Scientists have discovered enormous white dunes made of methane ice on Pluto. They were found in high-resolution images taken by NASA’s New Horizons spacecraft. KNAU’s Melissa Sevigny reports it’s a mystery how they formed.
On Earth, dunes are created when wind blows sand grains into wavy patterns. But scientists say Pluto’s thin atmosphere means it’s not very windy there.
Will Grundy of Flagstaff’s Lowell Observatory is a coauthor on the paper. He says, "The calculations in the paper show it’s possible to keep particles moving once they’re moving, but there’s probably not enough wind on Pluto to start them moving. That’s the conundrum, how do you get them started?"
One idea is during the daytime, frozen nitrogen on Pluto’s surface sublimates from solid ice to vapor. The little puffs of vapor toss methane ice crystals into the air, where they’re snatched up by the breeze. But Grundy cautions other explanations are possible, such as dust devils or landslides.
The paper appeared this month in the journal Science.
The scientists examined a high-resolution image strip from Pluto's heart-shaped terrain; download it here.