PLEASE NOTE:
*
CCNet DEBATE, 18 November 1998: LEONIDS SPECIAL IV
FIRST REACTIONS
-------------------------------------------------
(1) SOME ASTRONOMERS GOT IT RIGHT IN THE FIRST PLACE
Iwan Williams <I.P.Williams@qmw.ac.uk>
(2) THERE WAS A SHORT METEOR STORM NEVERTHELESS
Richard A Kowalski <bitnik@bitnik.com>
======================
(1) SOME ASTRONOMERS GOT IT RIGHT IN THE FIRST PLACE
From Iwan Williams <I.P.Williams@qmw.ac.uk>
Dear Benny,
Now that the dust is settling over the Leonids, perhaps that it
is
pertinent to point out that as far as I am aware, four groups of
workers produced models of the Leonids that involved more than
just
calculating the orbit of Tempel-Tuttle, namely Yeomans, Yau &
Weismann, Wu and Williams, Jones and Brown, and Jenniskens. All
these works are published in refereed scientific journals. The
conclusions of all are remarkably similar, 1998 would not be
anything like 1966, in fact that 1998 was likely to be somewhat
akin
to 1866 or 1933. Jenniskens was marginally higher in his estimate
than Yeomans Yau and Weissman and Wu and Williams, but only
marginally so, with 10 000 as an upper limit.
There are two points to be made, one doing science gets it
correct
more often than wild speculation, and two, more seriously
perhaps,
Why did all four models get the rate about correct but the timing
(ie the longitude of the node) wrong by about half a degree. It
is
almost as if the comet had decided to work to equinox B1950
rather
than J2000!
All the four models also suggest that something will happen in
1999,
not being that much worse than 1998, so lets not forget 1999 and
that observations then are also necessary and valuable.
Best wishes to all
Iwan Williams
==============
(2) THERE WAS A SHORT METEOR STORM NEVERTHELESS
From Richard A Kowalski <bitnik@bitnik.com>
Benny
In the post from Ron Baalke by the Centre for Research in Earth
and
Space Technology Toronto, Ontario...
>Leonids meteor shower ... good news and bad news
>
>Generally speaking, a storm requires sightings of at least
1000
>meteors per hours, while a shower requires only about 100.
Attached is
>a list of the recent meteor showers for comparison.
IAU Circular #7052 states that "However, A. Fitzsimmons
reports that
a group of observers at La Palma observed about 1000 Leonids/hr
around Nov. 17.15, increasing to about 2000/hr around Nov.
17.19."
This would mean that the Leonids did produce a short storm this
year, using the criteria of 1000 per hour as the minimum for a
storm. Here at Quail Hollow there was only about 15 - 20
per hours
starting at Nov. 17.25 for ~4 hours. Almost all fireballs
however.
Richard A Kowalski
Quail Hollow Observatory
http://www.bitnik.com/QHO
761 Zephyrhills
*
CCNet DIGEST, 18 November 1998: LEONIDS SPECIAL III
METEOR STORM IN A TEACUP
---------------------------------------------------
(1) METEORS: MORE BEAUTY THAN BEAST
MSNBC <http://www.msnbc.com/news/213237.asp>
(2) HIT-AND-MISS METEOR DISPLAY
BBC Online Network
http://news.bbc.co.uk/hi/english/special_report/1998/11/98/the_leonids_98/newsid_216000/216446.stm
(3) DAZZLING SHOW, LITTLE DAMAGE
CNN Interactive <http://cnn.com/TECH/space>
(4) LEONIDS: THE GOOD NEWS .... AND THE BAD
Ron Baalke <BAALKE@kelvin.jpl.nasa.gov>
(5) HISTORICAL CATASTROPHISM: NO PARADIGM SHIFT IN ARCHAEOLOGY
YET
Mike Baillie <m.baillie@qub.ac..uk>
==================
(1) METEORS: MORE BEAUTY THAN BEAST
MSNBC <http://www.msnbc.com/news/213237.asp>
By Alan Boyle
Nov. 17 — Tuesday’s Leonid meteor shower brought
sighs of delight
from skywatchers — and cautious sighs of relief from
satellite
experts. The storm of space grit turned out to be less severe
than
expected.
THE METEOR SHOWER, which arises when Earth plows through a trail
of
interplanetary dust and ice left behind by Comet Tempel-Tuttle,
isn’t over quite yet. But as the shower passed its peak,
monitors
said they had picked up no signs of damage to the 500-plus
satellites in Earth orbit. [...]
