Stars, Gold, Dung Beetles and Us

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Who was it that first said that people are stardust?

Some people, of a certain age, might say Joni Mitchell, who sang, “We are stardust, we are golden, and we’ve got to get ourselves back to the gar-ar-den,” in her paean to the Woodstock festival. Others will say Carl Sagan, the author and host of “Cosmos.”

In fact, the answer goes back before those acolytes of beauty and consciousness were born. In 1929, the Harvard astronomer Harlow Shapley declared, “We organic beings who call ourselves humans are made of the same stuff as the stars” — a remarkable observation, considering that at the time nobody even knew what made the stars shine.

It would be 30 years before Geoffrey and Margaret Burbidge, William Fowler and Fred Hoyle showed in a classic paper that the atoms that compose us are not only the same as the ones in stars — most of them were actually manufactured in stars. Starting from primordial hydrogen and helium, denser elements like iron, oxygen, carbon and nitrogen were built up in a series of thermonuclear reactions and then spewed into space when these stars died and exploded as supernovas in a final thermonuclear frenzy.

Any gardener knows that ashes make good fertilizer. Our atoms were once in stars.

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