Inside a Star

Stars are balls of gas held together by gravity. Gravity is the same force that keeps us on the surface of the Earth instead of drifting off into space. The main gas in stars is called hydrogen.

We see stars because they give off a large amount of light. If you stand out in the sun, you can also feel the heat coming from it. All stars produce heat like this. Where does this energy come from?

The energy given out by stars comes from a process called “nuclear fusion” which turns hydrogen into another gas called helium. If the star is big enough and hot enough, fusion will carry on, turning the helium into other materials such as carbon and oxygen.

At each stage the new material will form in the centre, or “core”, of the star. If you could cut the star in half it would look a bit like an onion, like in the diagram below.

		Stars Introduction
		What Are Stars?
		The Sun
		Lives of Stars
		Variable Stars, or "Stars That Change".
		Objects to Observe with the Faulkes Telescope

Authors: Carolyn Brinkworth and Claire Thomas

Last updated: July 2001