When you buy through links on our articles, Future and its syndication partners may earn a commission.A very small body, far from the sun in an icy outer realm of the solar system, has mysteriously grown an atmosphere — and scientists are stumped as to how and why this happened.One possibility is that the atmosphere was produced through cryovolcanism, or basically ice volcanoes Another idea is the atmosphere could be related to an impact, but in that case, the impact must have happened relatively recently since such a thin atmosphere would leak into space and vanish within a thousand years.AdvertisementAdvertisementThe object with an atmosphere, designated (612533) 2002 XV93, is a trans-Neptunian object, or TNO, meaning it exists in the Kuiper Belt beyond the orbit of the outermost planet, Neptune. More specifically, it is a “plutino,” meaning that, like Pluto, it is in a 2:3 orbital resonance with Neptune. This means it orbits the sun twice for every three orbits that Neptune makes.Furthermore, (612533) 2002 XV93 is significantly smaller than Pluto, being about 310 miles (500 kilometers) across compared to Pluto’s diameter of 1,477 miles (2,377 kilometers).Pluto is massive enough to retain a thin atmosphere, known as an exosphere, when it is near perihelion (the closest point in its elliptical orbit to the sun). It also retains some ices, such as molecular nitrogen, methane and carbon monoxide, that can sublimate into gases. As Pluto begins to move away from the sun over the course of its 248-year-long orbit, those gases gradually freeze out again back onto the surface.However, no other object in the Kuiper Belt or beyond has been found to possess an exosphere, although methane outgassing has been detected on Pluto’s fellow dwarf planet, Makemake. The Japanese astronomers, both professional and amateur, who took part in a series of observations of (612533) 2002 XV93 as it occulted — or passed in front of — a star on January 10, 2024, didn’t expect to find an atmosphere either.AdvertisementAdvertisementIf an object such as (612533) 2002 XV93 were truly airless, then the star would instantly wink out as the object passed in front of it from our point of view. However, that’s not what happen …
