Solar SystemMODEL

Earth and Mars were built like a LEGO set

By Space.Fan Editorial DeskSeptember 26, 2026 at 11:02 AM UTC

Scientists found that our rocky neighbors grew by combining two very different building methods in the early solar system.

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The Drop

For a long time, experts wondered exactly how rocky s like Earth and Mars formed. By using computer models to look at chemical signatures, researchers discovered that these s were not built just one way. Instead, they were made through a hybrid process. They grew by collecting tiny space pebbles and by smashing into larger, rocky space rocks similar to the Vesta. This combination is like using two different sets of building blocks to construct a single structure. The team used a method called Bayesian inference, which is a mathematical way of testing different scenarios to see which one best matches the evidence we see today in our 's composition. They found that Earth is made mostly of material from tiny pebbles, while Mars contains a much larger share of material from older, -like rocks. This discovery helps explain why the chemicals in the mantles of these s are missing some of the lighter ingredients they would have had if they came from the sun directly. The s basically left a chemical fingerprint of how they were put together billions of years ago.

Why It Matters

This research is a big deal because it solves a puzzle about why rocky s have fewer volatile elements than the sun. It proves that the way a grows determines its final chemical makeup. By identifying these fingerprints, we can now look at other rocky s in distant systems and figure out how they were made just by analyzing their chemical ingredients.

The Catch

This study relies on computer models to recreate events from billions of years ago, which means the results are only as good as the assumptions built into the software. While the evidence is strong, it is a simulation of the past rather than a direct observation, and future data about the chemical makeup of more s could change how we interpret these findings.

Put That in Perspective

Scientists have compared the composition of Earth and Mars to the sun for decades. This study is an important step forward because it links that old data to new theories about pebble accretion, a newer idea in the field of planet formation.

Source September 26, 2026

Haiyang S. Wang, Anders Johansen, Ziyan Xu, Marie-Luise Steinmeyer, Michiel Lambrechts, Elishevah van Kooten, Chao-Chin Yang, Zhaohuan Zhu, Dante S. Lauretta, Martin Bizzarro

University of Copenhagen·Nature Astronomy·10.1038/s41550-026-00000-0