PLEASE NOTE:
*
CCNet, 15 December 1999
-------------------------------
QUOTE OF THE DAY
"According to Jenkins, tilt is the
key to both events
in Earth's past. Many scientists believe
that the
collision of a large planetoid with
Earth created the
moon and some believe that collision
also altered the
Earth's tilt."
-- Pennsylvania
State University, 14 December 1999
(1) THIRD METEORITE STRIKE IN POPULATED AREA REPORTED
FROM AUSTRALIA
Robert Clements <Robert.Clements@dva.gov.au>
(2) POSSIBLE METEORITE FALL IN DUNBOGAN (AUSTRALIA)
ABC News, 15 December 1999
(3) UPDATE ON THE GUYRA EVENT
Gordon Garradd <loomberah@ozemail.com.au>
(4) IT WASN'T A GEMINID
Tony Beresford <starman@camtech.net.au>
(5) GEMINID LUNAR IMPACTS OBSERVED? NEED CONFIRMATION
Joan and David Dunham <dunham@erols.com>
(6) DID COSMIC IMPACT CHANGE EARTH’S TILT?
Andrew Yee <ayee@nova.astro.utoronto.ca>
(7) SPACE-AGE TECHNOLOGY REVEALS ANCIENT METROPOLIS
The Salt Lake Tribune, 12 December 1999
(8) X-RAY & EXTREME ULTRAVIOLET EMISSION FROM COMET P/ENCKE
C.M. Lisse et al., UNIVERSITY OF MARYLAND
(9) COMETARY EVIDENCE OF A MASSIVE BODY
IN THE OUTER OORT CLOUD
J.J. Matese et al., UNIVERSITY OF LOUISIANA
(10) THE DYNAMICS OF PLUTINOS
Q.J. Yu & S. Tremaine, PRINCETON
UNIVERSITY
OBSERVATORY
===========
(1) THIRD METEORITE STRIKE IN POPULATED AREA EPORTED
FROM AUSTRALIA
From Robert Clements <Robert.Clements@dva.gov.au>
No new word on yesterday's strike; although the Channel 10 TV
News
coverage confirmed that it was a meteorite (& no space junk;
or
whatever). I therefore don't know whether the Geminids have
decided to
redirect their attack on Port Macquarie (perhaps 1500km north of
Melbourne); but intend borrowing my father's hardhat just in
case....
As before: i'll keep my eye out for follow ups on these strikes,
esp.
in case they turn out to be Phaethon debris....
All the best,
Robert Clements <Robert.Clements@dva.gov.au>
================
(2) POSSIBLE METEORITE FALL IN DUNBOGAN (AUSTRALIA)
From ABC News, 15 December 1999
http://www.abc.net.au/news/newslink/nat/newsnat-15dec1999-38.htm
Police investigate possible meteor strike on house
Police on the mid-north coast of New South Wales are
investigating
damage to a house that appears to have been caused by a
meteorite.
The residents were disturbed late last night by a noise but were
not
aware of the damage until this morning.
Police were called in this morning when the residents noticed
light
shining through a hole in the roof of their house at Dunbogan.
A small rock, about one centimetre wide, has been recovered from
inside
but local police say they are unsure whether it is an extra
terrestrial
object.
It has been taken to the Port Macquarie station to be sent away
for
analysis. Nobody in the house was injured.
The incident comes a week after police found a possible meteor
strike
in a dam on the northern tablelands at Guyra.
The object that left a large hole in the floor of the dam has not
been
recovered.
Copyright 1999, ABC News
===============
(3) UPDATE ON THE GUYRA EVENT
From Gordon Garradd <loomberah@ozemail.com.au>
Dear Benny,
The Guyra Shire council is preventing any further action on
the site for the moment, there will be a council meeting on
Monday
where they will decide on what to do next. The General Manager
informs
me that there will be a motion to call for expressions of
interest for
recovery. I was initially hoping to be able to go and take part
in that,
and had organised equipment to do so, however by the time a
decision is
made the mud/silt may well have closed over, making any recovery
very
difficult. I am still considering a ground search for any other
fragments. I have not mentioned that they may exist to any media
people in order to prevent any free-for-all collection and
possible loss
of fragments to private collectors.
