New images of Pluto have hinted at methane 'snow' coating the upper slopes of its forbidding mountains.
Data collected by the New Horizons spacecraft on its 2015 fly past the distant dwarf planet continues to trickle back to Earth, revealing new insights about its strange landscape.
Once assumed to be a relatively featureless rock at the edge of our Solar System, Pluto has been revealed as a dynamic and even more mysterious place -- complete with cryo-volcanoes, smooth plains and, now, snowcapped peaks.
The latest series of images show the tops of mountains in the region known as Cthulu, a 450-mile-wide area of dark red land which reaches 1,850 miles (or roughly halfway) around the equator of the dwarf planet.
Though the area is mostly dark -- which is thought to be caused by molecules of methane changing when exposed to sunlight and forming tholins -- the new pictures have exposed how the tops of some of its mountains are white, superficially reminiscent of the top of Earth's own mountains.
The material on top of the mountains in southeast Cthulu is bright, and "contrasts sharply" with the deep red of the plains in either side. Nasa said in a statement that the material is probably methane ice. "That this material coats only the upper slopes of the peaks suggests methane ice may act like water in Earth's atmosphere, condensing as frost at high altitude," said John Stansberry, a New Horizons researcher from Space Telescope Science Institute.
The images show that the bright ice matches where methane ice is present, indicating that the 'snow' is indeed condensed, frozen frost. They were captured with a resolution of around 680 metres per pixel, just 45 minutes before New Horizons made its closest flyby on 14 July 2015.
Other activity so far thought to have been documented on the planet's surface includes the movement of vast glaciers, made of nitrogen ice, that appear to be carrying huge and isolated 'hills' of water ice in their wake.
Recently released images from New Horizions show that the glaciers in Pluto's distinctive 'heart' (officially, 'Sputnik Planum') float in a sea of nitrogen in a similar manner to icebergs in the Arctic Ocean. The glaciation is probably itself caused by evaporating nitrogen condensing on higher areas of land, and flowing back to the basin of the heart.
New Horizons will continue to send back data from Pluto many months. It is currently heading further into the outer reaches of the Solar System on its long follow-up mission to a tiny, very dark rock around 45 kilometres across known as 2014 MU69.
This article was originally published by WIRED UK
