The Life of a Star

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The Main Cycle - Starring Our Sun

  As previously discussed, a star is a huge nuclear reaction surrounded by a tremendous mass of gas, held together by the gravitational force of that mass. Two separate forms of hydrogen atoms, deuterium (one proton, one neutron, one electron) and tritium (one proton, two neutrons, one electron), fuse to form helium atoms under tremendous gravitational force at the center of the star. When each helium atom (two protons, two neutrons, two electrons) is formed, a neutron is cast out, releasing a tremendous amount of energy. This reaction will continue until the star has exhausted its supply of hydrogen. So long as hydrogen is being fused to form helium, the star is said to be in its main sequence. Our sun falls into this category and should continue to do so for another 5 billion years.                                                                     Photo courtesy of NASA

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