There are millions of asteroids in the asteroid belt between Mars and Jupiter, but yesterday attention focused on just one. According to a couple of studies in Nature, a large asteroid called 24 Themis is rife with water ice and organic molecules, and the researchers say that it could be more evidence that the water so precious to life on Earth came to our planet on board such rocks.

Two research teams took infrared images of 24 Themis, which is about 120 miles in diameter and was discovered in 1853. This asteroid has an extensive but thin frosty coating. It is likely replenished by an extensive reservoir of frozen water deep inside rock once thought to be dry and desolate [AP].

The team, led by Humberto Campins, says finding so much ice on the surface was a surprise; at the asteroid’s distance from the sun—3.2 astronomical units (AU), or just more than three times further than the Earth—exposed ice has a “relatively short lifetime,” the scientists write. As a result, the idea of a below-surface reservoir seems likely. (Icy comets aren’t nearly so close to the sun on average; Halley’s comet can come within .6 AU of the sun, but then retreats to a farthest distance of more than 35 AU.)

(more…)

Astronomers have discovered the closest new star to us that’s been spotted in 63 years. Though “star” might be a stretch, depending upon whom you ask.

The new find, UGPS 0722-05, is less than 10 light years from here. But sky-watchers missed it for so long because it’s a brown dwarf, a member of the murky class of celestial objects that linger between gas giant planets and low-mass stars. Brown dwarfs have so little mass that they never get hot enough to sustain the nuclear fusion reactions that power stars like the sun. Still, they do shine, because they glow from the heat of their formation, then cool and fade [New Scientist]. This dwarf’s temperature is somewhere between 266 and 446 degrees Fahrenheit, making it the coldest scientists have even seen. With its minimal activity, the brown dwarf gives off just 0.000026 percent the amount of light that our sun does.

(more…)

The moment you read this, volcanic eruptions could be happening on Venus.

Planetary astronomers have been debating whether Venus is or was geologically active, and whether the geologic hotspots previous missions saw mean that Venus is one of the few places in the solar system to have experienced volcanism. Now, according to data from the European Space Agency’s Venus Express mission, there’s every reason to believe that Venus not only has been geologically active and volcanic during its lifetime, but also might still be today, according to Jörn Helbert, coauthor of the study in Science. “The solidified lava flows, which radiate heat from the surface, seem hardly weathered. So we can conclude that they are younger than 2.5 million years old — and the majority are probably younger than 250,000 years…. In geological terms, this means that they are practically from the present day” [Wired.com].

(more…)

The “young sun paradox” just won’t go away. For decades, scientists like Carl Sagan have tried to resolve this mystery of the early solar system—how the newborn Earth stayed warm enough to keep liquid water—but it continues to bob and weave around an answer. In the journal Nature, a team led by Minik Rosing proposes an alternate solution to the leading theory, which relies on the greenhouse effect hypothesis. But don’t expect the debate to end here.

The problem is this: The young Earth received much less heat from the sun. Four billion years ago, a lower solar luminosity should have left Earth’s oceans frozen over, but there is ample evidence in the Earth’s geological record that there was liquid water — and life — on the planet at the time [Space.com]. So what gives? The traditional explanation going back to the 1970s has been that a powerful greenhouse effect, far stronger than the one we experience today, kept the Earth basked in enough warmth to keep water sloshing around the planet’s surface as a liquid and not packed in solid ice. In 1972, Sagan and colleague George Mullen wrote that such an effect would have required intense carbon dioxide concentrations in the atmosphere during that period, the Archaen.

(more…)

Since NASA’s Stardust mission returned in 2006 from its trip of billions of miles collecting the dust of a comet called Wild2 and dropped it samples down to Earth in the Utah desert, the samples have raised all sorts of questions about how comets formed and what the early solar system was like. In a study this week in Science, there’s a new surprise. Scientists say that the comet sample contains chemicals that must have formed in our home turf, the inner solar system.

Lead researcher Jennifer Matzel studies a tiny particle taken from Stardust’s sample, a piece just five micrometers across. In it her team found the mark of materials that would have formed under high temperatures. Matzel, who specializes in using the decay rates of radioactive chemical elements to assess ancient dates, determined that the Stardust particle must have crystallized just 1.7 million years after the oldest solid rocks in the solar system were forming [San Francisco Chronicle]. After that, the researchers says, the particle must have been flung out to the Kuiper Belt, the region of icy comets revolving around the sun at a distance far past Neptune.

(more…)

Four decades later, the Murchison meteorite is still full of surprises. When this extraterrestrial hunk fell to Earth near its namesake town in Australia in 1969, people managed to salvage more than 200 pounds of it. And now a new analysis of the meteorite, published this week in the Proceedings of the National Academy of Sciences, shows that it could hold millions of carbon-containing compounds. Researchers say the findings provide insight into the complex chemistry present when the chunk of space-rock formed, back when our solar system was young.

