Iron Stardust
Daily Earth Science

Iron and stardust: A common bond

Iron commonly comes to mind in the context of construction, metallurgy, and industrial manufacturing. However, iron is one of the critical ingredients of life. Humans, animals, and plants all require iron to sustain life. Hemoglobin in the blood of every living human requires iron to function. About 70 percent of our body’s iron exists in blood cells, and this is true regardless of the color of a person’s skin. So, life on earth is bound together by stardust.

The story of iron begins in intergalactic space, deep within a type of star known as a red giant. Inside the star, its hydrogen is gone, and its helium converts to carbon and oxygen atoms. As the process continues, these atoms slowly change into the heaviest type of atom a star can produce – iron. When these atomic conversions finish running their course, the red giant contains vast amounts of iron. This stage marks the end of its life, and if the star is large enough, it becomes a supernova and undergoes one of the most violent processes know in the universe. The red giant explodes, spewing iron, carbon, and oxygen across the vast reaches of space. 

This intergalactic stardust eventually finds its way into gravity wells where it coalesces into planets. Our earth went through this process some 4.5 billion years ago. Within the core of planet earth, where temperatures exceed 6000 degrees C, iron is the dominant ingredient, and the crust of the planet, directly beneath our feet, contains about 5 percent iron. 

Common bonds

The Gaia hypothesis embraces the idea that organic and inorganic components of our planet bind together into a single, self-regulating system. This system is an interconnected web of life encircling the outer shell of the earth. Accordingly, human beings are only part of that web, not the web itself. The iron and stardust that originated in the heart of a red giant are also part of that web. 

Gaia theory, in its totality, is not accepted by many, and it is not proven. However, the concept that life is in an interconnected web is definitively real. If all of life on earth except humans disappeared tomorrow, then our days would be numbered. We require the web of life to survive as a species.

Human beings share a common universal origin. Discussions of equity and social justice ultimately rest on the recognition of this common heritage. When we look at our planet, we should remember that all life on our earth is locked in a symbiotic relationship. If we destroy enough of the web of life, then we destroy our species.  When we look at another person, we should remember that we share bonds that go far beyond our planet and our solar system. 

“We are stardust, we are golden, we are billion year old carbon, and we got to get ourselves back to the garden.” (Woodstock lyrics by Crosby, Stills, Nash & Young)  


What Is the Origin of Iron? (By Marc Chase – Sciencing) – Also:

Hemoglobin and Functions of Iron (UCSF Health) – Also:

Feature Image: Cygnus Loop supernova remnant (NASA) (Modified) – This file is in the public domain in the United States because it was solely created by NASA.

William House
William is an earth scientist and writer with an interest in providing the science "backstory" for breaking environmental, earth science, and climate change news.