Most of the meteors are smaller than a grain of sand and burn up
60
miles high in the atmosphere, posing no threat to Earth itself.
But
satellite experts warned that an intense storm, with grit flying
by
at 226 times the speed of sound, could have subjected satellites
to
a potentially deadly sandblasting. [...]
As it turned out, Tuesday’s storm was far less severe than
the
1966 event, and there was even some question whether it qualified
as
a storm at all.
“Things are actually looking pretty good, I think,”
said William
Ailor, director of the Center for Orbital and Re-entry Debris
Studies at the Aerospace Corp. “The storm may not actually
be up to
the storm class.”
He said the peak rate appeared to be about 300 meteors per hour,
an
estimate supported by U.S. Air Force observations. However, some
Europeans reported seeing as many as 2,000 meteors per hour.
Last week, Ailor predicted that one or two satellites would be
affected, but on Tuesday afternoon he said no damage had been
detected. That was probably due to the milder-than-expected
activity
as well as the precautions taken by spacecraft operators, he
said.
NASA said it also had detected no damage to its spacecraft as of
Tuesday afternoon. “It’s still kind of early to sum up,
but as of
now ... as far as we know nothing has suffered any untoward
effects,” said Jane Platt, a spokeswoman at NASA’s Jet
Propulsion
Laboratory.
Copyright 1998, MSNBC
=====================
(2) HIT-AND-MISS METEOR DISPLAY
BBC Online Network
http://news.bbc.co.uk/hi/english/special_report/1998/11/98/the_leonids_98/newsid_216000/216446.stm
The Leonid meteor storm arrived earlier than predicted, leaving
many
observers disappointed.
The light show - which was most visible in Asia - was caused by
tiny
fragments left in the wake of the comet Tempel-Tuttle.
As the Earth passes through this space debris, the dust particles
plunge into our atmosphere and burn up, producing streaks of
coloured light across the sky.
But scientists who had predicted a spectacular display "like
God's
own fireworks" on Tuesday night and Wednesday morning now
say they
were wrong.
'We got it wrong'
A team of Canadian and American scientists monitoring the event
in
Mongolia admitted the storm had arrived early and the best
sightings
were probably late on Monday and early on Tuesday.
Colonel Simon Worden, of the US Air Force, said: "We didn't
expect
that. It's very unusual."
The Leonids defied all the scientists' predictions and there was
nothing like the 10,000 meteors per hour which some experts had
predicted. [...]
While the lack of meteors was bad news for thrillseekers, it was
good news for global telecommunications as none of the world's
600
satellites were seriously damaged.
USAF Captain Steve Butow, said: "Most of the stuff that made
the
trails in the sky were probably no larger than the size of a
small
marble at the maximum. So no Armageddon tonight."
Copyright 1998, BBC
=====================
(3) DAZZLING SHOW, LITTLE DAMAGE
From CNN Interactive <http://cnn.com/TECH/space>
(CNN) -- The full force of the biggest meteor shower in decades
dazzled skygazers across Asia just before dawn on Wednesday, but
caused little damage to the some 600 satellites orbiting Earth.
Meteor dust particles smaller than grains of sand pelted
satellites
but caused no catastrophic damage, much to the relief of
governments, telecommunications firms and scientists alike.
"Everything is fine. We're operating the same as we expect
to each
day, Everything is just regular operations for us," said
Rebecca
Petruck, a spokeswomen for PanAmSat, which operates 18
satellites.
Incoming particles could have damaged the satellites themselves
or
generated electromagnetic pulses that can knock out a satellite's
computer brains.
Such satellites provide the world with weather data, TV signals,
military intelligence and more. [...]
Fears of major satellite disruptions from the Leonids were
sparked
in part after a PanAmSat satellite failed in May, knocking out
paging services across the United States and disrupting TV and
radio
transmissions.
Satellite companies and NASA took precautions by shifting solar
panels so their delicate faces would be turned away from the
stream
of debris. Electrical components also were turned off, reducing
the
chances a satellite would short-circuit if hit.
Experts said the odds of any damage were slim, although not
entirely
unlikely. A meteor shower destroyed the European's Space Agency's
Olympus satellite in 1993, the only such incident.