Back in 1969, researchers found amino acids and many other molecules in the carbon-rich rock.  Many researchers have analyzed the chondritic meteorite for amino acids and other possible precursors to life, because some theories hold that life on Earth began with the delivery of prebiotic organic compounds from space via asteroids or comets [Scientific American]. But scanning techniques have advanced since then, so the new team used tools like ultra-high-resolution mass spectrometry to take a fresh look at the meteorite.

(more…)

Both Uranus and Neptune have quirky magnetic poles—they’re located about 60 degrees off the geographic pole rather than very nearby, like ours is. The reason, researchers suggest in a new Nature Physics study, could be that oceans of diamond—yes, oceans of diamond—cover our solar system’s two most distant planets.

The diamond idea isn’t a new one, but it’s a terribly hard question to study because you have to get diamond to melt in the lab to study it, and this experiment was the first to document the pressure and temperature at which that happens. The mineral is notoriously hard, of course, but there’s something more: Diamond doesn’t like to stay diamond when it gets hot. When diamond is heated to extreme temperatures it physically changes, from diamond to graphite. The graphite, and not the diamond, then melts into a liquid. The trick for the scientists was to heat the diamond up while simultaneously stopping it from transforming into graphite [Discovery News].

(more…)

On January 7, 1610, Galileo Galilei pointed his “spyglass” to the heavens and stared up at Jupiter, one of the brightest lights in the evening sky, and noted what he at first assumed to be three bright stars near the planet. But over the following nights, he realized that those three bright bodies weren’t fixed in the heavens like stars, but rather seemed to dance around Jupiter along with a fourth, smaller body.

Galileo triumphantly announced his discovery of four “planets” that revolved around Jupiter in his March treatise, Starry Messenger [pdf]. Thinking of his pocketbook, he dutifully proposed naming them the Medicean Stars in honor of his patron, Cosimo de Medici. But the name didn’t stick, and today we honor the scientist rather than the patron by calling Jupiter’s four largest satellites the Galilean moons.

The discovery dealt a death blow to the Ptolemaic understanding of the universe, in which all planets and stars were believed to orbit the Earth. For, as Galileo wrote in his treatise, “our own eyes show us four stars which wander around Jupiter as does the moon around the earth.”

In the 400 years that have passed since Galileo first laid eyes on them, we’ve learned a great deal about the moons Io, Europa, Ganymede, and Callisto (all named after the mythological paramours of Jupiter). If all goes according to plan we’ll soon get to know them much more intimately–NASA and the European Space Agency are currently planning missions to closely observe three of the moons. Click though this gallery to view NASA’s most stunning photos of the four satellites, and to find out what we’ve discovered in the four centuries since Galileo began the work.

(For more on Galileo’s discovery and what it meant to science, check out this post from DISCOVER’s Phil Plait.)

Image: NASA/JPL/DLR

After three-plus decades of exploring the gas giants, passing the orbit of Pluto, and reaching points beyond, Voyager 2 has found something interesting near the edge of the solar system: surprisingly magnetic fluff. Researchers document their findings in this week’s Nature.

Of course, this fluff isn’t made from the dust bunnies you find under your bed, the ‘Local Fluff’ (a nickname for the Local Interstellar Cloud) is a vast, wispy cloud of hot hydrogen and helium stretching 30 light-years across [Discovery News]. Astronomers already knew this fluff was out there near the boundary area between our solar system and interstellar space. What surprised them is that the fluff is much more magnetized than they’d expected.

(more…)

When NASA’s Messenger space probe swung past Mercury on September 29, it snapped this picture of the innermost planet’s barren and strange landscape. The $446 million probe’s third flyby brought it within 142 miles (228 km) of Mercury’s surface to cover more uncharted terrain, leaving 98 percent of the planet now mapped [SPACE.com].

The images taken and the data recorded during the flyby are the last that will be acquired until Messenger finally slips into orbit around Mercury in 2011. The probe has now completed about three-quarters of its swooping 4.9-billion-mile journey that will eventually bring it into orbit.

Researcher Brett Denevi explains that this enhanced color shot shows a bright area surrounding an irregular depression, with steep sides and an odd shape, “all of which are hallmarks of something like a volcanic vent,” Denevi said [SPACE.com]. The double-ring basin in the center of the photo measures about 180 miles in diameter. It appears to be a relatively young impact crater–researchers believe it formed about 1 billion years ago–and the smooth stuff on the crater floor may be even younger volcanic material.

Related Content:
80beats: Space Probe Soon to Study Mercury’s Comet-Like “Tail”
80beats: Mercury Flyby Reveals Magnetic Twisters and Ancient Magma Oceans
80beats: Brand New Postcards From Mercury, Courtesy of Messenger Space Probe

Image: NASA

With much fanfare, NASA’s lunar probe smashed into the moon this past Friday in an attempt to excavate and study hypothetical traces of lunar water ice. As planned, the probe slung an empty rocket hull into a crater at the moon’s south pole. The LCROSS probe itself then followed behind the rocket hull, snapping photos and beaming them back to Earth before smashing into the very same crater. The impact appears to have gone off without a hitch, however the crash left many disappointed since the expected 6.2-mile-high cloud of dust, which was to be analyzed for traces of ice, never materialized. So far, astronomers using ground-based telescopes and the Hubble Space Telescope in orbit have not reported seeing any ejecta plume, but have cautioned that more time is needed to be sure [SPACE.com].

