretion. Brasser and his CU partner Stephen Mojzsis published a new paper saying that this gain would have been produced by a single collision event involving an impactor with a diameter of 745 miles (1,200 km).
Furthermore, the researchers say that the impact occurred after the formation of Mars’ core but before its crust solidified. They based their findings on the presence of zircon crystals in meteorites from Mars.
If the impactor arrived during the formation of the core, it would have ripped out the siderophiles. Neither could it have taken place once the crust had solidified because it would have left massive marks on the surface of the planet.
A giant impact could also explain why the northern and southern hemispheres of Mars look different. The southern hemisphere looks older and is pockmarked by craters. Meanwhile, the surface of the northern half of the planet seems smoother and younger. It also shows higher signs of volcanic activity.
There is also a theory that the giant impact created Phobos and Deimos, the two tiny moons of Mars. Other experts argue that Phobos is an asteroid that was captured by Mars’ gravity.
You can read more about our ever-expanding knowledge of Mars at Space.news.
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Asteroids are awkward to photograph. Can you imagine how hard it is to spot one of these tiny, dark lumps of rock against the blackness of our night sky? Plus, they don’t stay in one place. Like Earth, asteroids move around the Sun. And, as the Earth rotates, different asteroids become visible in the sky.
But astronomers don’t give up easily, and asteroids are something they really want to study.
Understanding what asteroids are made from will help us find out how our planet and Solar System were made. Studying them can even keep us safe — knowing where asteroids are and how they are moving means we'll know if one is on a crash-course with Earth!
The asteroid in this photograph is called Itokawa. It became famous in 2005 when a Japanese spacecraft called Hayabusa visited it and took some photographs – including this one! Thanks to Hayabusa, we know the exact (odd) shape of Itokawa and its size, which is just under twice the length of the Eiffel Tower. But what’s under the surface?
To answer this question astronomers’ eyes have been on Itokawa once again, using telescopes across the world. By very carefully watching how the asteroid spins around and using exact measurements of its weird shape, astronomers have been able to peer under the surface into Itokawa’s rocky heart. And what they found was very strange indeed.
Inside, the asteroid seems to be made of two very different pieces of rock that have somehow merged together. This means that Itokawa was probably formed when two asteroids crashed and stuck together!
Hayabusa’s mission to Itokawa was actually a bit of a disaster. The spacecraft was supposed to collect samples of material from the asteroid, but it wasn’t working properly. Luckily, the spacecraft accidentally bumped into the asteroid and happened to scrape off some rock to bring home! | 0.81308 | 3.385439 |
Crescent ♍ Virgo
Moon phase on 30 October 2013 Wednesday is Waning Crescent, 25 days old Moon is in Virgo.Share this page: twitter facebook linkedin
Previous main lunar phase is the Last Quarter before 3 days on 26 October 2013 at 23:41.
Moon rises after midnight to early morning and sets in the afternoon. It is visible in the early morning low to the east.
Moon is passing about ∠17° of ♍ Virgo tropical zodiac sector.
Lunar disc appears visually 5.9% narrower than solar disc. Moon and Sun apparent angular diameters are ∠1821" and ∠1933".
Next Full Moon is the Beaver Moon of November 2013 after 18 days on 17 November 2013 at 15:16.
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 25 days old. Earth's natural satellite is moving from the second to the final part of current synodic month. This is lunation 170 of Meeus index or 1123 from Brown series.
Length of current 170 lunation is 29 days, 12 hours and 15 minutes. It is 43 minutes longer than next lunation 171 length.
Length of current synodic month is 29 minutes shorter than the mean length of synodic month, but it is still 5 hours and 40 minutes longer, compared to 21st century shortest.
This lunation true anomaly is ∠285.3°. At the beginning of next synodic month true anomaly will be ∠315°. The length of upcoming synodic months will keep decreasing since the true anomaly gets closer to the value of New Moon at point of perigee (∠0° or ∠360°).
4 days after point of apogee on 25 October 2013 at 14:25 in ♋ Cancer. The lunar orbit is getting closer, while the Moon is moving inward the Earth. It will keep this direction for the next 6 days, until it get to the point of next perigee on 6 November 2013 at 09:28 in ♐ Sagittarius.
Moon is 393 568 km (244 552 mi) away from Earth on this date. Moon moves closer next 6 days until perigee, when Earth-Moon distance will reach 365 362 km (227 025 mi).
10 days after its descending node on 19 October 2013 at 21:47 in ♉ Taurus, the Moon is following the southern part of its orbit for the next 3 days, until it will cross the ecliptic from South to North in ascending node on 3 November 2013 at 06:52 in ♏ Scorpio.
23 days after beginning of current draconic month in ♏ Scorpio, the Moon is moving from the second to the final part of it.
7 days after previous North standstill on 23 October 2013 at 09:13 in ♊ Gemini, when Moon has reached northern declination of ∠19.509°. Next 6 days the lunar orbit moves southward to face South declination of ∠-19.511° in the next southern standstill on 6 November 2013 at 06:43 in ♐ Sagittarius.
After 4 days on 3 November 2013 at 12:50 in ♏ Scorpio, the Moon will be in New Moon geocentric conjunction with the Sun and this alignment forms next Sun-Moon-Earth syzygy. | 0.848363 | 3.188821 |
(CN) – Helium has been detected in the atmosphere of a planet outside our solar system for the first time, a team of astronomers reported Tuesday.
Helium – the second most common element in the universe – has been predicted to be one of most easily detected gases on large exoplanets, which orbit a star other than the sun. It is also one of the main components of the gas giants Jupiter and Saturn.
But despite helium’s prevalence in the universe, detection of it on large exoplanets has eluded astronomers until now.
Detailed in a study published in the journal Nature, the groundbreaking discovery reveals a massive volume of helium in the upper atmosphere of the exoplanet WASP-107b. Discovered in 2017, WASP-107b is 200 light-years from Earth in the constellation Virgo.
The astronomers say their findings could pave the way for scientists to detect more atmospheres around the Milky Way’s Earth-sized exoplanets.
“We hope to use this technique with the upcoming James Webb Space Telescope, for example, to learn what kind of planets have large envelopes of hydrogen and helium, and how long planets can hold on to their atmospheres,” said lead author Jessica Spake, a doctoral student at the University of Exeter in the United Kingdom.
“By measuring infrared light, we can see further out into space than if we were using ultraviolet light.”
Orbiting its host star every six days, WASP-107b has one of the chilliest atmospheres of any known exoplanet. At 932 degrees Fahrenheit, however, it is significantly hotter than Earth.
And while similar in size to Jupiter, the very low-density exoplanet is just 12 percent of its mass.
By analyzing the spectrum of light passing through the upper portion of WASP-107b’s atmosphere, the team was able to detect helium in an excited state.
The considerable strength of the signal measured capitalized on a new technique that does not rely on ultraviolet measurements, which have traditionally been used to analyze upper atmospheres of exoplanets. The astronomers believe this new approach, which uses infrared light, could establish new paths to exploring the atmospheres of Earth-sized exoplanets across the universe.
“The helium we detected extends far out to space as a tenuous cloud surrounding the planet,” said co-author Tom Evans, a research fellow at the University of Exeter. “If smaller, Earth-sized planets have similar helium clouds, this new technique offers an exciting means to study their upper atmospheres in the very near future.”
The first evidence of helium occurred as an unknown yellow spectral line signature in 1868. British astronomer Norman Lockyer was the first to suggest the line was due to a new element and subsequently named it after Helios, the personification of the sun in Greek mythology.
The research was funded by NASA, Tennessee State University, the state of Tennessee’s Centers of Excellence program, and the David and Lucile Packard Fellowship for Science. | 0.865555 | 3.823505 |
Image credit: NASA
A new study of Jupiter’s moon Europa may help explain how giant ice domes can form on its surface; places which could contain life. The study predicts that impurities in the water, like salt or sulfuric acid, could be the mechanism that allows blobs of ice to be pushed up through the 13 km thick sheet of ice that covers a water ocean. These blobs could contain microbes that lived inside the ocean and they would be much more accessible to a lander than trying to pierce the moon’s icy shell.
A new University of Colorado at Boulder study of Jupiter’s moon Europa may help explain the origin of the giant ice domes peppering its surface and the implications for discovering evidence of past or present life forms there.
Assistant Professor Robert Pappalardo and doctoral student Amy Barr previously believed the mysterious domes may be formed by blobs of ice from the interior of the frozen shell that were being pushed upward by thermal upwelling from warmer ice underneath. Europa is believed to harbor an ocean beneath its icy surface.
But the scientists now think the dome creation also requires small amounts of impurities, such as sodium chloride or sulfuric acid. Basically the equivalent of table salt or battery acid, these compounds melt ice at low temperatures, allowing warmer, more pristine blobs of ice to force the icy surface up in places, creating the domes.
“We have been trying for some time to understand how these ice blobs can push up through the frozen shell of Europa, which is likely about 13 miles thick,” said Pappalardo of the astrophysical and planetary sciences department. “Our models now show that a combination of upwelling warm ice in the frozen shell’s interior, combined with small amounts of impurities such as sodium chloride or sulfuric acid, would provide enough of a force to form these domes.”
A paper on the subject co-authored by Pappalardo and Barr was presented at the annual Division of Planetary Sciences Meeting held Sept. 2 through Sept. 6 in Monterey, Calif. DPS is an arm of the American Astronomical Society. The meeting schedule is available at http://dps03.arc.nasa.gov/administrative/schedule/index.html.
Europa appears to have strong tidal action as it elliptically orbits Jupiter – strong enough “to squeeze the moon” and heat its interior, said Pappalardo. “Warm ice blobs rise upward through the ice shell toward the colder surface, melting out saltier regions in their path. The less dense blobs can continue rising all the way to the surface to create the observed domes.”
The domes are huge – some more than four miles in diameter and 300 feet high – and are found in clusters on Europa’s surface, said Barr, who did much of the modeling. “We are excited about our research, because we think it now is possible that any present or past life or even just the chemistry of the ocean may be lifted to the surface, forming these domes. It essentially would be like an elevator ride for microbes.”
Barr likened the upwelling of warmer ice from the inner ice shell to its surface to a pot of boiling spaghetti sauce. “The burner under the pan sends the hottest sauce to the top, creating the bubbles at the surface,” she said. “The trouble is Europa’s icy skin is as cold and as hard as a rock.”
The idea that either small amounts of salt or sulfuric acid might help to create Europa’s domes was Pappalardo’s, who knew about similar domes on Earth that form in clumps in arid regions. On Earth, it is salt that is buoyant enough to move up through cracks and fissures in rock formations to form dome clusters at the surface.
“In addition, infrared and color images taken of Europa by NASA’s Galileo spacecraft seem to indicate some of the ice on the surface of these domes is contaminated. Impurities seen at the surface are clues to the internal composition of the Jovian moon, telling of a salty ice shell,” he said.
“The surface of Europa is constantly being blasted by radiation from Jupiter, which likely precludes any life on the moon’s surface,” said Barr. “But a spacecraft might be able to detect signs of microbes just under the surface.”
Both Pappalardo and Barr also are affiliated with CU-Boulder’s Laboratory for Atmospheric and Space Physics. The project was funded by NASA’s Exobiology Program and Graduate Student Research Program.
Pappalardo recently served on a National Research Council panel that reaffirmed a spacecraft should be launched in the coming decade with the goal of orbiting Europa. He currently is part of a NASA team developing goals for the Jupiter Icy Moons Orbiter mission.
The scientific objectives of the mission probably will include confirming the presence of an ocean at Europa, remotely measuring the composition of the surface and scouting out potential landing sites for a follow-on lander mission.
Original Source: University of Colorado at Boulder Press Release | 0.865475 | 3.806174 |
An X-ray view of the remnant left behind by Kepler’s supernova of 1604. The different colours indicate different energies of X-rays, while the background stars are from the Digitised Star Survey. Courtesy X-ray: NASA/CXC/NCSU/M.Burkey et al.; optical: DSS
This time of the year it is appropriate to contemplate the star of Bethlehem that is briefly mentioned in the in the New Testament’s Gospel of Matthew. Over the years astronomers have engaged in considerable speculation on what the star may have been, putting aside any considerations on whether it was meant to be purely miraculous or a rare, but natural phenomenon. With little description given – if it had been described as a hairy star we would know that it was a comet or if it had been described as new star we would know it was a nova or a supernova – there is scope for a wide range of suggestions: comet, nova, supernova, planetary conjunction and more.
Here we will mention just two of the theories that astronomers have suggested to account for the star. We will start with that of the late 16th/early 17th century German astronomer Johannes Kepler and then follow with Michael Molnar’s recent exposition that is regarded as a game-changer in tackling the problem.
In the autumn of 1604 European astronomers and astrologers were all carefully watching as the planets Jupiter, Saturn and Mars bunched close together in the sky. Kepler, observing from Prague, missed both the conjunction of Mars with Jupiter on 26 September and the conjunction of Mars with Jupiter on 9 October due to cloud. However, the day after the Mars-Jupiter conjunction a friend of Kepler saw a bright new star near Jupiter that Kepler himself saw a week later. He studied it diligently as it faded over the course of the next year and wrote up his observation in a book published in 1606. Of course, Kepler had no idea what he called the “Nova Stella” could have been; today we know that it was a supernova or exploding star and so far the last to be seen in our own galaxy.
From his observations Kepler drew the conclusion that important planetary conjunctions could be the precursors of the appearance of a new star. He calculated that there was a Saturn and Jupiter conjunction in June 7 BC and proposed that that was the time the star of Bethlehem appeared. He considered what this star may have been like and concluded that it “was not of the ordinary run of comets or new stars, but by a special miracle moved in the lower layer of the atmosphere”.
Not much credibility can be given to Kepler’s suggestion, but the work of Michael Molnar published as a book in 1999 has been treated most seriously by scholars. Molnar says that we should look for an event that astrologers of the time would have regarded as significant and not for phenomena such as novae or supernovae that modern astronomers would find of interest. As a first step Molnar deciphers the text describing that the star was seen “in the east” as meaning a heliacal rising, which is when a planet or star can be first seen in the dawn sky after a period of being too near the Sun.
