Artwork of the planets and their orbits according to General Relativity. In Newtonian theory, gravity is seen as a force, with planets attracted to their stars and forced to move in orbits. But according to Einstein's General Theory of Relativity, gravity is seen as a curvature or distortion of spacetime. Mass causes spacetime to warp, and planets orbit their stars because they are following the curves or 'indentations' in spacetime created by the stars. In this image, the Sun - at the centre - having the greatest mass, creates a warp in spacetime which the planets all adhere to. The planets themselves make much smaller warps owing to their lesses masses.