Tiny Kuiper Belt Object 2002 XV93 May Have Unexpected Atmosphere

A study published May 4 in Nature Astronomy suggests that 2002 XV93, a trans-Neptunian object (TNO) about 292 miles wide, may possess an extremely thin atmosphere—5 to 10 million times thinner than Earth's. This challenges assumptions that small icy bodies beyond Neptune cannot retain gases. On January 10, 2024, the object occulted a distant star, and observations from three sites in Japan showed a gradual dimming over 1.5 seconds, indicating atmospheric refraction. Lead author Ko Arimatsu of the National Astronomical Observatory of Japan notes that such a thin atmosphere can still bend starlight and reveals volatile gas activity. The atmosphere is likely short-lived (under 1,000 years) unless replenished by cryovolcanism or impacts. However, James Webb Space Telescope data found no surface ice, and independent verification is needed. Alan Stern of the Southwest Research Institute calls the findings profound if confirmed.