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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
www.spacew.com
28 May 2003
1. MAJOR X-CLASS SOLAR FLARE ALERTS
2. MIDDLE LATITUDE AURORAL ACTIVITY WATCH
MAJOR X-CLASS SOLAR FLARE ALERTS
Observers of the upcoming total annular solar eclipse (visit
www.skyandtelescope.com
for details) will be interested to learn that
a significant and developing active sunspot complex has evolved over
the last several days into a potential power-house for solar flare
activity.
Active sunspot Region 10365 is a rapidly developing/growing mass
of dense sunspots currently numbering in the neighborhood of 42. The
sunspot complex currently covers an area of approximately 1.2 billion
square kilometers. You could map more than twice the entire surface
area of the Earth into this spot complex. This region is also
presently visible to the unaided (but protected) eye. Remember never
to look directly at the Sun without appropriate eye protection.
Two powerful X-class solar flares were observed from this spot
complex within 1.5 hours of each other on the evening of 27 May EDT
(late in the UTC day of 27 May and early on 28 May). This activity was
preceded on 26 May by smaller M-class solar flares. Analysis of this
activity has revealed that most of these flare events were associated
with coronal mass ejections (CMEs) containing Earthward directed
components.
Interestingly, there is evidence suggesting that perhaps only two
of these coronal mass ejections may actually survive the trip to the
Earth. The others may be "cannibalized" by the strongest and fastest
coronal mass ejections. Cannibalism in space occurs when one coronal
mass ejection travelling faster than another overtakes the slower one
and cannibalizes it. This process of cannibalization irreversibly
changes the character of both of the coronal mass ejection
disturbances that are involved. Depending on the nature of the CMEs,
the end-product of the cannibalization may be a single disturbance
that is constructively reinforced to become stronger and more
volatile, or it may become a single disturbance that is weakened if
the two CMEs destructively merge together. In either case, the
end-product is invariably a CME that contains very little resemblance
to the original CME. For this reason, the Earth-bound impact of these
types of space weather disturbances are much more difficult to predict
with accuracy.
Each of the smaller M-class flare associated CMEs have a good
chance of producing a single cannibalized CME. Similarly, the two
X-class flares that were observed also may have produced CMEs that
have merged into a single disturbance. Whether these disturbances have
merged constructively or destructively (assuming that they have in
fact merged with other CMEs) remains an open question.
What is known is that at least two separate and distinct space
weather CME disturbances are expected to impact the Earth over the
coming days. The first, associated with the smaller M-class flares,
may impact the Earth on 29 May. The second and perhaps more energetic
disturbance is expected to impact the Earth early on 30 May (UTC time
- which translates to the late evening and early morning hours of
29/30 May, Eastern daylight time [EDT]).
Because these disturbances have the potential of being less
predictable and possibly more volatile than might normally be
observed, there is at least minor concern that their impact with the
Earth may be stronger than would normally be expected. For this
reason, warnings are being issued to alert of the potential for
geomagnetic storm activity and auroral storm activity ("northern
lights" activity) on 29 through perhaps 31 May inclusive, with
heaviest emphasis on 30 May. The official middle latitude aurora watch
is appended below and contains more details.
Additional major X-class solar flare activity is possible from
active sunspot Region 10365 over the coming days. There is also the
potential for energetic proton flares from this active region. Proton
flares are nothing more than solar flares that involve processes
capable of accelerating protons to near relativistic energies (>10 to
100 MeV) and velocities. These protons enhance the radiation
environment in space around the Earth and can pose a hazard to
satellite and (in less frequent cases) astronaut health, but are not a
health hazard to people living on the Earth. These energetic protons
also reac havoc with ionospheric-based radio communications systems by
producing a phenomenon known as polar cap absorption (PCA). PCA is
intense ionization of the polar ionosphere and can significantly alter
the character or strength of radio signals that propagate through
these regions of the ionosphere.
Region 10365 will remain in a sensitive position to throw other
coronal mass ejections toward the Earth during the next few days. It
will rotate behind the west limb of the Sun and will become incapable
of significantly affecting the Earth by this same time next week.
