Solar system's planets. Computer artwork of the eight planets of the solar system as redefined in August 2006. The Sun is at top. The planets from top to bottom are; Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. The International Astronomical Union (IAU) voted on 26 August 2006 to change the definition of a planet. Pluto was previously a planet but was demoted to a dwarf planet.