How do planets move?

When Nicolaus Copernicus introduced his heliocentric world view, with the planets orbiting a central Sun, he believed those orbits would be perfect circles. Johannes Kepler was the first to realise that planetary orbits are in fact elliptical. His three laws of planetary motion describe the relationship between a planet’s changing distance to the Sun, its changing orbital velocity, and its period of revolution around the Sun. Later, Isaac Newton’s universal law of gravity provided the mathematical basis for Kepler’s laws, which hold throughout the Universe.