New research indicates that Earth formed almost entirely from material within the inner Solar System. This finding challenges previous theories that suggested a significant portion of Earth's building blocks, including water-rich substances, originated beyond Jupiter.
Scientists Paolo Sossi and Dan Bower from ETH Zurich conducted the study. They analyzed existing measurements of isotope ratios from various meteorites, including samples from Mars and the asteroid Vesta. Their analysis compared these ratios to Earth's isotopic composition.
Isotopes are atoms of the same element with different masses. The researchers used a novel approach to analyze data from ten different isotope systems. Earlier studies typically focused on only two isotope systems.
The findings suggest that material from the outer Solar System accounts for less than two percent of Earth's total mass, possibly none. This implies that Earth's formation occurred in a relatively stable environment, gradually incorporating nearby planetary bodies. It also suggests that volatile substances, such as water, were present in the inner Solar System.
Jupiter likely played a significant role in this process. As the gas giant grew, its immense gravity created a barrier in the protoplanetary disk around the young Sun. This barrier limited the movement of material from the outer Solar System into the inner region.
The study's results also show that Earth's material composition is similar to that of Mars and Vesta. Researchers hypothesize that Mercury and Venus may share this pattern, but direct testing is not yet possible due to a lack of rock samples from those planets.
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