MIDDLE LATITUDE AURORAL ACTIVITY WATCH - 28-31 MAY 2003
VALID BEGINNING AT: EFFECTIVE IMMEDIATELY VALID UNTIL: 23:00 UTC (7 pm
EDT) ON 31 MAY
HIGH RISK PERIOD: 30 MAY (UTC DAYS) MODERATE RISK PERIOD: 28 - 31 MAY
PREDICTED ACTIVITY INDICES: 30, 30, 35, 20 (28 MAY - 31 MAY)
POTENTIAL MAGNITUDE OF MIDDLE LATITUDE AURORAL ACTIVITY: MODERATE -
HIGH
POTENTIAL DURATION OF THIS ACTIVITY: MAIN BELT = 12 - 24 HOURS MINOR
BELT = 24 - 48 HOURS
ESTIMATED OPTIMUM OBSERVING CONDITIONS: NEAR LOCAL MIDNIGHT
EXPECTED LUNAR INTERFERENCE: NONE - LOW
OVERALL OPPORTUNITY FOR OBSERVATIONS FROM MIDDLE LATITUDES: FAIR
AURORAL ACTIVITY *MAY* BE OBSERVED APPROXIMATELY NORTH OF A LINE
FROM...
OREGON TO SOUTHERN IDAHO AND POSSIBLY NORTHERN UTAH TO WYOMING TO
NORTHERN NEBRASKA TO IOWA TO ILLINOIS TO INDIANA TO OHIO AND POSSIBLY
NORTHERN KENTUCKY AND NORTHERN WEST VIRGINIA TO MARYLAND.
ACTIVITY *MAY* ALSO BE OBSERVED APPROXIMATELY NORTH OF A LINE FROM...
IRELAND TO SOUTHERN UNITED KINGDOM AND POSSIBLY NORTHERN FRANCE TO
BELGIUM TO THE NETHERLANDS TO THE NORTHERN THIRD OF GERMANY TO
NORTHERN POLAND TO NORTHERN BELARUS TO NORTH-CENTRAL RUSSIA.
NEW ZEALAND AND SOUTHEASTERN TO SOUTH-CENTRAL REGIONS OF AUSTRALIA
ALSO HAVE A FAIR CHANCE TO OBSERVE PERIODS OF ACTIVITY.
SYNOPSIS...
A series of solar coronal mass ejections are expected to impact
the Earth over the next 72 hours. The first disturbance may impact on
29 May and produce enhanced levels of activity. The most disturbed
interval is expected on 30 May when effects of what may be a more
energetic coronal mass ejection are expected to reach the Earth. This
latter disturbance is associated with two major X-class solar flares
and has the potential for producing periods of moderate to strong
auroral activity over the high and middle latitude regions. The
intensity of the activity probably will not be particularly
significant. However, since the potential for cannibalistic CME
activity is fairly high (a faster CME overtaking a slower CME), the
level of predictability is reduced. There is a chance some regions of
this disturbance may involve strongly enhanced magnetic fields capable
of coupling more strongly with the Earth's magnetosphere to produce
strong auroral storm activity. There is also the possibility periods
of activity may be fairly weak. Because of these uncertainties and the
complex space weather situation which is evolving from this (and other
ambient) activity, this watch is based on an optimistic projection
favoring a slightly stronger disturbance than would otherwise be
expected. The near-new phase of the moon, which will contribute to
optimally dark skies will also enhance the potential for observing
activity from middle latitudes, particularly on 30 May.
There is a strong potential for additional major solar flare
activity from active solar Region 10365. Future activity from this
region may involve additional Earthward-directed coronal mass ejection
activity that could serve to prolong the duration of favorable
conditions for middle latitude sightings of auroral activity.
This watch will remain valid through 23:00 UTC (7 pm EDT) on 31
May. It will then be updated or allowed to expire. For updated
information, visit:
www.spacew.com/aurora/forum.html
. For
real-time plots of current activity, visit:
www.spacew.com/plots.html
PLEASE REPORT OBSERVATIONS OF AURORAL ACTIVITY TO:
www.spacew.com/submitsighting.html
NOTICE: THE NEXT HOME-STUDY INTERNET SPACE WEATHER FORECASTING
COURSE will commence on 16 June 2003. This course is suitable for
anyone to take (there are no prerequisites). It teaches you how to
analyse solar activity and predict space weather impacts of this
activity on the Earth and Earth-based technology systems (including
predicting the occurrence of auroral activity). It includes over 600
pages of printable curriculum and may also optionally include several
powerful software packages developed for space weather studies and
research.
Details are available at:
www.spacew.com/www/course.html
The last offering of this course was October 2002. We do not know
when the next class may be offered. We encourage all who are
interested to consider enrolling soon.
** End of the AstroAlert Bulletin **
