Atmosphere spotted around small, distant solar system object

Key Points:

• Astronomers have detected a thin atmosphere around the small trans-Neptunian object (TNO) 2002 XV93, marking the first time an atmosphere has been found on such a tiny body in the outer solar system, previously thought too small to support one.
• The atmosphere, about 5 to 10 million times thinner than Earth's, was discovered during a rare stellar occultation event observed from multiple locations in Japan, where the gradual dimming of a star's light indicated the presence of an atmospheric layer.
• Possible origins of the atmosphere include cryovolcanic activity releasing gases like methane or nitrogen, or a recent impact by another Kuiper Belt object, with the latter scenario suggesting the atmosphere might last only a few hundred years.
• Future observations, including those by the James Webb Space Telescope, aim to characterize the atmosphere's composition and evolution, helping to determine whether 2002 XV93 is unique or if other small Kuiper Belt objects also harbor atmospheres.
• This discovery challenges previous assumptions about small TNOs, revealing that the Kuiper Belt is more dynamic and active than once believed, with potential implications for understanding the building blocks of life in the outer solar system.