In a complex discussion Molnar establishes the event as the heliacal rising of Jupiter on 17 April 6 BC, when Jupiter also approached the crescent Moon. Although the crescent Moon was too thin and too close to the Sun to be seen, according to Molnar that made no difference as the astrologers of the time could calculate that the event happened and that was sufficient for them.
The conclusion that the star of Bethlehem was an unobservable celestial event is somewhat unsatisfactory and Molnar may not be right in his choice of event. However, his idea of thinking about the star on the basis of the astrology of the time instead of the view point of contemporary astronomy represent a shift in attitude that is likely to be followed by future scholars. That these future scholars will ever come up with a definitive answer seems unlikely, but like the astronomers so far, they will have fun trying.
W. Burke-Gaffney, SJ, “Kepler and the star of Bethlehem”, Journal of the Royal Astronomical Society of Canada, Volume 31, pp 417-425 (1937)
Michael Hoskin, David W. Hughes and J. Neville Birdsall, Review Symposium “The star of Bethlehem”, Journal of the History of Astronomy, volume 33, pp 386-394 (2002)
Michael R Molnar, “The star of Bethlehem: the legacy of the Magi”, Rutgers University Press, New Brunswick and London (1999) | 0.86884 | 3.756377 |
Jupiter's Length of Rotation & Revolution
Although Pluto had to say goodbye to planet status, Jupiter is not going anywhere. Pluto’s problem centered on its small mass, but Jupiter has that covered. The other planets in Earth’s solar system pale in comparison to Jupiter. In fact, Jupiter is so massive that it could hold the other seven planets. Although Jupiter is a standout, it still rotates on its axis and orbits the sun, just like Earth does. However, the time required for these events to occur is very different.
When a planet rotates, it turns on its axis. On Earth, this causes day and night. Most planets, including Jupiter, rotate counterclockwise. When it comes to rotation, Jupiter is the leading planet once again; it has the fastest spin. Jupiter completes its rotation in just under 10 Earth hours. Because Jupiter is primarily made of gases, the entire planet does not rotate at the same rate. Just above and below its equator, Jupiter’s rotation takes 9 hours and 50 minutes. The speed slows by about 5 minutes for areas farther from the equator. The average rate for the whole planet is 9.9 hours.
The Battle of the Bulge
As Jupiter spins, it is not a perfect sphere. The equator protrudes, making the planet look like a flattened ball. In a completely rounded ball, any radius has the same measurement. On Jupiter, the distance from the planet’s center to the poles is about 41,507 miles. However, the radius to its equator is more than 44,428 miles. Because of its squashed shape, astronomers believe that Jupiter has a rock core even though the planet is primarily made of hydrogen and helium gases.
Quite a Trip
Like all the planets, Jupiter orbits the center of the mass of the solar system, which is close to the sun’s surface. However, since the sun contains so much of the system’s mass, it appears that the planets revolve around their star. Jupiter’s average orbit is more than 480 million miles from the sun. Compare that to Earth’s, which is about 93 million miles. Earth tilts 23.5 degrees on its axis, which causes the seasons. This is a significant angle, and summer occurs in the hemisphere with the pole closest to the sun. Jupiter, however, tips only about 3 degrees, so it does not have different seasons.
A Slow Jouney
Jupiter orbits the sun in an oval pattern. To follow this path, the planet must travel more than 3 billion miles. This trip takes almost 12 Earth years. Jupiter’s neighbors show dramatic contrast. The small planet Mars, which is closer to the sun, completes its orbit in about two Earth years. Saturn lies beyond Jupiter and takes almost 30 years to orbit. Almost 5,000 asteroids share Jupiter’s orbit around the sun, which earns them the label “Trojan asteroids.” About 65 percent of these asteroids precede the planet, while the rest trail slightly behind.
- IAU: Pluto and the Developing Landscape of Our Solar System
- NASA Education: What Is Jupiter?
- San Jose State University: The Direction of the Rotation of Planets
- Universe Today: Rotation of Jupiter
- Nanjing University: School of Astronomy and Space Sciences: Chapter 11
- Universe Today: How Long Does It Take Jupiter to Orbit the Sun?
- Northwestern University: Qualitative Reasoning Group -- What Are the Orbital Lengths and Distances of Objects in Our Solar System?
- Swinburne University of Technology: Cosmos -- Trojan Asteroid
- Ablestock.com/AbleStock.com/Getty Images | 0.879586 | 3.608406 |
Crescent ♏ Scorpio
Moon phase on 18 December 2079 Monday is Waning Crescent, 25 days old Moon is in Scorpio.Share this page: twitter facebook linkedin
Previous main lunar phase is the Last Quarter before 3 days on 15 December 2079 at 06:43.
Moon rises after midnight to early morning and sets in the afternoon. It is visible in the early morning low to the east.
Moon is passing first ∠4° of ♏ Scorpio tropical zodiac sector.
Lunar disc appears visually 6.8% narrower than solar disc. Moon and Sun apparent angular diameters are ∠1822" and ∠1950".
Next Full Moon is the Wolf Moon of January 2080 after 19 days on 7 January 2080 at 01:45.
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 25 days old. Earth's natural satellite is moving from the second to the final part of current synodic month. This is lunation 988 of Meeus index or 1941 from Brown series.
Length of current 988 lunation is 29 days, 19 hours and 2 minutes. It is 22 minutes shorter than next lunation 989 length.
Length of current synodic month is 6 hours and 18 minutes longer than the mean length of synodic month, but it is still 45 minutes shorter, compared to 21st century longest.
This New Moon true anomaly is ∠148.4°. At beginning of next synodic month true anomaly will be ∠174.6°. The length of upcoming synodic months will keep increasing since the true anomaly gets closer to the value of New Moon at point of apogee (∠180°).
9 days after point of perigee on 9 December 2079 at 06:48 in ♊ Gemini. The lunar orbit is getting wider, while the Moon is moving outward the Earth. It will keep this direction for the next 5 days, until it get to the point of next apogee on 23 December 2079 at 21:45 in ♑ Capricorn.
Moon is 393 399 km (244 447 mi) away from Earth on this date. Moon moves farther next 5 days until apogee, when Earth-Moon distance will reach 406 703 km (252 714 mi).
1 day after its descending node on 17 December 2079 at 08:14 in ♎ Libra, the Moon is following the southern part of its orbit for the next 13 days, until it will cross the ecliptic from South to North in ascending node on 31 December 2079 at 23:44 in ♈ Aries.
13 days after beginning of current draconic month in ♈ Aries, the Moon is moving from the second to the final part of it.
8 days after previous North standstill on 9 December 2079 at 17:56 in ♊ Gemini, when Moon has reached northern declination of ∠28.228°. Next 4 days the lunar orbit moves southward to face South declination of ∠-28.189° in the next southern standstill on 23 December 2079 at 10:12 in ♑ Capricorn.
After 4 days on 23 December 2079 at 06:31 in ♑ Capricorn, the Moon will be in New Moon geocentric conjunction with the Sun and this alignment forms next Sun-Moon-Earth syzygy. | 0.848363 | 3.068913 |
Nature always humbles us on both large and small scales, but never more so than when finding surprising similarities between lowly slime mold networks and the filamentary nature of the cosmos itself. To wit, astronomers at the University of California at Santa Cruz have used a slime mold model to fill gaps in models of the local cosmic web. That is, filaments of matter both seen and unseen which trace the gaseous and galactic structure of the universe.
It seems counterintuitive that the growth patterns of a bright yellow slime mold typically found growing on dead logs in the forest could help fill gaps in the local cosmic web. But Physarum polycephalum does so effectively and with more efficiency than the best algorithms computers can muster.
In a paper appearing in The Astrophysical Journal Letters, the authors note that they were able to come up with a computer algorithm based on the mold’s own characteristic behavior and test it against a computer simulation of the growth of dark matter filaments lying within 500 million light years of Earth.
The research provides the first conclusive association between the diffuse gas in the space between galaxies and the large-scale structure of the cosmic web, says the university.
“By using the slime mold simulation to find the location of the cosmic web filaments, including those far from galaxies, we could then use the Hubble Space Telescope’s archival data to detect and determine the density of the cool gas on the very outskirts of those invisible filaments,” Joe Burchett, postdoctoral fellow in astronomy and astrophysics at Santa Cruz, said in a statement. “Scientists have detected signatures of this gas for over half a century, and we have now proven the theoretical expectation that this gas comprises the cosmic web.”
The team noticed a striking similarity between how the slime mold builds complex filaments to capture new food, and how gravity, in shaping the universe, constructs the cosmic web strands between galaxies and galaxy clusters, says the Space Telescope Science Institute.
Burchett gave co-author Oskar Elek, a computational media scientist at Santa Cruz, a dataset of 37,000 galaxies from the Sloan Digital Sky Survey (SDSS), the university reports. When they applied their new algorithm to it, the result was a pretty convincing representation of the cosmic web, notes the university.
Using data from the Hubble Space Telescope’s Cosmic Origins Spectrograph, the team was able to observe the distinctive absorption signature in the spectrum of light that passes through it, and the sight-lines of hundreds of distant quasars that pierce the volume of space occupied by the SDSS galaxies, says the university.
This lowly slime mold does a good job of characterizing the large-scale structure of the Universe over a wide range of scale, Burchett told me.
“I see how it works from a mathematical and [topological] perspective, but that doesn't diminish my continued amazement that the slime mold-inspired method handles this difficult problem so elegantly and efficiently,” Burchett told me. | 0.889641 | 4.051763 |
When astronomers observe some past dwarfs, they sometimes notice a small amount of hydrogen trapped in the upper layers of a star. It is believed that this tiny stellar husk is the result of absorption of interstellar hydrogen gas, but now the team of researchers suggests that this is due to something else: most likely, comets slide down into the ancient atmosphere of white dwarfs from the Oort cloud.
White dwarfs form after the stars of the solar type consume most of their hydrogen fuel. This causes the star to move from a quieter state to a more cruel one - a red giant. In the end, after the powerful stellar convulsions, the red giant explodes, leaving a dense white dwarf in its place.
The structure of the white dwarf is not supported by external pressure, the source of which is a thermonuclear reaction, but due to the quantum pressure created by the remaining electrons, which interfere with its own gravity. This balance between forces creates a very dense stellar object, which can have a mass comparable to the Sun, but have the diameter of the Earth. Thus, white dwarfs can continue to shine for many billions of years.
When observing the spectrum of white dwarfs, astronomers note that many of them have atmospheres rich in various metals. From the point of view of astronomy, this means that there are trapped elements in the upper layers of the white dwarf heavier than helium. Depending on the elements present, astronomers interpret these astronomical imprints as the result of the destruction of asteroids or even planets that survived the death of their own star. This shredded, dusty material, in the form of rain, is showered on white dwarfs, leaving spectroscopic imprints of the death of planetary systems. This explored area of the white dwarf leads scientists to some fascinating observations of star systems that resemble our solar system, or rather, it will look like in a few billion years when our sun runs out of fuel and it turns into a white dwarf. Planets and asteroids located next to the corpse of our Sun will be torn apart, thereby enriching the white dwarf of our Sun with metals.
In a new study, accepted for publication in the Monthly Notices of the Royal Astronomical Society, astrophysicist Dmitry Veras and his colleagues at the University of Warwick found a possible mechanism that links the atmosphere of a white dwarf with not hydrogen, but metals.
"We are exploring the possibility that the gradual accretion of the Oort comets, which are a rich source of hydrogen, by the comets, contributes to an obvious increase in the volume of hydrogen in the atmosphere of a white dwarf," writes Veras.
"It used to be believed that the buildup of hydrogen in a white dwarf atmosphere is the result of interstellar hydrogen collected by a white dwarf, but for the observed values, there must be another source," says Veras.
Our solar system has a region of space containing billions of ice bodies - comets. This region, known as the Oort cloud, is located at a distance of one light year. Periodically, with a close star passage, the gravitational calm of comets is broken and knocks them out of the Oort cloud. Under the force of gravity of the Sun, comets begin their journey to the inner part of the solar system. The presence of comets has been detected around other stars, primarily due to the detection of comet dust around young stars. But the Veras team, using computer simulation, shows that the spectroscopic trace of hydrogen in the atmosphere surrounding the white dwarf stars is due to falling comets from the Oort ex-cloud.
The researchers note that only a small number of white dwarfs with traces of the presence of hydrogen were studied and most of them are located quite close to the Sun and in the direction of the galactic bulge (the center of the Milky Way). It is in this region, where galactic tides and stellar winds are strongest, perhaps a stronger influence on the Oort exo-clouds.
This is another example of how fascinating white dwarf systems are - they are remnants of dead stars, but we still see some interesting dynamic behavior. | 0.894011 | 4.114743 |
More than two decades before the first exoplanet was discovered, an experiment was performed using a moving flame and liquid mercury that could hold the key to habitability on tidally locked worlds.
The paper was published in a 1969 edition of the international journal, Science, by researchers Schubert and Whitehead. The pair reported that when a Bunsen flame was rotated beneath a cylindrical container of mercury, the liquid began to flow around the container in the opposite direction at speeds up to four times greater than the rotation of the flame. The scientists speculated that such a phenomenon might explain the rapid winds on Venus.
On the Earth, the warm equator and cool poles set up a pressure difference that creates our global winds. These winds are deflected westward by the rotation of the planet (the so-called Coriolis force) promoting a zonal (east-west) air flow around the globe. But what would happen if our planet’s rotation slowed? Would our winds just cycle north and south between the equator and poles?
Such a slow-rotating scenario may be the lot of almost all rocky exoplanets discovered to date. Planets such as the TRAPPIST-1 system and Proxima Centauri-b all orbit much closer to their star than Mercury, making their faint presence easier to detect but likely resulting in tidal lock. Like the moon orbiting the Earth, planets in tidal lock have one side permanently facing the star, creating a day that is equal to the planet’s year.