Copyright 1998, CNN
===============
(4) LEONIDS: THE GOOD NEWS .... AND THE BAD
From Ron Baalke <BAALKE@kelvin.jpl.nasa.gov>
Centre for Research in Earth and Space Technology
Toronto, Ontario
Leonids meteor shower ... good news and bad news
November 17, Toronto -- Billed as the first meteor storm of the
modern
space age, the "two-part" Leonids storm didn't quite
live up to
scientists' expectations earlier this afternoon, but still
offered
viewers in the Far East a fantastic display during its two-hour
peak
beginning at roughly 2:20 pm EST.
Ground observations collected by the Canadian science teams in
Ulaan
Baator, Mongolia and at Tindal Air Force Base, Australia,
revealed a
density of roughly 100-200 meteors per hour, posing little threat
to
Earth's satellite fleet. This number falls many times shy of the
Leonids meteor storm of 1966, which coincided with the last trip
by
parent comet Tempel-Tuttle as part of its normal 33-year orbit
around
the Sun.
"While it wasn't what we anticipated, it was a great
opportunity for
our science team to further develop our predictive model,"
said
Richard Worsfold, CRESTech's Leonids project manager, who is with
the
Australia team at Tindal. "But, it's great news for
satellite
operators, who now only have to worry for part-B of the storm,
which
isn't until this time next year."
In superlative terms, this year's Leonids will not go down in
history
as the first of the modern space age but as one of many showers.
However, if "part B" of the storm takes place as
predicted next year,
as now seems to be the case, all records are still up for grabs.
The 1999 storm, or shower, will be visible on November 17 next
year,
although this time visible over Europe and the Middle East and
will
quite definitely be the last opportunity for a major meteor storm
for
at least another 30 years.
As of the shower's end, no satellites operators had reported
anomalies. In all likelihood, these reports will, if applicable,
be
generated over the next several days or weeks at the discretion
of
satellite owners.
Generally speaking, a storm requires sightings of at least 1000
meteors per hours, while a shower requires only about 100.
Attached is
a list of the recent meteor showers for comparison.
* 1998 -- Leonids -
100 to 200 meteors/hour at peak
* 1998 -- Draconid
meteors - 300 meteors/hour at peak
* 1993 -- Perseid
meteors - 350 meteors/hour at peak
* 1985 -- Draconid
meteors - 500 meteors/hour at peak
* 1969 -- Leonids -
350 meteors/hour at peak
* 1966 -- Leonid
meteors - 100,000 meteors/hour at peak (storm)
The Centre for Research in Earth and Space Technology (CRESTech)
is a
not-for-profit science and technology organization created to
conduct
multidisciplinary collaborative research and development in Earth
and
space sciences. It is based in Toronto, Canada and supported by
the
Ontario government=B9s Centres of Excellence program.
For more information on CRESTech's Leonids Program, please visit
www.crestech.ca, or contact:
Andre Bellefeuille
CRESTech Communications
(416) 665-5464 office,or (416) 707-9120 cell
==================
(5) HISTORICAL CATASTROPHISM: NO PARADIGM SHIFT IN ARCHAEOLOGY
YET
From Mike Baillie <m.baillie@qub.ac.uk>
Benny, Hi.
Brad Schaefer made an interesting point in the tail of his recent
piece on 'Meteors that Changed the World'. He stated
"The final episode reminds readers that the
Tunguska blast, the
Brazilian Tunguska, and Comet Shoemaker-Levy 9 all
demonstrate
that bombardment is ongoing, and the paradigm in
public thinking
has turned completely around."
Now as someone who has quite recently lectured to a range of
archaeological audiences and who has asked for shows of hands on
whether people had ever heard of Tunguska or Shoemaker Levy 9, I
can
report that the average response i.e. people who have heard of
the
phenomena, ranges between 10% and 30%. Of those 10-30% almost
none
seem to have drawn any conclusions from what they heard and none
at
all had considered the implications for the last 5000 years. My
deduction from this is that in archaeological circles there is no
paradigm which even contains the concept of comets. Thus the
paradigm in public thinking probably does not apply to
archaeologists and I'm sure most ancient historians would fall
into
that category as well. It is for this reason that publishing BAR
728
(NATURAL CATASTROPHES DURING BRONZE AGE CIVILISATIONS) was such a
masterstroke. The first comprehensive survey of the issues of
cometary hazard arrive in the archaeological literature
unannounced -
a metaphorical bolt from the blue. I'm quite sure the silence
will be
deafening, unless of course the paradigm in archaeological
thinking
has indeed turned completely around.
Mike Baillie
Palaeoecology Centre
School of Archaeology and Palaeoecology,
Queen's University, Belfast
fax (01232) 335354
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