Universe Today

March 2, 2012December 23, 2015 by Ray Sanders

Hubble Spots Mysterious Dark Matter ‘Core’

This composite image shows the distribution of dark matter, galaxies, and hot gas in the core of the merging galaxy cluster Abell 520, formed from a violent collision of massive galaxy clusters. Image Credit: NASA, ESA, CFHT, CXO, M.J. Jee (University of California, Davis), and A. Mahdavi (San Francisco State University)

[/caption]Astronomers are left scratching their heads over a new observation of a “clump” of dark matter apparently left behind after a massive merger between galaxy clusters. What is so puzzling about the discovery is that the dark matter collected into a “dark core” which held far fewer galaxies than expected. The implications of this discovery present challenges to current understandings of how dark matter influences galaxies and galaxy clusters.

Initially, the observations made in 2007 were dismissed as bad data. New data obtained by the Hubble Space Telescope in 2008 confirmed the previous observations of dark matter and galaxies parting ways. The new evidence is based on observations of a distant merging galaxy cluster named Abell 520. At this point, astronomers have a challenge ahead of them in order to explain why dark matter isn’t behaving as expected.

“This result is a puzzle,” said astronomer James Jee (University of California, Davis). “Dark matter is not behaving as predicted, and it’s not obviously clear what is going on. Theories of galaxy formation and dark matter must explain what we are seeing.”

Current theories on dark matter state that it may be a kind of gravitational “glue” that holds galaxies together. One of the other interesting properties of dark matter is that by all accounts, it’s not made of same stuff as people and planets, yet interacts “gravitationally” with normal matter. Current methods to study dark matter are to analyze galactic mergers, since galaxies will interact differently than their dark matter halos. The current theories are supported by visual observations of galaxy mergers in the Bullet Cluster, and have become a classic example of our current understanding of dark matter.

Studies of Abell 520 are causing astronomers to think twice about our current understanding of dark matter. Initial observations found dark matter and hot gas, but lacked luminous galaxies – which are normally detected in the same regions as dark matter concentrations. Attempting to make sense of the observations, the astronomers used Hubble’s Wide Field Planetary Camera 2 to map dark matter in the cluster using a gravitational lensing technique.

“Observations like those of Abell 520 are humbling in the sense that in spite of all the leaps and bounds in our understanding, every now and then, we are stopped cold,” said Arif Babul (University of Victoria, British Columbia).

Jee added, “We know of maybe six examples of high-speed galaxy cluster collisions where the dark matter has been mapped, but the Bullet Cluster and Abell 520 are the two that show the clearest evidence of recent mergers, and they are inconsistent with each other. No single theory explains the different behavior of dark matter in those two collisions. We need more examples.”

The team has worked on numerous possibilities for their findings, each with their own set of unanswered questions. One such possibility is that Abell 520 was a more complicated merger than the Bullet Cluster encounter. There may have been several galaxies merging in Abell 520 instead of the two responsible for the Bullet Cluster. Another possibility is that like well-cooked rice, dark matter may be sticky. When particles of ordinary matter collide, they lose energy and, as a result, slow down. It may be possible for some dark matter to interact with itself and remain behind after a collision between two galaxies.

Another possibility may be that there were more galaxies in the core, but were too dim for Hubble to detect. Being dimmer, the galaxies would have formed far fewer stars than other types of galaxies. The team plans to use their Hubble data to create computer simulations of the collision, in the hopes of obtaining vital clues in the efforts to better understand the unusual behavior of dark matter.

If you’d like to learn more about the Hubble Space Telescope, visit: http://www.nasa.gov/hubble

March 2, 2012December 23, 2015 by Tammy Plotner

Europa’s Acidic Oceans May Prohibit Life

Europa's bizarre surface features suggest an actively churning ice shell above a salty liquid water ocean. That liquid could carry amino acids and signs of life to the surface. Credit: JPL

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The more we explore our solar system, the more we find things in common. Jupiter’s frigid moon – Europa – is about the size of our satellite and – like Earth – home to some very hostile environments. Underneath what is surmised to be an icy crust a few miles deep, Europa may possess an acidic ocean that could extend down as much as 100 miles (160 km) below the surface. We know from exploring our home planet that life happens under some very extreme conditions here… But what about Europa? What are the chances that life could exist there, too?

Check out liquid water on Earth and you’ll find some form of life. As a given, scientists hypothesize other worlds which contain water should also support life. According to recent studies, Europa’s ocean might even be saturated with oxygen – further supporting these theories. However, there’s a catch. Like Earth, surface chemicals are continually drawn downward. According to researcher Matthew Pasek, an astrobiologist at the University of South Florida, this could constitute a highly acidic ocean which “is probably not friendly to life — it ends up messing with things like membrane development, and it could be hard building the large-scale organic polymers.”