The dim stars orbited by these planets can mean they receive a similar level of radiation as the Earth, placing them within the so-called “habitable zone.” However, tidal lock comes with the risk of horrific atmospheric collapse. On the planet side perpetually facing away from the star, temperatures can drop low enough to freeze an Earth-like atmosphere. The air from the dayside would then rush around the planet to fill the void, freezing in turn and causing the planet to lose its atmosphere even within the habitable zone.
The only way this could be prevented is if winds circulating around the planet could redistribute the heat sufficiently to prevent freeze-out. But without a strong Coriolis force from the planet’s rotation, can such winds exist?… Read more | 0.807361 | 3.838576 |
Is it possible to use ionized gas as fuel? Have you ever wondered what makes those neon signs glow? Or what makes the auroras so spectacular? You guessed it – it’s ionized gas. When a gas is ionized, it visually manifests as bright light, as seen in fluorescent lamps, neon lights, and even outer space. This ionized state of a gas is called plasma, which is the fourth state of matter (after solids, liquids and gases). Ionized gas as fuel is more common than you might expect.
Did you know? Plasma fills most of outer space – including the sun, solar wind, the space between planets and galaxies, and the space between virtually all other celestial bodies in the universe!
What is ionization or ionized gas?
When sufficient energy is provided to a gas, the atoms or molecules in the gas either trap electrons or lose electrons, thus forming ions. They are said to acquire a negative charge when they gain electrons and a positive charge when they lose electrons.
When a significant portion of a given amount of gas is ionized, it is referred to as plasma. The electrical characteristics of the gas change dramatically when ionized.
How is ionized gas produced?
Gases are usually ionized by one of two methods – electron ionization, in which a beam of electrons is passed through the gas to be ionized, or chemical ionization, in which a ‘reagent’ gas is introduced into the gas to be ionized. Other methods include field desorption, particle bombardment, laser desorption, and atmospheric pressure ionization. Either way, ionized gas as fuel has many applications.
Ionized gas as Fuel
Ionized gases find a wide variety of industrial and engineering applications. Let’s examine a few examples of ionized gas as fuel in one form or another:
Plasma torch: A plasma torch is a device for generating a jet of plasma.
Plasma Arc Cutting: Plasma torches are a main component in plasma cutters that are used to cut materials like stainless steel, aluminium, copper and other electrical conductors. These plasma cutters are employed in fabrication, industrial construction, scrapping, and in the automotive industry (for repairs and restorations). With ionized gas as fuel. plasma cutters offer high speed and precision and are a low-cost option for large industries as well as small hobby shops.
Plasma spraying: This is a type of coating process in which molten material like metals or alloys are coated onto a surface. Plasma torches propel the molten material towards a substrate, thus forming a uniform deposit or coating on its surface. Plasma spraying is typically adopted to coat structural materials, in order to protect them from extreme temperatures, corrosion, and wear.
Plasma arc welding: Plasma torches are also utilised in arc welding processes. Plasma is forced through a copper nozzle, which constricts the arc and propels the plasma to exit at a high velocity, with temperatures reaching up to 28,000 degrees Celsius.
Waste treatment: Plasma torches are employed in the conversion of organic matter from wastes, into syngas (synthetic gas), which primarily constitutes hydrogen and carbon monoxide. Waste is melted and vaporized, and the resulting syngas is used to generate electricity.
Internal combustion engines: The syngas obtained from plasma gasification is easily combustible and is therefore, used as fuel for internal combustion engines.
Ionized gases are used in magnetohydrodynamic (MHD) generators to produce electricity. Ionized gases are made to pass through a magnetic field, thereby generating an electric current. These systems are said to be approximately 25% more efficient than nuclear power plants, in electricity generation.
Air ionisers as air purifiers
Did you know that air can be ionized? An air ionizer uses high voltage to ionize air molecules, which then become positively or negatively charged. These charged ions attach themselves to particulate matter in the air and are collected by the ionizer, thus ‘purifying’ the air. These air purifiers are utilized in the removal of asthma-inducing particles and other allergens from the air. However, they are also said to produce ozone gas, because of which they are not very popular.
This is a new technique that is emerging, which uses ionized gas to kill microbes that are resistant to other cleaning methods. It is mostly being researched for use in space exploration, specifically for sterilizing spacecraft, so as not to ‘contaminate’ other moons and planets.
The fact that ionized gas is not just another ‘gas’ like oxygen or hydrogen, but the fourth state of matter, shows its significance and importance in our universe. Emerging technologies that make use of ionization, are typically low-cost and more efficient than conventional systems, whether they are used in electricity generation, spacecraft sterilization, or industrial applications. As researchers gradually discover more uses for ionization, and consequently, ionized gases, and opportunities for ionized gas as fuel, it is apparent that they will continue to be of tremendous value, especially to the scientific and engineering community in the years to come. | 0.864077 | 3.240843 |
Crescent ♏ Scorpio
Moon phase on 11 December 2058 Wednesday is Waning Crescent, 25 days old Moon is in Libra.Share this page: twitter facebook linkedin
Previous main lunar phase is the Last Quarter before 3 days on 8 December 2058 at 04:51.
Moon rises after midnight to early morning and sets in the afternoon. It is visible in the early morning low to the east.
Lunar disc appears visually 6.4% narrower than solar disc. Moon and Sun apparent angular diameters are ∠1828" and ∠1949".
Next Full Moon is the Cold Moon of December 2058 after 18 days on 29 December 2058 at 20:25.
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 25 days old. Earth's natural satellite is moving from the second to the final part of current synodic month. This is lunation 728 of Meeus index or 1681 from Brown series.
Length of current 728 lunation is 29 days, 13 hours and 2 minutes. It is 1 hour and 17 minutes longer than next lunation 729 length.
Length of current synodic month is 18 minutes longer than the mean length of synodic month, but it is still 6 hours and 45 minutes shorter, compared to 21st century longest.
This lunation true anomaly is ∠294°. At the beginning of next synodic month true anomaly will be ∠321.5°. The length of upcoming synodic months will keep decreasing since the true anomaly gets closer to the value of New Moon at point of perigee (∠0° or ∠360°).
5 days after point of apogee on 6 December 2058 at 07:43 in ♌ Leo. The lunar orbit is getting closer, while the Moon is moving inward the Earth. It will keep this direction for the next 22 days, until it get to the point of next perigee on 3 January 2059 at 02:24 in ♌ Leo.
Moon is 392 081 km (243 628 mi) away from Earth on this date. Moon moves closer next 22 days until perigee, when Earth-Moon distance will reach 405 679 km (252 077 mi).
11 days after its ascending node on 29 November 2058 at 23:07 in ♉ Taurus, the Moon is following the northern part of its orbit for the next 2 days, until it will cross the ecliptic from North to South in descending node on 14 December 2058 at 09:40 in ♐ Sagittarius.
11 days after beginning of current draconic month in ♉ Taurus, the Moon is moving from the beginning to the first part of it.
8 days after previous North standstill on 2 December 2058 at 15:32 in ♋ Cancer, when Moon has reached northern declination of ∠26.007°. Next 5 days the lunar orbit moves southward to face South declination of ∠-25.991° in the next southern standstill on 16 December 2058 at 18:17 in ♑ Capricorn.
After 4 days on 15 December 2058 at 16:12 in ♐ Sagittarius, the Moon will be in New Moon geocentric conjunction with the Sun and this alignment forms next Sun-Moon-Earth syzygy. | 0.83659 | 3.233728 |
Kevin Schawinski had a problem:
In 2007 he was an astrophysicist at Oxford University and hard at work reviewing seven years’ worth of photographs from the Sloan Digital Sky Survey—images of more than 900,000 galaxies. He spent his days looking at image after image, noting whether a galaxy looked spiral or elliptical, or logging which way it seemed to be spinning.
Technological advancements had sped up scientists’ ability to collect information, but scientists were still processing information at the same rate. After working on the task full time and barely making a dent, Schawinski and colleague Chris Lintott decided there had to be a better way to do this.
There was: a citizen science project called Galaxy Zoo. Schawinski and Lintott recruited volunteers from the public to help out by classifying images online. Showing the same images to multiple volunteers allowed them to check one another’s work. More than 100,000 people chipped in and condensed a task that would have taken years into just under six months.
Citizen scientists continue to contribute to image-classification tasks. But technology also continues to advance.
The Dark Energy Spectroscopic Instrument, scheduled to begin in 2019, will measure the velocities of about 30 million galaxies and quasars over five years. The Large Synoptic Survey Telescope, scheduled to begin in the early 2020s, will collect more than 30 terabytes of data each night—for a decade.
“The volume of datasets [from those surveys] will be at least an order of magnitude larger,” says Camille Avestruz, a postdoctoral researcher at the University of Chicago.
To keep up, astrophysicists like Schawinski and Avestruz have recruited a new class of non-scientist scientists: machines.
Researchers are using to help with a variety of tasks in astronomy and cosmology, from image analysis to telescope scheduling.
“Five years ago, [ algorithms in astronomy] were esoteric tools that performed worse than humans in most circumstances,” Nord says. Today, more and more algorithms are consistently outperforming humans. “You’d be surprised at how much low-hanging fruit there is.”
Machine learning can help observatories schedule telescopes so they can collect data as efficiently as possible. Both Schawinski’s lab and Fermilab are using a technique called reinforcement learning to train algorithms to solve problems like this one. In reinforcement learning, an algorithm isn’t trained on “right” and “wrong” answers but through differing rewards that depend on its outputs. The algorithms must strike a balance between the safe, predictable payoffs of understood options and the potential for a big win with an unexpected solution. […] | 0.84278 | 3.42025 |
When I was 12, I made the mistake of watching the Paul W. S. Anderson horror film, Event Horizon. It gave me nightmares for weeks: The movie’s title refers to an experimental spaceship that could create artificial black holes through which to travel, making interstellar trips trivial. But the crew, upon activating the ship’s gravity drive, ended up somewhere like Hell. Possessed by what appears to be the ship itself—it seems to acquire a will of its own—they mutilated themselves and one another. A crew member had the presence of mind to broadcast a final message, amid the screams, to any would-be rescuers: liberatis me (“save me”). Black holes have held me in a state of trembling fascination ever since. I doubt they lead to some demonic dimension but, like the existence of God, such a realm can’t, strictly speaking, be disproven, only judged improbable.
I couldn’t put the possibility out of mind as I read Einstein’s Shadow: A Black Hole, a Band of Astronomers, and the Quest to See the Unseeable. The book, by science writer and editor Seth Fletcher, is about Sheperd Doeleman and the other scientists behind the Event Horizon Telescope, the goal of which was to photograph a black hole. Doeleman, Fletcher writes, thought his team “could cause a historical disjuncture—before the first picture of a black hole, and after.” A few months ago, they unveiled the picture of galaxy Messier 87’s central black hole, with gas—in hues of red, orange, and yellow—glowing around it. It was mesmerizing. It showed the shadow cast by the event horizon, confirming a prediction of Einstein’s theory of general relativity.
In May, in a conversation with Doeleman, Chris Anderson, of TED, asked, “Where do you end up if you fall into a black hole?” Being in Vancouver, Doeleman joked, “Vancouver. Here we are.” But then went on to call black holes “the central mystery of our age.” Why? “Because that’s where the quantum world and the gravitational world come together. What’s inside is a singularity, where all the forces become unified because gravity finally is strong enough to compete with all the other forces”—the strong, weak, and electromagnetic. But we can’t see the singularity. “The universe has cloaked it in the ultimate invisibility cloak. We don’t know what happens in there.”
And yet the mystery goes deeper: What might be more puzzling than the innards of a black hole is the trouble of defining one in the first place. That’s what Erik Curiel found out when he asked theoretical and experimental physicists, mathematicians, and philosophers, “What is a black hole?” Curiel, a physicist and philosopher himself, at the Munich Center for Mathematical Philosophy, reported on his experience chatting with these researchers in a Nature Astronomy paper, titled “The many definitions of a black hole.” One response in particular, he thought, from Beatrice Bonga, who specializes in gravitational waves at the Perimeter Institute, was emblematic of the rest. “Your five-word question is surprisingly difficult to answer,” she told him, “...and I definitely won’t be able to do that in five words.”
Isn’t a black hole just a region in space where matter has become so dense that not even light can escape its gravity? Simple? Well, no. That’s the layman’s way of expressing the effect of the event horizon, which was classically defined, Curiel says, as “the boundary of the causal past of future null infinity.” He explains that the definition “tries to take the intuition that a black hole is a ‘region of no escape’ and make it precise.” Curiel thought many of the folks he spoke to would bring this up, but most didn’t. Those who did mentioned it partly to point out its problems. Curiel writes:
This definition is global in a strong and straightforward sense: the idea that nothing can escape the interior of a black hole once it enters makes implicit reference to all future time—the thing can never escape no matter how long it tries. Thus, in order to know the location of the event horizon in spacetime, one must know the entire structure of the spacetime, from start to finish, so to speak, and all the way out to infinity. As a consequence, no local measurements one can make can ever determine the location of an event horizon. That feature is already objectionable to many physicists on philosophical grounds: one cannot operationalize an event horizon in any standard sense of the term. Another disturbing property of the event horizon, arising from its global nature, is that it is prescient. Where I locate the horizon today depends on what I throw in it tomorrow—which future-directed possible paths of particles and light rays can escape to infinity starting today depends on where the horizon will be tomorrow, and so that information must already be accounted for today. Physicists find this feature even more troubling.
Sean Gryb, a quantum gravity theorist at the Perimeter Institute, told Curiel, “The existence of [a classical event horizon] just doesn’t seem to be a verifiable hypothesis.”
