In 1705 Halley correctly linked historical descriptions of particularly bright comets to the reappearance of just one, which would later be named Halley’s Comet, based on his computation of the orbits of comets.[75] Halley also changed the theory of the Newtonian universe, which described the fixed stars. When he compared the ancient positions of stars to their contemporary positions, he found that they had shifted.[76] James Bradley, while attempting to document stellar parallax, realized that the unexplained motion of stars he had early observed with Samuel Molyneux was caused by the aberration of light. The discovery was proof of a heliocentric model of the universe, since it is the revolution of the earth around the sun that causes an apparent motion in the observed position of a star.