Magnetic fields on the sun's northeastern limb erupted around 17:45 UT on April 16th, producing one of the most visually-spectacular explosions in years. NASA's Solar Dynamics Observatory recorded the blast at extreme ultraviolet wavelengths:
© NASA/SDO
The explosion, which registered M1.7 on the Richter Scale of solar flares, was not Earth-directed. A CME produced by the blast is likely to hit NASA's STEREO-B spacecraft, but probably no planets.

This event confirms suspicions that an active region of significance is rotating onto the Earth-facing side of the sun. Stay tuned for updates.

Update: Using data from SDO, Steele Hill of NASA's Goddard Space Flight Center has assembled a must-see movie of the event. The movie shows the explosion unfolding at 304 Angstroms, a wavelength which traces plasma with a temperature around 80,000 K.