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 ...

The four "Galilean moons" were named after Italian astronomer Galileo Galilei, who is thought to have discovered them in 1610. As night falls, Jupiter will rise in the east-northeast, among the ...

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 ...