A simplified illustration of the parallax of an object against a distant background due to a perspective shift. When viewed from Viewpoint A, the object appears to be in front of the blue square. When the viewpoint is changed to Viewpoint B, the object appears to have moved in front of the red square.
From top to bottom: Io, Europa, Ganymede, Callisto. The Galilean moons are the four largest moons of JupiterâIo, Europa, Ganymede, and Callisto. They were discovered by Galileo Galilei around January 1610 and were the first group of objects found to orbit another planet. Their names derive from the lovers of Zeus.
Discovery by Simon Marius. An interesting occurrence in the discussion on who discovered Jupiter is that of Simon Marius. Just a few nights after Galileo made his observations Simon Marius, a Dutch astronomer, saw Jupiterâs moons using his telescope. He was responsible for naming the said moons after Greek gods.