Galileo Galilei was an Earth astronomer and physicist who lived in Italy, Europe, from 1564 to 1642.
He discovered Jupiter's four largest moons: Io, Europa, Ganymede and Callisto. He also found the Milky Way to be a multitude of stars instead of merely a cloud as Earth scientists had previously believed. He confirmed Copernican theories that Earth was not the center of the universe, although religious authorities made him renounce his support for those claims on the premise of a death sentence for disobedience.
In 2269, the immortal Flint claimed to have known Galileo personally. (TOS: "Requiem for Methuselah")
Several Federation shuttlecrafts were named after Galileo during the 23rd and 24th centuries. (See: Galileo)
In 2369, Professor O'Brien taught her class about Galileo rather than the Prophets. (DS9: "In the Hands of the Prophets")