Meteorite material presumed to be devoid of water because it formed in the dry inner Solar System appears to have contained sufficient hydrogen to have delivered to Earth at least three times the mass of water in its oceans, a new study shows.

While the idea that enstatite chondrite (EC) meteorites contained enough hydrogen to provide water to the growing proto-Earth has been proposed, efforts to rigorously test this scenario have been hampered by difficulties in measuring hydrogen concentrations in ECs — an obstacle this study overcame.

According to models of Solar System formation, Earth should be dry. However, our blue planet’s vast oceans, humid atmosphere and well-hydrated geology boldly defy such predictions, making it unique among the other rocky planets of the inner Solar System.

Enstatite chondrite meteorites, once considered ‘dry,’ contain enough water to fill the oceans — and then some.

A new study finds that Earth’s water may have come from materials that were present in the inner solar system at the time the planet formed — instead of far-reaching comets or asteroids delivering such water. The findings published on August 28, 2020, in Science suggest that Earth may have always been wet.

Researchers from the Centre de Recherches Petrographiques et Geochimiques (CRPG, CNRS/Universite de Lorraine) in Nancy, France, including one who is now a postdoctoral fellow at Washington University in St. Louis, determined that a type of meteorite called an enstatite chondrite contains sufficient hydrogen to deliver at least three times the amount of water contained in the Earth’s oceans, and probably much more.

Our blue planet having water seems such a simple and obvious fact that the question of why Earth has water at all feels like a trivial one. However, the origin of this key ingredient for life has remained a long-standing topic of debate. According to models of Solar System formation, Earth, as an inner Solar System planet, should have little to no water. On page 1110 of this issue, Piani et al. ([ 1 ][1]) analyze enstatite chondrite meteorites, a material similar to Earth’s main building blocks, and address the origins of Earth’s water.

Early models of planetary formation predicted that the nebular gas near our young Sun was too hot to form ice.