Galileo was the person who invented the telescope. With this invention, he discovered that the earth is not at the center of the solar system, and four of the moons were observed that orbits around Jupiter. He also observed the different types of phases of the planet Venus and the sunspots. These observations made him support Copernicus's heliocentric theory in which the sun is assumed to be at the center of the solar system and all other planets and stars revolve around it.
In the early centuries, people thought that the earth is the center of the universe and all the planets and the heavenly bodies move around the earth. This theory is known as Geocentrism. Whereas Heliocentrism is the theory where the sun is believed to be the center and all the other planets and the heavenly bodies move or revolve around the sun.
Galileo was the first to use used the early versions of the telescope and made significant discoveries about the space. Galileo made several studies and in 1601, Galileo with the help of the rudimentary telescope observe that the planet Venus went same phases like the moon. This is against the theory of the geocentrism that everything orbited around the earth, and further proved that Venus moved around the sun. Galileo also learned and found out about the four moons of the Jupiter that orbits around Jupiter. This also broke the early belief that everything orbits around the earth.
