Tiny 500-km world beyond Neptune may host a fleeting atmosphere

A 2024 stellar occultation suggests the 500-km trans-Neptunian object 2002 XV93 has a global atmosphere of about 100–200 nanobars, thin but detectable for such a small body; without replenishment it would escape in under 1,000 years. The gas species aren’t identified yet, and possible sources include a recent collision or ongoing cryovolcanism. Webb observations found no obvious surface ice reservoir to explain it, so independent verification through future occultations or infrared spectroscopy is needed to determine the origin and fate of this ephemeral atmosphere.