Hills of ice float in Pluto's cold heart
Hills of water-ice appear to be floating atop the frozen nitrogen within Pluto's icy heart.
Scientists working with data sent to Earth from NASA's New Horizons spacecraft think that the hills are probably bits of ice mountains that have fallen into the flat, nitrogen ice-filled plain called Sputnik Planum.
The hills flow over time as icebergs might in the Arctic Ocean on Earth, but instead of floating in water, these 'bergs are floating on nitrogen, carbon monoxide and methane that has the "texture of toothpaste," according to a NASA blog post.
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The hills of ice "float" on the nitrogen because "water ice is less dense than nitrogen-dominated ice," NASA said in a statement.
The New Horizons team has informally named a closely-clumped group of hills the "Challenger Colles" in honor of the astronauts who died in the Challenger explosion 30 years ago.
It's possible that the hills which make up the Challenger Colles -- that measure 37 by 22 miles across -- have actually been "beached" due to possibly shallow nitrogen ice in that part of Sputnik Planum, NASA said.
The space agency thinks the hills group together like that because they move with the nitrogen ice, which transports the icy chunks to certain parts of the plain, allowing the hills to cluster together.
NASA's New Horizons is still sending plenty of data back to Earth. Scientists think it will take the spacecraft about one year for the craft to send back the data it collected from its July 14 flyby of Pluto.
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Miriam Kramer worked as a staff writer for Space.com for about 2.5 years before joining Mashable to cover all things outer space. She took a ride in weightlessness on a zero-gravity flight and watched rockets launch to space from places around the United States. Miriam received her Master's degree in science, health and environmental reporting from New York University in 2012, and she originally hails from Knoxville, Tennessee. Follow Miriam on Twitter at @mirikramer.
