We can often use our knowledge of planet Earth to explain things we see in other worlds, although we may need to change physics to account for different temperatures or low atmospheres. But planetary scientists cannot always assume that a familiar landscape element is formed in a familiar way.
When the New Horizons spacecraft gave us our first glimpse of Pluto, there were plenty of alien wonders. But there were also mountain peaks sprinkled with something bright, very similar to the snow-capped peaks of the Earth. On Earth, these snow caps are produced by heavy rainfall as the air rises above the mountains and cools, combined with colder temperatures at higher altitudes.
On Pluto, this explanation cannot work for several reasons. First, temperatures in general growing while climbing a few kilometers from the surface of Pluto due to gases absorbing solar energy. Winds also tend to blow down as the colder surface cools the air near it, making it denser. So what forms the bright dust and how do you get there?
To the west of Pluto̵
To understand why methane ice would form in these places, researchers turned to a climate model on the dwarf planet. The model allowed methane and nitrogen ice to form (or disappear, turning into gas), and the researchers directed the conditions during a visit to New Horizons. Only by using physics and topography, the model successfully makes methane ice in the mountains and craters of Cthulhu. Many places can see some methane frost at night, but disappear during the day. But the higher concentration of methane gas at higher altitudes leads to a net accumulation of mountain peaks during this daily cycle.