Sun Officially A Sphere: First Ever Stereo Images of the Entire Sun, Farside Seen

It's official: The sun is a sphere.

Rotating solar sphere made from a combination of imagery from the two STEREO spacecraft, together with simultaneous data from the Solar Dynamic Observatory.This movie is made from data taken on January 31, 2011. Because the STEREO separation was still less than 180 degrees at that time, the small gap on the far side of the Sun has been interpolated over to simulate the full 360 degree view that STEREO will see

Credit: NASA



Latest image of the far side of the Sun based on high resolution STEREO data, taken on February 2, 2011 at 23:56 UT when there was still a small gap between the STEREO Ahead and Behind data. This gap will start to close on February 6, 2011, when the spacecraft achieve 180 degree separation, and will completely close over the next several days. 

Credit: NASA

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 Sunday: 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.

› Download this and more STEREO 360 videos

"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.

Credit: NASA

"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.

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.

› Download this and more STEREO 360 videos Credit: NOAA/SWPC

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."

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.

An artist's concept of STEREO spacecraft.

Credit: NASA


"There are many fundamental puzzles underlying solar activity," says Vourlidas. "By monitoring the whole sun, we can find missing pieces."

As the STEREO spacecraft have moved out on either side of Earth they have imaged more and more of the Sun's surface. This video shows how our coverage of the Sun has increased. The Sun is shown as seen by the two STEREO spacecraft and the Earth orbiting Solar Dynamic Observatory (SDO). The steadily shrinking black wedge shows the unobserved area on the Sun's far side. The data show the Sun in extreme ultraviolet light at 304 angstrom.

Credit: NASA

The need for space weather services has grown significantly in past years as the technology we rely on for everyday life has become increasingly vulnerable to space weather. America's vulnerability to space weather is rising fast as our national and global critical technology infrastructure becomes more complex and dependent on advance technology. These recent advances in our technological infrastructure drive emerging space weather service needs undreamed of just a decade ago. Our advanced technological infrastructure will face challenges from the increase in solar activity and are being addressed at the highest levels of government.

 

Credit: NOAA Space Weather Prediction Center

Farside direct observations from STEREO (left) and simultaneous helioseismic reconstructions (right). Medium to large size active regions clearly appear on the helioseismic images, however the smaller ones fall within the noise level. STEREO observations of the far-side will help calibrate and further improve the helioseismic technique.

 

Credit: NASA/Goddard Space Flight Center/SECCHI/GONG(NSO/NSF)/HMI 

Researchers say these first-look whole sun images are just a hint of what's to come. Movies with even higher resolution and more action will be released in the days and weeks ahead as more data are processed. Stay tuned!

These views are the result of observations by NASA's two Solar TErrestrial Relations Observatory (STEREO) spacecraft. The duo are on diametrically opposite sides of the sun, 180 degrees apart. One is ahead of Earth in its orbit, the other trailing behind.

For the STEREO Sun360 Teaser, go here.

For the full visualization showing STEREO's path go here.

For the visualization showing STEREO's increasing coverage of the sun (visual 3) go here.

For animations of STEREO observing a CME (visual 2), go here. 

Source: NASA