Astronomers Detect Atmosphere on Distant Kuiper Belt Object

Astronomers have identified a thin atmosphere surrounding (612533) 2002 XV93, a trans-Neptunian object approximately 500 kilometers in diameter, located beyond Pluto in the Kuiper Belt. This discovery challenges the prevailing belief that such small, icy bodies lack the gravitational strength to retain atmospheres.

The observation was made on January 10, 2024, when 2002 XV93 passed in front of a distant star, an event known as a stellar occultation. A team led by Ko Arimatsu at Japan's National Astronomical Observatory observed the event from multiple locations. The gradual dimming of the star's light suggested the presence of an atmosphere, as opposed to the abrupt disappearance expected if no atmosphere were present.

Calculations indicate that the atmosphere is 5 to 10 million times thinner than Earth's and 50 to 100 times thinner than Pluto's. Its composition is likely methane, nitrogen, or carbon monoxide. The atmosphere's origin remains uncertain; it may result from cryovolcanic activity releasing internal gases or from a recent impact by another Kuiper Belt object.

Further observations, particularly with the James Webb Space Telescope, are planned to confirm the atmosphere's presence and composition. This finding suggests that small icy worlds beyond Neptune may be more dynamic than previously thought.