Asteroid Crashes Likely Gave Earth Its Water
Illustration: Artist’s impression of a 6-mile-wide asteroid striking the Earth. Scientists think approximately 70 of these dinosaur killer-sized or larger asteroids hit Earth between 3.8 and 1.8 billion years ago. Credit: Don Davis
Asteroids from the inner solar system are the most likely source of the majority of Earth’s water, a new study suggests.
The results contradict prevailing theories, which hold that most of our planet’s water originated in the outer solar system and was delivered by comets or asteroids that coalesced beyond Jupiter’s orbit, then migrated inward.
“Our results provide important new constraints for the origin of volatiles in the inner solar system, including the Earth,” lead author Conel Alexander, of the Carnegie Institution of Washington, said in a statement. “And they have important implications for the current models of the formation and orbital evolution of the planets and smaller objects in our solar system.”