The Sun
Physics: AQA GCSE Higher, topic 8.1.2
The Sun
The Sun was formed from a cloud of dust and gas (called a nebula). The forces of gravity pulled the dust and gas together.
Cloud of gas and dust
- The gas and dust collapsed.
- The cloud suddenly decreased in volume as the pressure in the cloud increased.
- This formed a protostar.
Main sequence
- Materials continued to collide (come together) until the temperature and pressure were high enough for hydrogen nuclei to start fusing and form helium (in nuclear fusion).
- The star then went into a stable period, called a ‘main star sequence’.
Nuclear fusion
- The energy released from the nuclear fusion in the Sun keeps the Sun’s core hot.
Stable
- The Sun is still in its stable main sequence phase.
- In this phase, the outward force of the energy released by nuclear fusion is balanced by the force of gravity pulling the Sun inwards.
Test yourself on The Sun
Which of these are true of the Sun?
In the Sun, what process creates a force outwards, balancing the inward force of gravity?
Formation of the Sun