The simple official answer to this question is 8. The solar system planets in order from the Sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. This has been correct since 2006 when the International Astronomy Union actually defined what a Planet is and also what a Dwarf Planet is. There are now 5 official dwarf planets: Ceres, Pluto, Haumea, Makemake, Eris.