Galileo was a Tuscan astronomer, physicist, mathematician, inventor and philosopher who was most famous for his idea of a heliocentric universe. The heliocentric universe was the idea that the sun, not the earth, was at the center of the solar system. This idea built on Copernicus’ model and was highly controversial at the time. While studying mathematics at the University of Pisa, Galileo established his “Principle of Inertia” (similar to Newton’s First Law) and mathematically described physics. Galileo was the first to view, document, and sketch the moon and all its features. He was the first to discover that Venus had phases like the moon, which confirmed his findings towards the heliocentric universe. Galileo discovered the four largest moons orbiting Jupiter, which were later named the “Galilean Moons”. Galileo also used his telescope to monitor and record sunspots on the surface of the sun, and developed the fundamental concept of Basic Relativity which would later serve as the basis for Einstein’s Special Theory of Relativity. Galileo demonstrated to Europeans that through scientific experimentation and analysis physical phenomena could be explained. This approach opened the doors for the Scientific Revolution in Europe.