NASA's Hubble Telescope Finds Evidence Of Water Vapour In Jupiter's Moon

Ganymede's ocean would reside roughly 160 kilometres below the crust, therefore, the water vapour would not represent the evaporation of this ocean.

Astronomers have uncovered the first evidence of water vapour in the atmosphere of Jupiter's moon Ganymede by using new and archival datasets from NASA's Hubble Space Telescope. According to the study published in the journal Nature Astronomy on Monday, the water vapour forms when ice from the moon's surface turns from solid to gas. Previous studies have offered circumstantial evidence that Ganymede, the largest moon in the solar system, contains more water than all of Earth's oceans, NASA said. However, temperatures there are so cold that water on the surface is frozen solid, according to the US space agency.