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(meteorobs) Last Minute Leonid Info and Tips
The Leonid meteor shower occurs every year between November 14 and the
21st as the earth encounters particles left behind from comet
Temple-Tuttle. This comet orbits the sun every 33.25 years and leaves
debris in a slightly different path with every return. The debris the
earth encounters is normally sparse creating no more than 10-15 meteors
per hour at best.
What makes this year exceptional is that the debris fields or paths
orbiting near the comet, which last passed the sun in 1998, has a much
higher concentration of material than in normal years when the comet is
far from the inner solar system. In 2001 the earth will pass close to
three separate paths of the comet. These paths were created by the comet
in 1699, 1767 and 1866. When the earth passes close to each one of these
paths there is the chance of increased meteor activity.
The first encounter will occur when the earth will pass close to the
path created in 1767 near 10:00 Universal Time on November 18. Observers
in extreme northwestern South America, Central America and North America
can see this possible outburst. This time corresponds to 2:00 AM Pacific
Standard Time and 5:00 AM Eastern Standard Time. Rates as high as 30 per
minute have been predicted at this time.
The second possible outburst will occur some seven hours later near
17:30 Universal Time. This outburst will be caused by the path created
in 1699 and is best seen by observers in eastern Australia and all of
the western Pacific region including Japan, Korea, and eastern China.
This time corresponds to 1:30 AM in Korea and 4:30 AM in eastern
Australia on the morning of the 19th. Rates as high as 30 per minute
have also been predicted at this time. By this time the Americas' will
have moved into daylight, with the sun obscuring that region from seeing
further activity.
The last possible outburst may be the best as the earth passes very
close to the path created by the comet in 1866. Closest approach occurs
near 18:15 Universal Time which is only 45 minutes after the 1699
encounter. This time favors the same regions mentioned above for the
17:30 outburst. Rates as high as 100 per minute have been predicted at
this time. Another reason the predicted rate is so high is that there is
the possibility that the material from the 1699 path will still be
active thus we have activity from both sources occurring
simultaneously.
Please note that these times and rates are only estimates. We cannot
predict with 100 percent certainty the exact time and activity since we
do not know the exact location and intensity of each path. The actual
times and strengths may differ considerably. The key is to be out at
least an hour BEFORE these times just in case the outbursts occur early.
Leonid meteors cannot be seen during the early evening hours. These
meteors can begin to appear as soon as the radiant (the area of the sky
the meteors seem to originate) rises in the east. This occurs during the
mid evening hours for high northern latitudes, late evening hours for
mid northern latitudes, and after midnight for those located in
equatorial regions and the Southern Hemisphere.
When the radiant lies near the horizon the Leonid meteors cannot
penetrate far into the earth's atmosphere. At this time they are only
able to skim the upper atmosphere. Meteors seen at this time are called
"earthgrazers" and can be quite spectacular. They often last several
seconds and can span a great distance of the sky.
As the earth rotates and we move into the morning hours the Leonid
radiant will rise higher into the sky and the meteors will strike the
atmosphere at a more direct angle creating shorter paths. These meteors
may be less striking than the earthgrazers but they will certainly be
much more numerous as less of them will be obscured by the horizon.
Tips for watching the shower:
1. Watch near the times indicated above on the morning of the 18th for
those in the western hemisphere and on the morning of the 19th (local
time) for those watching from eastern Asia and the western Pacific
region.
2. Watch from rural areas free from light pollution. While a few meteors
may be bright enough to be seen from cities, most of them will be
fainter and will be obscured by bright city lights.
3. Be comfortable! Don't stand and watch. Use a lounge chair and
blankets to make yourself comfortable.
4. Don't watch for 5 minutes and give up if you don't see much. Meteors
often appear to arrive in bursts. A few minutes may go by with little
activity and then you may see a sudden burst of activity the next
minute.
5. Leonid meteors can be seen in any portion of the sky. It is probably
best if you face the darkest direction available at your location. The
typical Leonid meteor last much less than one second and often leaves
behind a persistent train. Leonid meteors seen close to the radiant and
close to the horizon (in any direction) will appear shorter and slower
than those seen high in the sky far from the radiant. Just be sure to
look up at least halfway into the sky so that none of your field of view
is wasted on the ground.
6. Make this a family event! Since this is a Sunday morning in the
Americas', get the entire family involved. Next year's shower is
hampered by a full moon and after that it will not be until 2099 that we
see Leonid activity this strong again.
Wishing you all clear and meteor-streaked skies!
Robert Lunsford
AMS Visual Meteor Program Coordinator
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http://www.meteorobs.org/storms.html
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