Curiel spoke to some researchers who made black holes out to be even more exotic than I thought possible. For example, theoretical physicist Domenico Giulini, of Leibniz University Hannover, was skeptical that black holes were physical things at all. “It is tempting but conceptually problematic to think of black holes as objects in space, things that can move and be pushed around,” he said. “They are simply not quasi-localized lumps of any sort of ‘matter’ that occupies [spacetime] ‘points.’” But others, like Ramesh Narayan, at the Harvard-Smithsonian Center for Astrophysics, are less fanciful. “A black hole is a compact body of mass greater than four solar masses—the physicists have shown us there is nothing else it can be.”
Black holes, it cannot be denied, are both simple and complicated. For Chiara Mingarelli, a gravity-wave researcher, it’s those two qualities that make black holes so fascinating. “It’s this interesting duality of them being really simple and really complicated. So they’re really simple. You can describe them by their mass and their spin, right? But what’s past the event horizon? What does the singularity actually look like? Is it actually this point of infinite curvature? It is some sort of quark soup? What does it look like?” She imagines that, as light travels toward the singularity, in all sorts of wonderful orbits, there must be fireworks. “I try to imagine it as like a water fountain, having light coming out and then falling back in on itself as it approaches the event horizon.”
Watch the rest of Mingarelli’s interview with Nautilus here. She discusses her reaction to the detection of gravitational waves, how they compress space and time, and whether it is fair for only a few people to win the Nobel Prize for spotting them.
Brian Gallagher is the editor of Facts So Romantic, the Nautilus blog. Follow him on Twitter @BSGallagher.
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Researchers from the European southern Observatory have confirmed the existence of the smallest planet of the Solar system — Hygeia, which is located in the asteroid belt between Jupiter and Mars. A dwarf planet is the fourth-largest in the main asteroid belt after Ceres, Vesta and Pallas. Despite its tiny size (diameter of the dwarf planet is approximately equal to the distance from Moscow to Nizhny Novgorod), the found object has a spherical form and claims to be a full-fledged dwarf planet.
Size comparison of dwarf planets from the asteroid belt
New observations using the Very Large Telescope showed that the surface discovered Hygeia is devoid of any large craters, which could indicate the formation of the dwarf planet in the Wake of a major collision of two other dwarf planets in the distant past of the Solar system. Scientists expected to find at least one large, deep pool shock, similar to what was found on the West. The new study also showed that Gigeya has a spherical shape, thus taking the status of the smallest of the dwarf planet Ceres.
In addition, the study of the surface Hygeia showed that a small planet was formed as a result of a major frontal collision with another celestial body, which occurred about 2 billion years ago, completely destroyed the parent body. Once the remaining parts together, creating a modern asteroid belt, Gigeya acquired a round shape. That is a tremendous explosion of two prehistoric objects provoked the appearance is not five, and six dwarf planets, which were subsequently discovered and registered.
© 2019, paradox. All rights reserved. | 0.86716 | 3.389846 |
By Eric Hand and Nature magazine
Venus would seem to be a tempting destination for planetary probes: conveniently close, and an extreme laboratory for atmospheric processes familiar on Earth. So why won't NASA send a mission there? That was the frustrated question coming from scientists at the annual meeting of NASA's Venus Exploration Analysis Group (VEXAG) near Washington, D.C., on August 30-31. They perceive an agency bias against Venus, a planet that hasn't seen a U.S. mission since the Magellan probe radar-mapped its shrouded surface in the early 1990s, and which won't see one any time soon, after NASA this year rejected a bumper crop of Venus proposals. [Slide Show: 8 of the Most Extreme Places in the Solar System]
"A lot of us are dismayed," says David Grinspoon, astrobiology curator at the Denver Museum of Nature and Science in Colorado, who is a co-investigator on several of the proposals. Some of the reasons for the planet's neglect are obvious: surface temperatures that would melt lead and thick clouds of sulfuric acid make data gathering a challenge for landers and orbiters alike. And—unlike Mars—Venus is neither a plausible haven for life nor a potential destination for astronauts.
But Grinspoon says that something more insidious is at work. Without new missions supplying data for analysis, funding for Venus research has dwindled, leading to fewer students entering the field—and a smaller constituency to lobby for missions. "Because of this feedback loop, the community has shrunk," he says. Research grants mentioning Venus have accounted for just 2 percent of NASA's planetary-science funding since 2005.
Internationally, things aren't much better. Europe's Venus Express, a probe cobbled together using instruments designed for missions to Mars and a comet, has only partly satisfied a craving for data since it arrived in 2006. And last December, Japan's Akatsuki spacecraft failed to enter orbit and overshot the planet.
[Click here for "Forgotten Planet" infographic: https://www.nature.com/news/2011/110902/full/477145a/box/1.html]
In May, Venus researchers got a double dose of further bad news. In NASA's New Frontiers medium-class mission line, a mission to return asteroid samples prevailed over a proposed Venus lander that would have lasted a precious three hours on the surface. And there were no Venus missions among the three finalists in the Discovery low-cost planetary-mission competition, although one-quarter of the proposals had targeted the planet (see "Forgotten planet").
Of the seven Discovery proposals for Venus missions, reviewers gave six the lowest possible ranking, guaranteeing their rejection. Only one, an atmospheric mission, received a solid "category II" score. With so many proposals, and with mission teams averaging 20 people each, some Venus scientists wondered whether enough unbiased colleagues were left in the community to competently review the proposals. But Jim Green, director of planetary science at NASA, says that he found plenty of qualified reviewers from outside the United States. "There were just better proposals" for other Solar System targets, he says.
Michael New, the NASA program scientist who ran the competition, says that Venus scientists need a clearer consensus on their goals and the measurements that they want to make. Those who want to map the surface, for instance, have not determined how much better than Magellan their radar instruments have to be. NASA may invite another round of Discovery proposals in 2012.
Grinpoon hopes that by then, the unanswered scientific questions will be impossible to ignore. He wants to know why Earth's global climate models break down on Venus, which has an atmosphere composed of 97 percent carbon dioxide—and what that reveals about the hidden fine-tunings of Earth models.
Similarly, Gordon Chin, a project scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, proposed a mission that would explain why the same chemical processes that destroy ozone in Earth's atmosphere stabilize carbon dioxide in Venus's. And Suzanne Smrekar, VEXAG co-chair and a scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif., wants to follow up on a 2010 finding in which she and her colleagues used Venus Express data to identify hot spots on the planet's surface—evidence for volcanism within the past few million years. A clearer picture of volcanism on Venus and its history could help to explain how the planet's runaway greenhouse effect got going. "We need another laboratory to test what we think we know on Earth," says Chin.
This article is reproduced with permission from the magazine Nature. The article was first published on September 2, 2011. | 0.912517 | 3.029768 |
Energetic particles in our heliosphere are key in the understanding of the evolution and the current status of our solar system. The energy distributions of ions and electrons are widely used to understand acceleration phenomena in the heliosphere and in the vicinity of planets and moons. Knowing the energy spectra of those particles can tremendously help in the characterization of plasma sources and sinks of many different environments in the Milky Way and beyond. The knowledge of those energetic particle distributions in fact is essential in many fundamental plasma physics problems. They are a very nice tool to investigate acceleration mechanisms, geochemistry and solar-system evolution, atmospheric composition and solar-system evolution, and last but not least energetic particles are important in studying the configuration and dynamics of planetary magnetospheres and the interaction of magnetospheric plasma with their moons, rings, neutral gas, or dust clouds.
Energetic particles in the energy range between 1 eV to 1020 eV can be found everywhere in our solar system as sketched in Fig. 12.1. Their sources can be either outside our solar system from galactic or extra-galactic interstellar space or inside our solar system from the Sun or the planets or created in various acceleration processes in interplanetary space or inside planetary magnetospheres, i.e., at interplanetary shocks, corotating interaction regions, planetary bow shocks or at the termination shock of the heliosphere. Types of energetic particles range from electrons to charged atoms and molecules to neutral atoms and molecules as well as dust particles. Figure 12.2 shows the particle intensity versus energy spectra of various types of energetic particles (left) and for cosmic rays (right).
This chapter focuses on the description of charged energetic particle populations from the Sun and particle distributions inside planetary magnetospheres (including galactic cosmic rays (GCRs) as a potential source of charged particles in planetary radiation belts). Energetic particles from acceleration processes at shocks are reviewed in Ch. 7 of Vol. II.
In order to set the scene for later sections and without going into much detail we introduce the motion of charged particles in a magnetic field. For further details and equation derivations the reader is referred to books like Roederer (1970) or Walt (1994). A excellent text used for this chapter is Kallenbach et al. (2006). | 0.877569 | 3.909171 |
NASA’s New Horizons spacecraft took this photo of Pluto on July 13, 2015, when it was just 476,000 miles away from the ex-planet and preparing for its closest approach. [Image credit: NASA/APL/SwRI]
Nine years after losing its planetary status, Pluto is back in the spotlight. New Horizons, a spacecraft launched just six months prior to Pluto’s demotion, flew by the dwarf planet on July 14, giving the world an up-close and personal view of the most controversial body in the Solar System.
The New Horizons team has completed its nine-day close surveillance period, which means the mission scientists are finished with Pluto’s photo shoot. But it will take a full year for them to retrieve all their data and begin to really analyze the world’s favorite dwarf planet in detail. Meanwhile, the spacecraft that made it all possible continues to drift closer and closer to the edge of the solar system.
New Horizons’ unprecedented, high-res images of Pluto revealed its enormous heart, an approximately 1,000-mile-wide, featureless region dubbed Tombaugh Reggio in tribute to Pluto’s discoverer Clyde Tombaugh. Inside the heart, scientists discovered frozen plains covered in fascinating patterns and carbon monoxide ice, which could mean that convection on Pluto might be actively shaping its surface. The plains look a bit like the dried, cracked mud that can be found on Earth’s surface, with 12-mile-wide contiguous, irregular shapes.
The closest view of Pluto also revealed icy mountains of around 11,000 feet, or about as high as California’s Mammoth Mountain. NASA believes these mountains can’t be more than 100 million years old, which is young compared to the age of the entire solar system (4.5 billion years). So the origin of these icy peaks is unclear. Usually such geological formations occur because of gravitational interactions with much larger planets, but Pluto and its moons are all so small that something else must be causing the formations, perhaps an internal heat source that scientists previously underestimated.
Pluto also wagged its tail for New Horizons. The spacecraft detected a massive outflow of cold, ionized gas shaped much like the tail of a comet heading toward the Sun. Plasma coming from the Sun constantly bombards Pluto, stripping it of its atmosphere and creating a teardrop-shaped trail of nitrogen and methane. Similar tails exist around Venus and Mars.
Though Pluto certainly stole the show, it wasn’t the only item on the spacecraft’s agenda. Three of Pluto’s five moons also made an appearance during the mission, starting with a portrait of Charon and Pluto taken during the spacecraft’s approach. Little Charon had a second close-up, revealing very few craters and a mysterious stain on its north pole. Finally, Nix and Hydra had their turn in the spotlight, although their photos were blurry and pixelated.
After spending nine years en route to Pluto, the future of New Horizons is not yet certain. It will continue to drift farther into the Kuiper Belt: A region in the outer realm of the solar system that contains trillions of icy space rocks and is thought to harbor secrets from the formation of the Solar System. But whether New Horizons will continue to do science or idly drift along depends on whether NASA grants the team more funding. They already know they’d like to visit at least two or three small Kuiper Belt objects with their extended mission, but NASA won’t reach a decision until 2017. | 0.871078 | 3.651358 |
It may have only appeared as a tiny, glowing spot hovering over a distant galaxy, but the sight made a precocious 10-year-old amateur astronomer the youngest person ever to have detected the stellar explosion known as a supernova.
Kathryn Aurora Gray of Fredericton, New Brunswick in Canada discovered the supernova explosion in a galaxy, called UGC 3378, within the faint constellation of Camelopardalis. The galaxy is approximately 240 million light-years away.
"I'm really excited. It feels really good," Gray told the Toronto Star.
Gray made the discovery on Jan. 2 using images that were taken of galaxy UGC 3378 on New Year's Eve. The supernova was then verified by Illinois-based amateur astronomer Brian Tieman and Arizona-based amateur astronomer Jack Newton, who then reported it to the International Astronomical Union's Central Bureau for Astronomical Telegrams.
Gray reported the stellar explosion under the supervision of her father, Paul Gray, who has made six prior supernova discoveries, and family friend David Lane, who has found three others himself. The photos of galaxy UGC 3378 were taken using a telescope belonging to Lane.
Supernovas are powerful and violent explosions that signal the deaths of stars several times more massive than our sun. These cosmic blasts are interesting to astronomers because they manufacture most of the chemical elements that went into creating the Earth and other planets. Distant supernovas can also be used to estimate the size and age of our universe.
The last supernova found in our galaxy occurred several hundred years ago, and they are considered relatively rare events. Astronomers can increase their odds of discovering a supernova by repeatedly checking and comparing many different galaxies.
A new supernova reveals itself as a bright point of light that was not present in previous observations. And, since a supernova can outshine millions of ordinary stars, it is often easy to spot one with a modest telescope, even in distant galaxies like UGC 3378.
Despite being the discoverer of this one, Gray didn't get to bestow a name on the object, which is known simply as Supernova 2010lt.
Copyright © 2010 Space.com. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed. | 0.825306 | 3.427549 |
A comment I frequently hear from those who have just purchased a telescope is this: "I’ve seen the moon and a few planets … Venus, Jupiter and Mars … but I can never find Saturn. I’d really like to see the famous rings that encircle it, but I can never seem to readily identify it."
It's a valid complaint, but this week you may have a chance to see the ringed planet for yourself, weather permitting.
Unlike Venus and Jupiter which can be immediately identified by their great brilliance, or Mars by its distinctive fiery orange color, to the naked eye there really isn’t anything distinctive about Saturn. It appears as a bright "star" shining with a steady, sedate yellow-white glow, but it really isn't all that eye-catching.
Indeed, many night sky neophytes to astronomy may have passed over it visually without knowing exactly what it is. Some nearby benchmark would certainly help to guide one to it.
