1573-1624

German astronomer among the first to use the telescope for viewing celestial objects. He discovered Jupiter's satellites, if not before then shortly after Galileo, but waited until 1614 to publish his observations. Marius computed tables of the mean periodic motions of the Jovian satellites, directed attention to variations in their brightness, and assigned the names by which they are known today. He was the first to view the Andromeda nebula through a telescope (1612).