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

A new study suggests Earth formed almost entirely from material in the inner Solar System, challenging the idea that water-rich material from beyond Jupiter played a major role. If correct, Earth’s water may have been present much closer to the young Sun than scientists previously thought. Scientists “truly astonished” by discovery that challenges Earth’s origin story.

The birth of two planets (light brown dots) in a protoplanetary disc around the young star WISPIT 2. 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. "We were truly astonished" Planetary scientists Paolo Sossi and Dan Bower of ETH Zurich compared existing measurements of isotope ratios from many meteorites, including samples associated with Mars and the asteroid Vesta, with the isotopic composition of Earth.