Our Sun is a perfect example of a star, and there is an incredible amount of stars in the Universe. It is a star among hundreds of billions of stars within our Milky Way Galaxy, and our galaxy is one of billions of galaxies in the universe. Stars live for a very long time; millions, billions, or tens of billions of years so we can never really observe the life of a star; its birth, life, and death. In determining the life cycle of a star, astronomers observe many of the billions of stars around us and see them at different stages of life, therefore piecing together a star's evolution.

A star is born from clouds of gas and dust called nebulae found in interstellar space. Nebulae are composed mainly of hydrogen and helium, but also contain traces of heavier elements. It is...