The atmosphere of Pluto could freeze and disappear by 2030

Life is hard for the Pluto dwarf planet. After losing its planet status in 2006 for its small size, it could be confronted with a next atmospheric armageddon.

Astronomers have studied the seasonal changes in Pluto's surface pressure using a technique called stellar ground concealment. An occultation occurs when an object such as a moon or planet blocks light coming from an object farther away such as a star, an eclipse of the sun, reaching the Earth. By observing how Pluto blocks the light of distant stars, you can measure information about the density, pressure and temperature of the atmosphere.

"We have been able to build seasonal patterns of Pluto and how it reacts to changes due to the amount of sunlight received while orbiting the sun," said Andrew Cole of the University of Tasmania in a statement. "What we have discovered is that when Pluto moves farthest away from the sun and during the winter of the northern hemisphere, nitrogen freezes from the atmosphere."

It is already very cold on the surface of Pluto, with a surface temperature ranging from minus 378 to minus 396 degrees Fahrenheit (minus 228 to minus 238 degrees Celsius). We now know that some seasons are colder than others – cold enough so that nitrogen, which forms the bulk of the atmosphere – freezes.

And the atmosphere also changes with time. Atmospheric pressure has tripled in the last thirty years. The models of the dwarf planet show that the majority of the atmosphere will condense until there is almost nothing left. "Our predictions show that by 2030, the atmosphere will freeze and disappear all over the planet," Cole said.

If this happens, it will change the way Pluto appears to us. The freezing of nitrogen would reflect more sunlight, which would make Pluto appear brighter in the sky. But the terrain of the dwarf planet will be different too. The colors observed by the New Horizons mission to Pluto in 2015, like the bright red terrain shown in the image above, can be hidden under the nitrogen frost.

The results will soon be published in the journal Astronomy & Astrophysics. You can view the article on the arXiv prepublication archive.