What is a Star?

Image of Sun courtesy of SOHO(an international cooperation between ESA and NASA)

A star (such as the Sun shown in the image) is a ball of gas which has, at its heart, a nuclear fusion reactor. It is important to know something about how stars work, for several reasons.

One star, the Sun, is the source of almost all the energy used by living things, including humans. We could not survive without it.

Fusion experiments currently under construction will try to copy the Sun in a small and controlled way. If they can achieve this, scientists believe they could obtain a great deal of energy on Earth without creating a lot of pollution.

Stars are the places where large atoms are built. Past generations of stars formed the gas and dust from which the planets and life were made.

So stars play a key part in our story.