And on Wednesday night (July 25), you’ll have two benchmarks to lead you to the solar system's "lord of the rings."
How to spot Saturn
As darkness falls, look toward the west-southwest sky. Roughly one-quarter up from the horizon to the point overhead will be the moon, just hours from attaining its half or first quarter phase. To the moon’s upper right you’ll see two bright star-like lights.
The lower one (the one closest to the moon) is actually a star — the bluish first magnitude star, Spica in the constellation of Virgo. Spica ranks 16th among the brightest stars in the sky. The light you see coming from Spica started on its journey to Earth 260 years ago, when Benjamin Franklin was dabbling with electricity and the Liberty Bell arrived in Philadelphia.
Above Spica , the "star" farthest from the moon and shining sedately with a yellow-white hue is — you guessed it — Saturn. It shines just a bit brighter than Spica.
With the planet properly identified, night sky observers with a telescope can try it out on Saturn, which is sometimes referred to as one of the grandest sights of the night sky.
In order to see Saturn's magnificent rings, you’ll need an eyepiece magnifying at least 30-power. If you have a 2.4-inch telescope, your best view of Saturn will come at 60-power. With a 3-inch telescope, try 75-power; with a 6-inch, 150-power is a good choice.
Right now, the north side of the rings are tilted nearly 13 degrees toward Earth. They haven’t been this wide-open in five years, so now is a good time to check them out.
More night sky treats near Saturn
Something else to look for is a small star roughly four ring-lengths from Saturn. That’s not a star, however, but Saturn’s largest moon Titan,the only natural satellite known to have a dense atmosphere, and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found.
During the next several weeks, there is another planet in the night sky to seek out. The planet Mars, which currently sits about 10 degrees (the width of your clenched fist held at arm’s length) to the west (or right) of Spica and Saturn, will be approach and in mid-August they’ll make for an eye-catching configuration in our early evening sky.
Editor's note: If you snap an amazing photo of Saturn the moon and Spica that you'd like to share for a possible story or image gallery, send images and comments to managing editor Tariq Malik at [email protected].
Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for The New York Times and other publications, and he is also an on-camera meteorologist for News 12 Westchester, New York. | 0.835256 | 3.767533 |
The hottest-known planet in our galaxy is being stretched into the shape of a football and rapidly consumed by its parent star, new observations from the Hubble Space Telescope show.
The extrasolar planet on the cosmic menu, called WASP-12b, may only have another 10 million years left before it is completely devoured, Hubble scientists announced Thursday.
WASP-12b is so close to its sun-like star that it is superheated to nearly 2,800 degrees Fahrenheit and stretched into an elongated shape by enormous tidal forces.
Because of those phenomenal forces, the planet's atmosphere has ballooned to nearly three times Jupiter's radius and is pouring material onto its parent star. WASP-12b is 40 percent more massive than Jupiter.
This effect of matter exchange between two stellar objects is commonly seen in close binary star systems, but this is the first time it has been seen so clearly for a planet. The system was observed with the new Cosmic Origins Spectrograph (COS) instrument on Hubble.
"We see a huge cloud of material around the planet which is escaping and will be captured by the star. We have identified chemical elements never before seen on planets outside our own solar system," said team leader Carole Haswell of The Open University in the United Kingdom.
The distortion of the planet by the star's gravity was first predicted in a paper published in February in the journal Nature by Shu-lin Li of Peking University in Beijing. That work predicted that the gravitational tidal forces working on the planet would make its interior so hot that it greatly expands the planet's outer atmosphere.
Now Hubble has confirmed this prediction.
The planet's parent star, WASP-12, is a yellow dwarf star located approximately 600 light-years away in the winter constellation Auriga. The exoplanet it is slowly destroying was discovered by the United Kingdom's Wide Area Search for Planets (WASP) in 2008.
The unprecedented ultraviolet (UV) sensitivity of COS enabled measurements of the dimming of the parent star's light as the planet passed in front of the star.
These UV spectral observations showed that absorption lines from aluminum, tin, manganese, among other elements, became more pronounced as the planet transited the star, meaning that these elements exist in the planet's atmosphere as well as in the star. The fact the COS could detect these features on a planet offers strong evidence that the planet's atmosphere is greatly extended because it is so hot, researchers said.
The new observations of WASP-12b are detailed in the May 10 issue of The Astrophysical Journal Letters.
Copyright © 2010 Space.com. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed. | 0.91678 | 3.91451 |
The Hubble Space Telescope has failed to reveal the expected number of stars in the mysterious, galaxy-sized cloud of hydrogen known as VIRGOHI21. The research bolsters the idea that the gas cloud is the only known example of a ‘dark galaxy’ that never kick-started star birth.
Galaxies are thought to coalesce from normal, or baryonic, matter that has collected in clouds of hypothetical dark matter. But surveys have turned up fewer galaxies than expected, suggesting that – for unknown reasons – some galaxies are stillborn, and simply fail to form stars.
The discovery of VIRGOHI21 in 2005 seemed to provide the first evidence that dark galaxies existed. However, a number of researchers suggested that VIRGOHI21 was pulled out of the nearby galaxy NGC 4254 when another galaxy called NGC 4262 shot past it at 900 kilometres per second. Indeed, NGC 4254 has a single prominent arm of stars that curls round towards VIRGOHI21, suggesting some sort of link between the two.
But Robert Minchin of the Arecibo Observatory discounts such “hit-and-run” models. “If the hydrogen in VIRGOHI21 had been pulled out of a nearby galaxy, the same interaction should have pulled out stars as well,” says Minchin.
He and colleagues used Hubble to observe a patch of sky 50,000 by 50,000 light years across, centred on the hydrogen cloud’s position. They found just 119 red giant stars. That is the number found in a typical region of the same size in intergalactic space and three times fewer than expected if the cloud were a large piece of celestial wreckage.
Instead, Minchin believes NGC 4254’s arm of stars was created by the gravity of VIRGOHI21 itself. He came to this conclusion after studying the object with the Westerbork Synthesis Radio Telescope (WSRT) in the Netherlands, which detects emission from atoms of hydrogen. Watch an animation showing VIRGOHI21 and its two galactic neighbours from a variety of perspectives.
The new, relatively high-resolution WSRT measurements suggest that VIRGOHI21 is indeed a single object, ruling out previous suggestions that its rotation was an illusion caused by two passing gas clouds.
But they do confirm a mystery raised by previous studies. The object’s normal matter weighs a few hundred million times the mass of the Sun. But its dark matter – inferred by studying the rotation speed of the cloud – appears to weigh at least 100 times as much.
That ratio is much higher than expected – in all other galaxies, dark matter outweighs normal matter by a factor of only 10. “Even if this is a dark galaxy, it is not what you expect to find. The number of baryons is too low,” says Michael Merrifield of the University of Nottingham in the UK, who was not on Minchin’s team.
Minchin acknowledges that this is a puzzle. A number of surveys at Arecibo and other radio observatories aim to find more examples of dark galaxies, which could shed light on how much dark matter they contain. So far, however, the surveys are finding little to match the characteristics of VIRGOHI21. | 0.840479 | 4.040205 |
NASA selects ‘Option B’ for Asteroid Redirect Mission
NASA has announced that it has selected “Option B” for its Asteroid Redirect Mission (more commonly referred to as ARM), meaning that rather than towing an entire asteroid into lunar orbit, it will instead retrieve a boulder from an asteroid and bring it into a distant retrograde lunar orbit. Using Solar Electric Propulsion (SEP), an uncrewed spacecraft will retrieve a boulder from a yet-to-be-determined asteroid and tow it into lunar orbit, where it will be visited by astronauts on a future Orion / SLS mission.
NASA Associate Administrator Robert Lightfoot said that Option B offers more choices for what object the ARM spacecraft will retrieve.
“The Asteroid Redirect Mission will provide an initial demonstration of several spaceflight capabilities we will need to send astronauts deeper into space, and eventually, to Mars,” Lightfoot said. “The option to retrieve a boulder from an asteroid will have a direct impact on planning for future human missions to deep space and begin a new era of spaceflight.”
Option B is estimated at costing $100 million more than Option A, but Lightfoot points out that, excluding the launch vehicle, Option B is still less than $1.25 million for the robotic part of ARM.
So far, NASA has not yet selected an asteroid, but contenders include Itokawa, Bennu, and 2008 EV5. There should be one or two additional candidates each year. Before selecting an asteroid, scientists will have to determine its size, shape, rotation, and precise orbit.
The ARM robotic spacecraft’s Solar Electric Propulsion (SEP) system, which collects sunlight through solar arrays and converts it to electricity, will be slower than a conventional rocket, but cheaper and require fewer launches.
After rendezvous with the asteroid, the spacecraft will deploy robotic arms to capture a boulder up to four meters in diameter. Before towing it to Earth, NASA will test techniques to deflect an asteroid should one be detected on collision course with Earth. By putting itself in a halo orbit, the spacecraft will test the gravity tractor technique, in which the mutual gravitational attraction between spacecraft and asteroid would nudge the asteroid off its course.
It will take six years for the ARM spacecraft to tow the boulder into lunar orbit. Some time later, a crewed mission will visit the boulder in an Orion Multipurpose Crew Vehicle launched by the 70 metric ton version of the Space Launch System (SLS). That launch will take place sometime after Exploration Mission 2 (EM-2), the first crewed flight of Orion, currently planned to take place sometime in 2021. Astronauts would then collect samples from the boulder for return to Earth.
In addition to retrieving asteroidal samples, the crewed mission will test the procedures required for a mission to Mars, including the docking mechanism that will connect the Orion with the robotic spacecraft carrying the boulder. The astronauts will conduct extravehicular activity using new space suits designed for use in deep space, and the retrieval of samples will provide data on how best to collect samples from Mars. The material from the asteroid might provide information to scientific research firms or corporations that might be interested in asteroid mining in the future.
Collin R. Skocik has been captivated by space flight since the maiden flight of space shuttle Columbia in April of 1981. He frequently attends events hosted by the Astronaut Scholarship Foundation, and has met many astronauts in his experiences at Kennedy Space Center. He is a prolific author of science fiction as well as science and space-related articles. In addition to the Voyage Into the Unknown series, he has also written the short story collection The Future Lives!, the science fiction novel Dreams of the Stars, and the disaster novel The Sunburst Fire. His first print sale was Asteroid Eternia in Encounters magazine. When he is not writing, he provides closed-captioning for the hearing impaired. He lives in Atlantic Beach, Florida. | 0.843554 | 3.109384 |
Breakthrough Listen Publishes Most Comprehensive and Sensitive Search for Radio Technosignatures Ever Performed
Largest Data Set in the History of the Search for Extraterrestrial Intelligence Released to The Public.
Over one thousand stars scanned for signals using Green Bank and Parkes Telescopes; Data released to the astronomical community.
San Francisco – June 18, 2019 – Breakthrough Listen – the astronomical program searching for signs of intelligent life in the Universe – has submitted two publications to leading astrophysics journals, describing the analysis of its first three years of radio observations and the availability of a petabyte of radio and optical telescope data. This represents the largest release of SETI data in the history of its field.
Listen is performing detailed observations of a sample of 1702 nearby stars (within about 160 light years from Earth) using the Green Bank Radio Telescope (GBT) in West Virginia and CSIRO’s Parkes Radio Telescope in Australia. In addition, exploration of a wide swath of our Galaxy's disk is underway at Parkes1, observations of a one-million-star sample will soon commence2 at the MeerKAT telescope in South Africa, Lick Observatory’s Automated Planet Finder is being used to search for optical signals3, and collaborations continue to grow with a number of partner facilities4 across the globe.
The Breakthrough Listen science team at the University of California, Berkeley’s SETI Research Center (BSRC)5 has developed a number of techniques to search the data for “technosignatures” – evidence of technology (such as transmitters or propulsion devices) built by civilizations beyond Earth. These techniques include searches for powerful signals occupying a narrow range of radio frequencies, and scans for bright lasers used for communication or propulsion, as well as new algorithms built on machine learning techniques that are being used to study unexplained astrophysical phenomena6 in addition to the technosignature search.
Building on the results presented by the team in 20177 that reported on the analysis of 692 stars observed with GBT, Breakthrough Listen has now submitted a more wide-ranging and detailed analysis of 1327 nearby stars (almost 80% of Listen’s nearby star sample), observed over the last three years as part of a joint program between GBT and Parkes. With these new results, Breakthrough Listen has completed the most comprehensive and sensitive radio search for extraterrestrial intelligence (SETI) in history. Additionally, the experience gained during the first three years of the program means that Listen is poised soon to extend these results to higher frequencies, more signal types and (with the MeerKAT program) thousands of times more stars.
Searching for a needle in a haystack
The search “pipeline” scans through billions of radio channels, looking for signals that are too narrow and well-defined to result from natural processes. The vast majority of the detected radio signals are from our own human technology, but the team applies two techniques to filter out these interfering signals in search of potential “needle in a haystack” signatures of extraterrestrial intelligence. The first filter selects only narrow-band signals that are drifting in frequency, rejecting many interferers that arise in the vicinity of the telescopes, while preserving signals with a Doppler drift (change in frequency with time due to their motion relative to the telescope). The second filter removes signals that do not appear to originate from a fixed point on the sky. By performing comparison scans of regions of sky near to the star being targeted, signals not coming from the direction of the target star can be removed.
These two techniques reduce the size of the “haystack” from tens of millions of signals down to just a handful. The few remaining technosignature candidates were carefully examined, and determined to be outlying examples of human-generated radio frequency interference that survived the two cuts. Despite the lack of true technosignature detections, however, the scientific paper describing the analysis places the most stringent limits to date on the prevalence of radio-transmitting extraterrestrial civilizations in our Galactic neighborhood.
The results of this analysis are presented in a paper submitted for publication in the Astrophysical Journal, led by Breakthrough Listen Project Scientist for Parkes, Dr. Danny Price. A preprint, and associated background information and links to analysis software8, are also available.
