There are eight recognized planets in our solar system. These planets, in order from the Sun, are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Each planet varies significantly in size, composition, and distance from the Sun. Mercury is the smallest and closest to the Sun, while Jupiter is the largest. The planets are classified into two main categories: terrestrial planets (Mercury, Venus, Earth, Mars), which are rocky, and gas giants (Jupiter, Saturn, Uranus, Neptune). Pluto was previously considered the ninth planet but has since been reclassified as a dwarf planet by the International Astronomical Union.