Based on size the planets can be grouped into small and large planets.

Planets are said to be smaller if they are less 13000km in diameter. Small planets in the solar system are Mercury, Venus, Earth, Mars, and Pluto. Mercury and Pluto are said to be the smallest planets because they are so tiny planets.

Planets having diameter more than 48000 km are said to be large planets. These planets are also called as Gas giants. And large planets in the solar system are Jupiter, Saturn, Uranus, and Neptune.

Based on composition planets are classified into Rocky and Gas planets.

Rocky planets are those made up of rocks and metals. These planets are heavy and so they move slowly around the sun. These planets are also called as terrestrial planets. These planets have a combination of hydrogen, helium, and water. Rocky planets will not have rings and have only few moons.

Rocky planets are Mercury, Venus, Earth, Mars and Pluto.

Gas planets are those made up of helium and hydrogen gases. These planets are light in their weight and so they can move quickly. These planets have rings and also have many moons.

Gas planets are Jupiter, Saturn, Uranus and Neptune.