The dark terrain informally known as Cthulhu Regio sweeps nearly halfway around Pluto’s equator, with light-colored peaks sticking up from the surrounding plains. What is that light-colored stuff? Apparently, it’s methane frost.
Evidence for Pluto’s methane meteorology was laid out today by the science team behind NASA’s New Horizons mission.
The piano-sized spacecraft’s cameras zeroed in on Cthulhu when it flew past Pluto last July 14. Most of the region is covered with a layer of dark reddish tholins, a substance that forms when sunlight breaks down hydrocarbons such as methane.
Then there are those bright peaks in southeast Cthulhu: When the scientists looked closely at compositional data collected by New Horizons’ Ralph/Multispectral Visible Imaging Camera, they found that the bright areas on top of Cthulhu’s mountains matched up with the spectral signature of methane ice.