First Ever STEREO Images of the Entire Sun   
   February 6, 2011: It's official: The sun is a sphere.   
       
   On Feb. 6th, NASA's twin STEREO probes moved into position on opposite sides   
   of the sun, and they are now beaming back uninterrupted images of the entire   
   star-front and back.   
       
   "For the first time ever, we can watch solar activity in its full   
   3-dimensional glory," says Angelos Vourlidas, a member of the STEREO science   
   team at the Naval Research Lab in Washington, DC.   
       
   NASA released a 'first light' 3D movie on, naturally, Super Bowl Sun-day:   
   [...]   
   The solar sphere as observed by STEREO and the Solar Dynamics Observatory on   
   January 31, 2011. Because the STEREO separation was still slightly less than   
   180o at that time, a narrow gap on the far side of the Sun has been   
   interpolated to simulate the full 360o view. The gap and quality of farside   
   imaging will improve even more in the days and weeks ahead. [YouTube video]   
   [full 42MB movie]   
       
   "This is a big moment in solar physics," says Vourlidas. "STEREO has revealed   
   the sun as it really is--a sphere of hot plasma and intricately woven magnetic   
   fields."   
       
   Each STEREO probe photographs half of the star and beams the images to Earth.   
   Researchers combine the two views to create a sphere. These aren't just   
   regular pictures, however. STEREO's telescopes are tuned to four wavelengths   
   of extreme ultraviolet radiation selected to trace key aspects of solar   
   activity such as flares, tsunamis and magnetic filaments. Nothing escapes   
   their attention.   
   [...]   
   An artist's concept of STEREO surrounding the sun. [more]   
       
   "With data like these, we can fly around the sun to see what's happening over   
   the horizon-without ever leaving our desks," says STEREO program scientist   
   Lika Guhathakurta at NASA headquarters. "I expect great advances in   
   theoretical solar physics and space weather forecasting."   
       
   Consider the following: In the past, an active sunspot could emerge on the far   
   side of the sun completely hidden from Earth. Then, the sun's rotation could   
   turn that region toward our planet, spitting flares and clouds of plasma, with   
   little warning.   
       
   "Not anymore," says Bill Murtagh, a senior forecaster at NOAA's Space Weather   
   Prediction Center in Boulder, Colorado. "Farside active regions can no longer   
   take us by surprise. Thanks to STEREO, we know they're coming."   
       
   NOAA is already using 3D STEREO models of CMEs (billion-ton clouds of plasma   
   ejected by the sun) to improve space weather forecasts for airlines, power   
   companies, satellite operators, and other customers. The full sun view should   
   improve those forecasts even more.   
       
   The forecasting benefits aren't limited to Earth.   
       
   "With this nice global model, we can now track solar storms heading toward   
   other planets, too," points out Guhathakurta. "This is important for NASA   
   missions to Mercury, Mars, asteroids... you name it."   
   [...]   
   Observing solar storms from two points of view has allowed forecasters to made   
   3D models of advancing coronal mass ejections (CMEs), improving predictions of   
   Earth impacts. Credit: NOAA/SWPC [movie]   
       
   NASA has been building toward this moment since Oct. 2006 when the STEREO   
   probes left Earth, split up, and headed for positions on opposite sides of the   
   sun (movie). Feb. 6, 2011, was the date of "opposition"-i.e., when STEREO-A   
   and -B were 180 degrees apart, each looking down on a different hemisphere.   
   NASA's Earth-orbiting Solar Dynamics Observatory is also monitoring the sun   
   24/7. Working together, the STEREO-SDO fleet should be able to image the   
   entire globe for the next 8 years.   
       
   The new view could reveal connections previously overlooked. For instance,   
   researchers have long suspected that solar activity can "go global," with   
   eruptions on opposite sides of the sun triggering and feeding off of one   
   another. Now they can actually study the phenomenon. The Great Eruption of   
   August 2010 engulfed about 2/3rd of the stellar surface with dozens of   
   mutually interacting flares, shock waves, and reverberating filaments. Much of   
   the action was hidden from Earth, but plainly visible to the STEREO-SDO fleet.   
       
   "There are many fundamental puzzles underlying solar activity," says   
   Vourlidas. "By monitoring the whole sun, we can find the missing pieces."   
       
   Researchers say these first-look images are just a hint of what's to come.   
   Movies with higher resolution and more action will be released in the weeks   
   ahead as more data are processed. Stay tuned!   
       
       
   Author: Dr. Tony Phillips | Credit: Science@NASA   
       
   More Information   
   Download a self-guided Science Briefing explaining this historic "First."   
       
   Solar Terrestrial Relations Observatory -- STEREO home page   
       
   Solar Dynamics Observatory -- SDO home page   
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.59   
    * Origin: NCS BBS (1:3828/7)