On this date, Jan. 7, 1610, astronomer Galileo Galilei, with a homemade telescope ... Europa and Ganymede became known as the Galilean moons of Jupiter. Learn more about NASA’s current mission ...

Jupiter’s four largest moons – Io, Europa, Ganymede and Callisto – were the first ever discovered orbiting another planet. They were spotted by Galileo Galilei more than 400 years ago ...

On a cold January day in 1642, Galileo Galilei took his last breath ... but pockmarked with craters. Jupiter had its own moons, four of them (now called the Galilean Moons), revolving around ...

NASA scientists have sought to understand planet Jupiter, the gas giant whose mass is more than the rest of the planets in ...

In the 1990s, however, NASA's Galileo spacecraft captured magnetic measurements near Callisto that suggested that its ice shell surface—much like that of Europa, another moon of Jupiter—may ...