Radio telescopes map space molecules, revealing star‑formation sites

Astronomers have long traced the origins of the elements that compose the Earth’s crust, living organisms, and even the human body back to the cores of the first stars. In the 1970s, physicist Carl Sagan famously remarked that “we are made of star‑stuff,” a statement that captures the process by which heavier elements are forged in stellar interiors and later dispersed into space. When massive stars exhaust their nuclear fuel, they explode as supernovae, ejecting newly created atoms into the interstellar medium where they mix with gas and dust.

The expelled material eventually coalesces into new generations of stars and planetary systems. In the protoplanetary disk that surrounds a young star, dust grains rich in carbon, nitrogen, oxygen, and heavier metals collide and stick together, forming planetesimals that grow into rocky planets. On Earth, these building blocks were incorporated into the planet’s mantle, crust, and eventually the biosphere, giving rise to the complex chemistry required for life.

This chain of stellar nucleosynthesis and planetary accretion explains why the same elements that once powered the hearts of ancient stars now make up the minerals in our rocks, the chlorophyll in plants, and the proteins in human cells. Understanding this cosmic cycle provides a profound context for the interconnectedness of the universe and the origins of life on Earth.