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Galactic Inquirer

How the Earth Got its Water

6 May 2015, 16:50 UTC
How the Earth Got its Water
(200 words excerpt, click title or image to see full post)

Despite compelling evidence for water throughout our Milky Way Galaxy and within our local Solar System, the specific origin of water on Earth remains controversial. We know that the Earth formed some 4.6 billion years ago, as the primordial Solar System gravitationally congealed from the pre-planetary disk of debris that surrounded the proto-Sun. Once the Sun “turned on” its thermonuclear fires, things began to change in a big way.

The primitive Solar System was a busy chaotic place. Did Earth’s cargo of precious water come home-grown 4.6 billion years ago or was it delivered via comets during the Late Heavy Bombardment that ended 3.9 billion years ago? (Caltech-JPL/NASA)

Some scientists contend that the inner Solar System was too hot for any water to remain in the rocky bits that ultimately came together to form the Earth. They look to wayward comets and asteroids that formed farther from the scalding Sun as the key provisioners of Earth’s oceans. However, others find important discrepancies in the relative amounts of regular water and “heavy” (deuterated) water in their comparisons of the Earth, comets, and meteorites. ...

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