The Earth and Mars were formed from material coming, above all, from the inner solar system; only a small percentage of the building blocks of these two planets originated beyond the orbit of Jupiter. This is what is determined by a new study by a group of researchers led by the University of Münster (Germany) that publishes its conclusions in the journal Science Advances.
The theory that the four rocky planets grew to their current size by accumulating millimeter-sized bits of dust from the outer solar system is not tenable based on these results.
To answer the question of how the planets of the inner solar system formed in the first place, scientists from the University of Münster (Germany), the Observatoire de la Cote d’Azur (France), the California Institute of Technology (USA). USA), the Natural History Museum in Berlin (Germany) and the Free University of Berlin (Germany) determined the exact composition of the rocky planets Earth and Mars, presenting the most comprehensive comparison to date of the isotopic composition of the Earth , Mars, and the pristine building material of the inner and outer solar system, using meteorites that have traveled from Mars and crashed on Earth.
“We wanted to find out if the basic components of the Earth and Mars originated in the outer or inner Solar System,” says Christoph Burkhardt of the University of Münster, and leader of the work.
Basic components of the beginning of the solar system
They looked at the isotopic compositions of titanium, zirconium and molybdenum in the samples, as well as measurements of 17 more meteorites from Mars. They then compared the composition of these meteorites to meteorites thought to have landed on Earth from inside and outside the solar system. Comparing the two, the researchers found that the composition of Earth and Mars is more consistent with meteorites coming from within the solar system than from outside , suggesting that terrestrial planets like Earth and Mars formed from several collisions between material from the inner solar system, rather than the accumulation of material from the outer solar system.
“The fact that Earth and Mars apparently contain mainly material from the inner Solar System fits well with the formation of planets from collisions of large bodies in the inner Solar System,” concludes Christoph Burkhardt.
This does not mean that the theory of the accumulation of material from the outer solar system is inherently wrong. After all, studies have shown that this method is effective in forming the nuclei found in gas giants. However, the study shows that for Earth and Mars, and probably for Mercury and Venus as well, the main force in the formation of these rocky worlds was material from the inner solar system.
Referencia: Christoph Burkhardt et al, Terrestrial planet formation from lost inner solar system material, Science Advances (2021). DOI: 10.1126/sciadv.abj7601