Posted on by Jason Major

How Many Asteroids Are Out There?

Answer: a LOT. And there’s new ones being discovered all the time, as this fascinating animation by Scott Manley shows.


Created using data from the IAU’s Minor Planet Center and Lowell Observatory, Scott’s animation shows the progression of new asteroid discoveries since 1980. The years are noted in the lower left corner.

As the inner planets circle the Sun, asteroids light up as they’re identified like clusters of fireflies on a late summer evening. The clusters are mainly positioned along the outer edge of Earth’s orbit, as this is the field of view of most of our telescopes.

Once NASA’s WISE spacecraft begins its search around 2010 the field of view expands dramatically, as well as does the rate of new discoveries. This is because WISE’s infrared capabilities allowed it to spot asteroids that are composed of very dark material and thus reflect little sunlight, yet still emit a telltale heat signature.

While Scott’s animation gives an impressive — and somewhat disquieting — illustration of how many asteroids there are knocking about the inner Solar System, he does remind us that the scale here has been very much compacted; a single pixel at the highest resolution corresponds to over 500,000 square kilometers! So yes, over half a million asteroids is a lot, but there’s also a lot of space out there (and this is just a 2D top-down view too… it doesn’t portray any vertical depth.)

While most asteroids are aligned with the horizontal plane of the Solar System, there are a good amount whose orbits take them at higher inclinations. And on a few occasions they even cross Earth’s orbit.

(Actually, on more than just a few.)

Read: 4700 Asteroids Want to Kill You

An edge-on view of the Solar System shows the positions of asteroids identified by the NEOWISE survey. About 4700 potentially-hazardous asteroids (PHAs) have been estimated larger than 100 meters in size. (NASA/JPL-Caltech)

As far as how many asteroids there are… well, if you only consider those larger than 100 meters orbiting within the inner Solar System, there’s over 150 million. Count smaller ones and you get even more.

I don’t know about you but even with the distances involved it’s starting to feel a little… crowded.

You can see more of Scott Manley’s videos on YouTube here (including some interesting concepts on FTL travel) and learn more about asteroids and various missions to study them here.

Inset image: the 56-km (35-mile) wide asteroid Ida and its satellite, seen by the Galileo spacecraft in 1993. (NASA)

Posted on by Nancy Atkinson

Hubble Goes to the eXtreme in Stunning New Deepest View Ever of the Universe

This image, called the Hubble eXtreme Deep Field (XDF), combines Hubble observations taken over the past decade of a small patch of sky in the constellation of Fornax. With a total of over two million seconds of exposure time, it is the deepest image of the Universe ever made, combining data from previous images including the Hubble Ultra Deep Field (taken in 2002 and 2003) and Hubble Ultra Deep Field Infrared (2009). The image covers an area less than a tenth of the width of the full Moon, making it just a 30 millionth of the whole sky. Yet even in this tiny fraction of the sky, the long exposure reveals about 5500 galaxies, some of them so distant that we see them when the Universe was less than 5% of its current age. The Hubble eXtreme Deep Field image contains several of the most distant objects ever identified. Credit: NASA

The Hubble eXtreme Deep Field (XDF) combines Hubble observations taken over the past decade of a small patch of sky in the constellation of Fornax. With a total of over two million seconds of exposure time, it is the deepest image of the Universe ever made. Credit: credit: NASA, ESA, G. Illingworth, D. Magee, and P. Oesch (University of California, Santa Cruz), R. Bouwens (Leiden University), and the HUDF09 Team

Oh my! The Hubble Space Telescope has just outdone itself, taking the deepest-ever view of the Universe. But the new image really is a compilation of work over the past ten years, as the eXtreme Deep Field, or XDF was assembled by combining ten years of observations, with over 2 million seconds of exposure time, taken of a patch of sky in the center of the original Hubble Ultra Deep Field from 2004. The XDF is a small fraction of the angular diameter of the full Moon.

