Origin of the Solar System (WJEC GCSE Science (Double Award)): Revision Note

Origin of the Solar System

Formation of the Sun

• The Sun formed from a massive cloud of dust and gas called a nebula

• Gravity pulled this cloud together into a giant ball

• As the nebula collapsed, the centre of this ball became very dense and hot and began to rotate

• Eventually nuclear fusion was able to begin and a dense protostar formed – our Sun

A Nebula

A nebula is a cloud of gas and dust in space

Formation of the Planets

• The planets in the Solar System formed from the remaining matter in the nebula

• This nebula contained many elements that were created during a supernova explosion in the distant past

• As the protostar Sun became hotter, gas was pushed further out into the Solar System than solid matter

• As a result, solids in the inner Solar System were pulled together by gravity to form solid planets

  • This is why the 4 planets nearest to the Sun (Mercury, Venus, Earth and Mars) are rocky and small 

• Gases in the outer Solar System were pulled together by gravity to form gas planets

  • This is why the 4 planets furthest from the Sun (Jupiter, Saturn, Uranus and Neptune) are gaseous and large

Formation of the Solar System

The Solar System formed from a nebula with the Sun in the centre, then solid planets closer to the Sun and gaseous planets further away