At a post-impact briefing, many in the press expressed concern about the mission’s success. In response, LCROSS project scientist Anthony Colaprete outlined several reasons why the impacts may not have thrown up plumes immediately visible after the impacts, including the [impact] hitting the inner walls of the crater at an angle that ejected the impact pit dust sideways instead of straight up. “Luck plays a part in this,” he said, adding. “We have the data we need to address the questions we have and that’s the bottom line” [USA Today]. The researchers also say it’s possible that the rocket hull hit bedrock instead of loose, gravelly soil as expected, and therefore kicked up only a small debris cloud that wasn’t visible to LCROSS.

(more…)

Astronomers have found an enormous and diffuse new ring of Saturn that lies far, far beyond the rest of the planet’s famous circlets. Researchers say the new ring is comprised of debris ejected from Saturn’s outlying moon Phoebe during impact. The new discovery also solves a puzzle regarding the curious two-faced appearance of Saturn’s moon Iapetus, whose leading hemisphere is much darker than its trailing side [New Scientist].

The ring, which has claimed the title of largest known ring in the solar system, starts about 3.7 million miles from Saturn and extends outward another 7.4 million miles. Its diameter is equivalent to 300 Saturns lined up side to side. And its entire volume can hold one billion Earths…. “This is one supersized ring” [CNN], says Anne Verbiscer, coauthor of the study published in Nature. The ring has the same orbital tilt as the moon Phoebe–both are tilted at a 27 degree angle from Saturn’s main ring plane–which supports the theory that Phoebe’s ejected dust feeds the ring.

(more…)

Today in the innermost region of our solar system, NASA’s Messenger space probe will swoop past Mercury for the third and final time. The maneuver will give scientists a close look at the dense, iron-rich, oddball planet, and will also alter the probe’s trajectory and prepare it to begin orbiting Mercury in March 2011.

As Messenger travels within 142 miles of Mercury at 12,000 miles per hour, the spacecraft’s camera will swivel to stare at a succession of craters and other geological features…. One target will be an old 90-mile-wide crater. Another will be young 13-mile crater and a splash of light-colored soil surrounding it. A third crater of interest has materials of unusual color perhaps produced by violent volcanic eruptions [The New York Times]. When this third flyby is complete, 95 percent of the planet will have been mapped in high resolution.

(more…)

NASA’s new Lunar Reconnaissance Orbiter has only been on the job for three months, but even while researchers were calibrating its instruments it was already making new discoveries about our moon. The orbiter swooped down above the moon’s mysterious south pole, and measured temperatures in the permanently shadowed craters that are the lowest ever detected in our solar system. It has also detected traces of hydrogen in various lunar locations, which may indicate buried water ice.

The extent of the deep freeze in the southern lunar craters surprised scientists, says lunar scientist David Paige: “Right here in our own backyard are definitely the coldest things we’ve seen in real measurements.” Temperatures there were measured at 397 degrees below zero. That’s just 62 degrees higher than the lowest temperature possible. Pluto is at least a degree warmer even though it is about 40 times farther away from the sun [AP].

Such temperatures probably allowed for the preservation of ices of water, methane, or ammonia from ancient comet collisions…. Such ices could be valuable resources that human lunar explorers could use. And they would help answer questions about the arrival of such “volatiles” to the Earth-moon system – evidence that Earth’s geological processes have largely erased from its own surface [Christian Science Monitor]. Researchers scheduled the LRO to scrutinize the moon’s south pole in particular because of this combination of potentially useful resources and scientifically interesting sites.

(more…)

The mighty planet Jupiter has 63 official moons, but it turns out there’s always room for more. Researchers used computer models to map the past trajectory of the comet 147P/Kushida-Muramatsu, and determined that for about 12 years it circled Jupiter as a temporary moon. At the ongoing European Planetary Science Congress, astronomers declared that the comet completed two complete orbits of the gas giant, and remained in orbit from 1949 to 1961.

The 1,300-foot-wide comet had a happier fate than other comets that got too close to Jupiter, and were dragged all the way in for a crash landing. Only one temporary satellite has been observed falling prey to a planet’s pull: comet Shoemaker-Levy 9, which broke apart and crashed into Jupiter in 1994…. Unlike [Shoemaker-Levy], comet Kushida-Muramatsu eventually escaped Jupiter’s gravity. It currently circles the sun in the solar system’s asteroid belt, between the orbits of Mars and Jupiter [National Geographic News].

(more…)