Ptolemy thought that all celestial objects like planets, Sun, Moon, and stars orbited Earth. The earth in the center of the universe, did not move at all.

Copernicus thought that the planets orbited the Sun, and that the moon orbited Earth. The Sun, in the center did not move, nor did the stars.

Is the idea that a spinning cloud of dust made of mostly light elements, called a Nebula flattened into a protoplanetary disk, and became a solar system consisting of a star with orbiting planets

It is believed that nine protoplanets - one for each of the present day planets - were formed and these were originally much larger than the finished planet.

Developed by T.C. Chamberlin and F.R. Moulton of the 20th century.Planets were formed by the accumulation of extremely small bits of matter planetisimal that revolved around the sun

The Tidal Theory, proposed by James Jeans and Harold Jeffreys in 1918. It suggests that a huge tidal wave, raised on the sun by a passing star was drawn and became detached. As gaseous material condensed it separated into masses and took the form of planets.

Proposed by C.F. von Weizsacker and modified by Gerald P. Kuiper

"Earth-centered"

"Sun-centered"