Scientists have discovered the first evidence of water vapor on Ganymede, Jupiter's largest moon.

They used new and archival datasets from the Hubble Space Telescope to find the vapor, which forms when ice on the surface sublimates and turns from solid to gas.

A team led by Lorenz Roth of the KTH Royal Institute of Technology in Stockholm, Sweden examined data captured by Hubble's Cosmic Origins Spectrograph in 2018 and images the Space Telescope Imaging Spectrograph obtained between 1998 and 2010.

Ultraviolet images captured by the STIS in 1998 showed “colorful ribbons of electrified gas called auroral bands,” according to NASA (which launched Hubble as a joint project with the European Space Agency).