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Welcome to Everything Science
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Everything Earth Science
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Written by Everything Science
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Jul 19, 2009 at 12:00 AM |
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Establishing a key link between the solar cycle and global climate, research led by scientists at the National Science Foundation (NSF)-funded National Center for Atmospheric Research (NCAR) in Boulder, Colo., shows that maximum solar activity and its aftermath have impacts on Earth that resemble La Niña and El Niño events in the tropical Pacific Ocean.
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Scientists find link between solar cycle and global climate similar to El Nino/La Nina.
Credit: NCAR
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The research may pave the way toward predictions of temperature and precipitation patterns at certain times during the approximately 11-year solar cycle.
"These results are striking in that they point to a scientifically feasible series of events that link the 11-year solar cycle with ENSO, the tropical Pacific phenomenon that so strongly influences climate variability around the world," says Jay Fein, program director in NSF's Division of Atmospheric Sciences. "The next step is to confirm or dispute these intriguing model results with observational data analyses and targeted new observations."
The total energy reaching Earth from the sun varies by only 0.1 percent across the solar cycle. Scientists have sought for decades to link these ups and downs to natural weather and climate variations and distinguish their subtle effects from the larger pattern of human-caused global warming.
Building on previous work, the NCAR researchers used computer models of global climate and more than a century of ocean temperature to answer longstanding questions about the connection between solar activity and global climate.
The research, published this month in a paper in the Journal of Climate, was funded by NSF, NCAR's sponsor, and by the U.S. Department of Energy.
"We have fleshed out the effects of a new mechanism to understand what happens in the tropical Pacific when there is a maximum of solar activity," says NCAR scientist Gerald Meehl, the paper's lead author. "When the sun's output peaks, it has far-ranging and often subtle impacts on tropical precipitation and on weather systems around much of the world." |
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Everything Space
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Written by Everything Science
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Jul 17, 2009 at 12:00 AM |
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The imaging system on board NASA's Lunar Reconnaissance Orbiter (LRO) recently had its first of many opportunities to photograph the Apollo landing sites. The Lunar Reconnaissance Orbiter Camera (LROC) imaged five of the six Apollo sites with the narrow angle cameras (NACs) between July 11 and 15, within days of the 40th anniversary of the Apollo 11 mission.
The early images obtained by LROC, operated by Arizona State University Professor Mark Robinson, show the lunar module descent stages left behind by the departing astronauts. Their locations are made evident by their long shadows, which result from a low sun angle at the time of collection.
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| The Apollo 14 lunar module (LM Antares) and the Apollo Lunar Surface Experiment Package are visible in this image (note the astronaut tracks between the two artifacts). At the current altitude and lighting the descent stage is clearly visible with its angular shadow (right) and shadow cast by leg (near arrow tip). The LROC NAC image data has not been calibrated, the faint vertical stripes are a natural part of the image and will be removed later after the full suite of calibration data is collected during the commissioning phase.
Credit: NASA/GSFC/Arizona State university
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"In a three-day period we were able to image five of the six Apollo sites – the LROC team anxiously awaited each image," says LROC Principal Investigator Mark Robinson, professor in the School of Earth and Space Exploration in ASU's College of Liberal Arts and Sciences. "Of course we were very interested to get our first peek at the lunar module descent stages just for the thrill – and to see how well the cameras had come into focus."
For additional information about the LROC instrument and to view the first Apollo landing site images, visit: http://lroc.sese.asu.edu.
The orbiter's current elliptical orbit resulted in image resolutions from the NACs that were slightly different for each site but were all about four feet per pixel. Since the deck of the descent stage is about 14 feet in diameter, the Apollo relics themselves fill about four pixels. However, because the Sun was low to the horizon when the images were acquired, even subtle variations in topography create long shadows. Standing just over ten feet above the surface, each Apollo descent stage creates a distinct shadow that fills roughly 20 pixels. |
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Everything Space
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Written by Everything Science
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Jul 15, 2009 at 12:00 AM |
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Many of the objects found today in the asteroid belt located between the orbits of Mars and Jupiter may have formed in the outermost reaches of the solar system, according to an international team of astronomers led by scientists from Southwest Research Institute (SwRI).
