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From NASA's Scientific Visualization Studio. New images from NASA's Luna...
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From NASA's Scientific Visualization Studio. New images from NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft show the moon's crust is being stretched, forming minute valleys in a few small areas on the lunar surface. Scientists propose this geologic activity occurred less than 50 million years ago, which is considered recent compared to the moon's age of more than 4.5 billion years.
A team of researchers analyzing high-resolution images obtained by the Lunar Reconnaissance Orbiter Camera (LROC) show small, narrow trenches typically much longer than they are wide. This indicates the lunar crust is being pulled apart at these locations. These linear valleys, known as graben, form when the moon's crust stretches, breaks and drops down along two bounding faults. A handful of these graben systems have been found across the lunar surface.
We think the moon is in a general state of global contraction because of cooling of a still hot interior," said Thomas Watters of the Center for Earth and Planetary Studies at the Smithsonian's National Air and Space Museum in Washington, and lead author of a paper on this research appearing in the March issue of the journal Nature Geoscience. "The graben tell us forces acting to shrink the moon were overcome in places by forces acting to pull it apart. This means the contractional forces shrinking the moon cannot be large, or the small graben might never form."
The weak contraction suggests that the moon, unlike the terrestrial planets, did not completely melt in the very early stages of its evolution. Rather, observations support an alternative view that only the moon's exterior initially melted forming an ocean of molten rock.
In August 2010, the team used LROC images to identify physical signs of contraction on the lunar surface, in the form of lobe-shaped cliffs known as lobate scarps. The scarps are evidence the moon shrank globally in the geologically recent past and might still be shrinking today. The team saw these scarps widely distributed across the moon and concluded it was shrinking as the interior slowly cooled.
Based on the size of the scarps, it is estimated that the distance between the moon's center and its surface shank by approximately 300 feet. The graben were an unexpected discovery and the images provide contradictory evidence that the regions of the lunar crust are also being pulled apart.
"This pulling apart tells us the moon is still active," said Richard Vondrak, LRO Project Scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "LRO gives us a detailed look at that process."
As the LRO mission progresses and coverage increases, scientists will have a better picture of how common these young graben are and what other types of tectonic features are nearby. The graben systems the team finds may help scientists refine the state of stress in the lunar crust.
"It was a big surprise when I spotted graben in the far side highlands," said co-author Mark Robinson of the School of Earth and Space Exploration at Arizona State University, principal investigator of LROC. "I immediately targeted the area for high-resolution stereo images so we could create a three-dimensional view of the graben. It's exciting when you discover something totally unexpected and only about half the lunar surface has been imaged in high resolution. There is much more of the moon to be explored."
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Watch in 1080p as massive solar eruptions take aim at our high-tech soci...
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Watch in 1080p as massive solar eruptions take aim at our high-tech society. 93 million miles away... an angry sun vents its rage. Dark regions, called sunspots, appeared unexpectedly on its surface... a sign of rising tension within. It had been three and a half years since the sun last erupted in fury...at the peak of an 11-year cycle of solar flare-ups.
Back then, we got ready for it... by shutting down satellites that were vulnerable to high levels of radiation. But no one expected this. In what should have been a low point in solar activity, the sun erupted in a series of massive explosions, called coronal mass ejections, or CMEs.
Electrified gas clouds weighing billions of tons raced outward. Solar telescopes recorded the action... The largest emission of solar x-rays ever seen. The hottest flares, at tens of millions of degrees. And the fastest... reaching speeds clocked at six million miles per hour.
The sun became a giant plasma weapon... more potent than any in science fiction... and pointed right at our home planet. On Earth... the Halloween storms produced some of the most spectacular auroras ever seen at the north and south poles. They also brought jolts of electricity that caused power outages in Sweden, and disrupted airline navigation.
In space, these storms damaged 28 communications satellites, and destroyed two. And they didn't stop there. As the energetic surge swept past Mars, it was so strong it burned out the radiation monitor aboard the spacecraft, Mars Global Surveyor. Ironically, this instrument was designed to study radiation that human explorers might encounter on future missions beyond Earth.
Months later, the rush of solar energy washed over the two Voyager spacecraft, on their way to the far reaches of the solar system. CMEs like these have been known to blast their way out the far edges of the solar system, where the solar wind meets the flow of gas around the galaxy itself.
This stormy season on the sun lasted about five weeks. It was by no means the worst. A solar eruption in 1859 was so powerful it set fire to telegraph offices... several people got nasty electric shocks, simply because they were working with metal objects... and for the next few nights, auroras were reportedly bright enough to read by.
A similar storm today could easily cause more than two trillion dollars in damage to our high-tech infrastructure, twenty times greater than hurricane Katrina. But believe it or not, the threat is about to get even worse. We are beginning to change the way we acquire and use energy... by expanding our power grid to accommodate wind farms...solar arrays... new nuclear plants ... and other renewable energy sources.
This grid will get larger... and smarter.... With microprocessors in most every device...communicating and negotiating with one another... running everything from air conditioners to power plants. A sudden surge of solar activity could strike the grid directly...inflicting a substantial amount of damage on the emerging smart power economy.
To understand what a powerful force the sun can be. Take a look at Venus. At almost exactly the same size and mass as Earth, it's truly our sister planet. The thinking is that long ago, fierce solar winds stripped off lighter water molecules from its upper atmosphere. What was left was a witches' brew of acidic gases and carbon dioxide that thickened at lower altitudes, rising to some 90 times the density of Earth's atmosphere.
At a concentration of 95% in Venus' atmosphere, CO2 gas trapped increasing amounts of sunlight and drove surface temperatures close to 1000 degrees Fahrenheit. How did Earth avoid such a harsh fate?
One of the main reasons is that our planet has what Venus lacks... a natural defense against solar attacks.
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RUSIA: Un terremoto magnitud 6.7 grados en la escala de Richter sacudió...
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RUSIA: Un terremoto magnitud 6.7 grados en la escala de Richter sacudió este domingo 26 de febrero 2012 el sudeste de Siberia sin causar víctimas ni daños materiales según informo ministerio ruso de Situaciones de Emergencia. El sismo se produjo a las 13:20 hora local en la republica de Tuva a unos 107 km de la ciudad de Kyzyl y el epicentro tubo una profundidad de 11.7 Km. El video que veremos fue filmado en la ciudad de Krasnoyarsk.
.Link video original
www.youtube.com/San1991G
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