Nothing on Earth can live without water. Therefore, the origin of water on Earth is the origin of life in the solar system (and the universe) as we know it.
Discovering where and how our world got its water may be key to finding life on other worlds, but the truth is we don’t know for sure where it came from.
However, it is generally accepted that one possible mechanism for delivering water was the bombardment of water-bearing asteroids and comets when Earth as we know it today was much younger.
But new analyzes have been collected from the rocks the moon And being brought to Earth during the Apollo era suggests that this may not, in fact, be the case.
Instead, according to a team of researchers at Lawrence Livermore National Laboratory, the most likely explanation is that the Earth was formed by its water. In other words, he was here the whole time.
“Earth was either born with the water we had, or we were struck by something that was essentially pure H2Oh, with nothing else in it, Cosmic chemist Greg Brenica explains from LLNL.
“This work eliminates meteorites or asteroids as potential sources of water on Earth and points strongly toward the ‘born with it’ option.”
The Moon may seem a strange place to look for Earth’s water. It is dusty, dry and not wet at all.
As it turns out, the Moon is a great place to study Earth’s history. The Moon was formed when there were two massive bodies – one the size of Marsand the other a little smaller than ours – bump into each other and turn into points that will become the Earth and the Moon.
Earth’s memory of this event has weathered over time, but because there are no lunar plate tectonics or weather, geological evidence is not eroded in the same way.
This does not mean that there are absolutely no processes there. Impacts from other bodies and past volcanic activity can alter the surface of the Moon. However, there are some samples in Apollo group which is relatively unchanged.
Now, according to The Giant Impact HypothesisThis giant crash 4.5 billion years ago depleted the Earth and Moon of volatile matter.
That is why, under this model, the moon is very dry; Compared to other bodies in the solar system that contain water, Most of the Earth is very dry tooespecially when you take its size into account.
To understand the history of the Earth-Moon system before the giant collision, the team looked at three lunar samples that crystallized 4.3 to 4.35 billion years ago, and examined two isotopes: the volatile isotope and the radioactive isotope rubidium-87 (87Rb) and the isotope in which it decays, strontium-87 (87SR).
The latter in particular is thought to be a good proxy for understanding the moon’s long-term fluctuating budget, and the relative abundance of moderately volatile elements, such as rubidium, reflects the behavior of more volatile species, such as water.
Interestingly, the team’s analysis revealed that there are very few 87Father in the Earth-Moon system, even before the giant collision. This indicates that both the proto-Earth and the collision, Theia, were severely depleted in volatile elements, suggesting that the volatile depletion was not the result of the gigantic impact after all.
This means that the various fluctuating distributions on Earth and the Moon are inherited from Earth and Theia, which may explain why Earth is so moist. It also suggests that both bodies may have been in the same general region of the Solar System, rather than Theia forming far away and migrating inland, and that the impact could not have occurred before 4.45 million years ago.
Although this challenges some accepted views about the composition of the Earth and the Moon, it accurately explains the origins of volatiles in the Earth-Moon system, the researchers say. Explains the differences in their volatile ratios, and explains the similarities in isotope ratios.
“There were only a few types of materials that could combine to form the Earth and the Moon, and they weren’t strange,” Cosmic chemist Lars Burg explains from LLNL.
“It’s possible that both were just large bodies that formed in roughly the same region that just happened to smash into each other a little over 100 million years after the solar system was formed…but fortunately for us, they did exactly that.”
The search was published in PNAS.
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