The team used numerical simulations to show that some comet-like objects residing in a disk outside the original orbit of the planets were scattered across the solar system and into the outer asteroid belt during a violent phase of planetary evolution.
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| Researchers collected this micrometeorite in the vicinity of CONCORDIA station in central Antarctica (Dome C, 73°S, 123°E).
Credit: CSNSM-Orsay-CNRS / IPEV
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Usually, the solar system is considered a place of relative permanence, with changes occurring gradually over hundreds of millions to billions of years. New models of planet formation indicate, however, that at specific times, the architecture of the solar system experienced dramatic upheaval.
In particular, it now seems probable that approximately 3.9 billion years ago, the giant planets of our solar system -- Jupiter, Saturn, Uranus and Neptune -- rearranged themselves in a tumultuous spasm. "This last major event of planet formation appears to have affected nearly every nook and cranny of the solar system," says lead author Dr. Hal Levison of SwRI.
Key evidence for this event was first identified in the samples returned from the Moon by the Apollo astronauts. They tell us about an ancient cataclysmic bombardment where large asteroids and comets rained down on the Moon.
Scientists now recognize that this event was not limited solely to the Moon; it also affected the Earth and many other solar system bodies. "The existence of life on Earth, as well as the conditions that made our world habitable for us, are strongly linked to what happened at this distant time," states Dr. David Nesvorny of SwRI.
The same dynamical conditions that devastated the planets also led to the capture of some would-be impactors in the asteroid belt. "In the classic movie 'Casablanca,' everybody comes to Rick's. Apparently throughout the solar system, the cool hangout for small objects is the asteroid belt," says Dr. William Bottke of SwRI. |
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Everything Biology
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Written by Everything Science
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Jun 29, 2009 at 12:00 AM |
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Most scientists who create models trying to understand the mechanics and aerodynamics of insect flight have assumed that insect wings are relatively rigid as they flap.
New University of Washington research using high-speed digital imaging shows that, at least for some insects, wings that flex and deform, something like what happens to a heavy beach towel when you snap it to get rid of the sand, are the best for staying aloft.
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| The wing of a Manduca sexta, or tobacco hawkmoth, reveals the extent of deformation during flight.
Credit: Armin Hinterwirth, University of Washington
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"The evidence indicates that flexible wings are producing profoundly different air flows than stiff wings, and those flows appear to be more beneficial for generating lift," said Andrew Mountcastle, a UW doctoral student in biology.
He used particle image velocimetry, a technique commonly used to determine flow velocities in fluids, to study how air flows over the wings of Manduca sexta, or tobacco hawkmoths. The method combined laser light and high-speed digital video to model air flow.
A hawkmoth's wings are controlled by muscles on the insect's body and have no internal muscles of their own. The bulk of the wing is something like fabric stretched back from a stiff leading edge, fabric that is elastic and bends from inertia as the wing accelerates or decelerates through each stroke.
To test the wings' function, they were attached to mechanical "flappers" that moved back and forth 25 times a second, the same frequency at which the moths flap their wings, with the focus on how the wings deformed with each motion reversal. While the machine placed the wings at the same dominant angle as in normal moth flight, it could only approximate natural motion in one axis of rotation, compared with the three axes controlled in actual moth flight.
For the research, wings were removed from moths and tested in the mechanical "flapper" immediately, while they maintained most of their natural elasticity. After that the wings were allowed to dry for 12 to 24 hours and covered with enough spray paint to restore their original mass, then the wings were tested again in their more rigid state. The high-speed video, when viewed in slow motion, provided graphic detail of how the wings deformed as they flapped. |
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