Astronomers have detected a thin atmosphere around a tiny celestial body in the outer solar system for the first time — an object previously thought to be too small to support the presence of an atmosphere.Thousands of frozen, rocky bodies called trans-Neptunian objects, or TNOs, exist in the Kuiper Belt on the edge of our solar system, remnants from its formation 4.5 billion years ago.The dwarf planet Pluto is the largest of these TNOs, so named because they’re found beyond the orbit of Neptune.AdvertisementAdvertisementThe frigid temperatures and weak surface gravity of the small bodies has long caused astronomers to believe they aren’t capable of retaining atmospheres — with the exception of Pluto, which has a thin one. Atmospheres, especially dense ones, typically form around large planets or moons, including Saturn’s biggest satellite, Titan.Meanwhile, dwarf planets Eris, Haumea, Makemake and dwarf planet candidate Quaoar, the largest TNOs after Pluto, don’t appear to have atmospheres.During a rare observation opportunity, astronomers in Japan spotted the thin shell of an atmosphere around a TNO known as (612533) 2002 XV93, according to a study published Monday in the journal Nature Astronomy.While Pluto has a diameter of 1,477 miles (2,377 kilometers), 2002 XV93 only spans about 311 miles (500 kilometers) across.The unexpected discovery — made by Dr. Ko Arimatsu, associate professor and senior lecturer at the National Astronomical Observatory of Japan, and his colleagues — could offer an unprecedented glimpse into how an atmosphere forms and remains around a small object, and change how astronomers think about objects in the Kuiper Belt.Seizing the observation opportunityAs January 2024 neared, Arimatsu and his colleagues prepared for the unique chance to observe a TNO as it passed in front of a bright star, as seen from Japan.Advertisement …
