Dark Side of the Sun

Well, no, there's no actual dark side of a luminous ball of burning gas, but there is an effective dark side, as in, the side of the sun we can't see at any given time.
Scientists aren't content to get just half of the picture, so they've launched the STEREO (Solar Terrestrial Relations Observatories) mission, a pair of NASA spacecraft that will orbit the sun simultaneously to provide a complete view of all sides of the star at once.

"Then there will be no place to hide and we can see the entire sun for the first time," STEREO project scientist Michael Kaiser of NASA's Goddard Space Flight Center.

The perfect spherical view will come on Feb. 6, 2011. Right now the satellites, which were launched in October 2006, are about 90 degrees apart, which allows a picture of about 270 degrees of the sun — the fullest view yet.

"The who goal of all of this is to try to get a better handle to try to predict solar storms, which cause cell phone disturbances, and disruptions to communications and power." Kaiser said. "We'd like to be able to predict these things as far in advance as possible to give us a longer warning time."

Solar storms are magnetic disruptions on the sun that release violent sprays of charged particles into space. These storms can produce magnificent displays of the Northern Lights. But some past storms have also cost airlines and satellite communications industries millions of dollars, and have led to large scale power blackouts (including one across the entire province of Quebec, Canada). Being able to reliably forecast these tempests in advance could make a huge difference in preventing disturbances on Earth.

Predicting solar weather is also important for the future of manned spaceflight. If astronauts are exposed to the intense radiation from solar storms while traveling beyond the protective magnetic field of the Earth, they could suffer serious harm. Even astronauts close to home who venture out for a spacewalk during a storm are put in danger.

"For future missions going to the moon and Mars, that's very important," Kaiser said. "Some of these solar storms can be very intense. If the astronauts were completely exposed to one of these storms the radiation could be high."

The STEREO mission also aims to improve our basic scientific understanding of the dynamics within the sun, which could shed light on the workings of stars in general.