Solar system
The solar system is compounded of the Sun, at the center, of nine planets (Mercure, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluton), of an asteroid ring located between Mars and Jupiter, of numerous satellites in orbit around the planets (the Moon for the Earth), of numerous comets, and of the Oort ring at its suburbs.
An excellent freeware allows to trek in the solar system and even more, with accurate pictures of the objects that are met. Its name is Celestia, that we can find in the web site http://www.shatters.net/celestia/
