Pluto’s ice-covered peaks are like Earth’s – but not

We can often use our knowledge of planet Earth to explain the things we see on other worlds, although we may need to adjust the physics to account for a different temperature or a weak atmosphere. Planetary scientists, however, cannot always assume that a familiar landscape feature has formed in a familiar way.

When the spaceship New Horizons first looked at Pluto up close, there were countless alien wonders. But there were also mountain peaks that were dusted with something bright and looked very similar to the snow-capped peaks of the earth. On earth, these snow caps are created by increased precipitation when air rises over the mountains and cools, combined with the colder temperatures at higher altitudes.

With Pluto, this explanation cannot work for several reasons. First, the temperatures in general increase They rise a few kilometers from Pluto’s surface because gases absorb solar energy. Winds also tend to blow gradient as the colder surface cools the air nearby and makes it denser. What forms the light dusting and how does it get there?

To the west of Pluto’s heart-shaped bright plain is a dark region called Cthulhu. Within this region there are a few mountain ranges that are distinguished by their light colored caps. The researchers analyze spectral data from images of this area and say the bright areas are mainly methane ice. It is also evident on the north-facing edges and walls of impact craters in the region.

To find out why methane ice would form in these locations, the researchers turned to a climate model of the dwarf planet. The model allowed methane and nitrogen ice to form (or disappear by converting it to gas), and the researchers studied conditions at the time they visited New Horizons. Just by inputting the physics and topography, the model successfully creates methane ice on the mountains and craters of Cthulhu. In many places, methane frost can form at night, but it disappears during the day. However, a higher concentration of methane gas at higher elevations leads to a net accumulation on the mountain tops during this daily cycle.