According to Charles Choi of Astrobiology Magazine, “The compounds in question are oxidants, which are capable of receiving electrons from other compounds. These are usually rare in the solar system because of the abundance of chemicals known as reductants such as hydrogen and carbon, which react quickly with oxidants to form oxides such as water and carbon dioxide. Europa happens to be rich in strong oxidants such as oxygen and hydrogen peroxide which are created by the irradiation of its icy crust by high-energy particles from Jupiter.”

Although it’s speculation, if Europa produces oxidants, they may also be drawn toward its core from ocean motion. However, it might be infused with sulfides and other compounds creating sulfuric and other acids before supporting life. According to the researchers, if this has happened for just half of Europa’s lifetime, the result would be corrosive, with a pH of about 2.6, “about the same as your average soft drink,” Pasek said. While this wouldn’t prohibit life from forming, it wouldn’t make it easy. Emerging life forms would have to be quick to consume oxidants and build an acid tolerance – a process which could take as much as 50 million years.

Are there similar acid-lovin’ lifeforms on Earth? You bet. They exist in acid mine drainage found in Spain’s Rio Tinto river and they feed on iron and sulfide for their metabolic energy. “The microbes there have figured out ways of fighting their acidic environment,” Pasek said. “If life did that on Europa, Ganymede, and maybe even Mars, that might have been quite advantageous.” It is also possible that sediments at the bottom of Europa’s ocean may neutralize the acids, even though Pasek speculates this isn’t likely. One thing we do know about an acidic ocean is that it dissolves calcium-based materials such as bones and shells.

It’s a lesson repeated on Earth…

Right now our oceans are absorbing excess carbon dioxide from the air which – when combined with seawater – forms carbonic acid. While it is mostly neutralized by fossil carbonate shells at the ocean’s bed, if it’s absorbed too quickly it can have some major ramifications on sea life such as coral reefs, plankton and mollusks. According to a recent study, this acidification is happening faster (thanks to human carbon emissions) than it has during four major extinction events on Earth in the last 300 million years.

“What we’re doing today really stands out,” said lead author Bärbel Hönisch, a paleoceanographer at Columbia University’s Lamont-Doherty Earth Observatory. “We know that life during past ocean acidification events was not wiped out—new species evolved to replace those that died off. But if industrial carbon emissions continue at the current pace, we may lose organisms we care about—coral reefs, oysters, salmon.”

According to this new research, our carbon dioxide levels have escalated by 30% in the last century. This means we’ve jumped to to 393 parts per million, and ocean pH has fallen by 0.1 unit, to 8.1–an acidification rate at least 10 times faster than 56 million years ago, says Hönisch. If this continues, the Intergovernmental Panel on Climate Change predicts the pH may drop as much as another 0.3 units… a drop that will constitute major biologic changes. While you might scoff at the extinction of a few forms of plankton or the annihilation of a small coral or shellfish, there is a ripple effect that cannot be denied.

“It’s not a problem that can be quickly reversed,” said Christopher Langdon, a biological oceanographer at the University of Miami who co-authored the study on Papua New Guinea reefs. “Once a species goes extinct it’s gone forever. We’re playing a very dangerous game.”

It may take decades before ocean acidification’s effect on marine life shows itself. Until then, the past is a good way to foresee the future, says Richard Feely, an oceanographer at the National Oceanic and Atmospheric Administration who was not involved in the study. “These studies give you a sense of the timing involved in past ocean acidification events—they did not happen quickly,” he said. “The decisions we make over the next few decades could have significant implications on a geologic timescale.”

For now, we’ll look to Europa and wonder at what may exist below its frozen waves. Is there an acid-loving form of life just waiting to bubble to the surface for us to find? Right now researchers are developing a drill which could assist in looking for extreme forms of life. The “penetrator” could eventually be part of a Europa exploration mission which could begin as early as 2020.

“Penetrators are the most feasible, cheapest and safest option for a landing on Europa today, and the knowledge to build those is there,” said Peter Weiss, a post-doc now at the National Center for Scientific Research (CNRS) in France. “Otherwise, we won’t have any confirmation on astrobiology on Europa — or maybe even in the solar system — during our lifetime.”

Original Story Source: Astrobiology Magazine. For Further Reading: Physorg.com.

March 2, 2012December 23, 2015 by Jason Major

Is There Life on Earth?

