July 20, 2024
Where did Earth's water come from?
Earth formed from the dust and gas of the nebula that surrounded our infant Sun. This artist’s concept shows the protoplanetary disk of material around a young star. The disk contains the individual components of water — hydrogen and oxygen — and water in both ice and vapor forms.
Earth formed from the dust and gas of the nebula that surrounded our infant Sun. This artist’s concept shows the protoplanetary disk of material around a young star. The disk contains the individual components of water — hydrogen and oxygen — and water in both ice and vapor forms.

Karen Meech doesn’t spend a lot of time digging through Earth’s rocks. An astronomer by trade, she is usually behind the telescope, investigating comets and looking for hints about how Earth got its water. But a field trip to Iceland in 2004 ultimately sent her scrambling through the craters of Hawaii nearly a decade later in search of clues about the liquid that helped birth life on this planet.

On that fateful Icelandic tour, Meech saw geothermal areas with gas billowing out of the ground. The guide told the group not to worry — it was only water. “Then she said, ‘This is probably primordial water,’ and it set a lightbulb off,” Meech says.

The flavors of water

The source of Earth’s water has been a long-standing mystery; Meech herself has been trying to solve it for at least 20 years. Most of that search has focused on sorting out the various isotopes of hydrogen that go into making the water — or “the flavor of water,” as Lydia Hallis of the University of Glasgow calls it. One of those “flavors” is heavy water, a form of water that incorporates deuterium, an isotope of hydrogen whose nucleus contains one proton and one neutron. Normal hydrogen lacks a neutron, so water with deuterium weighs more than ordinary water.

By simulating conditions in the early solar system, researchers can calculate the ratio of heavy water to ordinary water when the planets were forming. On Earth, the observed ratio is higher than it would have been in the young solar system, leading many astronomers to suspect that the water was imported because the ratio should remain constant over time. Today, most scientists believe asteroids carried water to the young, dry Earth.

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See Also:

(1) Surprise 4,000-mile ‘ice corridor’ found on Saturn’s moon Titan

(2) Cosmic conundrum: Just how fast is the universe expanding?

(3) Venus reimagined: A new image of an active world

(4) Merging neutron stars gave solar system heavy elements

(5) A mathematical method for calculating black-hole properties from gravitational-wave data

(6) New water cycle on Mars discovered

(7) Suppressed star formation in the early universe

(8) Catastrophic meteors: How space scientists hope to protect ‘the only planet we know’

(9) Dark matter mystery: Could this theory explain the Milky Way’s bizarre behaviour?

(10) The universe’s first supernovae spewed jets of material into nearby galaxies

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