LOS ANGELES (AP) -- Scientists say there may be an ocean lurking below on the biggest moon in the solar system.
The Jupiter moon Ganymede is one of a growing number of moons that are thought to have water underground.
Ganymede's ocean is believed to be much deeper than oceans on Earth -- about 60 miles (96 kilometers) thick and sandwiched between an icy crust and rocky mantle.
The latest evidence comes from the Hubble Space Telescope, which observed the moon's magnetic field to get a glimpse of its interior.
Scientists have long suspected there was an ocean beneath Ganymede and they say Hubble provides the most convincing evidence yet.
The European Space Agency wants to launch a mission in 2022 to explore Jupiter and three of its moons including Ganymede.