A Full Halo CME (September 16, 2004)
Hi-res C2 TIF image (2.7M).
Hi-res C3 TIF image (4.0M).
MPEG: Large (312K), Small ( 56K)
Quicktime: Large (647K), Small (200K)
The LASCO coronagraphs, which create artificial solar eclipses by blocking the light of the solar disk so we can see the much fainter glow of the Sun's hot corona, observed a full "halo" coronal mass ejection (CME) early on 2004 September 12. A "halo" CME is one in which gas from the corona is observed heading out from the Sun in all directions so that it resembles a circular halo. This indicates that the ejected gas, and embedded magnetic field, are headed either directly toward, or directly away from the earth. This one was nearly headed towards us, but may only strike the earth's magnetosphere a grazing blow. CMEs occur fairly frequently but usually head off to one side or the other; halo CMEs occur much less frequently. This one was associated with an M-class flare from active region 672, near the disk center on the Sun and associated with the largest sunspot visible right now. (The bright object seen on the left in the C3 video clip is Jupiter.)
Since the magnetospheric impact was minimal, the resulting auroral displays were confined to the polar regions. Had it been stronger, we might have been able to see aurora as far south as Virginia.
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