The new full-color XDF image is even more sensitive than the Hubble Ultra Deep Field image from 2004 and the original Hubble Deep Field image from 1995. The new XDF image contains about 5,500 galaxies, even within its smaller field of view. The faintest galaxies are one ten-billionth the brightness that the unaided human eye can see.
Continue reading “Hubble Goes to the eXtreme in Stunning New Deepest View Ever of the Universe”

Posted on by John Williams

Blowing a Super-duper Celestial Bubble

Image credit: X-ray: NASA/CXC/U.Mich./S.Oey, IR: NASA/JPL, Optical: ESO/WFI/2.2-m. Zoom by John Williams/TerraZoom using Zoomify

When NASA combines images from different telescopes, they create dazzling scenes of celestial wonder and in the process we learn a few more things. Behold this wonder of combined light, known as LHA 120-N 44, or N 44 for short. Zoom into the scene using the toolbar at the bottom of the image. Click the farthest button on the right of the toolbar to see this wonder in full-screen. (Hint: press the “Esc” key to get back to work)

Continue reading “Blowing a Super-duper Celestial Bubble”

Posted on by Nancy Atkinson

New ‘Sun-Skirting’ Comet Could Provide Dazzling Display in 2013

2013 is looking to be a promising year for potential naked-eye comets, as a new comet has been discovered that will likely skirt close to the Sun, and could provide a stunning display late next year. The comet, named Comet C/2012 S1 (ISON), as it was discovered by a Russian team at the International Scientific Optical Network (ISON), is currently about the distance of Jupiter’s orbit. But it is projected to come within less than 2 million km from the Sun at perihelion by November 28, 2013. Ernesto Guido and Giovanni Sostero from the Remanzacco Observatory in Italy, along with their colleague Nick Howes from the UK have imaged the comet with the RAS telescope in New Mexico, and say, “According to its orbit, this comet might become a naked-eye object in the period November 2013 – January 2014. And it might reach a negative magnitude at the end of November 2013.”

This new comet joins Comet C/2011 L4 PanSTARRS, which is projected to come within 45 million kilometers (28 million miles) of the Sun on March 9, 2013, which is close enough for quite a bit of cometary ice to vaporize and form a bright coma and tail. Comet PanSTARRS will be visible at perihelion to southern hemisphere, while Comet ISON should be visible to mid-latitude northern hemisphere skywatchers, according to the Remanzacco team.

Orbit diagram from JPL’s Small Body Database of Comet ISON, as of Sept. 25, 2012. Credit: JPL

Right now, Comet ISON is at magnitude +18, and only larger telescopes can see it. How bright will the comet get, and could it even be visible during daytime? That’s the big question which only time will answer. Just 2 million km distant from the Sun is incredibly close, and if the comet stays intact, some estimates say it could reach a brilliant negative magnitude of between -11 and -16. Comparatively, the full Moon is about magnitude -12.7.

But this will happen only if the comet will stay together. Comets can be fairly unpredictable, and other comets that have come that close to the Sun — such as Comet Elenin in 2011, Comet LINEAR in 1999 and Comet Kohoutek in 1973 — failed to live up to expectations of brightness and visibility.

But other comets have survived, like Comet Lovejoy earlier this year, which came two times closer, and Comet McNaught in 2007 which became visible even in daylight when it reached magnitude -5.5. It was not as close to the Sun as Comet ISON will be, however, as McNaught was about 24 million km away.

The discovery of C/2012 S1 (ISON) was made by Vitali Nevski, of Vitebsk, Belarus, and Artyom Novichonok, of Kondopoga, Russia with a 0.4-meter reflecting telescope near Kislovodsk, Russia.

You can see the ephermides of the Comet ISON here, from the Minor Planet Center.

The a Remanzacco Observatory team has more images, including an animation of Comet ISON on their website.

You can see the full visibility calculations of Comet ISON done by Daniel Fischer here.

Posted on by David Gonzales

Bringing You There: Final Shuttle Flyby Over Kennedy Space Center

This will never be seen again. Last week, the remaining Shuttle Carrier Aircraft (NASA 905) lofted a Space Shuttle into the sky for the final time. After taking off, NASA 905 and Endeavour made one final low pass over the Kennedy Space Center runway before making way towards the West coast. These 2 videos were shot for Universe Today and show these vivid moments up-close from alongside the runway.

