Cosmic Recipe for Earthlings

Cosmic Recipe for Earthlings

 By Doroty Setton

Illustration by Kellie Jaeger, agsandrew/Shutterstock

Discover Magazine

September 2013


star-explosionStars cook up nearly all of the approximately 60 atomic elements in people’s bodies. But exactly how that works remains a mystery. Astrophysicists have developed cutting-edge computer simulations to grapple with an array of related puzzles:

• What were stars like when they first appeared in the universe over 13 billion years ago, starting the process of modern element production?

• What do we know about the nature of the death of massive stars — signaled by Type II supernovae — that fashion crucial elements such as calcium and oxygen?

• How might the burned-out stars called white dwarfs be brought to ruin by other stars in so-called Type Ia supernovae, inciting the fiery alchemy that yielded much of the iron in our blood and the potassium in our brains?

Scientists are still trying to figure out what triggers an individual Type Ia supernova and to determine the identity of the partner star to the exploding white dwarf. The Hubble Space Telescope’s recent discovery of the earliest known Type Ia supernova from more than 10 billion years ago, plus other results, favor a scenario in which two white dwarfs merge.

Human Body Ingredients

The four ingredients below are essential parts of the body’s protein, carbohydrate and fat architecture. (Expressed as percentage of body weight).

Oxygen — 65.0%


Critical to the conversion of food into energy.

Carbon — 18.5%

The so-called backbone of the building blocks of the body and a key part of other important compounds, such as testosterone and estrogen.

Hydrogen — 9.5%

Helps transport nutrients, remove wastes and regulate body temperature. Also plays an important role in energy production.

Nitrogen — 3.3%

Found in amino acids, the building blocks of proteins; an essential part of the nucleic acids that constitute DNA.

The results indicate that crucial elements in people formed later in the history of the universe than many had expected, says David Jones, the lead astronomer on the Hubble study. “It took (very roughly) about 750 million years longer to form the first 50 percent of the iron in the modern universe.”

Super Nova explosions are a source of about a dozen major elements in people, including iron, calcium, phosphorus, potassium, sulfur and zinc.