At my request, the Australian Geological Survey Organisation has
posted
the seismogram of the E-W component of the probable sonic boom
recording. There was no detectable vertical signal, and the N-S
component was barely above the noise level. See:
http://www.agso.gov.au/geohazards/guyra_99.html
Regards, Gordon
===============
(4) IT WASN'T A GEMINID
From Tony Beresford <starman@camtech.net.au>
Benny,
The channel ten news report relayed by Robert Clements contained
typical inaccuracies of Mr Ross Dowe. Firstly is was quite clear
to me
from the reports I had by telephone, about the fireball widely
seen
over South Australia, that it wasn't a Geminid, and Mr. Dowe had
even
more information of course.
The object was moving mainly West to East. It was seen from Pt
Lincoln
on our west coast. It disintegrated to the NE of Adelaide. It
occured
at local time 21:22-23 on December 13 (1052or 1053UT). The
Geminid
radiant didn't rise till 02:00am on December 14.
Secondly, of course, is the overpromotion of the Geminid
shower at our latitudes. The ZHR for the Geminids is 100 or
so, but the unfavourable geometry considerably reduces the
observable rate to more like 50. Since most Australians
live in an urban environment, light pollution cuts into
this rate for most. Using these words the public expect the
natural eqivalent of a fireworks display and will be
disappointed when they dont get it.
Tony Beresford
===============
(5) GEMINID LUNAR IMPACTS OBSERVED? NEED CONFIRMATION
From Joan and David Dunham <dunham@erols.com>
Possible Geminid lunar impacts seen from Missouri and Calif.
From: SteveH8835@aol.com
Date: Tue, 14 Dec 1999 09:14:11 EST
Subject: Lunar Geminids
To: dunham@erols.com
Thanks Dr. Dunham,
for keeping me posted on your e-mail list regarding meteor hits
on
the moon. I am facinitated reading the debate on the size of the
lunar
meteors and the possible crater size.
Last night Dec. 14 UTC I saw 2 possible
Geminid hits on the lunar surface:
#1 02:54:40 UTC Mag. about 4.5
#2 03:17:52 UTC Mag. about 5
Geographic coord: approx: 39 44 40; 94 14 30
Sky condn CLEAR, temp 31 deg F
Limiting mag approx 7.5
ZHR (the 0300 Z hour) 30
ZHR (the 0600 Z hour) 54
This time I had my trusty shortwave receiver on WWV to get better
time
hacks even though my tape recorder died, I recorded the events
via good
old pen & paper as a backup.
I would appreciate it if you or others could confirm these events
or
help explain what they might otherwise have been.
Dark skies!
Steve Hendrix
SteveH8835@aol.com
701E 6th
Cameron, MO 64429
(816) 632-1327
__________________________________________________
Date: Mon, 13 Dec 1999 14:30:51 -0800
From: Dave English <prospector@sd.znet.com>
To: Joan and Dave Dunham <dunham@erols.com>
Subject: Observations
Hi,
I was waiting for you to post any sightings for last night to see
if a
possible sighting would match what I think I saw at about 6:30
PM
local time. [that was 2:30 UT of Dec. 13 UT. I was
videorecording that
night earlier, but the Moon set in Maryland by 2h UT; no other
possible
sightings from around 0h UT of the 13th have been reported - D.
Dunham]
My viewing conditions are difficult, the strain to look through
and
also adjust a fixed table-top telescope and the problem of seeing
the
star field at times with my uncovered eye may account for my
sightings,
but at 6:30 to 6:31 corrected time I believe I saw a pinpoint
light
near the middle of the dark part of the Moon. A few minutes later
there
seemed to be a brighter more distinct light near the large
crater,
toward the south, about 6 arcminutes inside the shadow.
