Mysterious world beyond Pluto may have atmosphere, study says

A new study suggests that a tiny, icy world beyond Pluto harbors a thin, delicate atmosphere that may have been created by volcanic eruptions or a comet strike. Just 300 miles or so across, this mini Pluto is thought to be the solar system's smallest object yet with a clearly detected global atmosphere bound by gravity, said lead researcher Ko Arimatsu of the National Astronomical Observatory of Japan. "This is an amazing development, but it sorely needs independent verification. The implications are profound if verified," said Southwest Research Institute's Alan Stern, the lead scientist behind NASA's New Horizons mission to Pluto and beyond. He was not involved in the study. If confirmed, the rock would become just the second world past Neptune in our solar system to host an atmosphere — after only Pluto itself. The finding offers fresh insight into our solar system's farthest, coldest objects in a region known as the Kuiper Belt. Researchers used three telescopes in Japan to observe the object in 2024 as it passed in front of a background star, briefly dimming the starlight. "It changes our view of small worlds in the solar system, not only beyond Neptune," Arimatsu said in an email. …