Of all of his telescope discoveries, he is perhaps most known for his discovery of the four most massive moons of Jupiter, now known as the Galilean moons: Io, Ganymede, Europa and Callisto. When NASA sent a mission to Jupiter in the 1990s, it was called Galileo in honor of the famed astronomer.
WWI was ignited when Archduke Franz Ferdinand—heir to the Austro-Hungarian Empire—was shot to death by the Serbian nationalist Gavrilo Princip on June 28, 1914.