“This data release is a tremendous milestone for the Breakthrough Listen team,” said Dr. Price. “We scoured thousands of hours of observations of nearby stars, across billions of frequency channels. We found no evidence of artificial signals from beyond Earth, but this doesn't mean there isn't intelligent life out there: we may just not have looked in the right place yet, or peered deep enough to detect faint signals.”
Breakthrough Listen strives to make as much data as possible available to the public, so that the astronomical community, deep learning experts, and anyone else so inclined can download and examine the results from its observations. It is the team’s hope that the data will be used for other kinds of astronomical investigations in addition to technosignature searches, and also that those with relevant expertise can help the program develop better and faster algorithms to detect and filter potential candidate signals.
The datasets examined in the analysis paper led by Dr. Price are now publicly available through the Breakthrough Listen Open Data Archive9 and also through a beta interface hosted by BSRC10, which provides access to the same datasets, but with additional search options. In addition to the GBT and Parkes data described above, the archive also contains data from our observations of FRB 12110211 (the first repeating fast radio burst detected), scans of the interstellar asteroid `Oumuamua12, and a trove of optical data from APF. Together these amount to almost 1 petabyte of publicly-available data – the equivalent of around 1600 years of streaming audio from your favorite online music service. A description of the data formats, analysis tools, and archival system can be found in a second new paper13 submitted for publication by the Listen team, led by Matt Lebofsky, BSRC's Lead System Administrator.
“While we have been making smaller subsets of data public before in varying forms and contexts,” said Lebofsky, “we are excited and proud to offer this first cohesive collection along with an instruction manual, so everybody can dig in and help us search. And we’re just getting started – there’s much more to come!”
Breakthrough Listen is a scientific program searching for evidence of technological life in the Universe. It aims to survey one million nearby stars, the entire galactic plane and 100 nearby galaxies at a wide range of radio and optical bands.
The Breakthrough Initiatives are a suite of scientific and technological programs, founded by Yuri Milner, investigating life in the Universe. Along with Breakthrough Watch, they include Breakthrough Listen, the largest ever astronomical search for signs of intelligent life beyond Earth; and Breakthrough Starshot, the first significant attempt to design and develop a space probe capable of reaching another star.
Yuri Milner founded Mail.ru Group in 1999 and under his leadership it became one of Europe’s leading internet companies. He took that business public in 2010 and founded DST Global to focus on global internet investments. DST Global became one of the world’s leading technology investors and its portfolio has included some of the world's most prominent internet companies, such as Facebook, Twitter, WhatsApp, Snapchat, Airbnb, Spotify, Alibaba, and others. Yuri lives in Silicon Valley with his family.
Yuri graduated in 1985 with an advanced degree in theoretical physics and subsequently conducted research in quantum field theory. Yuri and his wife Julia, partnered with Sergey Brin, Priscilla Chan and Mark Zuckerberg, Pony Ma, and Anne Wojcicki to fund the Breakthrough Prizes – the world’s largest scientific awards, honoring important, primarily recent, achievements in Fundamental Physics, Life Sciences and Mathematics. In July 2015, together with Stephen Hawking, Yuri launched the $100 million Breakthrough Listen initiative to reinvigorate the search for extraterrestrial intelligence in the Universe, and in April 2016 they launched Breakthrough Starshot – a $100 million research and engineering program seeking to develop a technology for interstellar travel.
13 Also available at seti.berkeley.edu/listen2019 | 0.914074 | 3.27431 |
Good news for the search for extraterrestrial life: the TRAPPIST-1 System might be rich (very rich!) in water and all of the planets are mostly made of rock. Using data from NASA’s Spitzer and Kepler space telescopes, researchers calculated the densities of TRAPPIST-1 planets more precisely than ever, and they determined that all of the planets are mostly made of rock. Additionally, some have up to 5 percent of their mass in water, which is around 250 times more than the oceans on Earth. Researchers published their findings in a recent study in the journal Astronomy and Astrophysics titled “The nature of the TRAPPIST-1 exoplanets” .
On February 22, 2017, NASA astronomers have announced that seven Earth-sized planets have been discovered around an ultra-cool dwarf star named TRAPPIST-1 which is located around 39 light-years from the Earth. The big news was: three of them were orbiting their star in the habitable zone. Astronomers and space enthusiasts were very excited by the discovery. But we can’t know for sure whether they could support life until we get more comprehensive observations of the system, including data on the planets’ atmospheres.
According to the new study, “while the sizes of the TRAPPIST-1 planets are all known to better than 5% precision, their densities have significant uncertainties (between 28% and 95%) because of poor constraints on the planet’s masses”.
The goal of the study is to improve our knowledge of the TRAPPIST-1 planetary masses and densities using transit-timing variations (TTV).Notes 1 According to the paper, the complexity of the TTV inversion problem is known to be particularly acute in multi-planetary systems (convergence issues, degeneracies and size of the parameter space), especially for resonant chain systems such as TRAPPIST-1. To overcome these challenges, researchers used a novel method that employs a genetic algorithm coupled to a full N-body integrator that they applied to a set of 284 individual transit timings. Using this approach, researchers efficiently explored the parameter space and derived reliable masses and densities from TTVs for all seven planets, with precisions ranging from 5% to 12%. Researchers found that TRAPPIST-1 c and e likely have largely rocky interiors, while planets b, d, f, g, and h require envelopes of volatiles in the form of
thick atmospheres, oceans, or ice, in most cases with water mass fractions less than 5%.
Table of Contents
Ice, liquid of vapor?
Naturally, the form of water on TRAPPIST-1 planets would depend on how much radiation (heat) they receive from their star. The closest ones are more likely to host water in the form of atmospheric vapor, while those farther away may have water frozen on their surfaces as ice. TRAPPIST-1e is the rockiest planet of them all, but is still believed to have the potential to host some liquid water.
Water is nice, what about atmospheres?
Using NASA’s Hubble Space Telescope, astronomers conducted the first spectroscopic survey of the Earth-sized planets (d, e, f, and g) around TRAPPIST-1, including tree that are in the habitable zone (e, f and g). Hubble reveals that at least three of the exoplanets (d, e, and f) do not seem to contain puffy, hydrogen-rich atmospheres similar to gaseous planets such as Neptune.
Additional observations are needed to determine the hydrogen content of the fourth planet’s (TRAPPIST-1g) atmosphere. Hydrogen is a greenhouse gas, which smothers a planet orbiting close to its star, making it hot and inhospitable to life. The results, instead, favor more compact atmospheres like those of Earth, Venus, and Mars.
As a planet in the TRAPPIST-1 system passes between us and the star, it blocks out a tiny portion of the star’s light. Precise telescopes like Hubble can look at changes in specific wavelengths of light, which provide clues to the composition and size of the planet’s atmosphere. Hubble observations in May 2016 of TRAPPIST-1 b and c showed that these planets do not seem to have thick, puffy hydrogen-rich atmospheres. This indicates a higher chance that they are rocky, terrestrial planets rather than mini gas-giants. These two planets are considered not in the habitable zone, though. Hubble then observed planets d, e, f and g in December 2016 and January 2017 in near-infrared wavelengths, and the results were similar: Hubble found no sign of thick, puffy hydrogen-rich atmospheres for any of the four planets. The data suggest that there isn’t this gas-giant like atmosphere for planets d, e, and f. The data from this round of observations was not as strong for planet g, which is also in the habitable zone like e and f, so while there’s no evidence for a thick, hydrogen-rich atmosphere on TRAPPPIST-1g, the researchers are not yet ruling it out.
Planets e, f, and g orbit at distances where temperatures would allow for liquid water, while d is likely a little too hot because it is so close to the star. Hubble has yet to take observations of planet h, which is outside the system’s habitable zone (too far from the star). But it’s worth noting though, that even the planets outside of the habitable zone might be able to have liquid water somewhere on its surface in certain conditions. It’s also worth noting that if any of these planets have high-altitude clouds and hazes, that would block Hubble’s ability to detect a tick, hydrogen-rich atmosphere, but such an atmosphere does not likely exist on these exoplanets. Many possibilities remain for what types of atmospheres these planets have, or whether they even have atmospheres. The TRAPPIST-1 planets could have compact atmospheres similar to Mars, Venus and Earth, or something entirely different.
The combination of atmospheric gases is important. Find oxygen and the methane in the same atmosphere, and you’ve got something special. There are ways to build up oxygen or methane in a planetary atmosphere, but the only way you get them both in the same atmosphere at the same time is if you produce them both super rapidly. And the only way we know how to do that is through life. Researchers hope to use Hubble’s ultraviolet capabilities to look for evidence of water vapor or methane, and NASA’s upcoming James Webb Space Telescope will look in the far-infrared to further characterize these atmospheres. Future telescopes also hope to look for hints of whether the planets are habitable and if life could be present. The TRAPPIST-1 system provides the best opportunity we currently have to study Earth-size exoplanets. Over the next few years, Hubble and other telescopes will work together, each contributing important observations. For the first time ever, we’ll have an in-depth understanding of a set of terrestrial planets outside our solar system.
Since Hubble’s observations in December 2016 and January 2017, NASA’s Kepler Space Telescope has also observed the TRAPPIST-1 system, and Spitzer Space Telescope began a program of 500 additional hours of TRAPPIST-1 observations, which will conclude in March. This new body of data helped study authors paint a clearer picture of the system than ever before.
What is TRAPPIST-1?
TRAPPIST-1 is an ultra-cool dwarf star, which is only about 9 percent as massive as our Sun. It is slightly larger than the planet Jupiter in size, but has much more mass. It is located 39.6 light-years (12.1 pc) from the Sun in the constellation Aquarius. It was discovered in 1999 and astronomers first discovered three Earth-sized planets orbiting the dwarf star in 2015. On 22 February 2017, astronomers announced four additional exoplanets around TRAPPIST-1, and three of them were in the habitable zone.
- Transit-timing variation (TTV) is a method for detecting exoplanets by observing variations in the timing of a transit. This provides an extremely sensitive method capable of detecting additional planets in the system with masses potentially as small as that of Earth. In tightly packed planetary systems, the gravitational pull of the planets among themselves causes one planet to accelerate and another planet to decelerate along its orbit. The acceleration causes the orbital period of each planet to change. Detecting this effect by measuring the change is known as Transit Timing Variations (TTV). “Timing variation” asks whether the transit occurs with strict periodicity or if there’s a variation.
- New Clues to TRAPPIST-1 Planet Compositions, Atmospheres on NASA website
- Hubble Probes Atmospheres of Exoplanets in TRAPPIST-1 Habitable Zone on NASA.gov
- “The nature of the TRAPPIST-1 exoplanets”. A study published in the journal Astronomy and Astrophysics.
Transit-timingvariation on Wikipedia
- TRAPPIST-1 on Wikipedia | 0.86997 | 3.872078 |
As chaotic as life is here on Earth, it’s not often that we have time to look up at the night sky and ponder the infinite frontier, much less keep track of what’s going on out there. But whether we pay attention or not, the universe keeps changing, often in drastic and jaw-dropping ways. For example, earlier this week, astronomers from the University of Michigan were able to confirm that two satellite galaxies of the Milky Way — the Small Magellanic Cloud (SMC) and the Large Magellanic Cloud (LMC) — collided at some point in the recent past.
Citing results published in Astrophysical Journal Letters, Phys.org reports that Michigan professor of astronomy Sally Oey, the lead author of the study, has been working with an international team to watch for “runaway” stars, which are stars that have been ejected from the SMC. In order to make these observations, the team used a recently launched orbiting telescope from the European Space Agency called Gaia. Gaia plots the movement of stars by repeatedly capturing images over the course of several years.
“We’ve been looking at very massive, hot young stars—the hottest, most luminous stars, which are fairly rare,” Oey said. “The beauty of the Small Magellanic Cloud and the Large Magellanic Cloud is that they’re their own galaxies, so we’re looking at all of the massive stars in a single galaxy.”
The reason that Oey and her fellow astronomers study runaway stars is to better understand the mechanisms that cause stars to be ejected. One is called the binary supernova scenario, and it involves one star of a gravitationally bound pair exploding as a supernova and shooting the other off like a slingshot.
“We want as much information about these stars as possible to better constrain these ejection mechanisms,” said Johnny Dorigo Jones, an undergraduate researcher on Oey’s team at Michigan. “Everyone loves marveling at images of galaxies and nebulae that are incredibly far away. The SMC is so close to us, however, that we can see its beauty in the night sky with just our naked eye. This fact, along with the data from Gaia, allow us to analyze the complex motions of stars within the SMC and even determine factors of its evolution.” | 0.884867 | 3.740063 |
High above Earth, The Planetary Society's LightSail 2 spacecraft is still sailing on sunbeams. During the 5 months since LightSail 2 deployed its solar sail on 23 July 2019, the spacecraft has continued to demonstrate the first controlled solar-sailing flight in Earth orbit.
LightSail 2 captured this image of the Gulf of Oman and the Persian Gulf on 14 December 2019. The sail appears slightly curved due to the spacecraft's 185-degree fisheye camera lens. The image has been color corrected and some of the distortion has been removed.
LightSail is a citizen-funded project from The Planetary Society to send a small spacecraft, propelled solely by sunlight, to Earth orbit.
Earth's atmosphere is a drag
LightSail 2 flies at a higher altitude than most satellites in low-Earth orbit. While the International Space Station orbits Earth at an altitude of about 400 kilometers, LightSail 2 orbits at about 720 kilometers. Since fewer spacecraft orbit at LightSail 2’s altitude, there wasn’t enough data on Earth’s atmospheric density to reliably predict how much atmospheric drag would slow down the spacecraft. We now know for certain that the atmosphere at 720 kilometers is dense enough to overcome the thrust imparted by solar sailing.
The team uses a simple on-off sail control strategy each orbit, turning the sail edge-on to the Sun’s rays when the spacecraft is traveling toward the Sun, and face-on to the Sun when moving away from it. Out of each 100-minute orbit, LightSail 2 spends 67 minutes either in eclipse or moving toward the Sun. Of the remaining 33 "sail-able" minutes each orbit, the spacecraft spends about 5 minutes turning to the desired orientation. Therefore, LightSail 2 enjoys at most 28 minutes of each orbit in an orientation for capturing the momentum of solar photons to change its velocity.
