NASA
This artist's conception shows 2007 OR10, nicknamed Snow White. Astronomers suspect that its rosy color is due to the presence of irradiated methane.
updated 10/23/2011 5:16:31 PM ET 2011-10-23T21:16:31

Scientists say a mysterious little world on the solar system's edge, nicknamed "Snow White," is covered in ice and may sport the wispy remnants of an atmosphere.

Even though Snow White — officially known as 2007 OR10, and orbiting the sun as part of the Kuiper Belt — is actually red, half of the surface is covered by water ice that probably spewed from ancient cryovolcanoes, researchers said.

The icy world's reddish hue likely comes from a thin layer of methane, the last gasps of an atmosphere that has been bleeding off into space for eons.

"You get to see this nice picture of what once was an active little world with water volcanoes and an atmosphere, and it's now just frozen, dead, with an atmosphere that's slowly slipping away," the study's lead author Mike Brown, of Caltech, said in a statement. [Looking Back on Killing Pluto: Q & A With Mike Brown]

A reddish, icy dwarf
Snow White is about half the size of Pluto. Like Pluto, it's part of the Kuiper Belt, which is the ring of icy bodies that orbit the sun beyond Neptune.

At the time of its discovery in 2007, Brown guessed that Snow White had broken off long ago from a dwarf planet called Haumea. Haumea, a weird, football-shaped body, is sheathed in water ice, so Brown figured that 2007 OR10 was, too — hence the nickname Snow White.

However, follow-up observations soon showed that Snow White, like many other Kuiper Belt objects, is actually quite red. So Brown and his team weren't expecting to find a lot of water ice when they used the 6.5-meter Magellan Baade Telescope in Chile to take a closer look at Snow White last year.

But that's just what they saw. Spectral data showed that water ice abounded on Snow White's surface.

"That was a big shock," Brown said. "Water ice is not red."

Brown and his colleagues reported their results last month in the Astrophysical Journal Letters.

Just like Quaoar?
Scientists know of one trans-Neptunian object that's both red and covered with water ice: Quaoar, which Brown and his team discovered in 2002. [Meet the Solar System's Dwarf Planets]

Researchers think Quaoar, which is slightly smaller than Snow White, once had an atmosphere composed of volatile compounds such as methane, carbon monoxide and nitrogen. But its gravity wasn't strong enough to hold onto these chemicals, and the icy world began losing its atmosphere to space.

Over time, everything but some methane escaped. And radiation from space has transformed those methane molecules — which consist of one carbon atom bonded to four hydrogen atoms — into long hydrocarbon chains, researchers said.

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Those chains look red to our instruments, and they sit atop Quaoar's water-ice surface.

Snow White's spectrum looks similar to Quaoar's, suggesting that similar processes occurred on both worlds, researchers said.

"That combination — red and water — says to me 'methane,'" Brown said. "We're basically looking at the last gasp of Snow White. For four and a half billion years, Snow White has been sitting out there, slowly losing its atmosphere, and now there's just a little bit left."

While Snow White definitely has a lot of water ice on its surface, the evidence for methane is not conclusive, Brown added. Researchers hope to use even bigger telescopes to study Snow White more closely.

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Gallery: The new solar system

Get the facts about dwarfs, giants, terrestrials and other denizens of our planetary realm.

Photos: Month in Space: January 2014

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    Stars, galaxies and nebulas dot the skies over the European Southern Observatory's La Silla Paranal Observatory in Chile, in a picture released on Jan. 7. This image also shows three of the four movable units that feed light into the Very Large Telescope Interferometer, the world's most advanced optical instrument. Combining to form one larger telescope, they are greater than the sum of their parts: They reveal details that would otherwise be visible only through a telescope as large as the distance between them. (Y. Beletsky / ESO) Back to slideshow navigation
  2. A balloon's view

    Cameras captured the Grandville High School RoboDawgs' balloon floating through Earth's upper atmosphere during its ascent on Dec. 28, 2013. The Grandville RoboDawgs’ first winter balloon launch reached an estimated altitude of 130,000 feet, or about 25 miles, according to coaches Mike Evele and Doug Hepfer. It skyrocketed past the team’s previous 100,000-feet record set in June. The RoboDawgs started with just one robotics team in 1998, but they've grown to support more than 30 teams at public schools in Grandville, Mich. (Kyle Moroney / AP) Back to slideshow navigation
  3. Spacemen at work

