Science & Tech · Science & Environment · 2 hrs ago
Early Solar System Bodies Were Built Mostly From Rock, Study Finds
Researchers found that the earliest planetesimals were made mostly of rocky chondrules, tiny fragments formed by intense heat.
These bodies formed around the young Sun during the Solar System’s first million years.
The team studied iron meteorites that preserve chemical clues about the materials in those early bodies.
The analysis suggests they were 83% to 92% chondrules, with very little icy, water-rich dust.
The researchers say compact chondrules may have clumped together more readily, a process known as aerodynamic sorting.
Icy material became more common in bodies that formed later, though what changed is not yet clear.
The findings could help scientists understand how planets and moons form elsewhere in the Universe.
A study found that the earliest planetesimals in the Solar System were made mostly of rock fragments called chondrules, with little icy dust.
Researchers analyzed iron meteorites to estimate the mix of materials in bodies formed during the Solar System’s first million years.
The earliest outer Solar System bodies were estimated to contain 83% to 92% chondrules.
The results suggest that chondrules dominated early, while icy matrix became more common in bodies formed later.
The study’s authors say aerodynamic sorting may have helped the compact chondrules clump together.
- Who
- An international team of researchers studied the meteorites. Earth and planetary scientist Damanveer Grewal of Yale University commented on the findings.
- What
- The study found that the earliest planetesimals were made mostly of chondrules, with little icy matrix.
- When
- The research concerns bodies formed during the Solar System’s first million years. The article was published on November 1, 2026.
- Where
- The study examined iron meteorites that had fallen to Earth, including evidence from bodies in the outer Solar System.
- Why
- The researchers aimed to determine the mix of chondrules and matrix in the earliest planetesimals.
This story does not have two clearly opposing sides.
The earliest planetesimals formed mostly from chondrules, according to the study.
Chondrules were winning out over matrix in the formation of planetesimals.
Icy matrix elements started to win out.
ScienceAlert published its report on the study.
- Estimated chondrule share
- 83% to 92% of the earliest outer Solar System bodies
- Study material
- Iron meteorites that had fallen to Earth
- Rock fragments
- Chondrules
- Icy dust
- Matrix, containing water ice and organic molecules
- Study journal
- Nature Astronomy
What people are saying
The earliest bodies in the outer Solar System were built from 83 percent to 92 percent chondrules, with very little of the icy, volatile-rich dust that dominates later-forming objects.
Both tracers independently tell the same story: These early planetesimals were remarkably matrix-poor.
That convergence is what makes the result robust.
And now we know they were already being sorted and incorporated into the first generation of solid bodies from the very start.