The Iron in Your Blood and the Iron in the Stars - Why Your Body Is a Cosmic Archive

The iron atom in your hemoglobin molecule has a history that predates the Earth by billions of years. That specific atom - or more precisely, the nuclear configuration that constitutes that atom -...

The iron atom in your hemoglobin molecule has a history that predates the Earth by billions of years.

That specific atom - or more precisely, the nuclear configuration that constitutes that atom - was assembled in the core of a massive star through the silicon-burning process, the final stage of stellar nucleosynthesis before the core-collapse supernova that scattered the star's contents across the interstellar medium.

The iron atom survived the supernova. It drifted through space. It was incorporated into the molecular cloud that collapsed to form our solar system. It became part of the Earth.

It entered the biosphere. It was incorporated into the hemoglobin molecule that carries oxygen through your bloodstream right now. The atom is approximately five billion years old.