Mansell and his colleagues documented LightSail 2's orbital change during time intervals in which it was actively orienting itself for solar sailing and compared that change to periods in which the orientation was not controlled. When the spacecraft was randomly oriented, its semimajor axis—a measure of the size of the orbit—shrank by an average of 34.5 meters per day. When it was solar sailing, the orbit only shrank by an average of 19.9 meters per day. Yet, the rate is highly variable and the semimajor axis actually increased by as many as 7.5 meters some days when sailing, which means LightSail 2 increased its orbital energy during those periods.
This video shows LightSail 2's orientation with respect to the Sun during a single orbit on 24 September 2019. Gaps between data points have been interpolated. The red line shows the direction of the Sun, and the blue line shows the direction of the local magnetic field. When the sailing command is “feather,” LightSail 2 attempts to turn its sail edge-on to the solar photons, meaning the red arrow should be roughly parallel with the sail. (The Sun to -z angle should be roughly 90 degrees.) When the sailing command is “thrust,” LightSail 2 tries to turn its sail broadside to the solar photons, meaning the red arrow should roughly make a 90-degree angle with the sail. (The Sun to -z angle should be roughly 0 degrees.) For more, see https://www.planetary.org/blogs/jason-davis/heres-what-we-learned-so-far-ls2.html. Video credit: Justin Mansell, Purdue University
The increases in orbital energy from solar sailing are generally not enough to overcome atmospheric drag, so LightSail 2’s orbit is gradually decaying. Pre-launch orbital models predicted that the spacecraft would reenter Earth’s atmosphere and burn up about a year after sail deployment. But since there are few prior examples of spacecraft like LightSail 2 having high area-to-mass ratio, the actual timeline will provide new information about orbital decay rates.
Future solar sails will be used in higher Earth orbits, or on interplanetary trajectories. NASA's NEA Scout will ride a Space Launch System rocket out near the Moon and then use solar sailing to visit an asteroid. The LightSail 2 team is sharing data and expertise with the NEA Scout team.
The ups and downs of LightSail 2's orbit
If you've looked at our mission control page over the past few months, you may have noticed LightSail 2's orbital high and low points above the Earth, known as the apogee and perigee, respectively, have been cycling up and down.
This chart shows LightSail 2’s orbit apogee and perigee as reported by space-track.org since 8 July 2019. Sail deployment occurred on 23 July 2019. The entire dataset can be downloaded here.
Right after sail deployment in July, LightSail 2's apogee increased, while perigee decreased. In September, the trend reversed: apogee decreased, while perigee increased. In late October, the trend reversed again. And then it began reversing again in December.
This cycle has two causes: Earth’s nonspherical shape, and its orbital motion around the Sun. Earth's diameter at the equator is about 42 kilometers larger than it is at the poles, making its gravity stronger over the equator. This uneven gravity makes the positions of perigee and apogee precess, or wobble; if you were watching the spacecraft’s orbit from high above the north pole, you’d see it wobbling like a hula hoop spinning around your waist. While all this is happening, Earth is also revolving around the Sun, changing the angle between the light pressure from the Sun and the positions of LightSail 2’s apogee and perigee.
Justin Mansell, Purdue University
LightSail 2 Orbital Wobble
Earth’s uneven gravity makes LightSail 2’s orbit precess, or wobble. The direction of the Sun (red arrow) relative to the orbit also changes over time as the Earth orbits the Sun.
The best orientation for raising LightSail 2’s apogee is when perigee occurs on the thrust-on side of the orbit, as shown above in blue. Conversely, when perigee occurs on the thrust-off side of the orbit, as shown above in red, apogee decreases.
One of the mission’s major challenges stems from LightSail 2’s single momentum wheel, which the spacecraft uses to swing itself parallel and perpendicular to the Sun’s rays each orbit. The wheel hits a pre-defined speed limit about once per day, whereupon LightSail 2 must exit solar-sailing mode and stabilize itself with its electromagnetic torque rods.
Early in the mission, the team was doing this manually, which proved to be inefficient, especially when communications were spotty, or when the spacecraft was suffering from other technical glitches. The process is now automated, which has improved performance. In the new paper, the team conveys an important lesson for other solar sail spacecraft in Earth orbit: managing the momentum imparted by frequent sail orientation changes is a key technical challenge.
LightSail 2 only has solar cells on one side of its solar sail. LightSail 1 had a solar panel on the opposite side, but this was removed for LightSail 2's design so engineers could install a cluster of special mirrors used to laser-range the spacecraft from Earth. This process involves zapping LightSail 2 with a laser and measuring the reflection time to more accurately determine the spacecraft’s orbit.
Jason Davis / The Planetary Society
LightSail 2 with mini-DVD
LightSail 2 flew into space with a mini-DVD containing a Planetary Society member roster, a list of Kickstarter contributors, and names and images from the Society's "Selfies to Space" campaign.
In certain orientations, LightSail 2's solar sail entirely shadows the solar panels, and the spacecraft does not receive adequate power from the Sun, causing brownouts. The team has been able to work around brownouts by carefully managing the spacecraft's power budget and attitude-control mode. Future solar sail spacecraft should take sail shadowing into account for mission planning.
The LightSail 2 team recently added a new control mode to the spacecraft called sun-pointing. This mode is designed to keep the solar sail face-on to the Sun throughout its full orbit. A constantly Sun-facing attitude won’t reduce orbital decay like the on/off mode does, but it reduces momentum-wheel saturation and provides a favorable orientation for battery charging. It will also test the spacecraft’s pointing accuracy, and could provide a more consistent initial attitude for starting for on-off thrust maneuvers.
Finally, as the orbit shrinks, the team will study the effect of the sail on the rate of orbital decay, sharing the data with other teams who are studying the use of drag sails to deorbit spacecraft.
The Planetary Society
Madagascar from LightSail 2
LightSail 2 captured this image on 24 November 2019. The southern tip of Madagascar appears at right. North is approximately at the bottom of the image. A faint smoke plume can be seen casting a shadow. The sail appears slightly curved due to the spacecraft's 185-degree fisheye camera lens. The image has been color corrected and some of the distortion has been removed.
The Planetary Society
Australia and New Guinea from LightSail 2
LightSail 2 captured this image on 25 November 2019. The top end of Australia’s Northern Territory is in the center of the image. North is approximately at the bottom of the image. The city of Darwin is beneath the clouds near the tip of the sail’s middle boom. The island of New Guinea can be seen to the left. A lens flare also appears in the left part of the image. The sail appears curved due to the spacecraft's 185-degree fisheye camera lens. The image has been color corrected and some of the distortion has been removed. | 0.857024 | 3.713452 |
Astronomers See Brightest Light in 24 YearsSeptember 12, 2019, 4:55 PM HST (Updated September 12, 2019, 4:55 PM)
The enormous black hole at the center of the galaxy is having an unusually large meal of interstellar gas and dust, and researchers don’t yet understand why, according to a release from W.M. Keck Observatory.
“We have never seen anything like this in the 24 years we have studied the supermassive black hole,” said Andrea Ghez, UCLA professor of physics and astronomy and a co-senior author of the research. “It’s usually a pretty quiet, wimpy black hole on a diet. We don’t know what is driving this big feast.”
A paper about the study, led by the UCLA Galactic Center Group, which Ghez heads, was published Thursday, Sept. 12, 2019, in Astrophysical Journal Letters.
The researchers analyzed more than 13,000 observations of the black hole from 133 nights since 2003. The images were gathered by the W. M. Keck Observatory in Hawai‘i and the European Southern Observatory’s Very Large Telescope in Chile. The team found that on May 13, 2019, the area just outside the black hole’s “point of no return” (so-called because once matter enters, it can never escape) was twice as bright as the next-brightest observation.
They also observed large changes on two other nights this year. All three of those changes were “unprecedented,” Ghez said.
The brightness the scientists observed is caused by radiation from gas and dust falling into the black hole; the findings prompted them to ask whether this was an extraordinary singular event or a precursor to significantly increased activity.
“The big question is whether the black hole is entering a new phase—for example, if the spigot has been turned up and the rate of gas falling down the black hole ‘drain’ has increased for an extended period—or whether we have just seen the fireworks from a few unusual blobs of gas falling in,” said Mark Morris, UCLA professor of physics and astronomy and the paper’s co-senior author.
The team has continued to observe the area and will try to settle that question based on what they see from new images.
“We want to know how black holes grow and affect the evolution of galaxies and the universe,” said Ghez, UCLA’s Lauren B. Leichtman and Arthur E. Levine Professor of Astrophysics. “We want to know why the supermassive hole gets brighter and how it gets brighter.”
The new findings are based on observations of the black hole—which is called Sagittarius A*, or Sgr A*—during four nights in April and May using Keck Observatory’s Near-Infrared Camera, second generation (NIRC2) instrument and the Laser Guide Star Adaptive Optics (LGS AO) system on the Keck II telescope. The brightness surrounding the black hole always varies somewhat, but the scientists were stunned by the extreme variations in brightness during that timeframe, including their observations on May 13, 2019.
“The first image I saw that night, the black hole was so bright I initially mistook it for the star S0-2, because I had never seen Sagittarius A* that bright,” said UCLA research scientist Tuan Do, the study’s lead author. “But it quickly became clear the source had to be the black hole, which was really exciting.”
One hypothesis about the increased activity is that when a star called S0-2 made its closest approach to the black hole during summer 2018, it launched a large quantity of gas that reached the black hole this year.
Another possibility involves a bizarre object known as G2, which is most likely a pair of binary stars, which made its closest approach to the black hole in 2014. It’s possible the black hole could have stripped off the outer layer of G2, Ghez said, which could help explain the increased brightness just outside the black hole.
Morris said another possibility is that the brightening corresponds to the demise of large asteroids that have been drawn into the black hole.
NO DANGER TO EARTH
The black hole is some 26,000 light-years away and poses no danger to our planet. Do said the radiation would have to be 10 billion times as bright as what the astronomers detected to affect life on Earth.
Astrophysical Journal Letters also published a second article by the researchers, describing speckle holography, the technique that enabled them to extract and use very faint information from 24 years of data they recorded from near the black hole.
Ghez’s research team reported on July 25, 2019, in the journal Science the most comprehensive test of Einstein’s iconic general theory of relativity near the black hole. Their conclusion that Einstein’s theory passed the test and is correct, at least for now, was based on their study of S0-2 as it made a complete orbit around the black hole.
Ghez’s team studies more than 3,000 stars that orbit the supermassive black hole. Since 2004, the scientists have used a powerful technology that Ghez helped pioneer, called adaptive optics, which corrects the distorting effects of the Earth’s atmosphere in real-time. But speckle holography enabled the researchers to improve the data from the decade before adaptive optics came into play. Reanalyzing data from those years helped the team conclude that they had not seen that level of brightness near the black hole in 24 years.
“It was like doing LASIK surgery on our early images,” Ghez said. “We collected the data to answer one question and serendipitously unveiled other exciting scientific discoveries that we didn’t anticipate.”
Co-authors include Gunther Witzel, a former UCLA research scientist currently at Germany’s Max Planck Institute for Radio Astronomy; Mark Morris, UCLA professor of physics and astronomy; Eric Becklin, UCLA professor emeritus of physics and astronomy; Rainer Schoedel, a researcher at Spain’s Instituto de Astrofısica de Andalucıa; and UCLA graduate students Zhuo Chen and Abhimat Gautam.
The research is funded by the National Science Foundation, W. M. Keck Foundation, the Gordon and Betty Moore Foundation, the Heising-Simons Foundation, Lauren Leichtman and Arthur Levine, and Howard and Astrid Preston. | 0.868819 | 3.691965 |
A group of scientists says they “decisively” overturned the prevailing theory of how planets formed.
The most accepted notion was that the violent clash of objects formed increasingly large clusters until they became planets.
The new findings, however, suggest that the process was less catastrophic and that matter gradually accumulated without so many shocks.
The study appears in the journal Science and was presented at the meeting of the American Association for the Advancement of Science, in Seattle.
Alan Stern, principal investigator of the study, said the discovery was of «Great magnitude».
“Before there was the predominant theory of the late sixties of violent collisions and a more recent theory of smooth accumulation,” Stern told the BBC.
«Now the first became dust and the other is the only one still standing. This rarely happens in planetary science, but today we have solved the matter ».
Stern’s claims arise from the detailed study of an object in the confines of the solar system.
It is called Arrokoth, also known as Ultima Thule, and is located more than 6,000 million kilometers from the Sun, in a region called the Kuiper belt.
The scientists obtained images of high resolution from Arrokoth when NASA’s New Horizons spacecraft passed near it a little over a year ago.
The probe gave scientists their first chance to prove which of the two competing theories was correct: was it a shock or a delicate encounter?
The analysis performed by Stern and his team could not find evidence of a violent impact. They found no stress fractures, nor was there any flattening, indicating that the objects came together gently.
“This is completely decisive,” says Stern. “In one fell swoop, Arrokoth’s overflight could decide between the two theories.”
The scientist is optimistic because these Kuiper belt objects have remained largely the same since the formation of the solar system. They are, in effect, perfectly preserved fossils from this distant time.
The new theory of soft agglomeration was developed 15 years ago by Professor Anders Johansen at the Lund Observatory in Sweden. At that time I was a young PhD student. The idea came from computer simulations.
After talking with Stern, I gave Professor Johansen the phone first that his theory had been confirmed. There was a pause on the line before answering that “he felt great.”
«It is a special moment. I remember when I was a PhD student and I felt very nervous about these new results because they were very different from the previous ones, ”the professor added.
«I was worried that there was an error in my code or that I had made a miscalculation”.
«And then, when you see these results confirmed by real observations, it’s a true relief ».
Professor Johansen celebrated the occasion by eating pizza with his family.
