A Tiny Rock in the Outer Solar System Has an Atmosphere—But It Shouldn’t
For decades, “My very excited mother just served us nine pizzas” functioned as a handy mnemonic for anyone trying to remember the order of the planets. That is, until Pluto was unceremoniously demoted to a simple trans-Neptunian object (TNO) in the early 2000s. (The new mnemonic, for those curious, is “My very excited mother just served us nachos.”)
Pluto was unique among these outer bodies orbiting the sun beyond Neptune in that it was the only one with a thin atmosphere – or so we thought. New research published in Natural astronomy reveals that there is yet another trans-Neptunion object with an atmosphere, and it has astronomers perplexed.
A team of professional and amateur Japanese astronomers monitoring the TNO, known as 2002 XV93I noticed something special. When it passed in front of a star, the star’s light gradually faded during the transit instead of blinking, key evidence of the atmosphere.
Read more: “The Farm Boy Who Found Pluto”
What’s strange is that the 2002 XV93 there should be no atmosphere at all. At only about 300 miles in diameter, or one-fifth the size of Pluto, it is too small to hold one. And that’s not the only strange thing about this cosmic oddity. Observations from the James Webb Space Telescope revealed no deposits of frozen gas on the surface, leaving the team to wonder where the atmosphere came from in the first place. It is possible that it was produced by some sort of volcanic activity pushing icy gas toward the surface. Another alternative is that it was created by an encounter with a comet carrying gas with it.
Wherever it comes from, it won’t last long. Researchers estimate that the little atmosphere present on the 2002 XV93 will dissipate into space in about 1,000 years.
In space, nothing lasts forever, whether it’s a thin layer of gas on a frozen rock in the distance or the state of our ancient ninth planet.
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Main image: NAOJ