An Earthshine-lit moon sets over ESO's Paranal Observatory in Chile.

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It may seem like a silly question — of course there’s life on Earth — but what if we didn’t know that? What if we were looking at Earth from another vantage point, from another planet in another star system, perhaps? Would we be able to discern then if Earth were in fact teeming with life? All we’d have to go on would be the tiniest bit of light reflected off Earth, nearly lost in the intense glare of the Sun.

Researchers have found that the secret is knowing what kind of light to look for. And they discovered this with a little help from the Moon.

eso1210c — How Earthshine works. (ESO/L. Calçada)

By using Earthshine — sunlight light reflected off Earth onto the Moon — astronomers with the European Southern Observatory have been able to discern variations that correlate with identifying factors of our planet as being a happy home for life.

In observations made with ESO’s Very Large Telescope (VLT), the presence of oceans, clouds, atmospheric gases and even plants could be detected in the reflected Earthshine.

The breakthrough method was the use of spectropolarimetry, which measures polarized light reflected from Earth. Like polarized sunglasses are able to filter out reflected glare to allow you to see clearer, spectropolarimetry can focus on light reflected off a planet, allowing scientists to more clearly identify important biological signatures.

“The light from a distant exoplanet is overwhelmed by the glare of the host star, so it’s very difficult to analyze — a bit like trying to study a grain of dust beside a powerful light bulb,” said Stefano Bagnulo of the Armagh Observatory, Northern Ireland, and co-author of the study. “But the light reflected by a planet is polarized, while the light from the host star is not. So polarimetric techniques help us to pick out the faint reflected light of an exoplanet from the dazzling starlight.”

Since we have fairly reliable proof that life does in fact exist on Earth, this provides astronomers with a process and a benchmark for locating evidence of life on other distant worlds — life as we know it, anyway.

Night Sky Guide: March 2012

Special thanks to Ninian Boyle astronomyknowhow.com for information in parts of this guide.

March brings us some wonderful sights to see in the night skies for those who are armed with binoculars, telescopes or just their eyes.

The brightest object in the night sky this month (apart from the Moon) is the Planet Venus. Venus and mighty Jupiter have already been providing a treat n the western skies for naked eye observers, but by the middle of the month the two planets will inch even closer. There are other planetary conjunctions this month as well.

The stars of spring are starting to become more prominent and the mighty constellation of Orion sets earlier in the west as the nights roll on. The constellations of Leo, Coma Berenices and Virgo herald the region of the sky known as the “Realm of the Galaxies” more so as the month moves on.

We have Comet Garradd visible all night long through binoculars, as it starts to fade from 7th to 8th magnitude. You can find it near the north celestial North pole near the star Kochab or Beta Ursa Minoris (The little Bear) on the 6^th, and the star Dubhe in the Plough on the 21st. Scan this region with binoculars and you should pick it up as a faint misty patch of light.

The Sun continues to become more active as it approaches “Solar Maximum” in 2013 and this is a time when we need to be on our guard for sudden bursts of activity which can result in aurora for observers in high latitudes. Some large geomagnetic storms in the past have resulted in Aurora being spotted as far south as regions near the Caribbean and Mediterranean. Will we get a show like this soon?

Planets

There are going to be some excellent conjunctions this month, as planets and even sometimes the Moon are close together and appear in the same region of the sky.

Mercury. Keep an eye out for the tiny planet Mercury. This planet (closest one to the Sun) is notoriously difficult to see. The best time to try and catch it is on the 4th, low down near the western horizon shortly after sunset. Make sure the Sun has fully set if you plan to sweep the area with binoculars. Never ever look at the sun directly with binoculars, telescopes or your naked eyes – This will damage your eyes or permanently blind you!

Mercury 4 March — Mercury just after sunset - Beginning of March

Mars reaches what we call ‘opposition’ on the 3rd, when it is directly opposite the Sun in the sky from our point of view here on Earth. This is the best time to view the “Red Planet” with a telescope. Try and see if you can spot its ice caps and dark markings. It will need a clear steady sky and a good magnification to see these well, try different coloured filters and even have a go at webcam imaging this amazing Planet. On the 7th the nearly full Moon lies 10-degrees to the south of the planet Mars. You’ll know its Mars by its distinct orange/pink colour.

Venus & Jupiter bring us the highlight of the month when they appear to be very close to each other and are just separated by 3 degrees on the 15^th of March. The brightest out of the pair will be Venus with Jupiter below it and the pair will be an amazing sight – like a pair of heavenly eyes staring down at us. The two planets will be close to each other either side of the 15^th, so there should be plenty of picture-taking opportunities. The Moon joins the Venus and Jupiter on the 25th and 26^th and the thin crescent Moon will make the show even more stunning.

