Galileo Galilei didn't invent the telescope; he probably wasn't even the first person to point a spyglass skyward. But his powerful telescope design allowed him to see farther than anyone had before -- or at least anyone who had published his findings. His discoveries shook the foundations of Europe, earning him the title "Father of Modern Science."
With his 1609 telescope, he examined the moon, discovered four of Jupiter's moons, watched a supernova, discovered sunspots and verified the phases of Venus. He was also convicted of heresy for advocating a heliocentric view of the universe. One of Galileo's two remaining telescopes went on display this month for its first and only exhibition outside Italy, at the Franklin Institute in Philadelphia.