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TOPIC: The Earth


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RE: The Earth
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Japan Aerospace Exploration Agency (JAXA) and NHK (Japan Broadcasting Corporation) have successfully taken high definition moving images through the KAGUYA (SELENE) for the first time. The KAGUYA is a lunar explorer launched on September 14 (Japan Standard Time, JST) from the Tanegashima Space Centre.
The images were taken by the KAGUYA's onboard High Definition Television (HDTV), which was developed by NHK for space use. It is the first high-definition image shooting of the Earth from so deep in space - about 110,000 km away from the Earth - in human history. The moving image data acquired by the KAGUYA was received at the JAXA Usuda Deep Space Centre, then processed at NHK.

KAGUYASept1407
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These spectacular images are the most detailed true colour pictures of the Earth that we have ever seen.
The clear images, released by NASA, were pieced together from observations taken from a satellite of the land surface, oceans, sea ice and clouds.

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The Queen Maud block
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Researchers exploring a remote terrain in Arctic Canada have made discoveries that may rock the world of Canadian geology.
Geologists from the University of Alberta have found that portions of Canada collided a minimum of 500 million years earlier than previously thought. Their research, published in the American journal Geology, is offering new insight into how the different continental fragments of North America assembled billions of years ago.
Lead researcher Michael Schultz, a graduate student at the U of A, took advantage of a rare opportunity to explore the Queen Maud block of Arctic Canada, a large bedrock terrain that is said to occupy a keystone tectonic position in Northern Canada.
Because of its remote location, the Queen Maud block has remained understudied. Until now.

In terms of trying to figure out how Canada formed, this block held a lot of secrets - Michael Schultz.

The University of Alberta team reached the rugged Northern Canadian location in helicopters and discoveredthrough field work and lab analysisthat the sedimentary basins within the terrain, and the age and timing of high-temperature metamorphism of the rocks found there, challenged previous models.

Every time we did an analysis, it gave us a new piece of information that was nothing we were expecting, based on what was known in the geological community - Michael Schultz.

Schultz credits cutting-edge technology only recently developed in the department of Earth and Atmospheric Sciences at the University of Alberta with the ability to acquire large amounts of data from rocks of the Queen Maud block in record time. The technique, known as in-situ laser ablation, substantially reduces the preparation time for geochronology, the process of dating rocks and minerals.
As the Canadian Arctic starts to gain attention nationally and globally, Schultz believes the time is right to push for more geological exploration in the region.

All this newly discovered geological information means that large portions of Northern Canada are still very poorly understood, and in fact may contain rocks that nobody knows about. This has many implications, both academically and for mineral resources. Given the remote nature of these areas, investigation has to be initiated and funded by federal, provincial or territorial governments, and in cooperation with universities for facilities and additional expertise - Michael Schultz.

University of Alberta

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Earth's Orbit Eccentricity Precession, Last Million Years

[youtube=http://youtube.com/watch?v=hajMQpLv-YA]

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Earth's Orbit Inclination Precession, Last Million Years

[youtube=http://youtube.com/watch?v=HTSMdv8dxHQ]

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The Earth is smaller than assumed
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New measurements show a difference of several millimetres / Geodesists from the University of Bonn participated     
Although the discrepancy is not large, it is significant: Geodesists from the University of Bonn have remeasured the size of the Earth in a long lasting international cooperation project. The blue planet is accordingly some millimetres smaller than up to now assumed. The results are important, for example, to be able to demonstrate a climate contingent rise in sea level. The results have now appeared in the renowned Journal of Geodesy.
The system of measurement used by the Bonn Geodesists is invisible. It consists of radio waves that are transmitted into space from punctiform sources, the so-called Quasars. A network of more than 70 radio telescopes worldwide receives these waves. Because the gauging stations are so far apart from each other, the radio signals are received with a slight time-lag.

"From this difference we can measure the distance between the radio telescopes - and to the preciseness of two millimetres per 1,000 kilometres" - Dr. Axel Nothnagel, research group leader for the Geodesy Institute of the University of Bonn.

The procedure is called VLBI, which stands for "Very Long Baseline Interferometry." The technique can be used, for example, to demonstrate that Europe and North America are distancing from each other at a rate of about 18 millimetres annually. The distance of the gauging stations from each other allows the  size of the Earth or the exact location of the centre of the Earth to be determined.

"We have analysed the measurements and calculations from 34 partners in 17 countries. A combination of GPS and satellite laser measurements will enable the availability of the coordinates from almost 400 points on the surface of the Earth with unparalleled exactness" - Dr. Axel Nothnagel.

The results are the basis for a new coordinate system for the planet. With this system it would be possible, for example, to determine the track of so-called Altimeter-Satellites within a few millimetres precision. Altimeter-Satellites measure their altitude over the Earth's surface and can, for example, register a rise in sea level. Deviations from the flight path, however, falsify the result. If the satellite flies higher than expected, the distance to the surface of the Earth differentiates from what is recorded - the sea level appears lower than it really is.

