The green sun pictured below is an extreme-ultraviolet photo taken hours ago by NASA's STEREO-B spacecraft. What lies beneath the circled thicket of hot plasma and magnetic fields? It could be the most active sunspot of the year.
The circle marks the location of sunspot 1029. In late October, sunspot 1029 materialized on the Earth-facing side of the sun and quickly established itself as the biggest active region of 2009. It produced more than ten C-class solar flares, single-handedly quadrupling the number of such eruptions since the year began. For the past 11 days, sunspot 1029 has been transiting the farside of the sun, invisible from Earth.
STEREO-B can see the active region because the spacecraft is stationed over the sun's eastern horizon. Unfortunately, the glaring knot of extreme UV activity hides the sunspot's underlying dark core, and this limits how much we know about it. Has sunspot 1029 broken apart and diminished during its long farside transit? Or is it still its big, old active self? Answers will be revealed in 3 days when solar rotation turns sunspot 1029 toward white-light cameras on Earth. Stay tuned.
