For the first time, astronomers have found evidence of water vapour in Jupiter's atmosphere.Ganymede is the largest moon in our Solar System. It has an icy crust. Scientists think Ganymede could have a liquid ocean 100 yards (161 kilometers) below its surface. This ocean could be home to aquatic alien life.NASA announced Monday that it had found evidence of water vapour in Jupiter's thin atmosphere by studying the data of the Hubble Space Telescope over the past two decades.However, this water is unlikely to have come from the underground sea. It's more likely that it's ice that has vaporized from the moon's surface.Although it doesn't reveal much about the moon's potential to support alien life, this water vapour adds to scientists understanding of Ganymede. They knew it contained oxygen before.(NASA/ESA/Lorenz Roth)Above Hubble's 1998 ultraviolet images of Ganymede were initially interpreted to show the atmosphere's atomic Ox. However, the new analysis revealed that the differences in the color of the aurora correspond with the warming of Ganymede through the day when water would have sublimated into the atmosphere.NASA was told by Lorenz Roth, of the KTH Royal Institute of Technology, Stockholm, Sweden that "so far only the molecular oxygen has been observed." He led the team that discovered the vapor.This is caused by charged particles that erode the ice surface.Nature Astronomy published the research and data.Business Insider originally published this article.More Business Insider: