View of Pluto from NASA’s New Horizons spacecraft.

Pale dunes (centre and right) on Pluto were formed by the dwarf planet’s winds, which reach up to 40 kilometres an hour. Credit: NASA/JHUAPL/SwRI

Planetary science

Hundreds of methane dunes nestle at the base of Pluto’s mountains

The formations offer a surprise on a body with such a thin atmosphere.

Dramatic dunes of methane sweep across part of Pluto. The discovery shows that the dwarf planet’s atmosphere, although thin, can still generate winds powerful enough to blow particles across the surface.

Matt Telfer at Plymouth University, UK, and his colleagues studied images taken by NASA’s New Horizons spacecraft, which flew past Pluto in 2015. In the images, the dunes appear as parallel ridges near the edge of a great ice plain known as Sputnik Planitia.

The researchers’ calculations suggest that methane gas begins to waft off the methane-ice particles on Sputnik Planitia. This lofts the particles away from Pluto’s surface. Winds then deposit the grains into dunes similar to those seen on Mars and Titan.

Until now, some researchers thought that Pluto’s atmosphere, which is at 1/100,000th the pressure of Earth’s, could not support winds strong enough to sculpt dunes. But the team’s analysis shows otherwise.

The dunes probably formed in the past 500,000 years — which means Pluto is a geologically active world.