Neither comets nor asteroids got wet. There was a lot of water on Earth from the beginning
Recent research by researchers indicates that perhaps the Earth did not need an asteroid or comet to make water appear on its surface.
It is widely believed that our planet was dry shortly after it formed because it formed relatively close to a hot, very active young sun. According to this theory, most of the water currently on the Earth's surface has come here in the form of asteroids and comets from distant, frosty regions of the solar system. For years, there has been a dispute among scientists whether comets or asteroids are responsible for the water on Earth .
The latest research, published yesterday in the journal Science, indicates that this may be a purely academic discussion. The authors of the study analyzed 13 different meteorites from the group of enstatite chondrites, objects resembling space rocks from which the Earth formed 4.5 billion years ago.
Scientists found plenty of hydrogen in apparently dry meteorites - enough to conclude that the Earth was fairly wet from the outset. Calculations made in the course of the study indicate that the rocks from which the Earth was formed had at least three times more water than the oceans today.
Our discovery indicates that the components from which the Earth was formed may largely be responsible for the water on the planet, says Laurette Piani, researcher at the Center de Recherches Petrographiques et Geochimiques in Nancy, France.
Hydrogen-rich matter was present in the inner solar system at a time when the rocky planets were forming, although the temperatures were too high here for water to condense, adds Piani.
Along with colleagues, the author convincingly argues that the water on Earth may have come from enstatite chondrites.
The key question, however, is when this water appeared on the surface. In an article in the same issue of Science, Anne Perlier of the Houston Space Center notes that it is not known whether the water on Earth today is also from this time. If the water condensed quickly to the Earth's surface, it could evaporate during the great bombardment or during the formation of magma oceans. In that case, the debate about the origin of the present water from asteroids and comets would still make sense.
Nevertheless, the results of the research conducted by the authors constitute a key and, importantly, elegant piece of the whole puzzle. It turns out that at least some of the water on Earth may simply come from the cloud of matter that formed the Earth, Perlier concludes.
Neither comets nor asteroids got wet. There was a lot of water on Earth from the beginning
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