A plasma "croissant"--the same one seen in the previous picture--continues its journey from the sun in this 2007 image taken by the STEREO spacecraft. Such images are being combined to create the first 3-D pictures of solar storms, NASA announced on April 14, 2009.
The STEREO craft is the first to measure the speed and direction of solar ejections, such as the one pictured, that are headed toward Earth. The spacecraft are also able to sample the charged particles as they pass by, collecting information about their compositions and magnetic properties--major clues as to how the "space weather" will interact with Earth's magnetic field.
The new technology stands to extend early warnings about adverse space weather from about 12 hours to a full 24, said NASA's Michael Kaiser, a STEREO project scientist.