Saturn rises later in the evenings in the constellation of Virgo, the rings are now nicely tilted towards us and the planet looks stunning right throughout the month. If you have never seen Saturn through a telescope before, you must see it! It is the most beautiful of all the planets and one of the reasons so many people get interested in astronomy.

Moon phases

First Quarter – 1^st March
Full Moon – 8^th March
Last Quarter – 15^th March
New Moon – 22^ndMarch

Constellations

In March Orion is getting lower in the West and setting earlier as the spring constellations of Leo, Coma Berenices and Virgo come into view; this is the “Realm of the Galaxies.”

In the month of March the Earth’s orbit around the Sun means that during the night we see out from our own galaxy the ‘Milky Way’ into the depths of deep space. Because of this, we can see many other galaxies and some similar to our own, each contains hundreds of billions of stars. You will need a good telescope to see these amazing wonders; however a good pair of binoculars will show one or two faint fuzzy patches. Some of these faint fuzzy objects are many millions of light years distant.

A few brighter examples lay in the constellation of Leo the Lion. Have a look for M 95, M96 and M105; these are not far from Mars during March. You will need a dark Moonless night to see them well.

Another trio of galaxies still in the constellation of Leo are M65, M66 and NGC 3628 otherwise known as the ‘Leo Triplet’ A small telescope and a low to medium power should show these objects in the same field of view.

The region of sky within Leo, Coma and Virgo is packed with galaxies and whatever telescope you use, you will be sure to spot something.

For those of you without a telescope, see if you can discern the asterism of the ‘Bowl of Virgo’. This is a chain of five stars in a loose semi-circle pointing towards the ‘tail’ of Leo. The brightest star in the chain is Porrima. South of Porrima lays the brightest star in the constellation, called Spica. Saturn can be found to the east of this.

March 2, 2012December 23, 2015 by Ken Kremer

NASAs Proposed ‘InSight’ Lander would Peer to the Center of Mars in 2016

Artist rendition of NASA’s Mars InSight (Interior exploration using Seismic Investigations, Geodesy and Heat Transport) Lander. InSight is based on the proven Phoenix Mars spacecraft and lander design with state-of-the-art avionics from the Mars Reconnaissance Orbiter (MRO) and Gravity Recovery and Interior Laboratory (GRAIL) missions. Credit: JPL/NASA

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A Phoenix-like lander that would mine the deepest hole yet into Mars– to a depth of 5 meters – and unveil the nature of the mysterious deep interior and central core of the Red Planet is under consideration by NASA for a 2016 launch and sports a nifty new name – InSight.

The stationary “InSight” lander would be an international science mission and a near duplicate of NASA’s proven Phoenix spacecraft, Bruce Banerdt told Universe Today. Banerdt is the Principal Investigator of the proposed InSight mission.

“InSight is essentially built from scratch, but nearly build-to-print from the Phoenix design,” Banerdt, of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena , Calif, told me. The team can keep costs down by re-using the blueprints pioneered by Phoenix instead of creating an entirely new spacecraft.

“The robotic arm is similar (but not identical) to the Phoenix arm.”

Mars Interior
Insight’s goal is to investigate and deduce the nature of the interior of the Red Planet. Credit: JPL/NASA

However, the landing site and science goals for InSight are quite different from Phoenix.

InSight will have an entirely new suite of three science instruments, including two from Europe, designed to peer to the center of Mars and detect the fingerprints of the processes by which the terrestrial planets formed. It will determine if there is any seismic activity, the amount of heat flow from the interior, the size of Mars core and whether the core is liquid or solid.

NASA’s twin GRAIL lunar gravity probes are set to begin their own investigation into the interior and core of Earth’s Moon in early March 2012, and several science team members are common to GRAIL and InSight.

“The seismometer (SEIS, stands for Seismic Experiment for Interior Structure) is from France (built by CNES and IPGP) and the heat flow probe (HP3, stands for Heat flow and Physical Properties Probe) is from Germany (built by DLR),” Banerdt explained.

Phoenix successfully landed in the frigid northern polar regions of Mars in 2008 in search of potential habitats for life and quickly discovered water ice and salty soils that could be favorable for the genesis and support of extraterrestrial life.

