As you probably already know the sun is a star. It is the star closest to earth. It is really hot. The Sun is an average, yellow middle aged star. This part of a star life cycle is called main sequence. So the sun is a main sequence star. That means the sun is 4.6 billion years old. Even though it is really old, it still has 7 billion years of life. Main sequence stars are really hot. They are so hot that nobody has ever visited them. The sun has a lot of stages of life to go through. In its next stage, it will become a red giant. It will be all red and puffy. It will also be hotter. The sun is our closest star but it is really far away from earth.