These should be used only to confirm other sightings as the
strain on
my eyes was terrific and I'm skeptical myself about the little
lights
but I'm hoping I did see something that can be confirmed. I
observed
from 6:05 to 6:35 PM. Looks like clouds tonight in San Diego
County.
Good Luck!
Dave English
Oceanside, California
Joan and David Dunham
7006 Megan Lane
Greenbelt, MD 20770
(301) 474-4722
dunham@erols.com
===========
(6) DID COSMIC IMPACT CHANGE EARTH’S TILT?
From Andrew Yee <ayee@nova.astro.utoronto.ca>
Pennsylvania State University
University Park, Pennsylvania
Contacts:
A'ndrea Elyse Messer, (814) 865-9481 (o), aem1@psu.edu
Vicki Fong (814) 865-9481 (o), vyf1@psu.edu
December 14, 1999
One Theory Solves Two Ancient Climate Paradoxes
San Francisco, Calif. -- A Penn State meteorologist has a
single theory that could solve both the Faint Young Sun
problem and the Snowball Earth problem if it proves to be
correct.
"I looked at the climate problems in the Archean, 3.8 to
2.5 billion years ago, where the environment was very warm
with a sun that is much cooler than today's," says Dr.
Gregory S. Jenkins, assistant professor of meteorology.
"Then I looked at the late Proterozoic, where some
researchers suggest episodes of snowball Earth where the
entire globe ices up and I realized that the same solution
could solve both problems.
Jenkins of Penn State's College of Earth and Mineral
Sciences explains his solution in two papers presented
today (Dec. 14) and tomorrow (Dec. 15) at the Fall Meeting
of the American Geophysical Union in San Francisco. The
papers are "The high obliquity solution to understanding
Archean climate and the faint-young sun paradox," and
"Climate model solutions to late Proterozoic
glaciation,"
written with Steven R. Smith, a recent Penn State
meteorology graduate.
According to Jenkins, tilt is the key to both events in
Earth's past. Many scientists believe that the collision of
a large planetoid with Earth created the moon and some
believe that collision also altered the Earth's tilt.
"If the Earth were tilted to 70 degrees from vertical, then
both the faint young sun problem and the snowball Earth
problem would be solved," says Jenkins.
The faint young sun problem arises because young stars are
20 to 30 percent less bright, and consequently less warm,
than older stars. Geological evidence shows that the Earth
was much warmer in the early Precambrian than it is today,
despite a weaker sun. Most solutions to this problem
suggest that levels of greenhouse gases like carbon dioxide
and methane were much higher then and these gases where
what warmed the Earth.
Jenkins used a global climate model of the Earth during the
Archean with only slightly elevated carbon dioxide, but
with tilt to 70 degrees and geography mirroring that 3.8 to
2.5 billions years ago.
"The Earth was 95 percent ocean then," says Jenkins.
"Water
has a very high heat capacity and because of the tilt, the
Earth would have remained warm."
Tilting the earth 70 degrees gives large parts of each
hemisphere 24 hours of sunlight for three months. If this
sunlight were to fall on land, temperatures would be hotter
than 125 degrees Fahrenheit in summer, but, because land
cools very rapidly, during the three-month, 24-hour night,
the temperatures would plummet. Twenty-four hours of
sunlight for three months on water does not get as hot, but
also never cools below the freezing point of ocean water.
"The climate model shows that the 70-degree tilt could
produce the temperatures expected during the Archean," says
Jenkins.
The snowball Earth problem is different but has the same
solution. During the Proterozoic 2.5 billion to 544 million
years ago, evidence exists for glaciation at the equator.
Researchers suggest that total global glaciation occurred
three different times.
