* Astronomy

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RE: The Earth

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A new analysis of ancient minerals called zircons suggests that a harsh climate may have scoured and possibly even destroyed the surface of the Earth's earliest continents.
Zircons, the oldest known materials on Earth, offer a window in time back as far as 4.4 billion years ago, when the planet was a mere 150 million years old. Because these crystals are exceptionally resistant to chemical changes, they have become the gold standard for determining the age of ancient rocks.

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The Japan Aerospace Exploration Agency (JAXA) and NHK (Japan Broadcasting Corporation) successfully captured a movie of the "Full Earth-Rise"*1 using the onboard High Definition Television (HDTV) of the lunar explorer "KAGUYA " (SELENE) on April 6, 2008 (Japan Standard Time, JST, all the following dates and time are JST.) The KAGUYA is currently flying in a lunar orbit at an altitude of about 100 km.
An "Earth-rise," or the rising Earth over the Moon, was first captured by the Apollo project. The Earth rising image taken by the KAGUYA on November 7, 2007, was not a full Earth-rise (i.e. not all of the globe was seen in shining blue.) It missed some part. This time, a "full Earth-rise"*1 was taken by the onboard HDTV in faraway space, some 380,000 km away from the Earth. This is the world's first successful shooting of such a Full Earth-Rise. It was also very precious because it was one of only two chances in a year for the KAGUYA to capture a Full Earth-Rise when the orbits of the Moon, the Earth, the Sun and the KAGUYA are all lined up.

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A new global portrait by ESA (European Space Agency), taken from space, details Earths land cover with a resolution never before obtained.
Earths land cover has been charted from space before, but this map, which will be made available to the public upon its completion in July, has a resolution 10 times sharper than any of its predecessors.
The map is based on 20 Terabytes of imagery equivalent to the content of 20 million books acquired from May 2005 to April 2006 by Envisats Medium Resolution Imaging Spectrometer (MERIS) instrument.

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BBC The Blue Planet

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The future looks bright for the Earth but not in the way wed hoped. The slim chance our planet will survive when the Sun begins its death throes has been ruled out.
In a few billion years, the Sun will fuse the last of its hydrogen into helium, turn into a red giant and expand to 250 times its current size. At first, the Suns loss of mass will loosen its gravitational pull on Earth, which will allow the planet to migrate to a wider orbit about 7.6 billion years from now.

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New calculations by University of Sussex astronomers predict that the Earth will be swallowed up by the Sun in about 7.6 billion years unless the Earth's orbit can be altered.
Dr Robert Smith, Emeritus Reader in Astronomy, said his team previously calculated that the Earth would escape ultimate destruction, although be battered and burnt to a cinder. But this did not take into account the effect of the drag caused by the outer atmosphere of the dying Sun.

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The Earth's orbital behaviours are responsible for more than just presenting us with a leap year every four years. According to Michael E. Wysession, Ph.D., associate professor of earth and planetary sciences in Arts & Sciences at Washington University in St. Louis, parameters such as planetary gravitational attractions, the Earth's elliptical orbit around the sun and the degree of tilt of our planet's axis with respect to its path around the sun, have implications for climate change and the advent of ice ages.
People often think of orbits as circular, but they're not that smooth and simple. They are often a less-than-perfect eccentric circle.

"All planets travel in an ellipse around the sun, but the shape of that ellipse oscillates. When the Earth's orbit is more elliptical, the planet spends more time farther away from the sun, and the Earth gets less sunlight over the course of the year. These periods of more-elliptical orbits are separated by about 100,000 years. Ice ages occur about every 100,000 years, and they line up exactly with this change in the Earth's elliptical shape" - Michael E. Wysession, Ph.D.,

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Since we cant sample the deepest regions of the Earth, scientists watch the velocity of seismic waves as they travel through the planet to determine the composition and density of that material. Now a new study suggests that material in part of the lower mantle has unusual electronic characteristics that make sound propagate more slowly, suggesting that the material there is softer than previously thought. The results call into question the traditional techniques for understanding this region of the planet. The authors, including Alexander Goncharov from the Carnegie Institutions Geophysical Laboratory, present their results in the January 25, 2008, issue of Science.
The lower mantle extends from about 400 miles to 1800 miles (660-2900 kilometres) into Earth and sits atop the outer core. Pressures and temperatures are so brutal there that materials are changed into forms that dont exist in rocks at the planets surface and must be studied under carefully controlled conditions in the laboratory. The pressures range from 230,000 times the atmospheric pressure at sea level (23 GPa), to 1.35 million times sea-level pressure (135 GPa). And the heat is equally extremefrom about 2,800 to 6,700 degrees Fahrenheit (1800K4000K).
Iron is abundant in the Earth, and is a major component of the minerals ferropericlase and the silicate perovskite in the lower mantle. In previous work, researchers found that the outermost electrons of iron in ferropericlase are forced to pair up under the extreme pressures creating a so-called spin-transition zone within the lower mantle.

What happens when unpaired electronscalled a high-spin stateare forced to pair up is that they transition to what is called a low-spin state. And when that happens, the conductivity, density, and chemical properties change....Whats most important for seismology is the acoustic propertiesthe propagation of sound. We determined the elasticity of ferropericlase through the pressure-induced high-spin to low-spin transition. We did this by measuring the velocity of acoustic waves propagating in different directions in a single crystal of the material and found that over an extended pressure range (from about 395,000 to 590,000 atmospheres) the material became softerthat is, the waves slowed down more than expected from previous work. Thus, at high temperature corresponding distributions will become very broad, which will result in a wide range of depth having subtly anomalous properties that perhaps extend through most of the lower mantle - Alexander Goncharov.

The results suggest that scientists may have to go back to the drawing board to model this region of the Earth.

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The Anthropocene