The planets of the solar system are either gas giants—Jupiter, Saturn, Uranus, and Neptune—or smaller rocky bodies—Mercury, Venus, Earth, and Mars. Pluto, formerly regarded as the ninth planet, was in 2006 reclassified as a dwarf planet. The minor planets, or asteroids, orbit mainly between the orbits of Mars and Jupiter. Only Earth and Venus have substantial atmospheres
Middle English: from Old French planete, from late Latin planeta, planetes, from Greek planētēs 'wanderer, planet', from planan 'wander'