Coronal Mass Ejections |
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So how often does the Earth get 'hit' by a CME? The SOHO satellite which gives us pictures like the one above, watches the Sun round the clock and since 1996 it has detected thousands of these explosions. Most of them shoot out sideways and are not directed towards Earth. Some of them, however, head right towards Earth. They look like a sudden 'halo' of light expanding from nearly all around the edge of the Sun at the same time. Scientists look for these Halo CME events and note them carefully. Usually, within a few days, the CME produces effects here at Earth. To see how often Earth gets in the way, lets look at the table below compiled by Dr. Chris St.Cyr (Naval Research Lab/LASCO). Study the list, and answer the questions at the end. |
Appearance |
Speed |
Description of the Event |
|
Date |
Time [UT] |
[km/s] |
|
1998/06/01 |
11:27 |
272 |
Small bright front; falls apart in C2 |
1998/06/01 |
15:00 |
364 |
Jet. Part of continuous E limb activity? |
1998/06/02 |
02:04 |
249 |
Material; falls apart in C2 |
1998/06/02 |
02:59 |
254 |
Bright thick (flat?) structured arcade |
1998/06/02 |
08:08 |
1383 |
Bright streamer eruption; mega prom material |
1998/06/02 |
21:06 |
882 |
Structured material w/no obvious front |
1998/06/03 |
12:02 |
604 |
Thick structured loop; mega concave-out |
1998/06/04 |
02:04 |
1717 |
Halo CME. Extremely bright & structured |
1998/06/04 |
06:31 |
880 |
Serrated edge in C2; not much front in C2 |
1998/06/04 |
09:36 |
217 |
Asymmetric narrow loop(?) w/core |
1998/06/04 |
21:00 |
517 |
Non-radial ragged material |
1998/06/04 |
21:27 |
652 |
Thick ragged loop w/structured core |
1998/06/04 |
22:28 |
422 |
Structured material |
1998/06/05 |
01:30 |
499 |
Faint filled mound feature |
1998/06/05 |
07:02 |
755 |
Faint loop w/trailing structured loop(s) |
1998/06/05 |
10:28 |
431 |
Bright structured non-radial material |
1998/06/05 |
12:01 |
412 |
Halo CME. Starts as concentric loops |
1998/06/06 |
08:27 |
494 |
Non-radial fan |
1998/06/06 |
12:27 |
271 |
Faint material precedes slowly rising faint loop |
1998/06/06 |
all day |
537 |
Several blobs or loops ejected? |
1998/06/07 |
09:32 |
516 |
Halo CME. Bright structured halo (doily) |
1998/06/07 |
19:27 |
392 |
Non-radial material falls apart in C2 |
1998/06/08 |
08:01 |
143 |
Faint loop precedes brighter structured cloud |
1998/06/08 |
15:27 |
560 |
Bright structured in NE from swelling streamer |
1998/06/09 |
05:55 |
255 |
Thick arcade |
1998/06/09 |
08:27 |
197 |
Thin loop |
1998/06/09 |
09:27 |
314 |
Second thick arcade overlaps previous |
1998/06/09 |
11:27 |
508 |
Third structured arcade w/core; overlaps earlier |
1998/06/10 |
03:55 |
667 |
Bright & structured in SE; doily? |
1998/06/10 |
11:27 |
483 |
Blob precedes concave-out |
1998/06/10 |
16:06 |
421 |
Cloud /some structure |
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