The Sun has been observed and worshipped throughout much of human history. One of the first known monuments to the Sun was built in Newgrange, Ireland more than 5,000 years ago. One of the first Sun gods was Shamash of Babylonia, who was the all-seeing, all-knowing eye of justice. Later, the Egyptians believed that the Sun was the god Ra, who would sail across the sky by day in a boat.
But over the millennia, scientists have determined that the Sun is a big ball of gas -- mostly hydrogen, helium, and traces of other gases. It is 93 million miles from the Earth, has a mass of 2 million, trillion tons, and about 1 million Earths could fir inside. The Sun produces its energy because the tremendous pressure (about 500 billion pounds per square inch) as its core causes hydrogen to fuse into helium - this is nuclear fusion. During the process, some matter is converted into energy and released. Astronomers estimate that 5 million tons of matter is being converted into energy every second, which in turn could run everything on Earth for a million years - easily. Given the total mass of the Sun and energy output, scientists figure that the Sun has been "burning" by nuclear fusion for 4 1/2 billion years and will continue as such for another 5 billion years.
Follow your curiosity to the Fred G. Dale Planetarium at Wayne State College.