• Astronomers have for the first time detected a thin atmosphere around a trans-Neptunian object (612533) 2002 XV93, only 500 km wide.
  • The discovery is unexpected because objects of this size were thought unable to retain an atmosphere due to low gravity.
  • The atmosphere was detected during a stellar occultation in January 2024, when the star’s light gradually dimmed.
  • The atmosphere’s density is 5 to 10 million times less than Earth’s.
  • Two possible origins: cryovolcanism or an impact from another body releasing gases.
  • If impact-generated, the atmosphere may last only a few hundred years; if cryovolcanic, it could be long-lived.
  • Future observations with the James Webb Space Telescope will help determine the atmosphere’s nature and origin.

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