A chemical element that’s not even in H2O — sulfur — is the reason Earth first got its water, a new study finds, bolstering a similar claim made a year ago. The discovery means our planet was born with all it needed to create its own water and so did not have to receive it from elsewhere.
Water is essential to terrestrial life, but Earth formed in a region around the newborn sun that was so hot the planet should have been dry (SN: 5/6/15). Now two independent studies of a specific type of meteorite reach the same conclusion: Lots of hydrogen — a key component of water — came to Earth not as H2O but instead bonded with sulfur. This allowed the hydrogen to survive the heat and later join oxygen, the most common element in Earth’s crust, to create water.