3 Footpads of Phoenix Mars Lander atop Martian Ice
Phoenix thrusters blasted away Martian soil and exposed water ice. Proposed Mars InSight mission will build a new Phoenix-like lander from scratch to peer deep into the Red Planet and investigate the nature and size of the mysterious Martian core. Credit: Kenneth Kremer, Marco Di Lorenzo, Phoenix Mission, NASA/JPL/UA/Max Planck Institute

InSight will intentionally land in a far warmer and sunnier location nearer the moderate climate of the equator to enable a projected lifetime of 2 years (or 1 Mars year) vs. the 5 months survival of Phoenix extremely harsh arctic touchdown zone.

“Our planned landing site is in Elysium Planitia,” Banerdt told me. “It was chosen for optimizing engineering safety margins for landing and power.”

The more equatorial landing site affords far more sun for the life giving solar arrays to power the instruments and electronics.

“We have global objectives and can do our science anywhere on the planet.”

Elysium Planitia is not too far from the landing sites of the Spirit and Curiosity rovers. The Elysium Mons volcano is also in the general area, but it’s a long way from precise site selection.

InSight is a geophysical lander targeted to delve deep beneath the surface into the Martian interior, check its “vital signs”; like “pulse” though seismology, “temperature”, though a heat flow probe, and “reflexes”, through precision tracking.

The purpose is to answer one of science’s most fundamental questions: How were the planets created?

InSight will accomplish much of its science investigations through experiments sitting directly in contact with the Martian surface. The robotic arm will pluck two of the instruments from the lander deck and place them onto Mars.

“The arm will pick the SEIS seismometer and HP3 heat flow probe off the deck and place each on the ground next to the lander. The arm doesn’t have a drill, but the heat flow probe itself will burrow down as deep as 5 meters,” Banerdt elaborated.

The third experiment named RISE (Rotation and Interior Structure Experiment) is to be provided by JPL and will use the spacecraft communication system to provide precise measurements of Mars planetary rotation and elucidate clues to its interior structure and composition.

Right now on Mars, NASA’s Opportunity rover is conducting a Doppler radio tracking experiment similar to what is planned for RISE, but InSight will have a big advantage according to Banerdt.

“The RISE experiment will be very similar to what we are doing right now on Opportunity, but will be able to do much better, said Banerdt. “The differences are that we will get more tracking every week (Opportunity is power-limited during the winter months; that’s why she is currently stationary!) and will make measurements for an entire Mars year – we will likely only get a handful of months from Opportunity.”

Insight will also be equipped with 2 cameras and make some weather measurements.

“We have a camera on the arm and one fixed to the deck, both primarily to support placing the instruments on the surface, although they will be able to scan the landscape around the spacecraft. Both are Black & White,” Banerdt told me.

“We will measure pressure, temperature and wind, mostly to support noise analysis on the seismic data, but will also supply information on the weather.”

Mars has the same basic internal structure as the Earth and other terrestrial (rocky) planets. It is large enough to have pressures equivalent to those throughout the Earth's upper mantle, and it has a core with a similar fraction of its mass. In contrast, the pressure even near the center of the Moon barely reach that just below the Earth's crust and it has a tiny, almost negligible core. The size of Mars indicates that it must have undergone many of the same separation and crystallization processes that formed the Earth's crust and core during early planetary formation. Credit: JPL/NASA

InSight is one of three missions vying to be selected for flight in NASA’s Discovery Program, a series of low cost NASA missions to understand the solar system by exploring planets, moons, and small bodies such as comets and asteroids. All three mission teams are required to submit concept study reports to NASA on March 19.

Banerdt’s team is working hard to finalize the concept study report.

“It describes the mission design as we have refined it over the past 9 months since the NASA Step-1 selection.”

So there is no guarantee that InSight will fly. Because of severe budget cuts to NASA’s Planetary Science Division, NASA had to cancel its scheduled participation in two other Mars missions dubbed ExoMars and jointed planned with ESA, the European Space Agency, for launch in 2016 and 2018.

March 2, 2012December 23, 2015 by Nancy Atkinson

Star Trails as Seen From Space

Star trails from space. Credit: Don Pettit/NASA

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Astronaut Don Pettit has just put another wow-factor in astrophotography from the International Space Station, and provided a whole new perspective on a common but eye-catching photography technique of creating star trails. He posted two images on his Google+ page, with this description: “Star trails. I leave the shutter open for a long period, and our orbital motion makes the stars streak.” Just gorgeous.

