Whole Sun Imaged for the First Time

On February 6, NASA's twin STEREO probes moved into position on polar opposite sides of the sun and started beaming back the first images to capture the star's entire surface. "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.

This new ability should improve forecasts of solar eruptions. These violent magnetic events can wreak havoc with satellites and even power lines and railway signals on Earth. But without a view of the sun's entire surface, charged solar emissions can end up hurtling through space, even towards Earth, without warning. The twin probes left Earth in 2006, heading for the positions they have now reached. They are expected to beam back images of the entire sun for the next 8 years.

Mercury’s Comet-Like Appearance Spotted

Scientists from Boston University's Center for Space Physics report that NASA satellites designed to view the escaping atmosphere of the Sun have also recorded evidence of escaping gas from the planet Mercury. The STEREO mission has two satellites placed in the same orbit around the Sun that the Earth has, but at locations ahead and behind it.

This configuration offers multi-directional views of the electrons and ions that make up the escaping solar wind. On occasion, the planet Mercury appears in the field of view of one or both satellites. In addition to its appearance as a bright disk of reflected sunlight, a "tail" of emission can be seen in some of the images