Breakdown: Why Pluto’s atmosphere is disappearing

Published: Nov. 19, 2021 at 1:07 PM CST
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MEMPHIS, Tenn. (WMC) - Scientists are finding that Pluto’s atmosphere is going through a strange transformation.

On the night of August 15, 2018, as Pluto passed in front of a star, a Southwest Research Institute-led team of astronomers had deployed telescopes at numerous sites in the U.S. and Mexico to observe Pluto’s atmosphere as it was briefly backlit by the well-placed star.

When Pluto passed in front of a star on the night of August 15, 2018, a SwRI-led team of...
When Pluto passed in front of a star on the night of August 15, 2018, a SwRI-led team of astronomers measured the abundance of Pluto’s atmosphere, shown here in New Horizons 2015 flyby data, as it was briefly backlit by the well-placed star. These data indicate that the surface pressure on Pluto is decreasing and that its nitrogen atmosphere is condensing, forming ice on its surface as the object moves away from the Sun.(NASA/JHU-APL/SwRI)

Scientists used this occultation event to measure the overall abundance of Pluto’s tenuous atmosphere and found compelling evidence that it is beginning to disappear.

But why is this happening?

For about 25 years, Pluto has been moving farther and farther away from the sun, so its surface temperature has been decreasing. And with these recent observations, the researchers found evidence showing that Pluto’s atmosphere is actually refreezing back onto its surface as the dwarf planet gets colder and colder.

Scientists attributed this to a phenomenon known as thermal inertia.

Like Earth, Pluto’s atmosphere is predominantly nitrogen. Unlike Earth, Pluto’s atmosphere is supported by the vapor pressure of its surface ices, which means that small changes in surface ice temperatures would result in large changes in the bulk density of its atmosphere.

Pluto takes 248 Earth years to complete one full orbit around the Sun, during which, it’s distance from the Sun varies.

  • NOTE: It will have made its first full orbit since its discovery on March 23, 2178.

Currently, Pluto can get as close as 30 astronomical units (AUs) from the Sun (1 AU is the distance from the Earth to the Sun).

This distance keeps increasing, pushing Pluto into less sunlight and low-temperature area.

The atmosphere may vanish as Pluto moves farther from the Sun.

If Pluto’s atmosphere ultimately collapses and freezes over, the planet will likely appear brighter in the sky as it will then reflect more sunlight.

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