The solar system

The solar system consists of the Sun, with planets and smaller objects such as asteroids and comets in orbit around it.

Eight planets in the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and NeptuneThe planets in order from the Sun on the left (distances not drawn to scale)

The planets

There are eight planets in the solar system. Starting with Mercury, which is the closest to the Sun, the planets are:

  • Mercury
  • Venus
  • Earth
  • Mars
  • Jupiter
  • Saturn
  • Uranus
  • Neptune

This sentence is a way to remember the correct order:

My Very Easy Method Just Speeds Up Naming

Pluto and the dwarf planets

Scientists have discovered other objects orbiting the Sun. These include comets, asteroids, and dwarf planets like Pluto and Ceres. Pluto used to be considered the ninth planet in our solar system, but in 2006 scientists reclassified it as a dwarf planet. So now we have eight planets in the solar system.


A satellite is an object in orbit around a planet. The Moon is the Earth’s natural satellite, but humans have launched many artificial satellites into orbit.

The Moon is the Earth’s natural satellite
The Moon is the Earth’s natural satellite

Tom Kerss, astronomer at the Royal Observatory Greenwich, talks about natural and artificial satellites


Gravity is a force that attracts objects towards each other. The more mass an object has, the greater its force of gravity:

  • gravity forces between the Earth and the Moon keep the Moon in orbit around the Earth
  • gravity forces between the Sun and the Earth keep the Earth in orbit around the Sun