Science Explains Pluto Polygons

A recent study claims that strange geometric structures first seen on the tiny planet’s ground in 2015 are evidence of a process known as sublimation.

According to a new theory, the polygonal nitrogen ice on Pluto, which was discovered throughout a flyby by NASA’s New Horizons mission, froze straight from vapour instead of going first in a liquid stage.
Adrien Morison, a senior researcher at the University of Exeter in England, claimed his group’s findings are the first modeling-based explanation for why the polygons exist.

“Pluto is still geologically active despite being far away from the sun and having limited internal energy sources. This included at Sputnik Planitia, where the surface conditions allow the gaseous nitrogen in its atmosphere to coexist with solid nitrogen,” he explained.

Sputnik Planitia, a massive oval-shaped zone spanning Pluto’s equator, is the largest visible geological feature on the planet. The area is estimated to be 347,500 square miles in size and at least 1.2 to 1.8 miles below, according to assessments from 2016, when it was known as Sputnik Planum.

Simulation studies were used in the current study to illustrate that as Pluto’s nitrogen starts to cool throughout sublimation in Sputnik Planitia, it would generate polygons with the same size and topographical amplitude as observed in New Horizons’ photos. The latest model also agrees with bigger global climate simulations that reveal Sputnik Planitia sublimation began one million or two million years ago.

The scientists speculated that this sublimation mechanism may happen on more frozen planets in the planetary system, such as Triton (Neptune’s big moon) or the Kuiper Belt objects Eris and Makemake, which are further away in the solar system. However, more studies of their surfaces would almost certainly be necessary, necessitating the use of missions. There are currently no missions scheduled to visit those “locations”.