Yale study finds early Solar System favored chondrules over icy dust

September 22, 2026 at 05:00 AM2 min

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Yale University researchers found the first geochemical evidence that chondrules were preferentially incorporated into solid bodies during the Solar System's first million years. The study, published Sept. 18 in Nature Astronomy, shows the earliest outer Solar System bodies were built from 83% to 92% chondrules. This selectivity occurred even as later-forming objects contained more icy, volatile-rich dust.

Key Facts

The earliest bodies in the outer Solar System were built from 83% to 92% chondrules, with very little icy, volatile-rich dust.
The study was published Sept. 18 in Nature Astronomy.
Until now, scientists had only documented this type of sorting in objects that formed 2 to 4 million years after the Solar System began.
Damanveer Grewal, an assistant professor of Earth and planetary sciences at Yale, is the first author of the study.

Early Solar System Composition

The earliest stages of planet formation offered two major types of material: chondrules, millimeter-sized pieces of rock formed at high temperatures, and matrix, a cold, fine-grained dust rich in water ice and organic material. New research led by Yale University suggests that the Solar System strongly favored the heat-formed material almost immediately. Researchers found the first geochemical evidence showing that chondrules were already being preferentially incorporated into solid bodies during the Solar System's first million years. Chondrules are small rocky spheres found inside chondrites, which are among the most primitive meteorites preserved in geological collections.

Evidence from Iron Meteorites

Confirming what happened during the Solar System's first million years has been difficult because no preserved undifferentiated bodies from that period remain. Grewal and his colleagues approached the problem by examining chemical clues preserved in iron meteorites from the outer Solar System. Scientists have long known that carbonaceous chondrites from the outer Solar System show a pattern related to age: older examples tend to contain a greater proportion of chondrules and less matrix, while younger ones contain more of the cold, volatile-rich material. That pattern suggested that the regions where the first solid objects, known as planetesimals, were forming were already favoring heat-formed chondrules while excluding much of the icy dust.