NASA Achieves Perfection: Images of the Sun

Rebekah Gordon

On February 6, NASA completed a huge achievement: sending twin STERO probes into position on opposite sides of the sun to send back uninterrupted images and video of the sun. It’s official; the sun is a sphere.

“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 also released a 3D video of the sun on Super Bowl Sunday, which you can watch on NASA’s homepage. “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 sun and beams the images back to Earth. Researchers and scientists combine the two views to create a perfect sphere. However, STERO doesn’t project normal images. 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. “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.”

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. Yet, these forecasting benefits aren’t just 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.” These probes are working together to project images of 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 as it is going on. 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 probes. “There are many fundamental puzzles underlying solar activity,” says Vourlidas. “By monitoring the whole sun, we can find missing pieces.”

More images and movies will be released in the next days and weeks to come, so stay tuned!