    Russian cosmonauts Oleg Kotov, right, and Sergey Ryazanskiy perform maintenance on the International Space Station on Jan. 27. During the six-hour, eight-minute spacewalk, Kotov and Ryazanskiy completed the installation of a pair of high-fidelity cameras that experienced connectivity issues during a Dec. 27 spacewalk. The cosmonauts also retrieved scientific gear outside the station's Russian segment. (NASA) Back to slideshow navigation
  4. Special delivery

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  5. Accidental art

    A piece of art? A time-lapse photo? A flickering light show? At first glance, this image looks nothing like the images we're used to seeing from the Hubble Space Telescope. But it's a genuine Hubble frame that was released on Jan. 27. Hubble's team suspects that the telescope's Fine Guidance System locked onto a bad guide star, potentially a double star or binary. This caused an error in the tracking system, resulting in a remarkable picture of brightly colored stellar streaks. The prominent red streaks are from stars in the globular cluster NGC 288. (NASA / ESA) Back to slideshow navigation
  6. Supersonic test flight

    A camera looking back over Virgin Galactic's SpaceShipTwo's fuselage shows the rocket burn with a Mojave Desert vista in the background during a test flight of the rocket plane on Jan. 10. Cameras were mounted on the exterior of SpaceShipTwo as well as its carrier airplane, WhiteKnightTwo, to monitor the rocket engine's performance. The test was aimed at setting the stage for honest-to-goodness flights into outer space later this year, and eventual commercial space tours.

    More about SpaceShipTwo on PhotoBlog (Virgin Galactic) Back to slideshow navigation
  7. Red lagoon

    The VLT Survey Telescope at the European Southern Observatory's Paranal Observatory in Chile captured this richly detailed new image of the Lagoon Nebula, released on Jan. 22. This giant cloud of gas and dust is creating intensely bright young stars, and is home to young stellar clusters. This image is a tiny part of just one of 11 public surveys of the sky now in progress using ESO telescopes. (ESO/VPHAS team) Back to slideshow navigation
  8. Fire on the mountain

    This image provided by NASA shows a satellite view of smoke from the Colby Fire, taken by the Multi-angle Imaging SpectroRadiometer aboard NASA's Terra spacecraft as it passed over Southern California on Jan. 16. The fire burned more than 1,863 acres and forced the evacuation of 3,700 people. (NASA via AP) Back to slideshow navigation
  9. Where stars are born

    An image captured by NASA's Spitzer Space Telescope shows the Orion Nebula, an immense stellar nursery some 1,500 light-years away. This false-color infrared view, released on Jan. 15, spans about 40 light-years across the region. The brightest portion of the nebula is centered on Orion's young, massive, hot stars, known as the Trapezium Cluster. But Spitzer also can detect stars still in the process of formation, seen here in red hues. (NASA / JPL-Caltech) Back to slideshow navigation
  10. Cygnus takes flight

    Orbital Sciences Corp.'s Antares rocket rises from NASA's Wallops Flight Facility on Wallops Island, Va, on Jan. 9. The rocket sent Orbital's Cygnus cargo capsule on its first official resupply mission to the International Space Station. (Chris Perry / NASA) Back to slideshow navigation
  11. A long, long time ago...

    This long-exposure picture from the Hubble Space Telescope, released Jan. 8, is the deepest image ever made of any cluster of galaxies. The cluster known as Abell 2744 appears in the foreground. It contains several hundred galaxies as they looked 3.5 billion years ago. Abell 2744 acts as a gravitational lens to warp space, brightening and magnifying images of nearly 3,000 distant background galaxies. The more distant galaxies appear as they did more than 12 billion years ago, not long after the Big Bang. (NASA / NASA via AFP - Getty Images) Back to slideshow navigation
  12. Frosty halo

    Sun dogs are bright spots that appear in the sky around the sun when light is refracted through ice crystals in the atmosphere. These sun dogs appeared on Jan. 5 amid brutally cold temperatures along Highway 83, north of Bismarck, N.D. The temperature was about 22 degrees below zero Fahrenheit, with a 50-below-zero wind chill.

    Slideshow: The Year in Space (Brian Peterson / The Bismarck Tribune via AP) Back to slideshow navigation
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