SOLAR ACTIVITY: Something has exploded on the farside of the sun. Late yesterday, Dec. 4th, a billion-ton coronal mass ejection (CME) billowed over the sun's western limb. Click on the image to view a movie of the cloud recorded by the Solar and Heliospheric Observatory:

The blast site could be one of two farside active regions currently under surveillance by NASA's STEREO spacecraft, but those active regions don't seem to be in the right place to hurl a CME over the sun's western limb. The source might reveal itself in the days ahead as the sun's rotation turns unseen territory toward STEREO--or toward Earth. Stay tuned. (front page today only)