New Phenomena On The Sun
Huntsville AL (SPX) Mar 22, 2007
It's enough to make you leap out of your seat: A magnetic vortex almost as big as Earth races across your computer screen, twisting, turning, finally erupting in a powerful solar flare. Japan's Hinode spacecraft recorded just such a blast on Jan. 12, 2007.
"I managed to stay in my seat," says solar physicist John Davis of the Marshall Space Flight Center, "but just barely."
Davis is NASA's project scientist for Hinode, Japanese for Sunrise. The spacecraft was launched in Sept. 2006 from the Uchinoura Space Center in Japan on a mission to study sunspots and solar flares. Hinode's Solar Optical Telescope, which some astronomers liken to "a Hubble for the Sun," produces crystal-clear images with 0.2 arc-second resolution. (Comparison: 0.2 arc-second is a tiny angle approximately equal to the width of a human hair held about 100 meters away.) "We're getting movies like these all the time now," he says.
This particular movie is visually stunning, but the most amazing thing about it, notes Davis, is where the scene unfolded--in the sun's chromosphere. "We used to think the chromosphere was a fairly uneventful place, but Hinode is shattering those misconceptions."
Chromosphere means "sphere of color." It's the name astronomers of the 19th century gave to a narrow and very red layer of the sun's atmosphere they saw peeking over the edge of the Moon during solar eclipses. The color comes from the chromosphere's abundant hydrogen which emits light at a wavelength of 6563 Angstroms, also known as "hydrogen alpha" light. Hinode's telescope is equipped with filters tuned to this specific color.
The view from space is impressive. Visually, the chromosphere resembles a shag carpet with threads of magnetism jutting up from the floor below. Hinode's movies show the threads swaying back and forth as if blown by a gentle breeze. There is nothing gentle, however, about "spicules" shooting into the chromosphere from the underlying photosphere. "These are jets of gas as big as Texas," says Davis. "They rise and fall on time scales of 10 minutes."
And then there are the explosions. "The fact that Hinode is able to observe solar flares taking place in the chromosphere is very important," he says.
The origin of solar flares is a mystery. Researchers have long known that flares develop from magnetic instabilities near sunspots, but even after centuries of studying sunspots, no one can predict exactly when a flare is about to happen. This is a problem for NASA because astronauts in space are vulnerable to intense radiation and high-energy particles produced by the explosions. An accurate system of forecasting would help explorers stay out of harm's way.
Hinode may be looking right into the genesis zone of flares. If so, "it could teach us how flares work and improve our ability to predict them." Meanwhile, hang on and enjoy the show.
Hinode, Japanese for "sunrise," was launched Sept. 23, 2006, to study the sun's magnetic field and how its explosive energy propagates through the different layers of the solar atmosphere. The spacecraft's uninterrupted high-resolution observations of the sun will have an impact on solar physics comparable to the Hubble Space Telescope's impact on astronomy.
"For the first time, we are now able to make out tiny granules of hot gas that rise and fall in the sun's magnetized atmosphere," said Dick Fisher, director of NASA's Heliophyics Division, Science Mission Directorate, Washington. "These images will open a new era of study on some of the sun's processes that effect Earth, astronauts, orbiting satellites and the solar system."
Hinode's three primary instruments, the Solar Optical Telescope, the X-ray Telescope and the Extreme Ultraviolet Imaging Spectrometer, are observing the different layers of the sun. Studies focus on the solar atmosphere from the visible surface of the sun, known as the photosphere, to the corona, the outer atmosphere of the sun that extends outward into the solar system.
"By coordinating the measurements of all three instruments, Hinode is showing how changes in the structure of the magnetic field and the release of magnetic energy in the low atmosphere spread outward through the corona and into interplanetary space to create space weather," said John Davis, project scientist from NASA's Marshall Space Flight Center, Huntsville, Ala.
Space weather involves the production of energetic particles and emissions of electromagnetic radiation. These bursts of energy can black out long-distance communications over entire continents and disrupt the global navigational system.
"Hinode images are revealing irrefutable evidence for the presence of turbulence-driven processes that are bringing magnetic fields, on all scales, to the sun's surface, resulting in an extremely dynamic chromosphere or gaseous envelope around the sun," said Alan Title, a corporate senior fellow at Lockheed Martin, Palo Alto, Calif., and consulting professor of physics at Stanford University, Stanford, Calif.
Hinode is a collaborative mission led by the Japan Aerospace Exploration Agency and includes the European Space Agency and Britain's Particle Physics Astronomy Research Council. The National Astronomical Observatory of Japan, Tokyo, developed the Solar Optical Telescope, which provided the fine-scale structure views of the sun's lower atmosphere, and developed the X-ray Telescope in collaboration with the Smithsonian Astrophysical Observatory of Cambridge, Mass. The X-ray Telescope captured the rapid, time-sequenced images of explosive events in the sun's outer atmosphere.
"By following the evolution of the solar structures that outline the magnetic field before, during and after these explosive events, we hope to find clear evidence to establish that magnetic reconnection is the underlying cause for this explosive activity," said Leon Golub of the Smithsonian Astrophysical Observatory.
The Marshall Space Flight Center manages the development of the scientific instrumentation provided for the mission by NASA, industry and other federal agencies.
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Clemson Rocket Launches Test Alaskan Auroras
Clemson SC (SPX) Mar 21, 2007
It may have been 40 degrees below zero at the Poker Flat Research Range in Alaska, but aurora and weather came together one recent winter night in a perfect match for Clemson University researchers and students who launched four rockets to study heat in the upper atmosphere.
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