| I was first exposed to this phrase at school. The class of 1969 had donated a small sitting garden to the University; in the center was a squat cylinder of stone placed on its end, just the right height to be a small bench. On the top face (end) of the cylinder was etched an enormous mandala, covering the whole of that surface; on the sides, carved in the stone, was this quote:
We are all starstuff; billion year old carbon / got to get ourselves back into The Garden
I cannot be sure of the attribution now, from memory, but I'd bet it was from Carl Sagan.* I thought about that; every atom in our bodies other than hydrogen was formed by fusion, at some point in the past. Specifically, in the hearts of main-sequence and older stars, as they exhaust their hydrogen fuel and begin to fuse heavier elements that have remained as 'waste products.'
This continues until the star (if it is energetic/massive enough) begins to produce iron. Iron is the first fusion reaction (moving up the periodic table) that is endothermic; that is, it requires more energy than it gives off. This is the beginning of the end for the star; as it continues building iron atoms, it begins to lose energy into the iron itself, and its density begins to increase dramatically. Eventually, the combination of lower internal pressure from energy loss and higher density will cause the star to collapse in on itself, a process that will either stabilize with the star reaching a 'peak' energy and then cooling down into a red giant, or superheating its center of mass to the point where heavy elements themselves fuse. If the star is massive enough, its own weight will prevent this energy from escaping, and the star will continue its collapse - if it is on the correct side of Chandrasekhar's Limit it will turn into a collapsar, or black hole.
If it is light enough, it will suddenly heat its core into a fusion burst. That fusion is sudden and explosive; the star consumes itself in a burst of energy liberated from the destruction of its own material; that energy rushes outward, lost to the star forever, and hastening its death. The explosion created is a supernova; it is the only event known in the universe which is hot enough to produce the most heavy elements (like, say, gold) through fusion.
All the gold there is comes from the heart of one of these monsters. So, too, does the carbon- our life itself.
We are all starstuff.
*: Grzcyrgba informs me this is a quote from the song Woodstock, by either Joni Mitchell or Crosby, Stills, and Nash. Stealth Munchkin adds that it was both; written by Joni and popularized by CSNY. Since I was busy being born at that time, my knowledge of that time is weak. Thanks all!
I am further humbled by DejaMorgana, who tells me that Sagan later did use the phrase, and reminds me that it also found its way into the heavens to be spoken by Ambassador Delenn of the Minbari, on Babylon 5.
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