Spectacular force: A georeactor deep in the ancient Earth's D''-layer (dark orange layer near core) goes supercritical - suddenly increasing temperatures to 13,000ºC. This turns rock into vapour, creating a rising bubble which pushes mantle, crust and atmosphere into space in a giant eruption.
Credit: Theo Barten
One of the purposes of the Apollo missions was to gain more insight into the origin of the Moon and to help arbitrate between the two remaining hypotheses. But an analysis of the Moon samples brought back to Earth led to the conclusion that neither hypothesis could be correct.
"The density of the Moon turned out to be much lower than the Earth's density," says van Westrenen. "That excludes the accretion model, which says that the Earth and the Moon were formed from the same primordial material. [They] are simply too different."
Paradoxically, the second hypothesis – that the Moon was formed elsewhere in the Solar System and later captured – was excluded for exactly the opposite reason.
"In that respect, the Earth and the Moon are too similar," adds van Westrenen. "The ratio of isotopes oxygen-17 and oxygen-18 are identical in terrestrial and lunar rock, and deviates strongly from the isotope ratio in meteorites from Mars." These isotopes carry information about the distance from the Sun the rock formed, and indicate that the Moon and Earth must have formed at roughly the same distance.
Short of providing answers, the Moon missions generated many more questions. Some researchers then moved on to study other things, convinced that there wasn't enough data to solve the mystery. It was in this theoretical vacuum, in the mid-1970s, that two groups independently formulated a new idea: the impact hypothesis.
According to Bill Hartmann and Donald Davis of the Planetary Science Institute in Tucson, Arizona, and Alastair Cameron and William Ward of Harvard University in Boston, a cosmic object dubbed Theia (the mother of the Moon in Greek mythology), collided with the primordial Earth and created the Moon.
Van Westrenen himself signed up wholeheartedly to this hypothesis. "At first, the impact hypothesis seemed to solve all our problems," he says. "It gives you an Earth and Moon with the correct size, in the correct orbit."
A quarter of a century later, though, things have changed. In particular, computer simulations of the impact have become more advanced and detailed. And in turn, they have generated new mysteries.
It appears, for instance, that the impact needs fine-tuning to fit the data. "It can't have been a head-on collision," says van Westrenen. "It must have been a glancing collision with a moderate relative velocity. Any deviation in these parameters, and things go wrong; you knock the Earth apart or you don't end up with a Moon, because the debris will take off in all directions."
But the main puzzle that came from the simulations – detailed in the British journal Nature in 2003 – was that 'successful' impacts produce a Moon of about 80 per cent mantle material from the impactor.
"If the Moon is mainly made of impactor material, than it is much less likely that the ratio of oxygen isotopes for Moon and Earth would be the same," says van Westrenen. "That is only possible if the Earth and Theia were formed at the same distance from the Sun, which means that they have been chasing each other in more or less the same orbit until they collided."
The problem is that we don't see anything like that elsewhere in the entire Solar System. At the University of Arizona in Tucson, planetary scientist Jay Melosh is one of the proponents of the impact theory.
"The similarities do suggest that the proto-Earth and its impactor were formed at almost the same distance from the Sun. But that is not such a crazy idea," he argues. "The object must have been close to Earth, simply because it did impact, while other embryonic planets did not."
Robin Canup, from the Southwest Research Institute in Boulder, Colorado, and author of the 2003 Nature paper, agrees with Melosh: "We calculated the conditions for the impact velocity. This indicates that the impactor originated somewhere between the present orbits of Mars and Venus." That is, somewhere near the orbit of the Earth.
Birth of the Moon: a runaway nuclear reaction?
I read a rather instersting article about how writers approach stories regarding new scientific theories. And reading this article it struck me just how true there was in that article.
Once again, the guy with the new theory, in this case Rob de Meijer and his coleague, is being painted as mavericks. He is trying to attain legitimate consideration for his "radical" new theory. He has an uphill battle against the well established theories of his peers and they will do everything they can to debunk him and his ridiculous theory.
Well for one thing, why don't you let your readers decide for themselves whether a theory is outlandish.
Also, debunking theories, new or old is how science works. Theories are supposed to be able to stand up to scrutiny. Eventually, the evidence will either lend credence to or disprove the theory.
Not A 'Maverick' story in my world
From my read of the article, we have a scientist who has an interesting new idea about the moons formation that, if it proves to be viable, might explain some anomalies in the system, relative to the other popular explanations.
I don't see any "people are trying to suppress me" whining. I just see someone with a fledgling theory that seems properly (dis)provable and he's trying to put together an experiment that would properly put his theory to a test.
If he manages to build his anti-neutrino detector, I'd like to see what results it generates. Among other things, I'm curious about it detecting antineutrinos that are unrelated to either georeactors or human-built reactors -- and what that might expose about the universe around us.
THE MOON
IT SEEMS TO ME THAT THE MOON WAS CREATED IN A COLLISION. IT MAY NOT BE TRUTH. THE MOON WAS CREATED AT THE SAME TIME AS THE EARTH. IT NEED TO BE SUPER HOT TO FORM THE CIRCLE. IS LIKE A DROP OF WATER WHEN IT FALLS IT MAKES A PERFECT CIRCLE, BECAUSED OF THE GRAVITY. SO IF A COLLISION OCCURED THE MOON WOULD NOT BE IN A PERFECT SHAPE THAT IS NOW. IT WILL BE LIKE THE ASTEROIDS WITH NO FIGURE IN SHAPE. MAGMA ONCE IS COLD WILL DO DIFRENT SHAPES. BUT WHEN IS HOT AND CONTINUES TO BE HOT WILL FORM A PERFECT CIRCLE ONCE YOU DROP IT IN THE AIR. WILL FORM A PERFECT CIRCLE. AS THE MOON NEED TO SUPER HOT TO BE IN THE SHAPE THAT IS NOW.
Energy calculation
"....a one gigawatt nuclear reactor generates just 1017 joules a year.."
I guess this is probably meant to read "3 x 10^16 joules a year"
Calculations
Similarly " ...so you'd need the annual energy production of 1013 of these reactors to get the same amount."
I guess this should read "10^13".
Error in typography
On p5 of this article, surely the phrase "a one gigawatt nuclear reactor generates just 1017 joules a year," should read "a one gigawatt nuclear reactor generates just 10^17 joules a year,"
Errors fixed
Thank you, dear readers. Sometimes superscripting drops off in translations to the web, unless we keep out an eagle eye. All fixed now!
Wilson da Silva
Editor-in-Chief
page 5 (& printable) still broken.
page 5 (& printable) still broken.
The superscript tag isn't closed, so some text is missing and everything after it is in superscript.
You have (using the wrong brackets so they don't get exec'd):
[sup] 13[/su
where you need
[sup]13[/sup]
page 5 (& printable) still broken.
page 5 (& printable) still broken.
The superscript tag isn't closed, so some text is missing and everything after it is in superscript.
You have (using the wrong brackets so they don't get exec'd):
[sup] 13[/su
where you need
[sup]13[/sup]
I agree with the other visitor
Yes! Please fix your html so we don't need to view source to see the end of a sentence.
Also, and I ask so many media outlets to do this, put an e-mail address on your contact page specifically for typos, wrong information, etc, so we don't just post comments you're likely to not read often!