Tiny TNOs Get Temporary Atmospheres

An occultation observed for trans‑Neptunian object 2002 XV93 showed a gradual dimming of a background star, the hallmark of an atmosphere, even though the body is only ~300 miles across and JWST saw no surface frozen gases. The atmosphere is likely transient — possibly produced by cryovolcanic outgassing or a recent cometary encounter — and the team estimates it will be lost in roughly a thousand years. — If small outer‑solar‑system bodies can generate short‑lived atmospheres, models of volatile transport, surface activity, and Solar System chemical evolution must be updated, with implications for where transient processes (and biosignature‑mimicking chemistry) might occur.