AQA GCSE Physics

Revision Notes

8.1.1 The Solar System

Objects in The Solar System

  • The Sun lies at the centre of the Solar System
    • The Sun is a star which makes up over 99% of the mass of the solar system
  • There are 8 planets and an unknown number of dwarf planets which orbit the Sun
    • The gravitational field around planets is strong enough to have pulled in all nearby objects with the exception of natural satellites
    • The gravitational field around a dwarf planet is not strong enough to have pulled in nearby objects
    • There are 4 rocky planets: Mercury, Venus, Earth and Mars
    • There are 4 gas planets: Jupiter, Saturn, Uranus and Neptune
  • Some planets have moons which orbit them
    • Moons are an example of natural satellites
  • Artificial satellites are man-made and can orbit any object in space
    • The International Space Station (ISS) orbits the Earth and is an example of an artificial satellite
  • Asteroids and comets also orbit the sun
  • An asteroid is a small rocky object which orbits the Sun
    • The asteroid belt lies between Mars and Jupiter
  • Comets are made of dust and ice and orbit the Sun in a different orbit to those of planets
    • The ice melts when the comet approaches the Sun and forms the comet’s tail

The Solar System, downloadable IGCSE & GCSE Physics revision notes

The objects in our solar system

Exam Tip

You need to know the order of the 8 planets in the solar system. The following mnemonic gives the first letter of each of the planets to help you recall them:

My Very Easy Method Just Speeds Up Naming (Planets)

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, (Pluto)

Of course, Pluto has been classed as a dwarf planet since 2006, so you shouldn’t include it as one of the 8 planets, but old mnemonics still include it so that the mnemonic makes sense!

Our Place in Space

  • Our solar system is just one small part of the Milky Way galaxy
  • There are billions of stars in the Milky Way galaxy
  • Some of these stars also have planets which orbit them
  • The Universe is made up of many different galaxies

Our Place in Space, downloadable IGCSE & GCSE Physics revision notes

Our solar system is just one out of potentially billions in our galactic neighbourhood, the Milky Way. There are estimated to be more than 100 billion galaxies in the entire universe

Author: Katie

Katie has always been passionate about the sciences, and completed a degree in Astrophysics at Sheffield University. She decided that she wanted to inspire other young people, so moved to Bristol to complete a PGCE in Secondary Science. She particularly loves creating fun and absorbing materials to help students achieve their exam potential.

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