Earth’s oceans may have formed directly from the “star stuff” that coalesced into the early solar system, according to new research – challenging the idea that most of Earth’s water was delivered here by meteorites and comets.
Scientists studying rare meteorites thought to have formed in the hot inner solar system found that the ancient rocks contain more hydrogen than previously thought – and hydrogen, along with oxygen, is one of the two essential ingredients of water.
If the Earth formed from similar materials, then more than enough hydrogen would have been available to combine with oxygen to create all of the world’s water – many times more, in fact.
A piece of the meteorite Sahara 97096, an enstatite chondrite that was found to contain the equivalent of 0.5 percent of its weight in water.L. Piani / Museum of Natural History in Paris
“The Earth might have been wet from the beginning, when it started to form,” said Laurette Piani, a cosmochemist at the Petrographic and Geochemical Research Center in France and lead author of a paper on the new findings published Thursday in the journal Science.
Early models of the formation of the solar system suggested the Earth should be bone dry because it formed so close to the hot young sun. Instead, it’s flowing with life-sustaining water.
Scientists have tried to explain the mystery for years, and developed a theory that the young Earth was bombarded by water-rich meteorites and icy comets from the frozen outer solar system, which became our oceans, lakes, rivers and clouds.
But this exotic proposal doesn’t match tell-tale chemical traces in the Earth’s composition, and it doesn’t directly explain the many oceans worth of water locked up underground in the Earth’s rocks.
Piani and her colleagues examined enstatite chondrite meteorites thought to have formed in the hot inner parts of the solar system more than 4.5 billion years ago, alongside the Earth and the other rocky planets.
Only about 200 enstatite chondrite meteorites have ever been found, but they match specific aspects of the chemical composition of our planet.
That suggests they are similar to the “building blocks” that formed the Earth from an interstellar nebula – “star stuff” – in the early solar system, Piani said.