According to the statement of NASA, the Jupiter-orbiting moon Ganymede harbors an ocean beneath its icy surface which indicates the possibility of the presence of life. The discovery has been made with the help of Hubble Space Telescope and it unveils a mystery of the largest moon of the solar system. Previously, NASA’s now-defunct Galileo spacecraft had indicated that there is a subsurface ocean in Ganymede, while it was exploring Jupiter and its moon from 1995 to 2003.
Just like Earth, Ganymede has a liquid iron core which generates a magnetic field, which is embedded within Jupiter’s magnetic field. This leads to the formation of twin bands of glowing aurora around Ganymede’s northern and southern polar regions. With the rotation of Jupiter, its magnetic field shifts and this affects the position of Ganymede’s aurora.
Computer models suggested that if there was no ocean on Ganymede, the aurorae would rock back and forth across about six degrees of the moon’s circumference while orbiting Jupiter. However, the presence of salty, electrically conductive ocean stabilizes the aurorae and they only move about two degrees. Geophysicist Joachim Saur, with the University of Cologne in Germany commented “Jupiter is like a lighthouse whose magnetic field changes with the rotation of the lighthouse. It influences the aurora. With the ocean, the rocking is significantly reduced.”
More than 100 computer models were used by the scientists to find out if anything else is influencing Ganymede’s aurora. However, no such evidence was found and analysis of the data for both belts of aurora produced same results. The finding now adds to the list moons having subsurface water. Saturn’s moon Enceladus harbors hot springs beneath its icy crust. Jupiter moons Europa and Callisto also have water. According to the estimates, the ocean on Ganymede is 60 miles thick and 10 times deeper than the oceans of Earth.