Galileo first discovered that the Moon had mountains just like Earth. He also discovered 4 of Jupiter's moons. Using his telescope, Galileo made many observations of our Solar System. He came to believe that the idea that the Sun and other planets orbited around the Earth was not correct.
Sir Isaac Newton -- The Discoverer of Gravity! Sir Isaac Newton was an English mathematician and mathematician and physicist who lived from 1642-1727. The legend is thatNewton discovered Gravity when he saw a falling apple while thinking about the forces of nature
Nicolaus Copernicus was a Polish astronomer who put forth the theory that the Sun is at rest near the center of the Universe, and that the Earth, spinning on its axis once daily, revolves annually around the Sun. This is called the heliocentric, or Sun-centered, system.