There are 8 major planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. The inner planets are made of rock and include Mercury, Venus, Earth, and Mars. The outer planets are mostly made of gases and include Jupiter, Saturn, Uranus, and Neptune. There are also 3 dwarf planets: Pluto, Ceres, and Eris. Each planet has unique characteristics such as atmospheric composition, rotation, and presence of moons.