When the solar system first took up the task of building solid bodies—such as planets, moons and protoplanets—it basically had a choice between two ingredients: heat-forged chondrules, which were millimeter-sized bits of rock, and matrix, a fine-grained, cold dust loaded with water ice and organic molecules. And from the get-go, the solar system chose fire.

In a new Yale-led study, researchers provide the first geochemical evidence that within the first million years after the solar system began to form, it was already preferentially sorting for chondrules over matrix. Prior research had only been able to document this sorting process in objects that formed 2–4 million years after the solar system’s origin.

The study is published in the journal Nature Astronomy.