Planets

 The Solar System

The solar system is our local area of space. At its centre is the Sun, our nearest star, which accounts for almost all (99.9 per cent) of the solar system's mass. The Sun's gravity keeps the planets in their orbits.

Inner Planets

The four planets nearest the Sun are called the inner planets. They are also known as the rocky planets because they are balls of rock and metal. They are dense and have central cores made of iron.

Outer Planets

The four planets furthest away from the Sun are called the outer planets. They are huge balls of gas and liquid and are known as the gas giants. Uranus and Neptune are also known as the ice giants.