See his second stunning image below.

star trails 6-1 — Star trails, with a module from the International Space Station showing up in black. Credit: Don Pettit/NASA

March 1, 2012January 11, 2016 by Nancy Atkinson

Excellent Exoplanet Visualization: The Kepler Orrery II

About a year ago, Daniel Fabrycky from the Kepler spacecraft science team put together a terrific orrery-type visualization of all the multiple-planet systems discovered by the Kepler spacecraft as of February of 2011. With a new round of exoplanets just announced, here’s part two. This one is a visualization of the planetary systems discovered by Kepler that have more than one transiting object. There are 885 planet candidates in 361 systems, doubling the number of systems in the original Kepler Orrery. In the description of this video, Fabrycky says the orbits are to scale with respect to each other, and planets are to scale with respect to each other. The colors are in order of semi-major axis, and two-planet systems (242 in all) have a yellow outer planet; 3-planet (85) green, 4-planet (25) light blue, 5-planet (8) dark blue, 6-planet (1, Kepler-11) purple.

Watch and enjoy!

And as a reminder, we’ll be doing a live interview on Friday, March 2 to talk about the latest exoplanet discoveries by Kepler!

March 1, 2012December 23, 2015 by Nancy Atkinson

Next Live Interview: The Latest Exoplanet News from Kepler

Artist's conception of "Super-Earth" exoplanet Kepler-22b, which is about 2.4 times larger than Earth. Credit: NASA.

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Coming up next in our series of live interviews with astronomers and scientists is a discussion of the latest news from the Kepler mission. Joining us will be Darin Ragozzine, a postdoctoral researcher with the Kepler mission, at the Institute for Theory and Computation at the Smithsonian Astrophysical Observatory who studies transiting exoplanets, as well as the theory and dynamics of Kuiper belt objects.

The live interview will be a Hangout on Air, and be on Friday, March 2 at 18:00 UTC, 1 pm EST, 10 am PST. To watch the Hangout on Air, circle Fraser on Google+ and watch his feed for the link to the Hangout. There you can join in on the conversation and post your questions for us.

If you aren’t on Google+, you can also watch it live on the CosmoQuest Hangouts page, where there is also a place to post comments and questions. If you can’t watch live, we’ll post a recording of the Hangout later on UT.

March 1, 2012December 23, 2015 by Nancy Atkinson

Will Asteroid 2011 AG5 Hit Earth in 2040?

The orbit of asteroid 2011 AG5 carries it beyond the orbit of Mars and as close to the sun as halfway between Earth and Venus. Image credit: NASA/JPL/Caltech/NEOPO

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You may have heard about an asteroid in the news this week that has a 1 in 625 chance of hitting Earth on Feb. 5, 2040. So, will this asteroid, named 2011 AG5, really hit our planet? The quick answer is, probably not. But astronomers will need more observations of this asteroid to say one way or the other for sure.

“Because of the extreme rarity of an impact by a near-Earth asteroid of this size, I fully expect we will be able to significantly reduce or rule out entirely any impact probability for the foreseeable future,” said Donald Yeomans, head of the Near-Earth Object Observations Program at NASA’s Jet Propulsion Laboratory.

Yeomans classified the chance of impact as “unlikely” and here are some facts that we do know about Asteroid about 2011 AG5:

What is the potential that this asteroid will impact Earth?

Currently astronomers have this asteroid ranked as a “1” on the 1 to 10 Torino Impact Hazard Scale. A “1” means this asteroid will have a pass near the Earth that poses no unusual level of danger. Current calculations show the chance of collision is extremely unlikely with no cause for public attention or public concern. Very likely, subsequent telescopic observations will lead to re-assignment to Level 0. The 1 in 625 chance is what the predictions are for the data that NASA has right now. Further observations will likely decrease the odds, and may even bring it to zero.

How big is this asteroid?

2011 AG5 is a 140-meter-wide (460 feet) space rock. Its composition is not yet known – whether it is a rocky, iron or icy asteroid.

How many Near Earth asteroids are out there?

Asteroid 2011 AG5 is one of 8,744 near-Earth objects that have been discovered so far, as of this week (March 1, 2012). NEOs are objects that come within 1.3 AU of the Sun (with Earth at 1 AU, so it means they pass through our neighborhood.)

1,305 of these NEOs have been classified as Potentially Hazardous Asteroids (PHAs), which are those that are larger than about 150 m (500 ft) and come within 0.05 AU of Earth’s orbit, so 2011 AG5 is right at the edge of that classification.

How was this asteroid discovered?

It was discovered on Jan. 8, 2011, by astronomers using a 60-inch Cassegrain reflector telescope located at the summit of Mount Lemmon in the Catalina Mountains north of Tucson, Arizona.

Where is 2011 AG5 now?

Its orbit carries it as far out as beyond Mars’ orbit and as close to the Sun as halfway between Earth and Venus. See the image above for its approximate current location. Its proximity to the Sun from our vantage point on Earth means astronomers can’t make observations right now.

