Our sun is a star just like all of the points of light in our night sky. The reason the Sun is so bright and appears so much bigger than the other stars is simply because it is so close to the Earth. The Sun is actually pretty average. There are many stars that are much larger and much hotter. If you took the star Betelgeuse (in the constellation of Orion) and placed it where the Sun is, the Earth would actually be inside of it! With a radius of about 510 million miles Betelgeuse would stretch past Jupiter.
All stars produce their light from nuclear fusion within their cores. Our Sun combines hydrogen atoms to form helium, fusing about 329 million tons of material per second. The energy released in that one second is about as strong as 6.1 trillion “Little Boy” atomic bombs. The Sun has enough hydrogen to keep these reactions going for another 5 billion years. Once the Sun runs out of fuel it swell in size and become a red giant star. The sun will get so big Mercury, Venus, and the Earth, will be destroyed. After this phase of its life, the red giant Sun will begin pulsing in size eventually puffing its outer layers off into space and creating a planetary nebula.