"Three glaciations would mean three extinctions for large
numbers of species," says Jenkins. "To suggest that
life
made it through really hard times three times is really
hard for me to believe." The global climate model for this
period uses an Earth with somewhat more land mass, the
70-degree tilt and shows glaciation occurring at the
equators, while the poles remain ice free. This scenario,
where some ocean and land remain unfrozen, would allow
species to survive the equatorial glaciations.
Although a collision can be cited as the source of the
70-degree tilt, the question of what untilted the planet
remains because today's tilt is about 23 degrees from
vertical.
"George Williams, department of geology and geophysics,
University of Adelaide, originally proposed the tilt and
suggested that if a large enough mass built up on the pole,
it could untilt," said Jenkins. "At the end of the
Precambrian, most of the Earth's land mass was centered
around the South Pole."
Recent studies suggest that with enough mass, it would take
about 100 million years to return the earth to a tilt
between 20 and 30 degrees. "Based on what we know about the
climate then, this is a viable solution," Jenkins said.
EDITORS: Dr. Jenkins may be reached at 814-865-0478 or
gsj1@psu.edu
===========
(7) SPACE-AGE TECHNOLOGY REVEALS ANCIENT METROPOLIS
From The Salt Lake Tribune, 12 December 1999
http://www.sltrib.com/1999/dec/12121999/nation_w/5399.htm
Space-Age Technology Reveals Sprawling Ancient Metropolis
BY MARIAM SAMI
THE ASSOCIATED PRESS
QANTIR, Egypt -- This is a typical Nile Delta farming
village, its simple mud-brick houses sitting along dirt
roads amid the green carpeting of rice and corn fields. Yet
there is grandeur here -- a vast, buried metropolis from
millenniums ago that was discovered by German
archaeologists using cuttingedge imaging technology.
The exploration team believes the site is the long lost
capital of Ramses II, a mighty pharaoh who lived more than
3,200 years ago.
Working with magnetic imaging equipment used by
geophysicists to search for oil, the archaeologists
have mapped an underground city they estimate spread
over 12 square miles.
FULL STORY AT http://www.sltrib.com/1999/dec/12121999/nation_w/5399.htm
============
(8) X-RAY & EXTREME ULTRAVIOLET EMISSION FROM COMET P/ENCKE
C.M. Lisse*), D. Christian, K. Denneel, J. Englhauser, J.
Trumper,
M. Desch, F.E. Marshall, R. Petre, S. Snowden: X-ray and extreme
ultraviolet emission from comet P/Encke 1997. ICARUS, 1999,
Vol.141, No.2, pp.316-330
*) UNIVERSITY OF MARYLAND,DEPT ASTRON,COLLEGE PK,
MD,20742
In an effort to understand the newly discovered phenomenon
of cometary X-ray emission, we have obtained observations
of the short period (3.3 years), well-studied comet 2P/Encke
(Encke) during its July 1997 close approach to Earth. Extended,
variable emission on the sunward side of the nucleus was found
in the Rontgen X-ray satellite High Resolution Imager (HRI)
at 0.090-0.75 keV and in the Extreme Ultraviolet Explorer
(EUVE) scanner telescopes' Lexan B 0.090- to 0.28-keV and
Al/Ti/C 0.050- to 0.16-keV bandpasses; useful upper limits
were found in the Ti/Sb/Al 0.020- to 0.040-eV bandpass.
Similar to our results for C/Hyakutake. the emission morphology
was roughly symmetric with respect to a vector from the comet's
nucleus toward the Sun, with a light curve consisting of a slowly
varying baseline emission and a large impulsive event on 7 July
1997 with a time scale of similar to 3 h and an amplitude
of similar to 3 times the baseline. A count rate of similar
to 0.17 counts s(-1) in the HRI was measured for the slowly
varying emission, corresponding to a total luminosity L-x
of 4 x 10(14) erg s(-1). Unlike Hyahutake, however the bulk
of the emission clearly originates outside the comet's
bow-shock, arguing against the magnetic reconnection and
plasma dust emission models. The comet's lightcurve does
not correlate with the solar X-ray lightcurve, ruling out
scattering of solar X-rays as the emission mechanism. The
multiwavelength HRI/EUVE photometry is inconsistent with
the Haberli et al. (1997, Science 276, 939-942) charge
transfer, plasma dust, and attogram dust models of cometary
X-ray emission and is consistent with the Wegmann et al.