When will astronomers find out more and be able to make better predictions?

“In September 2013, we have the opportunity to make additional observations of 2011 AG5 when it comes within 91 million miles (147 million kilometers) of Earth,” said Yeomans. “It will be an opportunity to observe this space rock and further refine its orbit.”

Yeomans added that even better observations will be possible in late 2015.

Will this asteroid come close to Earth before 2040?

2011 AG5 will next be near Earth in February of 2023 when it will pass the planet no closer than about 1.2 million miles (1.9 million kilometers). In 2028, the asteroid will again be in the area, coming no closer than about 12.8 million miles (20.6 million kilometers). The Near-Earth Object Program Office says the Earth’s gravitational influence on the space rock during these flybys has the potential to place the space rock on an impact course for Feb. 5, 2040, but this has very unlikely odds of occurring at 1-in-625.

“Again, it is important to note that with additional observations next year the odds will change and we expect them to change in Earth’s favor,” said Yeomans.

impact event — Screenshot from the Impact Earth website animation.

If Asteroid 2011 AG5 were to hit Earth, what is the potential for damage to Earth?

According to calculations from the Impact Earth website, an object of this size would begin to break up in Earth’s atmosphere at an altitude of 65500 meters (215,000 ft). Some of the larger pieces would reach the ground, with the pieces hitting Earth’s surface (ground) at a velocity Of 2.64 km/s (1.64 miles/s). The impact energy would be 7.52 x 10^15 Joules, or 1.8 MegaTons.

This would not cause any global problems, as the planet as a whole would not be strongly disturbed by the impact.

The broken projectile fragments would strike the ground in an ellipse about 1.17 km by 0.824 km in diameter, and the result of the impact is a crater field, not a single crater. The largest crater would be about 400 meters in diameter (1,310 feet). The impact would create a Richter Scale Magnitude-like event of 4.8.

If you were 1-10 km away from the impact area, you would feel a sensation like a heavy truck striking building. Standing cars would be rocked noticeably. Indoors, dishes and windows, might be disturbed and walls might make a cracking sound. An air blast at speeds of 26.3 m/s = 58.9 mph would arrive approximately 10 – 30 seconds after impact.

If this impactor hit in an ocean, the impact-generated tsunami wave would arrive approximately 6.18 minutes after impact if you were 10 km away, with a wave amplitude is between: 4.78 and 9.55 meters (15.7 feet and 31.3 feet).

How often do asteroids hit the Earth?

Yeomans said that every day, Earth is pummeled by more than 100 tons of material that spewed off asteroids and comets. Fortunately the vast majority of this “spillover” is just dust and very small particles. “We sometimes see these sand-sized particles brighten the sky, creating meteors, or shooting stars, as they burn up upon entry into Earth’s atmosphere,” Yeomans said in his “Top Ten Asteroid Factoids” article. “Roughly once a day, a basketball-sized object strikes Earth’s atmosphere and burns up. A few times each year, a fragment the size of a small car hits Earth’s atmosphere. These larger fragments cause impressive fireballs as they burn through the atmosphere. Very rarely, sizable fragments survive their fiery passage through Earth’s atmosphere and hit the surface, becoming meteorites.”

More info:
Catalina Sky Survey
Minor Planet Center
Asteroid and Comet Impact Hazards website from NASA
NASA’s Near Earth Object Program
Impact Earth website

March 1, 2012December 23, 2015 by Nancy Atkinson

Thierry Legault: Astrophotography is an ‘Adrenaline Rush’

Thierry Legault with the equipment he uses for satellite images. Images courtesy of Thierry Legault.

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During one of the final space shuttle missions, photographer Thierry Legault traveled nearly 4,000 km across various locations in Europe to try and capture the shuttle docked to the International Space Station as the two spacecraft transited across the surface of the Sun.

“Essentially, I was trying to catch the clear sky so I could take images of an event that would last less than a second,” Legault said from his home in France.

This type of dedication to his craft, along with his attention to detail and quality has earned Legault the reputation as one of the top amateur astrophotographers in the world.

Amazingly, he started his astrophotography hobby — and his specialty of imaging objects in front of the Sun — just by chance. And now Legault has been shooting breathtaking images of spacecraft in orbit and astronomical objects and events for nearly 20 years.

“I began in 1993 with one of the first CCD cameras, the first year that CCD cameras were available for amateurs,” Legault said. “It was a wonderful time, because it was a time of pioneers, and it was a revolution after film.”

sunplane_legault — An Airplane in Front of the Sun Credit & Copyright: Thierry Legault

Intrigued by what could be done with digital equipment, he experimented by taking planetary and deep sky pictures and has now amassed a prolific portfolio of stunning images. In 2001 he took the first of the type of images he has become renown for.

