On October 18, 1989, the unmanned NASA spacecraft Galileo was launched on her mission to study the planet Jupiter and its moons. Named after the astronomer Galileo Galilei, it consisted of an orbiter and entry probe, which descended into Jupiter's atmosphere.
On January 7, 1610, physicist and astronomer Galileo Galilei turned his new telescope to the nocturnal sky to watch the planet Jupiter and discovered the eponymous four moons of Jupiter, Io, Europa, Ganimede, and Callisto.