Like most astronomers before him, he believed the Sun, Moon, and other planets circled the Earth. He thought that each space body moved in a small circle that was itself orbiting Earth.
1473 - 1543
Nicolaus Copernicus was an astronomer who proposed a heliocentric system, that the planets orbit around the Sun; this idea being heavily against the church at the time and he received a lot of criticism.
1571 - 1630
Made the discovery that planets move in an elliptical rather than a circle around the sun, also came up with the three of planetary motion.
1642 - 1727
Issac Newton discovered gravity, calculus, and the laws of motion. All of these discoveries have been used in astronomy to make discoveries and prove theories.
1656 - 1742
Halley predicted when a comet would fly by the Earth and therefore had it named after him.It marked the first time astronomers understood comets could be repeat visitors to our night skies. Astronomers have now linked the comet's appearances to observations dating back more than 2,000 years
He discovered Saturn's moons Iapetus, Rhea , Tethys (, and Dione . In 1675, Cassini discovered that Saturn's rings are separated into two parts, which is now called Cassini Division in his honor
1730 - 1817
Discovery of comets led to the compilation of a catalog of deep sky objects known today as the Messier Catalogue of nebulae and star clusters.
1738 - 1822
He made many discoveries including the finding of Uranus. But his biggest claim to fame was his ability to build telescopes.
1879 - 1955
Einstein's many visionary scientific contributions include the equivalence of mass and energy (E=mc2) and how the maximum speed limit of light affects measurements of time and space
His discovery in the 1920s that countless galaxies exist beyond our own Milky Way galaxy revolutionized our understanding of the universe and our place within it.