Astronomers Detect Atmosphere on Icy World Beyond Pluto

Astronomers have detected a thin atmosphere around (612533) 2002 XV93, an icy world located beyond Pluto. This discovery, reported in the journal Nature Astronomy, suggests that small celestial bodies in the outer solar system may harbor atmospheres, challenging conventional views.

The object is a plutino, orbiting the sun twice for every three orbits of Neptune. It is approximately 300 miles across and located more than 3.4 billion miles from Earth, farther than Pluto itself. Researchers used ground-based telescopes in Japan to observe the object as it passed in front of a background star, briefly dimming the starlight.

The atmosphere around (612533) 2002 XV93 is believed to be 5 million to 10 million times thinner than Earth's atmosphere and 50 to 100 times thinner than Pluto's. The likeliest atmospheric chemicals are methane, nitrogen, or carbon monoxide. According to lead researcher Ko Arimatsu of the National Astronomical Observatory of Japan, this discovery changes our view of small worlds in the solar system.

The origin of the atmosphere is still uncertain. It could be caused by volcanic eruptions, known as cryovolcanism, or a comet strike. Further observations, particularly by NASA's Webb Space Telescope, are needed to verify the makeup and persistence of the atmosphere. Astronomers suggest that if the atmosphere fades over time, it would support an impact origin.

Other astronomers have expressed caution about the findings. Jose-Luis Ortiz, a Spanish astronomer studying dwarf planets beyond Neptune, urged for more data before concluding it is indeed an atmosphere. The researchers acknowledge that exotic alternatives, such as a nearly edge-on ring, cannot be entirely ruled out.