Astronomers Detect Thin Atmosphere on Tiny Icy World Beyond Pluto

Astronomers have detected a thin atmosphere around the tiny, icy world (612533) 2002 XV93, located beyond Pluto in the Kuiper Belt. The object, measuring 300 miles (500 kilometers) across, showed signs of an atmosphere during observations in 2024 when it passed in front of a background star, briefly dimming the starlight.

Researchers used three telescopes in Japan to capture the event, revealing an atmosphere 5 million to 10 million times thinner than Earth's and 50 to 100 times thinner than Pluto's.

The study appeared Monday in the journal Nature Astronomy. 5 billion kilometers) from Earth and farther from the sun than Pluto. As a plutino, it circles the sun twice for every three orbits Neptune completes, placing it among the solar system's farthest, coldest objects.

Ko Arimatsu, lead researcher at the National Astronomical Observatory of Japan, stated the likeliest atmospheric chemicals are methane, nitrogen, or carbon monoxide. Arimatsu added that the finding challenges the conventional view that atmospheres are limited to large planets, dwarf planets, and some large moons. Further observations could clarify the atmosphere's origins and composition.

Arimatsu said NASA's Webb Space Telescope might verify the makeup. He noted, 'That is why future monitoring is so important. If the atmosphere fades over the next several years, that would support an impact origin.

Alan Stern, lead scientist for NASA's New Horizons mission to Pluto and beyond at Southwest Research Institute, commented on the study. Stern said, 'This is an amazing development, but it sorely needs independent verification. The detection offers new insights into Kuiper Belt objects, potentially from volcanic eruptions or a comet strike binding a delicate atmosphere by gravity.