The sun is a gigantic ball of hot gases. It is comprised of approximately 72 percent hydrogen, 26 percent helium and minute amounts of other elements, such as carbon, oxygen, neon, iron, nitrogen, magnesium and silicon.
The core, where the energy is produced, makes up about 25 percent of the sun. Sir Norman Lockyer and other astronomers discovered helium on the sun before it was discovered on Earth. The 27 million degrees Fahrenheit temperature of the sun's core is courtesy of intense gravitational forces and pressure. Nuclear fusion is a process of the sun in which hydrogen atoms fuse together to form helium atoms and energy.