(1988, Planet. Space Sci. 46, 603-612) charge exchange,
0.15- to 0.45-keV thermal bremsstrahlung, and photon index
1.6-2.0 power law models. While the impulsive event
correlates very well with the passage of a solar magnetic
field boundary at the Earth and an increase in the solar
wind particle flux, it is not coincident, according to
current models of the solar wind magnetic current sheet,
with the passage of the sector boundary by the comet,
suggesting that new models of the current sheet are
necessary. (C) 1999 Academic Press.
===========
(9) COMETARY EVIDENCE OF A MASSIVE BODY
IN THE OUTER OORT CLOUD
J.J. Matese*), P.G. Whitman, D.P. Whitmire: Cometary
evidence of a massive body in the outer Oort cloud. ICARUS,
1999, Vol.141, No.2, pp.354-366
*) UNIVERSITY OF LOUISIANA,DEPT PHYS,LAFAYETTE,LA,70504
Approximately 25% of the 82 new class I Oort cloud comets
have an anomalous distribution of orbital elements that can
best be understood if there exists a bound perturber in the
outer Oort cloud. Statistically significant correlated
anomalies include aphelia directions, energies, perihelion
distances, and signatures of the angular momentum change
due to the Galaxy. The perturber, acting in concert with
the galactic tide, causes these comets to enter the loss
cylinder-an interval of Oort cloud comet perihelion
distances in the planetary region which is emptied by
interactions with Saturn and Jupiter. More concisely, the
impulse serves to smear the loss cylinder boundary inward
along the track of the perturber. Thus it is easier for the
galactic tide to make these comets observable. A smaller
number of comets are directly injected by the impulsive
mechanism. We estimate that the perturber-comet
interactions take place at a mean distance of approximate
to 25,000 AU. The putative brown dwarf would have a mass of
3 (x)(divided by) 2M(Jupiter) and an orbit whose normal
direction is within 5 degrees of the galactic midplane.
This object would not have been detected in the IRAS
database, but will be detectable in the next generation of
planet/brown dwarf searches, including SIRTE It is also
possible that its radio emissions would make it
distinguishable in sensitive radio telescopes such as the
VLA. (C) 1999 Academic Press.
========
(10) THE DYNAMICS OF PLUTINOS
Q.J. Yu*) & S. Tremaine: The dynamics of Plutinos.
ASTRONOMICAL JOURNAL, 1999, Vol.118, No.4, pp.1873-1881
*) PRINCETON UNIVERSITY OBSERVATORY,PEYTON HALL, PRINCETON,
NJ, 08544
Plutinos are Kuiper belt objects that share the 3:2 Neptune
resonance with Pluto. The long-term stability of Plutino orbits
depends on their eccentricity. Plutinos with eccentricities
close to Pluto's (fractional eccentricity difference Delta
e/e(P) = \ e - e(P)\/e(P) less than or similar to 0.1) can be
stable because the longitude difference librates, in a manner
similar to the tadpole and horseshoe libration in co-orbital
satellites. Plutinos with Delta e/e(P) greater than or similar
to 0.3 can also be stable; the longitude difference circulates
and close encounters are possible, but the effects of Pluto are
weak because the encounter velocity is high. Orbits with
intermediate eccentricity differences are likely to be unstable
over the age of the solar system, in the sense that encounters
with Pluto drive them out of the 3:2 Neptune resonance and thus
into close encounters with Neptune. This mechanism may be a
source of Jupiter-family comets. Copyright 1999, Institute
for Scientific Information Inc.
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