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
Examiner Tip
When writing about the formation of the Solar System, make sure you can:
- State where solid and gaseous matter gathered in the Solar System
- Describe the role of gravity in pulling matter together
- Explain how heavier elements became a part of the nebula
