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The Question

(Submitted September 21, 2005)

Within one of your answers is a statement that I've heard before, but... never really fully understood. You wrote 'we are all star-stuff.' Do you mean, that people are made out of the same things (elements) that stars are made of? Are people made out of star-dust?

Thank you for a wonderful site. I appreciate your answers, and your time.

P.S. If... we all once were a star... A (very) young childs next question might be. 'Mom...? What do Star's really think about? Maybe the words really were...'Twinkle, twinkle little star. How I wonder... Who you are?'

The Answer

The statement that we are all "star stuff," coined by the late astronomer Carl Sagan (not sure if this was before or after Joni Mitchell sang "we are stardust; we are golden. we are billion year old carbon"), is meant to imply more than that we are made of the same elements that stars are made of. Beyond that, the elements themselves (carbon, nitrogen, oxygen, etc.) were synthesized, cooked up as it were, in the nuclear furnaces that are the deep interior of stars. These elements are then released at the end of a star's lifetime when it explodes, and subsequently incorporated into a new generation of stars -- and into the planets that form around the stars, and the lifeforms that originate on the planets.

-- Michael Loewenstein and Amy Fredericks for "Ask an Astrophysicist"

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