Climate at -354 (Pluto)

Where Math Meets Pluto | Pluto New Horizons:

In hindsight, one wonders why we were so surprised. For instance, the triple point (the location on the temperature-pressure phase diagram in which a material can coexist as solid, liquid and gas) of both carbon monoxide and molecular nitrogen is in the vicinity of 63 Kelvin (- 346 Fahrenheit), a temperature that is achievable on Pluto, given its distance from the sun.  We know from the Earth that when a system is near its triple point (as in the case of water), interesting phases can manifest, such as flowing water, glaciers and vapor. This is one of the reasons why the Earth and its surface morphology is such a cool place—no pun intended.

When we look at Pluto we see the informally-named Sputnik Planum (SP), which is probably a giant nitrogen ice sea, with a lot of methane and carbon monoxide to share the space. It has the texture of toothpaste and has flow timescales on the order of dozens of years.  We see in the surrounding mountain ranges evidence of glacier ice flowing into the basin of SP. The ice within the plains appears to be undergoing so-called “solid-state convection,” the overturning of the ice layer because it’s warmer below than above, which causes it to buoyantly rise to the surface. We see perplexing textures that look like pits and worms on various parts of SP, a phenomenon possibly due to the strong sublimation of nitrogen or possibly even methane. We see globules of glacier ice that look like coagulated jelly in various locations near the glacier flows.