[Ansteorra] This weekend's meteor shower
bkelley at accd.edu
Thu Nov 15 06:28:11 PST 2001
Greetings from Sir Emrys Shaunnon, staff astronomer at the Scobee
Planetarium in San Antonio.
As many across Ansteorra will be attending events this weekend,
allow me to mention a celestial event that may prove to be quite
spectacular. Sky watchers across the globe are anticipating the early
morning hours of November 17th and 18th. We may witness more than a
meteor shower - possibly a meteor storm!
The Cause of the Celestial Fireworks
The Leonid meteor shower is produced by comet Tempel-Tuttle, a
comet discovered in 1865 by Ernst Tempel and Horace Tuttle. Soon after
the comet's detection, calculations revealed that the comet orbited the
Sun every 33.25 years. Each November, our planet intersects
Tempel-Tuttle's orbit and we pass through the particle stream left in
the comet's wake. In normal years when the comet is far from the Sun
and we travel through a less dense portion of the particle stream, we
see a display of about 15 to 20 meteors per hour. However, when the
meteor shower's parent comet returns to the vicinity of both the Sun and
Earth, more intense meteor displays are often observed.
The comet's most recent visit took place in February of 1998. As a
result, the Leonid displays of 1999 and 2000 were quite good, with some
locations reporting hundreds of meteors observed for brief periods.
Once more our planet is about to pass through a concentration of rock
and ice particles and it's possible a very intense meteor shower may
take place this weekend.
In the November 2001 issue of Sky & Telescope magazine,
meteorologist Joe Rao assessed the predictions provided three teams of
specialists, who agree that two dramatic storms appear likely. A burst
lasting perhaps two hours is expected in the predawn hours of November
18th for observers throughout most of North and Central America. The
maximum rates should occur near 4:00 a.m. CST. With no moonlight
spoiling the view, the storm may briefly spawn anywhere from several
hundred to perhaps 1,000 or 2,000 meteors per hour for observers with
clear, very dark skies. Another prediction, issued recently by NASA
researcher Peter Jenniskens, argues that the hourly rate could top
4,000. An even bigger storm is expected 8 hours later for viewers
rimming the far-western Pacific Ocean.
The narrowest, densest part of the meteor swarm is a ribbon like
particle stream no more than an estimated 20,000 miles wide, but this
stream stretches out to the orbit of the planet Uranus. The Leonid
meteoroids and the Earth orbit the Sun in nearly opposite directions, so
the meteors collide with the Earth's atmosphere nearly head-on at a
speed of 44 miles per second! The average size of most meteoritic
particles is less than the diameter of a grain of sand. We are in no
danger because all the meteoritic particles vaporize during their fiery
passage through the Earth's protective atmosphere.
This famous meteor shower is called the Leonids because the meteors
appear to originate from the constellation of Leo the Lion, more
specifically from the stars that trace out the head of Leo.
Leo rise above the eastern horizon between midnight and 1:00 a.m. and as
the night progresses, Leo ascends higher above the eastern horizon.
This is why the Leonid meteor shower is best seen after midnight through
the predawn hours. The meteors will seem to come from the east, but
they will be seen all over the sky.
Best Observing Times - The early morning hours of November 17th and 18th
between the hours of midnight and 6:00 a.m., with a possible peak near
4:00a.m. Sunday morning the 18th.
Best Observing Equipment - Your eyes, binoculars and telescopes are not
Best Observing Location - Out in the country away from any bright
Highly Recommended - A comfortable chair and warm clothing.
An Important Announcement
If you are a sky watcher, you know that the city is the worst place
to watch a meteor shower due to the glare of city lights. Only a few,
bright meteors can be glimpsed from a city. A trip to the country is
And finally, Brianna and I plan to attend the Bodermarch event this
weekend and we would enjoy watching this event with you. A display of
celestial fireworks would be quite a way to celebrate the investiture of
a new Baron and Baroness!
Until then, "keep watching the skies",
Baron of Bjornsborg
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