The solar system has 8 planets there are 4 rock planets and 4 gas planets. first there is Mercury then Venus then Earth then Mars then Jupiter then Saturn then Uranus then Neptune. Mercury, Venus, Earth and Mars are the rock planets and Jupiter, Saturn, Uranus and Neptune are the gas planets. Earth is the only planet people, animal and plants can live on. The rock planets don,t have any rings and the gas planets do have rings. Saturn is the biggest planet and mercury is the smallest planet.