We Are Stardust
Every atom of oxygen in our lungs, of carbon in our muscles, of calcium in our bones, of iron in our blood - was created inside a star before Earth was born.
Hydrogen and helium, the lightest elements were produced in the Big Bang.
Almost all of the other, heavier, elements were produced inside stars.
Stars forge heavy elements by fusion in their cores. In a star of intermediate mass, these elements can mix into the star’s atmosphere and be spread into space through stellar winds.
During the supernova explosion of a massive star is the only time when elements heavier than iron are fused. The supernova expels this material across interstellar space.
The enriched material ejected by stellar winds and supernova explosions becomes parts of vast interstellar clouds. The Sun formed within such a cloud, where some of the heavy elements condensed to form Earth.
“I believe a leaf of grass is no less than the journeywork of the stars.” - Walt Whitman, Leaves of Grass