1610    Galileo Galilei observes three of the four largest moons of Jupiter for the first time. He named them, and in turn the four are called the Galilean moons. Ganymede not discovered by him until January 13.

1610    Galileo Galilei discovers Ganymede, 4th moon of Jupiter.

1973    Pioneer program: Pioneer 10 sends back the first close-up images of Jupiter.

1979    America's Voyager 1 spacecraft has its closest approach to Jupiter, 172,000 miles.

1994    Comet Shoemaker-Levy 9 collides with Jupiter. Impacts continue until July 22.

1994    Comet Shoemaker-Levy 9's Fragment Q1 hits Jupiter.

1995    The Galileo spacecraft arrives at Jupiter, a little more than six years after it was launched by Space Shuttle Atlantis during Mission STS-34.

1998    Data sent from the Galileo spacecraft indicates that Jupiter's moon Europa has a liquid ocean under a thick crust of ice.

2001    NASA's Galileo spacecraft passes within 112 miles of Jupiter's moon Io.

2003    ''Galileo'' mission is terminated by sending the probe into Jupiter's atmosphere, where it is crushed by the pressure at the lower altitudes.

2007    Jupiter flyby of the New Horizons Pluto-observer spacecraft.