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Research comparing silicon samples from Earth, meteorites and planetary materials, published in Nature (28th June 2007), provides new evidence that the Earth's core formed under very different conditions from those that existed on Mars. It also shows that the Earth and the Moon have the same silicon isotopic composition supporting the theory that atoms from the two mixed in the early stages of their development.

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The Earth's crust
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 If it weren't for the hot rocks down below Earth's crust, most of North America would be below sea level, report researchers who say the significance of Earth's internal heat has been overlooked.
Without it, mile-high Denver would be 727 feet below sea level, the scientists calculate, and New York City, more than a quarter-mile below. Los Angeles would be almost three-quarters of a mile beneath the Pacific.
In fact most of the United States would disappear, except for some major Western mountain ranges, according to research at the University of Utah.

"Researchers have failed to appreciate how heat makes rock in the continental crust and upper mantle expand to become less dense and more buoyant" - Derrick Hasterok, a graduate student in geology and geophysics.

Hasterok and his professor, David Chapman, published their findings in the June online issue of Journal of Geophysical Research-Solid Earth.
In what they said was the first calculation of its kind, the researchers said heat inside the planet accounts for half the reason land rises above sea level or higher to form mountains.
Scientists previously gave other factors greater weight in explaining elevation differences, such as the density and makeup of rocks and tectonic forces.
The Utah team calculated how much of North America would sink if the engine of heat was taken away, leaving regions as relatively cold as the bottom of the vast Canadian shield - bedrock that hasn't changed for billions of years.

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RE: The Earth’s core
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New studies show that iron, the principal constituent of the innermost parts of the earths core, becomes unusually soft at the extreme pressures and temperatures that prevail there. The findings, now being published in Science, enhance our possibility of understanding the innermost parts of the earth and how earthquakes occur, for example. In a more immediate perspective, scientists will have new tools for developing better materials.
The findings were attained by a team of Swedish and Russian researchers, who used advanced simulations on Swedish supercomputers. This new knowledge explains some of the seismic data­-signals from earth tremors­-that stations around the world gather and that have puzzled scientists until now.

These new discoveries about the innermost part of the earth provide an explanation for the low velocity of the seismic waves deep down in the earth. They explain, in turn, why signals from earth tremors look like they do, thereby facilitating the work of seismologists - Anatoly Belonoshko at the Royal Institute of Technology in Stockholm, who directed the studies.

The innermost core of the earth, which consists of highly compressed iron in a solid state, is known to have an extremely low degree of rigidity in regard to shear­-the impact of twisting or other forces. The iron at the centre of the earth therefore behaves largely like a fluid, which lacks all resistance to shear, making it easy for shifts to take place in the matter in the earths core. One consequence is that the seismic waves that move along the surface of the inner core move unexpectedly slowly.

Besides providing an entirely new potential for understanding a number of mysterious phenomena associated with the low velocity of the movement of these seismic waves, the methods we are using to explain the softness of the earths core can also be applied to materials science - Anatoly Belonoshko.

This dual nature of iron has been an enigma to researchers for more than 50 years, since iron in laboratory experiments has not evinced any tendency whatsoever to behave like a fluid under high pressure. The reason for this is the much lower temperatures in laboratory experiments compared with the centre of the earth.
The solution to the riddle of this soft iron lies in the how the iron atoms are arranged and can move under the conditions that prevail in the inner parts of the earth. The conditions can be likened to a solid structure in which the parts, instead of being nailed to each other, are fastened together with rubber bands. This makes it extremely easy for certain parts to shift in relation to each other.
A more scientific description is that the iron at the centre of the earth cannot be depicted as an average of single crystalline iron. Instead, it is a so-called polycrystalline material with liquid-like granule edges and masses of defects in the structure. Anatoly Belonoshko, in collaboration with his colleagues Natalia Skorodumova and Anders Rosengren, has been able to show that an external disturbance like shear is rapidly mitigated by a migration of atoms and a gliding of the liquid-like granule edges.
The study shows that traditional methods of mineral physics are valid, despite the unexpected behaviour of iron in the earths core, and that what is key to an enhanced understanding of the core of the earth is to be able to recreate the conditions there with great accuracy. A challenge for scientists is to further develop a new way to calculate the elastic properties of various materials at high temperatures.

The methods we use help us understand, and thereby describe and predict, properties of materials at high temperatures. This opens new avenues for the theoretical, and in the long term practical, construction of new materials - Anatoly Belonoshko.

The simulations were possible to perform with the help of the most powerful Swedish supercomputers, situated at the Centre for Parallel Computers (PDC) at the Royal Institute of Technology in Stockholm and the National Supercomputer Centre (NSC) in Linköping.

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