Fun_People Archive
17 Nov
Leonid Meteor Storm -- Satellite Operators Take Note

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From: Peter Langston <psl>
Date: Tue, 17 Nov 98 13:06:07 -0800
To: Fun_People
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Subject: Leonid Meteor Storm -- Satellite Operators Take Note

X-Lib-of-Cong-ISSN: 1098-7649
Excerpted-from: a message from Robert G Kennedy III

...[Bob Thomas] tells me that the Arecibo radiotelescope in Puerto Rico has
scanned the tube of cometary debris from Comet Tempel-Tuttle that the earth
will be passing through, and as of Sunday's forecast, they reported that
this year's Leonid meteor storm will be *very* heavy.
	...
Per my lecture this month at the Civic Center, the peak of the storm will
occur over eastern Mongolia about 3 am local time there. For Tennessee,
that equates to 2:00 EST in the afternoon tomorrow. The storm maximum is
expected to be one hour. Since Comet Tempel-Tuttle is traveling opposite to
the Earth's orbit around the sun, and the debris from the comet is falling
along the same trajectory as the comet itself, collisions will be almost
head on, not catching up. By definition, the time zone you're in does not
rotate into the leading edge of Earth until after midnight local time, so
don't expect to see much before 12 a.m. tonight. However, the intensity
will build continuously until local sunrise. It will still be building
after that, but you won't be able to see anything in the daytime except the
occasional fireball, say, bodies over 100 kg. The further west you are, the
better the show will be. The peak density over Mongolia is expected to be
10000+/hour, but the actual number could be 10X or 1/10th that figure. Here
in east Tennessee, expect ~20 meteors per hour (+/- a factor of 10) visible
to the naked, but fully dark adapted eye. Since the parent body is only ~4
km diameter, there shouldn't be any Dino Killer bolides (~10 km diameter).
If Mother Nature has slipped a joker into the deck, well, you'll be the
first to know (that you're going to become extinct). In that case, I'll be
seeing you in the stratosphere.

The collision geometry also means the relative velocity will be something
like 70 km/sec, which makes for *very* bright (and very brief) meteors. A
grain of sand at this speed has 160,000 joules of kinetic energy, 45 times
as much as an M-16 bullet just coming out of the barrel. If you had a hunk
of computerized equipment the size of a minivan - school bus, and fired a
two full magazines from a machine gun into it, what would you expect? So,
satellite operators take note.

© 1998 Peter Langston