Scientists “truly astonished” by discovery that challenges Earth’s origin story

Scientists have long debated where the raw material that formed Earth originally came from. Although our planet sits in the inner Solar System, many researchers have proposed that 6-40 percent of its building material arrived from the outer Solar System, beyond Jupiter.

That idea has been especially important for explaining how Earth acquired volatile substances such as water. If those materials came from farther out, then matter must have moved between the outer and inner regions of the Solar System while Earth was forming.

New research now challenges that picture.

Planetary scientists Paolo Sossi and Dan Bower of ETH Zurich compared existing measurements of isotope ratios from a wide range of meteorites, including samples associated with Mars and the asteroid Vesta, with the isotopic composition of Earth.

Isotopes are sibling atoms of the same element (same number of protons) that have a different mass (different number of neutrons).