Study Findings: Detection of an Atmosphere on a Trans-Neptunian Object Beyond Pluto

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Image (Credit): An artist’s rendering of NASA’s New Horizons spacecraft approaching Pluto with its largest moon Charon in the background. (NASA’s Goddard Space Flight Center/The Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)

Nature Astronomy abstract of study findings:

The only trans-Neptunioan object (TNO) with a detected atmosphere so far is Pluto, which has an average surface pressure of 10 μbar. Investigations of other large (>500 km) TNOs have only been able to establish upper limits of 1–100 nbar. A recent near-infrared study reported methane gas emission from Makemake, although its origin remains uncertain. Here we report that a stellar occultation campaign performed on 10 January 2024 of the ~250-km-radius plutino (612533) 2002 XV93 reveals a refractive signature, indicating a thin atmosphere. We derive a surface pressure of 100–200 nbar, above the previous limits for other larger bodies. This discovery shows that even a few-hundred-kilometre TNO can host, at least transiently, an atmosphere, challenging standard volatile-retention scenarios. Our findings suggest that a fraction of distant icy minor planets can exhibit atmospheres, potentially sustained by ongoing cryovolcanic activity or produced by a recent impact of a small icy object.

Citation: Arimatsu, K., Yoshida, F., Hayamizu, T. et al. Detection of an atmosphere on a trans-Neptunian object beyond Pluto. Nat Astron (2026).

DOI: https://doi.org/10.1038/s41550-026-02846-1

Study-related stories:

CNN – “Astronomers Find Atmosphere Around a Solar System Object that Shouldn’t Have One”

Science News – “A Small Object Past Pluto May Have a Thin Atmosphere”

The Japan Times– “Japan Astronomers Find Thin Atmosphere on Small Celestial Body Beyond Neptune”