Image copyright NASA / JHUAPL / SWRI Image caption The data from New Horizons revealed Pluto to be geologically diverse and dynamic

Scientists say they have found evidence of dunes of frozen methane on Pluto. Based on the data that New Horizons captured during its 2015 flyby of Pluto, scientists surmised the methane grains are released into the dwarf planet’s thin and rarefied atmosphere when solid nitrogen gets converted directly into gas (a process called sublimation). The research, which is published in the journal Science, suggests that the distant world is more dynamic than previously thought. Researchers said the dunes appear to be made mostly of icy specks of methane the size of sand, with some frozen nitrogen likely mixed in. Thought to be relatively recent, the parallel rows of dunes are in Pluto's heart-shaped region at the base of mountains as tall as the Alps and formed from giant blocks of ice with frosty methane snow caps. A detailed look at images of Pluto showed researchers the methane dunes spread across an area that forms the boundary between the icy plain called Sputnik Planitia (one of the largest features on Pluto) and a major mountain range that lies next to it. Even as the winds on Pluto reach maximum speeds of 30 to 40 kilometers an hour, they are sufficient, given the low surface pressure (100,000 times less than Earth) and weak gravity, for the dunes to form. With that warming of the ice below the surface, methane crystals should enable nitrogen ice to sublimate - and that would allow the methane crystals to be wafted into the atmosphere. Pluto’s gentle winds then carried and deposited the grains. Image copyright NASA / JHUAPL / SWRI

Pluto now joins Earth, Mars, Venus, Saturn's moon Titan and even the comet 67P - which a European Space Agency (Esa) mission landed on - as homes to dunes.
Pluto, the eponymous member of the plutino group, is discovered to have dunes of methane ice.