Photo courtesy SOHO consortium. The sun has "burned" for over 4.5 billion years. See more pictures of the sun.

The sun warms our planet every day, provides the light by which we see and is absolutely necessary for life on Earth. In this article, we will examine the fascinating world of our nearest star. We will look at the parts of the sun, the amazing way it makes light and heat, and its major features.

Because we see the sun everyday, we tend to take it completely for granted. But if you think about it, you come up with lots of questions such as:

• If the sun is in the vacuum of space, how does it burn?
• What keeps all that gas from leaking into space?
• How big is the sun?
• Why does it send out solar flares?
• When will it stop burning?
• Is the sun like other stars?

The answers to these questions are what make the sun so interesting!

The sun is a star, just like the other stars we see at night. The difference is distance -- the other stars we see are light years away, while our sun is only about 8 light minutes away (many thousands of times closer).

Officially, the sun is classified as a G2 type star based on its temperature and the wavelengths or spectrum of light that it emits. The sun is an "average" star, merely one of billions of stars that orbit the center of our galaxy.

The sun has "burned" for more than 4.5 billion years and will continue to do so for several billion more. It is a massive collection of gas, mostly hydrogen and helium. Because it is so massive, it has immense gravity, enough gravitational force to hold all of hydrogen and helium together (and to hold all of the planets in their orbits around the sun!).

The sun does not "burn" like wood burns. Instead the sun is a gigantic nuclear reactor, as you will learn on the following pages...