Galileo was a scientist who studied the Scientific Methods. Galileo invented the telescope. He observed four of Jupiters moons (Io, Europa, Callisto, and Ganymede) withhis telescope. We call these moons the Galilean satelites. He supported the heliocentric model. He saw that Venus went through phases like Earth's moon. This happened because the direction the sun was lighting Venus made it look like that as it was revolving around the sun.