Ptolemy thought that the sun and planets orbited the Earth (geocentric theory). In order of Mercury, Venus, Sun, Mars, Jupiter, and Saturn.
Jan 1, 1473
Copernicus thought that the planets revolved around the sun (heliocentric theory). Because of the rising and setting of the sun, moon and stars.
Jan 1, 1564
Galileo explained how to improve the telescope. He built the first highpowered astronomical telescope. So people could see Jupiter's moons and the surface of our moon.
Jan 1, 1571
Kepler discovered that the orbits of the planets were not flat circles but instead they were ellipses.
Sir Isaac Newton1642-1727
Newton explained that a body will preserve it's velocity and direction so long as no force in it's motion's direction acts on it, that is the law of inertia. Every particle of matter in the universe attracts every other particle with a force that is directly proportional to the product of the masses of the products and inversely proportional to the square of the distance between them. That is the law of gravity.