NASA’s STEREO-B spacecraft is monitoring an active region hidden behind the sun’s eastern limb.
On May 5th, it produced an impressive coronal mass ejection (movie) and a burst of Type II radio emissions caused by a shock wave plowing through the sun’s outer atmosphere. STEREO-B’s extreme UV telescope captured this image during the explosion:
Activity continued apace on May 6th with at least two more eruptions. Furthermore, recent UV images from STEREO-B reveal not just one but two active regions: image below.
At the root of all this activity is probably a complex of sunspots. The region is not yet visible from Earth, but the sun is turning it toward us for a better view. Readers with solar telescopes should keep an eye on sun’s northeastern limb for an emergence on May 7th or 8th.