Warning Signs (September 9 2005)
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On September 5, 2005, the C2 coronagraph observed a bulbous coronal mass ejection heading out from behind the left side of the Sun. This is just about where old sunspot region 798 would be. When we last saw this active region, it was producing several substantial solar storms. It was probably the source of several large solar storms that we could infer occurred on the far side of the Sun. The region was tracked using the sensing techniques of helioseismology. Its return would suggest that we might be in for some solar weather as the sunspot emerges again and begins to rotate around to face Earth more directly.
And just as scientists suspected it might perform, the same region, while still just at the Sun's left edge, erupted two days later with an X17 flare (almost off the scale) and an associated CME. If the estimate is correct, that would make it the fifth largest flare ever recorded. The active region will get a new number when it appears from around the edge, but it still seems to have at least the same if not more power than it showed us its last time around. This situation offers a good possibility that we could get some nice aurora sometime during the next two weeks.
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