Leonardo da Vinci was a genius, an artist, a writer, a musician, a scientist, and an inventor. He drew the first accurate human skeleton, invented scissors, created the technique of using shadows in pictures, painted the Mona Lisa, and countless other things. Isaac Newton was an English mathematician who discovered the law of gravity, which not only explained why an apple would fall off a tree, but also why the planets stayed on their orbit around the sun. Nicolaus Copernicus was the first one to conclude that the sun was the center of the universe. He was the first to challenge the Earth-centered universe theory. Galileo Galilei was the first scientist to use experiments to discover the laws of nature. He made his own telescope, observed our moon, and found four of Jupiter's moons. He also invented the very first thermometer. Those guys are awesome. Now who is James Watt?