The sun is at the heart of the solar system. All of the bodies in the solar system — planets, asteroids, comets, etc. — revolve around it. The distance from Earth to the sun is called an astronomical unit, or AU, which is used to measure distances throughout the solar system. The AU has been defined as 149,597,870,700 meters (92,955,807 miles).
Astronomers use the AU for measuring distances throughout the solar system. Jupiter, for example, is 5.2 AU from the sun. Neptune is 30.07 AU from the sun. On the outer edges of the solar system, the Oort Cloud, where comets are thought to originate, is 100,000 AU from the sun. The distance to the nearest star, Proxima Centauri, is about 250,000 AU. However, to measure longer distances, astronomers use light-years, or the distance that light travelsin a single Earth year, which is equal to 63,239 AU. So Proxima Centauri is about 4.2 light-years away.