Continue reading “Bringing You There: Final Shuttle Flyby Over Kennedy Space Center”

Posted on by Nancy Atkinson

A New, Automatic 3-D Moon

Korolev lobate scarp on the Moon, in 3-D. Lobate scarps, a type of cliff,are found mostly in the highlands on the Moon, and are relatively small and young. Credit: NASA/GSFC/Arizona State University.

Who doesn’t love 3-D images, especially of objects in space? But creating them can be a bit time-consuming for scientists, especially for images from orbiting spacecraft like the Lunar Reconnaissance Orbiter that takes images from just one angle at a time. Usually, it is “amateur” enthusiasts who take the time to find and combine images from different orbital passes to create rich, 3-D views.

But now, scientists at the University of Arizona and Arizona State University have developed a new automatic “brain” — a new automatic processing system that aligns and adjusts images from LRO, and combines them into images that can be viewed using standard red-cyan 3D glasses.

Alpes Sinuous Rille, an ancient channel formed as massive eruptions of very fluid lava poured across the surface of the Moon. Credit: NASA/GSFC/Arizona State University

Human vision sees in three dimensions because our eyes are set slightly apart and see the world from two different angles at once. Our brain then interprets the two images and combines them into a single three dimensional view.

It’s fairly easy to create 3-D views from the Mars rovers like Curiosity and Opportunity, because they have mast cameras and navigation cameras which operate in pairs to provide stereo views of the Martian surface.

Ancient radial scars of ejecta extend out from the Orientale basin for hundreds of kilometers and consist of aligned craters and massive dune-like forms. They formed as streamers of lunar rock thrown out from the Orientale impact and crashed back to the surface. Credit: NASA/GSFC/Arizona State University

But LRO orbits high above the Moon’s surface, and can see from only one angle at one time. However, images taken in different orbits, from different angles can be combined together to reconstruct a view in three dimensions.

And this new system can automatically combine the disparate shots together. The images here are a sample of what the team has created so far.

This ‘brain’ is provided by a new initiative, presented by team member Sarah Mattson (University of Arizona) to the European Planetary Science Congress on 25 September. The team have developed an This type of image is known as an anaglyph.

“Anaglyphs are used to better understand the 3D structure of the lunar surface,” said Sarah Mattson from the University of Arizona and LRO team member. “This visualization is extremely helpful to scientists in understanding the sequence and structures on the surface of the Moon in a qualitative way. LROC NAC anaglyEuropean Planetary Science Congress on 25 September. LROC NAC anaglyphs will also make detailed images of surface of the Moon accessible in 3D to the general public.”

The Lunar Reconnaissance Orbiter Camera – Narrow Angle Camera (LROC NAC) has acquired hundreds of stereo pairs of the lunar surface, and is acquiring more as the mission progresses. The LROC NAC anaglyphs make lunar features such as craters, volcanic flows, lava tubes and tectonic features jump out in 3D. The anaglyphs will be released through the LROC website as they become available.

Mattson presented the new system at the European Planetary Science Congress on September 25.

Posted on by John Williams

Finding Life in All the Unlikely, Unexpected Places

Just one of several weather stations set up at Chott El Jerid, a Tunisian saltpan, measuring temperature, humidity, ultraviolet radiation, wind direction and velocity. Image credit: Felipe Goméz/Europlanet

From orbit and on the ground, Mars looks inhospitable. But it doesn’t look much different than the freezing Antarctic plains, sun-baked saltpans in Tunisia or Spain’s corrosively acidic Rio Tinto, according to a few explorers from the Centro de Astrobiología (CAB) in Madrid, who today presented some of their findings of life during a press conference at the European Planetary Science Congress.

The biggest difference, however, is that life still thrives in these extreme locales on Earth.

“The big questions are: what is life, how can we define it and what the requirements for supporting life?” asks project leader Dr. Felipe Goméz. “To understand the results we receive back from missions like Curiosity, we need to have detailed knowledge of similar environments on Earth. Metabolic diversity on Earth is huge. We have found a range of complex chemical processes that allow life to survive in unexpected places.”

Over the past four years, Goméz and his colleagues have checked Earth’s most inhospitable locales; the Chott el Jerid saltpan in Tunisia, the Atacama Desert in Chile, Rio Tinto in southern Spain and Deception Island in Antarctica.