Engineer Maggie Aderin-Pocock, who co-presents the BBC’s Sky at Night program, warned that care must be taken to bring down a whole theory based on the observation of an object, but said that Stern’s interpretation “makes a lot of sense.”
«It is good to have this evidence because crash theory was a good theory, but it had some questions. Why did the objects stick and not bounce? There were many things that did not add up ». | 0.867377 | 3.513905 |
Look, I've seen a lot, OK? Globular clusters splayed across my screen, hundreds of thousands of stars sparkling. Galaxies so far away their distance crushes our sensibilities but still detailed enough to make an astronomer weep. Planets up close, worlds upon worlds, textured and varied.
So it takes a lot to make me sit back and go, "Oooof."
That stunning image shows three vast star-forming regions: the Omega Nebula (also called the Swan Nebula, if you see it upside down) on the left, the Eagle in the middle, and Sharpless 2-54 on the right. Each of these is a huge cloud of gas and dust, churning away to birth stars like queen bees in their hives.
But I need to describe the image itself for a moment. It's a mosaic using images taken by the European Southern Observatory's Very Large Telescope Survey Telescope equipped with the 256 megapixel OmegaCam. Dozens of images were stitched together to make the final product… a 3.3 billion pixel map of the sky.
It's gorgeous, isn't it? And this is a small, small version of it. The full-res JPG is 65,500 pixels wide, and it checks in at 1.3 gigabytes, so have fun. They also have the ridiculously huge original 93,000 pixel wide 3.3 billion pixel version, and that weighs in at 9.2 GB (in PSB format), if you want to choke your connection for the next few hours.
Even the 13,000 pixel image I downloaded is enough to show incredible detail. Here's the Eagle Nebula isolated for your perusal:
I've observed this nebula many times through my own telescope, but c'mon. Hubble made this nebula famous with the "Pillars of Creation", and you can see them just to the right of center, angled down to the lower right. But they're essentially lost in the middle of this maelstrom of gas, dust, newly formed stars, shock waves, and just background stars.
One thing that stood out to me is how you can see lots of background stars on the left, but just to the right of the nebula the sky gets much darker, and the star counts drops abruptly. That's because there's a giant molecular cloud there, a vast, dense, cold collection of dust and gas that doesn't glow, so it blocks light from stars behind it. The bright gas everywhere is made of hydrogen atoms heated by the young luminous stars in the Eagle, but the dark cloud is so cold atoms of hydrogen are still bound together to make H2, a hydrogen molecule. Some clouds like that are only a few degrees above absolute zero inside.
That picture shows a half dozen highlights of the big mosaic, including some dark snaking dust clouds, dense star-forming regions, star clusters, and shock fronts where denser material is being blasted away by the powerful energy emitted by nearby stars. And, not to bore you with repeating myself, but even this is just a crop of the larger image that shows 12 of these highlights. I just can't fit them in the blog reasonably sized for you to see. Go to the original to get the big stuff.
Images like this slay me. I have spent quite some time at the eyepiece ogling both the Eagle and the Omega (in fact, once you see it as the Swan it's hard to see it otherwise; I've shown it to many people and it's fun to hear them exclaim out loud once they see the swan shape to it), but it's not possible to see them like this. Not unless you have a 2.6-meter telescope equipped with a monster camera situated in phenomenally dark skies.
And yet… standing behind my 20-centimeter telescope, seeing these objects as faint and fuzzy, but still recognizable, there is a thrill. It's nothing like these images, sure, but I know that the photons hitting my eye have traveled over 7,000 light years. They started their journey when they were created as starlight slammed into hydrogen atoms, exciting them, then they flew across that unimaginable distance, ending in my retina.
Those photons came to me, directly. Images are cool, but yeah. There's nothing like that, either. | 0.810513 | 3.56058 |
Are aliens trying to contact us? Canadian telescope picks up mysterious radio signals from space
These are the first ever recorded 'fast radio bursts' from space under 700MHz, as detected by the CHIME telescope.
Mysterious signals from outer space known as "fast radio bursts" were picked up by a new radio telescope commissioned in British Columbia, Canada. These signals are reportedly the first ever FRBs at frequencies below 700 MHz, as detected by the Canadian Hydrogen Intensity Mapping Experiment (CHIME) on July 25. The signal has been named FRB 180725A. That said, the source of these milliseconds-long bursts of radio emissions is unknown. Scientists say they are one of the newer "cosmic mysteries" around, first detected about a decade ago and known to come from far beyond our Milky Way galaxy.
There could be several possible explanations for these signals, including exploding black holes, bursts from magnetars, or even highly advanced alien communities trying to reach out to us.
Having said that, CHIME is designed to collect data on FRBs and other sought-after questions in the field of astrophysics. As the telescope has been operational for less than a year, the detection of FRB 180725A is prelusory at this point. The discovery was reported in an online "Astronomer's Telegram" post to encourage other astronomers "to search for repeated bursts at all wavelengths."
These unknown but ubiquitous signals are estimated to arrive on Earth roughly a thousand times per day over our firmament. Being first detected and reported in 2007, only roughly two dozen FRBs were recorded until mid-2017.
Nonetheless, the CHIME FRB event rate is predicted to be between two to 50 FRBs per day. The Canadian telescope is being touted as one of the best detectors of FRBs owing to its large collection area, wide bandwidth, and enormous field-of-view.
Due to the high event-rate, researchers are saying that this relatively new astrophysical phenomenon can be studied extensively. Bright FRBs detected by CHIME are reported to the worldwise astrophysical community in real time as soon as they are discovered so that they can conduct multi-wavelength follow-up procedures to study the same.
Early indications for additional FRBs discovered in the past week suggest that they aren't coming from known sources on Earth, with frequencies clocking at 400 MHz - a significantly low figure as compared to previously known readings.
Having said that, researchers are saying that whatever is transmitting the repetitive FRB is a remarkably powerful source.
Scientists say the detection of FRB 180725A and further data surrounding the phenomenon are very preliminary at this point.
CHIME, along with other observatories, will be looking out for more clues to help solve the heavenly mystery. That said, it is "early days" for both the study of FRBs and particularly the FRB mentioned above. | 0.832468 | 3.455608 |
'Should Not Exist:' Giant Planet Orbiting Tiny Star Changes Everything We Know About How Planets Form
An international team of scientists has just discovered a disproportionately massive gas giant orbiting a tiny host star located thirty short light-years away from Earth according to the BBC. The team published their findings yesterday in the journal Science.
"Our most up-to-date models could never allow the formation of even one massive planet, let alone two,'' admits Alexander Mustill, a research team member from Lund Observatory.
The star, GJ 3512, is an M-type red dwarf. These are the most common stars in our galaxy. They are also the smallest, dimmest, and coolest stars – which also makes them the longest-lasting, because they burn through their hydrogen at a slower rate and can linger for trillions of years (stars like our Sun only last approximately ten billion years.) Proxima Centauri, our closest star after the Sun, is a red dwarf.
"Around such stars there should only be planets the size of the Earth or somewhat more massive Super-Earths," says Christoph Mordasini, a coauthor of the study from the University of Bern in Switzerland.
This planet, on the other hand, is much – much – larger than Earth or Super-Earths. We still know relatively little about it, but GJ 3512b is about half the size of Jupiter and has a long 204-day elliptical orbit. This ellipsis is an extreme oval, which indicates that there could be other even more massive undiscovered planets that we can't see exerting their gravitational pull.
Credit: Guillem Anglada-Escude - IEEC/Science Wave, using SpaceEngine.org. (CC BY 4.0)
The question is, how did it get there? This particular red dwarf star is only one-tenth the size of our Sun, but this gas giant is half the size of Jupiter. Planets form from the debris within a protoplanetary disc – a rotating cloud of dust and gas surrounding newborn stars. First, a rocky core is formed as debris snowballs onto itself, held together by sheer gravity. Once enough solid mass has accumulated, the planet may then take on large amounts of gas. "GJ 3512b, however, is...at least one order of magnitude more massive than the planets predicted by theoretical models for such small star," added Mordasini.
But this star isn't dense enough to have held enough material in its protoplanetary disc for such a large planet to form, and the implications are astounding. "I find it fascinating how a single anomalous observation has the potential to produce a paradigm shift in our thinking," said Juan Carlos Morales, the lead author of the study, "in something as essential as the formation of planets and, therefore, in the big picture of how our own Solar System came into existence." | 0.903171 | 3.752961 |
Finding Water on the Moon
Superstitions and horror movies usually take center stage on Friday the 13th, but on this day in November 2009, water was the talk of the town, actually of the planet. Why?
On November 13th NASA announced an exciting development—confirmation of water on the moon. It may not sound quite as dramatic as a visit from Jason in a hockey mask, but finding water on the moon could open the door to thrilling opportunities for space exploration and have a very real affect on life on earth. How?
This is an artist's concept of a small lunar outpost. Someday, larger lunar outposts may serve as a backup for civilization in case of a global catastrophe, like an asteroid impact or a pandemic.
1. Water on the moon could make space travel more efficient
When a shuttle takes off for the moon, it contains everything that the astronauts need to complete their mission and return safely. Engineers have come up with some innovative ways to reduce and reuse things in space, such as recycling urine into drinking water. If the moon could supply water for the return trip—both for astronaut use and for creating rocket fuel, the shuttle could be lighter and have more room for other equipment.
In addition, the existence of water on the moon increases the likelihood that the moon will someday have an outpost for explorers. Human existence is largely dependent on water, and having a natural supply of it available for drinking, agriculture, fuel, and other uses made this idea much more feasible. Such an outpost would give astronauts a place to perform in-depth research, test equipment, and prepare for future missions to Mars or other objects.
Ice Core sample taken from drill.
Image courtesy National Oceanic and Atmospheric Association (NOAA)
Photo by Lonnie Thompson, Byrd Polar Research Center, Ohio State University. Cropping by Audrius Meskauskas.
2. It could reveal the story of the solar system
Much of the water on the moon is likely in the form of ice hidden deep in its shadow-covered craters, where the temperature doesn’t get above freezing. If core samples of the ice in these places could be extracted and studied, they could provide insight into the climate story of the moon and, since the moon and Earth are so intertwined, the Earth.
This technique is already being used in places like the polar caps of Antarctica. As water and snow freeze, they also freeze information about the current temperature, composition of the atmosphere, and even local events like forest fires and volcano eruptions. By studying the different layers of ice and snow from different times, scientists can reconstruct a history of the climate going back thousands and even hundreds of thousands of years.
LCROSS flight hardware in clean room at NASA Ames Research with Left to right Tony Colaprete, LCROSS Principal Investigator, Kimberly Ennico, Payload Scientist, Co-Investigator Science team. Dana Lynch, Optical Engineer on LCROSS team
Photo Credit: NASA Ames Research Center / Dominic Hart
3. It’s really cool
As the closest object to the Earth, the moon has inspired and intrigued people from all across the world. Mayan, Hebrew, and Tibetan calendars are based on the moon. Egyptians saw lunar eclipses as bad omens. People have long associated a full moon with insanity (or “lunacy”), insomnia, accident rates, and fertility. When Galileo Galilei turned a telescope to the moon for the first time in history, most people believed that the moon was a perfect, smooth sphere.
A lot has happened in the 400 years since Galileo first saw the cratered surface of the moon. From observations with crude telescopes to observations with multi-million dollar telescopes to first-hand accounts from Neil Armstrong and the others that have walked on the moon, it may seem that there is nothing else to learn from our nearest neighbor. However, we have barely scratched the surface. Read on to find out more about what the moon can teach us.
Over the last 15 years observations have hinted at the presence of water on the moon, so in order to find out for sure NASA launched the Lunar CRater Observation and Sensing Satellite (LCROSS) in September 2009. Composed of two main parts, a rocket and a guiding spacecraft, LCROSS was sent into orbit around the Earth.
Artist's rendition of Centaur upper stage rocket approaching the moon with the Lunar CRater Observation and Sensing Satellite (LCROSS), 'shepherding satellite,' attached.
Artist's rendering of the LCROSS spacecraft and Centaur [rocket] separation.
A zoom-in of the fresh Centaur [rocket] impact as seen in the LCROSS near-infrared camera.
After orbiting the Earth a few times, LCROSS split in two and, at twice the speed of a bullet, the rocket crashed straight into a crater at the moon’s south pole. The blast kicked up a cloud of dust, rocks and debris from the crater floor while the guiding spacecraft took pictures. A few minutes later, the guiding spacecraft headed straight into the cloud and crashed into the moon, sending data about the debris back to Earth.
The guiding spacecraft had a lot of instruments on board for collecting data, but the primary instruments for detecting water were infrared spectrometers. When light passes through water molecules, the molecules absorb some very specific wavelengths of light in the infrared range. This changes the shape of the spectrum in a way that can only be explained by the presence of water. The data from LCROSS showed this telltale sign of water in the debris kicked up from the impact site.
Scientists are not sure exactly how much water there is on the moon, but LCROSS detected at least 25 gallons. That is a significant amount according to NASA, especially considering that the crater was only about 20 meters across.
Other data from LCROSS is still being analyzed and not much is known about the overall quantity or distribution of water on the moon. But we do know that advances in engineering, technology, and our understanding of the universe is opening many possibilities for the future—maybe even for a trip to Mars! But in order to be prepared for extreme experiences like this, we need a much better understanding of the space environment. The moon is a great training ground and just a 4-day trip away.
Spectrometers measure the amount of light coming from an object. They collect this data over a range of wavelengths, for example from red to blue light in the case of a visible light spectrometer.
The resulting graph has a specific shape that depends on the materials that the light had to pass through to get to the spectrometer.
Hunting for water on the moon, a brief but splashy history
*Note: Image 8 is out-of-date
Michigan State University, Chemistry Department
The Atlas V rocket with LRO [another satellite studying the moon] and LCROSS aboard launched from Cape Canaveral Air Force Station in Florida.
Credit: NASA/Bill Ingalls | 0.840939 | 3.21609 |
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