Latest image of the far side of the Sun based on high resolution STEREO data, taken on February 2, when there was still a small gap between the STEREO Ahead and Behind data. This gap started to close on February 6, when the spacecraft achieved 180 degree separation, and will completely close over the next several days.
Credit: NASA
An artist's concept of STEREO surrounding the sun.
Credit: NASA
MARYLAND: NASA's twin STEREO probes moved into position on opposite sides of the Sun on February 6th, and they are now transmitting uninterrupted images of the entire star - front and back.
Each STEREO probe photographs half of the star and beams the images to Earth, and researchers combine the two views to create a sphere.
"For the first time ever, we can watch solar activity in its full 3-dimensional glory," said Angelos Vourlidas, a member of the STEREO science team at the Naval Research Lab in Washington, DC. "This is a big moment in solar physics. STEREO has revealed the Sun as it really is - a sphere of hot plasma and intricately woven magnetic fields."
Hawk-eyed STERO catches everything
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," said STEREO program scientist Lika Guhathakurta at NASA headquarters.
"I expect great advances in theoretical solar physics and space weather forecasting."
No longer taking us by surprise
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," said Bill Murtagh, a senior forecaster at NOAA's Space Weather Prediction Centre 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.
Monitoring the Sun 24/7
"With this nice global model, we can now track solar storms heading toward other planets, too," said Guhathakurta. "This is important for NASA missions to Mercury, Mars, asteroids... you name it."
NASA has been building toward this moment since October 2006 when the STEREO probes left Earth, split up, and headed for positions on opposite sides of the Sun. February 6, 2011, was the date of ‘opposition’ - when STEREO-A and -B were 180 degrees apart, each looking down on a different hemisphere.
