Meteorite Studies Reveal Surprises About Earth's Formation
Space Climate Observatory (DSCOVR) satellite on Jan. 9, 2017.
Credit: NASA

Scientists now have a better understanding of three concepts regarding the early Earth: what kind of raw materials coalesced to form Earth long ago, when water arrived on our planet, and why Earth and its moon have such similar compositions. 

Two studies published Wednesday (Jan. 25) in the journal Nature suggest that Earth's main building blocks were rocks similar to meteorites known as enstatite chondrites, and that the planet got most of its water gradually during the formation process, rather than in one big burst toward the end.

"The results presented in these papers lead to the troubling conclusion that the meteorites in our collection are not particularly good examples of Earth's building blocks," Richard Carlson, a geochemist at the Carnegie Institution for Science in Washington, D.C., wrote in a commentary article that accompanied the two studies in Nature. (Carlson was not involved in either study.) [Photo Timeline: How the Earth Formed]