“I took a picture of a plane in front of the Sun,” Legault recalled, “and it was published on APOD (Astronomy Picture of the Day), and so now I have taken many images of things in front of the Sun.”

iss_shuttle_crop — Image of the solar transit of the International Space Station (ISS) and Space Shuttle Atlantis, 50 minutes after undocking from the ISS, before return to Earth, taken from the area of Mamers, Normandie, France on September 17, 2006. Credit and copyright, Thierry Legault

In 2006 he took pictures of the space station and space shuttle side by side just as the shuttle undocked. It was published by newspapers around the world, including a double page in the Guardian, was shown on CNN and other news shows, and was everywhere on the internet.

“It was an incredible success, which was very surprising. This type of imaging is very fun for me, as I like the challenge,” Legault said. “But it is interesting how taking a picture of a spaceship in front of the Sun is really something for non-astronomers, but yet I never received so much interest for all the other astronomy images I have taken.”

Legault said he has received emails and letters from people around the world expressing how much they enjoy his transit images.

halpha — One of the setups Legault uses for solar imaging. Image courtesy Thierry Legault

Living in the suburbs of Paris means there are plenty of lights to interfere with his astrophotography.

“Where I live is not a problem for taking pictures of some satellites, the Sun, the Moon and planets,” he said. “For deep space imaging and for the space station, I have to put everything in the van and drive 20-30 kilometers and go to the country; also for solar or lunar transits I have to go to the place where the transit is visible.”

iss_discovery_110228_eva — This is the first image ever taken from the ground, of an astronaut in extravehicular activity (EVA1). Steve Bowen, attached to the end of the ISS robotic arm (MSS), was working on a defective ammonia pump. The pump was hooked to the ISS mobile base system (MBS). All major elements of the robotic arm are visible, including the structures of the motorized joints and some elements along the arms (smaller than the astronaut). Credit and copyright, Thierry Legault.

For the STS-131 mission in May of 2010, Legault traveled to Spain, Switzerland, various parts of France, and for the STS-133 mission in February 2011, where he took the first-ever ground-based image of astronaut in spacewalk he drove to Germany, and to both the south and north of France, and between 3,000 and 4,000 kilometers.

All this driving and weeks of preparation is for an event that he never sees live with his own eyes, and usually lasts about a half a second. He uses CalSky.com to calculate the exact moment and exact location he will need to be to capture an event.

“For transits I have to calculate the place, and considering the width of the visibility path is usually between 5-10 kilometers, but I have to be close to the center of this path,” Legault explained, “because if I am at the edge, it is just like a solar eclipse where the transit is shorter and shorter. And the edge of visibility line of the transit lasts very short. So the precision of where I have to be is within one kilometer.”

Legault studies maps, and has a radio synchronized watch to know very accurately when the transit event will happen.

“My camera has a continuous shuttering for 4 seconds, so I begin the sequence 2 seconds before the calculated time,” he said. “I don’t look through the camera – I never see the space station when it appears, I am just looking at my watch!”

Atlantis during the STS-135 mission docked to the International Space Station, July 15, 2011. Credit: Thierry Legault. . — Atlantis during the STS-135 mission docked to the International Space Station, July 15, 2011. Credit: Thierry Legault.

For a transit event, he gets get a total of 16 images – 4 images every second, and only after he enlarges the images will he know if he succeeded or not.

“There is a kind of feeling that is short and intense — an adrenaline rush!” Legault said. “I suppose it is much like participating in a sport, but the feeling is addictive. I did it with a friend two years ago and now he is addicted too.”

Legault added that when he succeeds, it is a very satisfying feeling.

But Legault is not keeping the adrenaline rushes all to himself; he willingly shares his knowhow and techniques.

His website provides a wealth of knowledge about his techniques and equipment

In 2005 he wrote a book (in French) called Astrophotographie, that has sold over 6,000 copies, and he is working on getting it published in English. The book provides information on how to image constellations, stars, comets, eclipses, the Moon, planets, sun, and deep-sky objects, in accessible, nontechnical language. Legault also gives practical advice on equipment and technique, with answers to problems faced by every beginner. He also co-authored another book, “New Atlas of the Moon” with Serge Brunier, and in the March 2012 issue of Sky and Telescope, Legault wrote a detailed article on how to take detailed, ground-based images of the ISS.

Tomorrow on Universe Today, Legault will share his advice for avoiding “bad” astrophotography.