Pluto is Nice, but it’s Losing its Atmosphere

The thin blue atmosphere of Pluto could be completely frozen by the year 2030, new studies of the dwarf planet reveal. Observations of star occultations as Pluto passes in front of background stars have now shed new light on the nature of the atmosphere surrounding this distant world.

Pluto is the smallest, most distant, and coldest object in the solar system known to possess an atmosphere. This thin layer of nitrogen gas (with traces of methane and carbon monoxide) periodically freezes before reforming as gas as the tiny world makes its way around the Sun.

“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 [until there is] almost nothing left. What our predictions show is that by 2030 the atmosphere is going to frost out and vanish around the whole planet,” explained Dr. Andrew Cole of the University of Tasmania.

Down in Front!

Stellar occultation takes place when a body (such as Pluto) passes in front of a star as seen from Earth. By studying the starlight passing through the atmosphere of Pluto, astronomers are able to gain insights into the density, temperature, and composition of the gasses surrounding the dwarf planet.

A look at what it would be like to fly over the frozen surface of Pluto. Credit: NASA

These observations were taken between 2002 and 2016 with the 1.3 meter (52 inch) Harlingten telescope at the Greenhill Observatory. This data was then combined with observations from July 2015, when New Horizons became the first spacecraft to ever pass by Pluto and its system of moons, out in the reaches of the Kuiper Belt. Dramatic red markings on the surface of the world, including a massive heart-shaped feature named Tombaugh Regio, may be hidden by ice when the atmosphere of Pluto falls to the ground.

Pluto has always been a favorite locale for science fiction writers, including the minds behind Futurama. Used under fair use.

“The complexity of the Pluto system — from its geology to its satellite system to its atmosphere — has been beyond our wildest imagination. Everywhere we turn are new mysteries,” said Alan Stern, New Horizons principal investigator from the Southwest Research Institute (SWRI).

A Cold Reception

As Pluto orbits the Sun every 248 years, it experiences seasons, just as we do on Earth. When it is winter in the northern hemisphere of that world, the tenuous gaseous atmosphere can freeze into solid material, falling to the surface, where it remains locked on the ground until temperatures warm up once more. Surface temperatures on Pluto fluctuate between 238 to 228 degrees below zero Celsius (396 to 378 below zero Fahrenheit).

Neptune was a freezeup and — furthest out of all — Pluto, the ninth planet, a revolving snowball.

Past Pluto was a dark spot where a planet ought to be. The balloon took its position to orbit endlessly.

-The Tenth Planet, John Foster

Venetia Burney, the 11-year-old girl who named the planet Pluto. Public Domain image.

Puppy Love

Pluto was long known as the ninth planet before being demoted to a dwarf planet status in 2006 by the International Astronomical Union (IAU).

The name Pluto was first suggested by 11-year-old Venetia Burney of Oxford, England, in 1930. This same year, Walt Disney introduced their newest character, a dog named Pluto.

With or without an atmosphere, and whether we call it a planet or dwarf planet, Pluto still has a big heart.

The Cosmic Companion

Exploring the wonders of the Cosmos, one mystery at a time


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James Maynard is the author of two books, and thousands of articles about space and science. E-mail:

The Cosmic Companion

Exploring the wonders of the Cosmos, one mystery at a time