Featured: The Super Moon of May 5_ 2012

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From: ThePresident
Super moon appeared Saturday May 5 2012, 11:54PM Eastern Time. A "supermoon" is the coincidence of a full moon (or a new moon) with the closest approach the Moon makes to the Earth on its elliptical orbit, or perigee, leading to the technical name for a supermoon of the perigee-syzygy of the Earth-Moon-Sun system. The association of the Moon with both oceanic and crustal tides has led to claims that the supermoon phenomenon may be associated with increased risk of events such as earthquakes and volcanic eruptions. However, the evidence of such a link is widely held to be unconvincing. The Moon's distance varies each month between approximately 357,000 kilometers (222,000 mi) and 406,000 km (252,000 mi) due to its elliptical orbit around the Earth (distances given are center-to-center). The size and brightness of an object follows an inverse-square law, which means that a full moon at perigee is 12% larger and brighter than an average full moon. However, because the offset of the moon's orbit versus its phases is only two days, this change in appearance is gradual from month to month and therefore is not usually noticeable to a casual observer. Richard Nolle has argued that within ±3 days of a supermoon, the Earth is more subject to natural disasters such as earthquakes and volcanic activity due to the Moon's increased gravitational force.[5] Speculations have moved the goalposts to within 1 or 2 weeks of a supermoon to suggest a causal relationship with specific natural disasters such as the 2011 Tōhoku earthquake and tsunami and the 2004 Indian Ocean earthquake and tsunami.[9][10] Such a widening of the effect window is unjustified as in both cases the Moon was farther from the Earth than average, making a supermoon effect impossible.[3] Some studies have reported a weak correlation between lunar activity and shallow, very low intensity earthquakes. However, no evidence has been found of any correlation with major earthquakes.[11][12][13] Unjustified claims that the lunar tides trigger earthquakes are rooted in a lack of appreciation that the stress in the Earth is described by a tensor with six independent parameters and that earthquakes occur as slip on existing, weak fault planes. Any change in stress, by lunar tides, by impounding a reservoir, or by a large nearby earthquake, changes the local stress tensor in specific directions. If one wishes to estimate whether a given change advances or hinders slip on a fault, one has to know the orientation of the fault. It is equally likely that the change of the stress due to the moon clamps the fault shut, rather than advancing slip on it. This is why Ohtake[14] has carefully considered the orientation of the fault planes in earthquakes that he showed were correlated with lunar tides. The 2011 Tōhoku earthquake and tsunami is the only earthquake of 8.0 magnitude or greater to have occurred within 2 weeks of the 14 extreme supermoons from 1900 to the present date,[15][16][17] suggesting that the claim of a supermoon effect on the incidence of large-scale earthquakes is unjustified. http://en.wikipedia.org/wiki/Supermoon Another "super-Moon" is in the offing. The perigee full Moon in May will be as much as 14% bigger and 30% brighter than other full moons of 2012. Published on Mar 9, 2012 by ScienceAtNASA. Visit http://science.nasa.gov/ for more.
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