An orbit is the path of an object around a particular point in space, for example the path the Moon takes around the Earth. Orbits are determined by gravity, and are often 'elliptical', the shape of an oval. At the same time that the Earth orbits around the sun, it also rotates around itself once every 24 hours! This rotation is what causes Earth to have day and night. “One day' is actually equal to the time the Earth takes to rotate once around its axis and includes both daytime and night time!