The most massive stars eventually end their lives with an explosion called a supernova. This explosion ejects the heavy elements into space. An Introduction quiz. The Sun is composed mainly of hydrogen and helium. The Sun's luminosity is referred to as one solar luminosity.
Stars produce energy through a process known as fusion.
Fusion occurs when lighter elements, such as hydrogen, combine into heavier elements, such as helium, with a release of energy. Stars do not shine forever. Stars are of a finite size, which means that eventually they will run out of fuel, much like a car runs out of gas.