ETH Zurich study finds Earth formed entirely from inner Solar System material

September 16, 2026 at 04:01 PM2 min

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A new study by ETH Zurich planetary scientists Paolo Sossi and Dan Bower, published in Nature Astronomy, concludes that Earth's building material came entirely from the inner Solar System. The analysis of ten isotope systems in meteorites found that outer Solar System material accounts for less than two percent of Earth's mass, challenging the long-held view that 6-40 percent arrived from beyond Jupiter.

Key Facts

The study, published in Nature Astronomy, analyzed ten isotope systems in meteorites, compared with earlier studies that typically used only two.
Researchers Paolo Sossi and Dan Bower of ETH Zurich found that outer Solar System material accounts for less than two percent of Earth's total mass, and possibly none at all.
The analysis indicates Earth is composed entirely of non-carbonaceous material, which formed in the inner Solar System.
The findings challenge the previously proposed exchange of material between the inner and outer Solar System reservoirs during Earth's formation.

Isotope Analysis Method

The ETH Zurich team based its analysis on existing measurements from ten different isotope systems found in meteorites, including samples associated with Mars and the asteroid Vesta. Earlier studies typically focused on only two isotope systems, whereas the new approach applied statistical calculations rarely used in geochemistry. Sossi described the work as a data science experiment, noting that the statistical methods employed are a powerful tool not commonly applied in the field.

Meteorite Classification

Since the early 2010s, isotopes of elements such as chromium and titanium have allowed scientists to divide meteorites into two broad groups: non-carbonaceous and carbonaceous. Non-carbonaceous meteorites formed exclusively in the inner Solar System, while carbonaceous meteorites contain more water and carbon and originated in the outer Solar System. According to the new analysis, Earth is made entirely from non-carbonaceous material, with no evidence for the previously proposed exchange of material between the inner and outer reservoirs.