FARGO - "We are stardust. We are golden. We are billion year old carbon." This comes from the 1969 Joni Mitchell song, "Woodstock." The song may be a dated, hippie, period piece, but there is some good science in the chorus. Stars shine because of the nuclear fusion of hydrogen to form helium in the star's interior. After billions of years, most of a star's hydrogen is used up so the star's core collapses and gets even hotter.

Depending on the star's mass, the collapsing core may cause additional fusion reactions which produce heavier elements such as iron. Some of these stars explode in a massive supernova which flings all these elements into space, where they collide with interstellar dust and gas. This is where chemical compounds like carbon and water, the stuff that we are made of, are formed in the universe. We are, in fact, stardust.