CME observed by STEREO

The first coronal mass ejection (CME) observed by STEREO. This image was taken on Dec. 9 with STEREO's SECCHI/Cor2 coronagraph. A coronagraph blocks the bright disk of the sun allowing scientists to see the sun's faint outer atmosphere, the corona. The white circle shows the location of the solar disk. The mass ejection can be seen on the right hand side of the image as outward directed streak ending in a faint ring. Copyright@NASA.