In a surprising turn for solar‑system science, a little‑known rock orbiting beyond Pluto appears to possess a thin atmosphere, according to a team of Japanese astronomers. The object, catalogued as (612533) 2002 XV93, is about 500 kilometers wide and drifts roughly 6 billion kilometers from the Sun—about 40 times Earth’s distance.
The discovery came during a rare stellar occultation in January 2024, when the distant world passed in front of a far‑away star. Instead of the starlight cutting off instantly, the light dimmed gradually, suggesting a tenuous veil of gas was filtering some of the star’s glow. The astronomers estimate the atmosphere is five to ten million times thinner than Earth’s, a density comparable to the outer edges of Pluto’s own thin envelope.
Lead researcher Ko Arimatsu of the National Astronomical Observatory of Japan told reporters that “until now, Pluto was the only trans‑Neptunian object with a confirmed atmosphere.” The finding, published in Nature Astronomy, challenges the long‑standing view that such small, icy worlds are mostly inactive and unchanging.
Ice volcanoes or comet smash?
The team can’t yet pinpoint how the atmosphere formed. Possible explanations include gas erupting from ice volcanoes—cryovolcanism—or a recent comet impact that lofted material into space. If the latter, the atmosphere could be short‑lived and may gradually dissipate.
Other scientists urge caution. Jose‑Luis Ortiz, a Spanish astronomer who studies dwarf planets beyond Neptune, noted that an alternative explanation could be a narrow ring system hugging the object’s surface. Both teams call for follow‑up observations, especially with the James Webb Space Telescope, to settle the debate.
The result adds a new wrinkle to the ongoing discussion about Pluto’s planetary status. While the US President Donald Trump’s administration has floated a proposal to restore Pluto to full planet rank, the existence of another world with an atmosphere in the same region could complicate that argument.
Planetary scientist Adeene Denton commented on social media, “It’s wild to ‘make Pluto a planet again’ while decimating the careers of those of us that study it!”
Whether (612533) 2002 XV93 keeps its atmospheric veil or loses it to space, the discovery shows that the distant reaches of our solar system are far more dynamic than once thought.
Reference(s):
Mysterious world beyond Pluto may have an atmosphere, astronomers say
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