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January 5, 2012
The tranquillityite, a rare mineral found on the moon, was discovered in rocks in Australia.
An ore brought back to Earth by the astronauts who went to the moon and that was long thought to be specific to the Moon, was found in old rocks from Australia more than a billion years, have scientists said Thursday.
Image above: Apollo 11 - Aldrin poses on the Moon, on landing site in the southern Sea of Tranquillity (Mare Tranquillitatis).
The tranquillityite is a mineral that is named after the place where it was found in 1969: Sea of Tranquility, a plain of basalt located on the moon.
This mineral has "long been regarded as a mineral unique to the moon," until geologists find samples in Western Australia, said Birger Rasmussen, an Australian scientist.
Caption: A microscopic image of a rock with red-brown tranquillityite crystals as well as brightly colored pyroxene crystals and grey-white-black feldspar crystals. Credit: Birger Rasmussen.
"He had never been found in other terrestrial samples" for over 40 years, told AFP the scientific, Curtin University, Perth (west).
"They did not come from the Moon"
Samples of the moon were considered "extremely valuable" and were subjected to very detailed amount of exams, when we were in fact "has always been under our noses," he noted.
"We have always been on Earth, they are not just coming from the moon," said the scientist, who published his research in the publication Geology. "This means that basically we have the same chemical phenomena and the same processes that occur on the Moon and on Earth."
The Moon
This mineral, rare, has so far been found in six different locations in Australia. Particular, it allows a precise dating of rocks that contain it, said Birger Rasmussen.
Which brings us back to the question: How these are formed the earth and the moon? There are three main theories:
Theory of fission
During the early youth of the Earth, it is still hot and soft, our planet would have turned fast enough on itself to flatten the globe and brings out by centrifugal force, part of its material . The ejected material would then remained trapped in the terrestrial gravitational field, and would have formed the Moon Lunar after cooling. This theory is contradicted by the nature of the chemical composition between the two stars, which is remarkably different, especially in the proportion of iron.
Theory of the simultaneous formation
During contraction of the gaseous material of proto planetary disk, the Moon and Earth were formed simultaneously and jointly from the same "lump" on earth. Always fanciful idea in terms of the difference in chemical composition of rocks ... Moreover, this theory is not able to account for the difference in size between the core proportional lunar and Earth's core.
Theory of collision
Fortunately, planetary scientists proposed in recent years a third scenario that seems to fit all the criteria: that of the collision.
How the Moon was born
This theory postulates that, very early in the history of the solar system, when Earth was still a malleable ball of molten rock, a planetoid the size of Mars collided with it. This hypothetical planet even has a name: Theia.
The violence of the shock would have removed a huge amount of matter in space, a significant part would have remained trapped in the gravitational field, the other beyond ever the power of attraction.
This material is entered into orbit rotation (according to the rotary motion of the Earth) and would be flattened disc-shaped, to form a ring of dust and rocks similar to those of Saturn's ring ... But this land would agglomerated in the space of just a few years, forming a spherical mass and warm, which on cooling became our Moon.
As for the planetoid responsible for the collision, it is thought that its nucleus would have largely been absorbed by the Earth's core and mantle, the rest going to form the core of the Moon.
This theory, supported by the analysis of samples of lunar rocks brought back during the Apollo missions, has also passed various simulations to estimate the age of the collision 42 million years after solar system formation.
The Moon is much lighter than the Earth, and indeed, the simulations show that it is the light elements of our planet that would have mostly been ejected into space and that would have been likely to form the Moon. The fact is that the Moon has the same minerals as the Earth, but in different proportions: The light elements are very present, very little heavy ...
In addition, at the time of the collision, the iron core of the Earth was already almost formed, which explains the very small proportion of iron in the Moon compared to that of Earth.
To date, all the differences and similarities between the composition of our planet and the Moon can be explained by that theory, so it's more accepted today. It explains how one side their elements have a common origin, while providing the reason for the difference in proportions between the two ... Finally, it explains why our planet is the only planet in the inner solar system to have a satellite if bulk.
Images, Videos, Text, Credits: NASA / Birger Rasmussen / AFP / Youtube / Wikipedia / Astrofiles.net / Orbiter.ch / Translation: Orbiter.ch.
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