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Mystery of Our Moon's Ancient Dynamo--"Generated a Powerful Magnetic Field 3.6 Billion Years Ago" (Weekend Feature)

 

 

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Exactly what powered the dynamo remains a mystery. One possibility is that the lunar dynamo was self-sustaining, like Earth’s: As the planet has cooled, its liquid core has moved in response, sustaining the dynamo and the magnetic field it produces. In the absence of a long-lived heat supply, most planetary bodies will cool within hundreds of millions of years of formation.

MIT's research on an ancient lunar rock in 2011 suggested that the moon harbored the long-lived dynamo — a molten, convecting core of liquid metal that generated a strong magnetic field 3.56 billion years ago. The findings point to a dynamo that lasted much longer than scientists previously thought, and suggest that an alternative energy source may have powered the dynamo.

The magnetic field existed until at least 3.56 billion years ago, an MIT study suggests — about 160 million years longer than scientists had thought. “It seems like the lunar dynamo lasted very late in the Moon’s history,” says Benjamin Weiss, a palaeomagnetics expert at the Massachusetts Institute of Technology (MIT) in Cambridge. “That’s a very surprising result.” Weiss and his colleagues, led by MIT planetary scientist Clément Suavet, report the findings today in the Proceedings of the National Academy of Sciences1.

“The moon has this protracted history that’s surprising,” says Weiss, an associate professor of planetary science at MIT. “This provides evidence of a fundamentally new way of making a magnetic field in a planet a new power source.”

 

                                      

 

The MIT paper is the latest piece in a puzzle that planetary scientists have been working out for decades. In 1969, the Apollo 11 mission brought the first lunar rocks back to Earth — souvenirs from Neil Armstrong and Buzz Aldrin’s historic moonwalk. Since then, scientists have probed the rocky remnants for clues to the moon’s history. They soon discovered that many rocks were magnetized, which suggested that the moon was more than a cold, undifferentiated pile of space rubble. Instead, it may have harbored a convecting metallic core that produced a large magnetic field, recorded in the moon’s rocks.

A dynamo still exists within Earth because heat, produced by the radioactive decay of elements within the planet, maintains the core’s convection. Models have shown that if a lunar dynamo were powered solely by cooling of the moon’s interior, it would have been able to sustain itself only for a few hundred million years after the moon formed — dissipating by 4.2 billion years ago, at the very latest.

However, Weiss and his colleagues found some surprising evidence in a bit of lunar basalt dubbed 10020. The Apollo 11 astronauts collected the rock at the southwestern edge of the Sea of Tranquility; scientists believe it was likely ejected from deep within the moon 100 million years ago, after a meteor impact. The group confirmed previous work dating the rock at 3.7 billion years old, and found that it was magnetized — a finding that clashes with current dynamo models.

Weiss collaborated with researchers at the University of California at Berkeley and the Berkeley Geochronology Center, who determined the rock’s age using radiometric dating. After a rock forms, a radioactive potassium isotope decays to a stable argon isotope at a known rate. The group measured the ratio of potassium to argon in a small piece of the rock, using this information to ascertain that the rock cooled from magma 3.7 billion years ago.

Weiss and graduate student Erin Shea then measured the rock’s magnetization, and found that the rock was magnetized. However, this didn’t necessarily mean that the rock, and the moon, had a dynamo-generated magnetic field 3.7 billion years ago: Subsequent impacts may have heated the rock and reset its magnetization.

To discard this possibility, the team examined whether the rock experienced any significant heating since its ejection onto the moon’s surface. Again, they looked to isotopes of potassium and argon, finding that the only heating the rock had experienced since it was ejected onto the lunar surface came from simple exposure to the sun’s rays.

“It’s basically been in cold storage for 3.7 billion years, essentially undisturbed,” Weiss says. “It retains a beautiful magnetization record.”

Weiss says the rock’s evidence supports a new mechanism of dynamo generation that was proposed by scientists at University of California at Santa Cruz (UCSC). This hypothesis posits that the moon’s dynamo may have been powered by Earth’s gravitational pull. Billions of years ago, the moon was much closer to Earth than it is today; terrestrial gravity may have had a stirring effect within the moon’s core, keeping the liquid metal moving even after the lunar body had cooled.

Francis Nimmo, a professor of earth and planetary sciences at UCSC and one of the researchers who originally put forth the new dynamo theory, says Weiss’ evidence provides scientists with a new picture of the moon’s evolution.

“We generally assume that cooling is the main mechanism for driving a dynamo anywhere,” says Nimmo, who was not involved in the study. “This lunar data is telling us that other mechanisms may also play a role, not just at the moon, but elsewhere, too.”

The Daily Galaxy via Massachusetts Institute of Technology and nature.com

Comments

This is bogus article because he main stream scientific community knows full well the moon is hollowed out. 3 separations missions of slamming high speed objects prove the moon rings like a bell when it shouldn't be doing that at all.
They also cannot explain why the moon is the only object in our entire solar system that doe not spin on it's axis. How is it that our moon all pull the earths' water twice a day and yet given the earths' pull is 4 times greater it still can't pull the moon on it's axis 1 single inch?

And why is the USA refusing to reveal where the 400 kilos of moon rocks are to Russia and other countries who wish to study them?
What is on the backside of our moon that others don't want revealed? Why are 1 million photos of Clemetine mission missing for study?

you are a idiot, the does not spin because it is tidally locked to earth. same goes for the planet mercury is locked to the sun. and we have seen the back side of the moon, you need to get help or get off the drugs !

You guys are both wrong. The moon is only a few thousand years old as this is when God created the earth, sun, moon, and stars. No Planets. Even the earth is not a planet, but a flat plane. When you talk millions of years or millions of miles, no one can prove that, it's all theory. You can find out more at ItsHisStory.com/globe

I thoroughly enjoyed this comment thread.

The Earth is flat and the moon is a giant simulation complete with raster lines...

They assume and theorize because they have no proof of what 'science' tells as true. All lies of the 'science religion' take millions of years to prove but no one lives for millions of years to disprove them. They claim evolution but can't prove it as everything exists without any evidence of evolving and nothing today is evolving! The earth is flat and un-moving and 'outer space' is faked by the 'science cult' telling you you are insignificant when in reality you are a unique being created for the pleasure of God. There is no truth in science, as even their math lies, and they don't tell you of the 'golden ratio' that is the math of creation, in everything including the 'design' of humanity!

As soon as I saw the number of comments I knew the crazy gang had beaten us to to my friends.
I will leave the rebuttal to you.
Oh dear me...................................

The stupid crew came by early on this one..

Darwinism.. You sure do take a long time to kick in.

Why does John Stewart keep throwing religion at a science publication. The only thing to do is ban him, since we all know that "ya can't fix stupid!"

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