May 31, 2018 - Science

Earth-like dunes of icy methane found on Pluto

The mountain range on the edge of the Sputnik Planitia ice plain, with dune formations in the bottom half of the picture.

Ridges of dune formations on the mountainous edge of Pluto's Sputnik Planitia ice plain. Image: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Despite its thinner atmosphere and lower gravity, Pluto is home to icy dunes resembling those on Earth, according to research published today in the journal Science.

The big picture: Pluto's surface is far more dynamic and diverse than researchers expected before NASA's New Horizon's spacecraft flew closely past it in 2015. The finding also suggests similarities between the dwarf planet and our own.

"It gives us further information about our own planet’s formation — the world we’re all standing on right now."
— Matt Telfer, geographer, University of Plymouth

What they saw: In July 2015, NASA's New Horizons spacecraft captured images of Sputnik Planitia, a large plain of mostly nitrogen ice on the western side of Pluto's now-iconic heart. Amid the mountains and glaciers there, Telfer and colleagues spotted 357 pale ridges and six darker perpendicular streaks that are telltale characteristic of dunes.

  • The formations, which stretch across an area about 47 miles wide, are similar to those seen in satellite images of the Sahara.
  • "They are a weather vane left on the landscape that tells us which way the wind has blown," Telfer told Axios.

How they formed: Pluto's roughly 20 mph winds are strong enough to keep particles blowing but not strong enough to get them airborne in the first place.

  • It's possible that as Pluto's surface is warmed by the distant sun, frozen nitrogen particles turn from solid to gas, the researchers suggest. That gas then lifts off the surface, carrying the still frozen methane grains upward where the wind can then pick them up and move them.
  • But there are other possible processes to explain their formation, including a crystallization process they're still studying, Telfer says.

One more thing: Pluto's dunes are long transverse ridges, similar to some found on Earth, Mars, Titan and other bodies throughout the solar system.

"Despite radically different conditions or different processes, sometimes similar landscapes result," Telfer says. " [S]ome of these science fiction landscapes may not be that incredible."
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