One of the largest sunspots in years is rotating over the sun's northeastern limb. NASA's Solar Dynamics Observatory took this picture of AR1339 during the early hours of Nov. 3rd:

Image
© SDO
Measuring some 40,000 km wide and at least twice that in length, the sprawling sunspot group is an easy target for backyard solar telescopes. Two or three of the sunspot's dark cores are wider than Earth itself.

Naturally, such a large sunspot has potential for strong flares. NOAA forecasters estimate a 50% chance of M-class solar flares during the next 24 hours. One such eruption has already occured: An M4-flare at 2200 UT on Nov. 2nd produced a bright flash of extreme UV radiation (SDO movie) and hurled a coronal mass ejection (CME) into space. The CME is not heading our way. Future CMEs could have greater effect as AR1339 turns toward Earth in the days ahead.

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