While visiting Chott el Jerid, the team tracked huge changes in environmental conditions throughout the day but it was a small rise in surface temperature after dusk that caught their eye. “We found that this is caused by water condensing on the surface and hydrating salts which releases heat in an exothermic reaction,” he said in the press release. This is very interesting from the perspective of the REMS instrument on Curiosity — it gives us away to follow when liquid water might be present on the surface.”

The team also built a three-dimensional picture of the subsurface in the saltpan by measuring the electrical properties of the soil. While drilling several meters into the subsurface at Chott el Jerid and in the Atacama Desert, researchers found bacteria at depth that was completely isolated from the surface. The researchers found not only bacteria, but also single-celled halophilic organisms that are able to oxidize metabolites under both aerobic and anaerobic conditions.

Along the surface of Chott El Jerid, which is made up of very pure sodium chloride with a trace of other salts, the team found small pieces of organic matter within the salt crystals. Once analyzed, they found populations of halophilic, salt-loving, dormant bacteria. In the laboratory, they were able to rehydrate the samples and bring the bacteria back to life, Goméz said.

Another unexpected find occurred while studying outcrops of the mineral jarosite at Rio Tinto in Spain. Jarosite, found on the surface of Mars by the Mars Exploration Rover Opportunity, forms only in the presence of water that contains high concentrations of metals, such as iron. The outcrops at Rio Tinto also are extremely corrosive. Yet, sandwiched between layers in the salt crusts, the team found photosynthetic bacteria. Unexpectedly, iron in the salt crust seems to protect bacteria from ultraviolet radiation, Goméz said. Samples of bacteria with iron present were exposed with high levels of ultraviolet radiation. They survived while bacteria samples without iron were destroyed.

“What the bacteria we found in Rio Tinto show is that the presence of ferric compounds can actually protect life. This could mean that life formed earlier on Earth than we thought. These effects are also relevant for the formation of life on the surface of Mars,” says Goméz. The team also found that salt provides stable conditions that can allow life to survive in very hard environments.

“Within salts, the temperature and humidity are protected from fluctuations and the doses of ultraviolet radiation are very low,” explained Goméz. “In the laboratory, we placed populations of different bacteria between layers of salt a few millimetres thick and exposed them to Martian conditions. Nearly 100% of deinoccocus radiodurans, a hardy type of bacteria survived being irradiated. But fascinatingly, about 40% of acidithiobacillus ferrooxidans – a very fragile variety of bacteria – also survived when protected by a salt crust.”

The findings have implications not only for studying possible life on Mars, but also for the development of life on early Earth.

Source: European Planetary Science Congress (EPSC) 2012 Press Release

Image Details: Photosynthetic bacteria at Rio Tinto. Credit: Felipe Goméz

About the author: John Williams is owner of TerraZoom, a Colorado-based web development shop specializing in web mapping and online image zooms. He also writes the award-winning blog, StarryCritters, an interactive site devoted to looking at images from NASA’s Great Observatories and other sources in a different way. A former contributing editor for Final Frontier, his work has appeared in the Planetary Society Blog, Air & Space Smithsonian, Astronomy, Earth, MX Developer’s Journal, The Kansas City Star and many other newspapers and magazines. Follow John on Twitter @terrazoom

Posted on by Nancy Atkinson

Want to Look Inside a Burning Rocket Engine?

Here’s a bit of pretty amazing hobby rocket porn. Ben Krasnow walks us through — in a rather matter-of-fact way — of how he built a hybrid rocket engine in his shop using a piece of acrylic so he could see inside and watch the gaseous oxygen burn. As one commenter on You Tube described it, “Hey guys, I was bored, so I built a transparent rocket engine in my garage. No big deal.”

“This engine is only meant to run for 10 seconds at most,” says Krasnow in his video, “and so this construction isn’t going to last long enough to make a reusable rocket, let’s just say. This is definitely for demo only!”

Next up, Krasnow will travel through time to contact Montgomery Scott to find out how to create transparent aluminum. If seeing this video makes you want to do an impression of Tim the Toolman Taylor, Krasnow also has a video tour of his shop.

