From: LARRY KLAES (ljk4_at_msn.com)
Date: Mon Jun 16 2003 - 05:58:09 PDT
----- Original Message -----
From: Cary Oler
Sent: Monday, June 16, 2003 8:37 AM
To: sun-earth_at_SkyandTelescope.com
Subject: AstroAlert: "Return of the King" - A Powerful Sunspot Returns with a Bang!
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This Is SKY & TELESCOPE's AstroAlert for Sun-Earth Interactions
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A s t r o A l e r t
Sun-Earth Alert
Solar Terrestrial Dispatch
http://www.spacew.com
16 June 2003
"RETURN OF THE KING" - A POWERFUL SUNSPOT COMPLEX RETURNS WITH A BANG
Approximately every 2 weeks, solar observers can watch sunspots rotate
across the face of the Sun from the eastern solar limb to the western limb.
Similarly, sunspots that rotate behind the western limb of the Sun and out of
our view often survive long enough to travel behind the Sun and back into
view on the eastern limb.
This is what is believed to have happened to active sunspot complex
10365. This spot complex was responsible for significant levels of solar
activity in May, including 5 major solar flares - 3 of which were powerful
X-class solar flares (the most powerful solar x-ray flare rated). On 29 and
30 May, a strong geomagnetic and auroral storm that was attributed to
energetic solar flare activity from Region 10365 was observed. Auroral
activity affected primarily the northern Russian and European regions.
Activity began to die out rapidly just before North America entered darkness,
enraging North American observers who were keen to catch another display of
the Northern Lights.
This strong active region appears to have survived its transit on the
far-side of the Sun and has heralded its return by producing two energetic
solar flares. The first one was observed on 15 June as a long-duration minor
M-class flare. At that time, the active region was still over 24 hours away
from rotating into view. The x-rays from solar flares are emitted higher in
the solar corona and are therefore visible from the Earth before the actual
sunspots become visible. Then, at 7:57 pm EDT on 16 June (23:57 UTC), this
active region unleashed a powerful and fairly long-duration class X1.3 event
that was accompanied by moderately strong radio emissions and evidence of a
moderately strong coronal mass ejection. The mass ejection is, in all
likelihood, not directed Earthward. However, if additional major levels of
activity from this spot complex occur over the next two weeks, there could be
a chance for sky watchers to observe auroral activity once again.
Solar observers are encouraged to watch the southeastern solar limb over
the coming days. Already there has been notable activity in the form of
limb surging. Today's X-class solar flare also produced a visible dynamic
loop prominence system.
Major solar flare activity may persist from this active region. It is
almost impossible to determine with any certainty the flare potential because
the spot complex is just now barely visible on the eastern limb of the Sun.
Limb foreshortening effects strongly inhibit attempts to determine magnetic
characteristics that are vital to flare potential analyses. So until a better
analysis becomes possible within the next 3 to 4 days, the established
history of the active region as a source of strong solar flare activity will
continue to be the primary indicator of flare potential.
Current near real-time observations of the Sun in h-alpha are available
through the Global H-Alpha Solar Patrol Network, a collaboration between many
professional solar observatories providing real-time imaging of the Sun.
Nearly continuous 24-hour/day coverage of the Sun is possible when all sites
are free of clouds and all equipment are functioning normally. The interface
to this network and products acrued through this network (i.e. daily movies
of activity) are available at: http://www.spacew.com/sunnow. So whether you
have a suitably equipped solar telescope or not, you can watch the effects of
this active region in real-time, at your leisure.
** End of the AstroAlert Bulletin **
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