The tenuous nitrogen atmosphere of the dwarf planet Pluto is predicted to ultimately collapse and freeze over.

Pluto is the smallest, coldest and most distant dwarf planet with an atmosphere in the Solar System.

It orbits the Sun every 248 years, and its surface temperature is between minus 378 and minus 396 degrees Fahrenheit (minus 228 – minus 238 degrees Celsius). Its atmosphere consists of nitrogen, with traces of methane and carbon monoxide.

University of Tasmania astronomer Andrew Cole and colleagues aimed to record the seasonal evolution of Pluto’s surface pressure by observing ground-based stellar occultations to gain the atmosphere’s profile including density, pressure and temperature.

“We were able to construct seasonal models of Pluto and how it responds to changes with the amount of sunlight it receives as it orbits the Sun,” Dr. Cole said.

“What we found was when Pluto is farthest away from the Sun, and during its winter in the northern hemisphere, nitrogen freezes out of the atmosphere.”

“The atmospheric pressure has tripled over the past three decades, but as the dwarf planet orbits, our modeling showed that most of the atmosphere would condense out to almost nothing left.”

“What our predictions show is that by 2030 the atmosphere is going to frost out and vanish around the whole planet.”

“If it does freeze over, Pluto may appear brighter in the sky due to sunlight reflecting,” he added.

The study’s results were also used in comparison with NASA’s New Horizons mission which gathered data during a flyby of Pluto in 2015.

“The striking red terrain seen in the New Horizons images could fade away if they are snowed under with nitrogen frost,” Dr. Cole said.

The findings will be published in the journal Astronomy & Astrophysics.

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E. Meza et al. 2019. Pluto’s lower atmosphere and pressure evolution from ground-based stellar occultations, 1988-2016. A&A, in press; arXiv: 1903.02315