Posted on by Nancy Atkinson

Astrophoto: A Year of Mars Observations by Efrain Morales

Mars from July, 2011 to June 2012. Credit: Efrain Morales, Jaicoa Observatory

Superman has nothing on this big “S” created by putting together views of Mars for one full year. Efrain Morales from the Jaicoa Observatory in Puerto Rico compiled just a few images of Mars he captured from July of 2011 to June of 2012, and this collage shows the size differences in how Mars appeared in a telescope as the planet moved toward and then reached opposition in March of 2012, and how it appeared during the months afterward. Also visible is how the North Polar Cap decreased in size as the seasons changed on the red Planet.

Equipment: LX200ACF 12 inch, OTA, CGE mount, Flea3 CCD, TeleVue 3x barlows, Astronomik LRGB filter set. See more of Efrain’s work at his website.

Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.

Posted on by Jason Major

Astronomers Discover Milky Way’s Hot Halo

Artist's impression of the huge halo of hot gas surrounding the Milky Way Galaxy. Credit: NASA

Artist’s illustration of a hot gas halo enveloping the Milky Way and Magellanic Clouds (NASA/CXC/M.Weiss; NASA/CXC/Ohio State/A.Gupta et al.)

Our galaxy — and the nearby Large and Small Magellanic Clouds as well — appears to be surrounded by an enormous halo of hot gas, several hundred times hotter than the surface of the Sun and with an equivalent mass of up to 60 billion Suns, suggesting that other galaxies may be similarly encompassed and providing a clue to the mystery of the galaxy’s missing baryons.

The findings were reported today by a research team using data from NASA’s Chandra X-ray Observatory.

In the artist’s rendering above our Milky Way galaxy is seen at the center of a cloud of hot gas. This cloud has been detected in measurements made with Chandra as well as with the European Space Agency’s XMM-Newton space observatory and Japan’s Suzaku satellite. The illustration shows it to extend outward over 300,000 light-years — and it may actually be even bigger than that.

While observing bright x-ray sources hundreds of millions of light-years distant, the researchers found that oxygen ions in the immediate vicinity of our galaxy were “selectively absorbing” some of the x-rays. They were then able to measure the temperature of the halo of gas responsible for the absorption.

The scientists determined the temperature of the halo is between 1 million and 2.5 million kelvins — a few hundred times hotter than the surface of the Sun.

But even with an estimated mass anywhere between 10 billion and 60 billion Suns, the density of the halo at that scale is still so low that any similar structure around other galaxies would escape detection. Still, the presence of such a large halo of hot gas, if confirmed, could reveal where the missing baryonic matter in our galaxy has been hiding — a mystery that’s been plaguing astronomers for over a decade.

Unrelated to dark matter or dark energy, the missing baryons issue was discovered when astronomers estimated the number of atoms and ions that would have been present in the Universe 10 billion years ago. But current measurements yield only about half as many as were present 10 billion years ago, meaning somehow nearly half the baryonic matter in the Universe has since disappeared.

Recent studies have proposed that the missing matter is tied up in the comic web — vast clouds and strands of gas and dust that surround and connect galaxies and galactic clusters. The findings announced today from Chandra support this, and suggest that the missing ions could be gathered around other galaxies in similarly hot halos.

Even though previous studies have indicated halos of warm gas existing around our galaxy as well as others, this new research shows a much hotter, much more massive halo than ever detected.

“Our work shows that, for reasonable values of parameters and with reasonable assumptions, the Chandra observations imply a huge reservoir of hot gas around the Milky Way,” said study co-author Smita Mathur of Ohio State University in Columbus. “It may extend for a few hundred thousand light-years around the Milky Way or it may extend farther into the surrounding local group of galaxies. Either way, its mass appears to be very large.”

Read the full news release from NASA here, and learn more about the Chandra mission here. (The team’s paper can be found on arXiv.org.)

Inset image: NASA’s Chandra spacecraft (NASA/CXC/NGST)

NOTE: the initial posting of this story mentioned that this halo could be dark matter. That was incorrect and not implied by the actual research, as dark matter is non-baryonic matter while the hot gas in the halo is baryonic — i.e., “normal” —  matter. Edited. – JM