PLEASE NOTE:
*
CCNet, 9 December 1999
------------------------
QUOTES OF THE DAY
"There are reasons to expect that
meteoroid streams
will contain large objects, not merely
the tiny
fragments one detects as visual meteors
in the
atmosphere. And these large objects are
not
necessarily like the meteorites
(assumedly largely or
entirely of asteroidal origin) which
reach the ground
intact".
-- Duncan Steel,
9 December 1999
"The founding population from which
the world's
present population is derived consisted
of about 2,000
individuals".
-- Marcus
Feldman, 8 December 1999
(1) THE REAL LESSON FROM THE MARS PROJECT FAILURES
Benny J Peiser <b.j.peiser@livjm.ac.uk>
(2) NEO-CATASTROPHISM & PLANETARY FORMATION
Andrew Yee <ayee@nova.astro.utoronto.ca>
(3) DID JUPITER GIVE BIRTH TO URANUS & NEPTUNE?
BBC Online News, 8 December 1999
(4) NEW EVIDENCE OF CATACLYSMIC VOLCANIC EVENTS
Andrew Yee <ayee@nova.astro.utoronto.ca>
(5) NAMN - NASA 1999 GEMINID CAMPAIGN
Mark Davis <MeteorObs@charleston.net>
(6) HOW 2000 PEOPLE CONQUERED THE WORLD
San Jose Mercury News, 7 December 1999
(7) LARGE METEOROIDS
Duncan Steel <D.I.Steel@salford.ac.uk>
(8) SOME CORRECTIONS ON PHAETHON, HERSCHEL & INTELLIGENCE
TESTS
Duncan Steel <D.I.Steel@salford.ac.uk>
(9) LUNAR CRATER GIORDANO BRUNO
Michael Paine <mpaine@tpgi.com.au>
(10) REFERENCE TO WATCHFUL CLERICS
Rolf Sinclair <rolf@santafe.edu>
(11) IN DEFENSE OF MILANKOVIC'S ICE-AGE THEORY
Steve Drury <s.a.drury@open.ac.uk>
(12) NO UNIFORM GLOBAL ICE-AGE
Alasdair Beal <a.beal@btinternet.com>
(13) AND FINALLY: HAPPY BIRTHDAY, WILLIAM WHISTON
============
(1) THE REAL LESSON FROM THE MARS PROJECT FAILURES
From Benny J Peiser <b.j.peiser@livjm.ac.uk>
"Failure is nothing new in spaceflight and there is nothing
that can be done about it" writes David Whitehouse (BBC
Online, 8 December 1999). David is absolutely right in his
stoical assessment of the latest Mars fiasco. After all,
the fact that two relatively cheap Mars spacecrafts have
been lost within the last three months does not come as a
complete surprise. Indeed, the speed of scientific
progress and debate is such that it is more than likely
that both failures will soon be largely forgotten.
Better and more sophisticated Mars programmes -
although unmanned - will follow soon.
The real repercussions of the Mars flops are much more
serious: What these failures (and many previous ones)
demonstrate is the fact of inherent deficiency and
technical problems when it comes to spacetechnology. There
are still only a relatively small number of space projects
(mainly due to costly programmes). As a result, it is
inevitable that a significant proportion of these projects
will flop. In space, failure is still the norm, although
the proportion of bungled projects will certainly decrease
over time.
In view of chancy spacetechnology, the issue of planetary
defense and how to prepare for a worst case scenario will
need to be redressed sooner rather than later. If the
scientific and military communities of the free world wish
to reassure the global village that the NEO impact hazard
can - if required - be handled competently and at any time,
more groundwork as well as actual trial runs have to be
initiated eventually. Given the gigantic difficulties NEO
deflection technologies face in any case, it is essential
to commence a programme of progressive experimentation on
cosmic intervention. Only from the inescapable failures
these projects will yield over many decades of trial and
error, an effective system of planetary defense will
ultimately emanate that deserves its name. To postpone such
experimental undertakings until planetary defense
technology will actually be required in an emergency - at
some unknown time in the future - is both shortsighted and
politically imprudent.
Benny J Peiser
9 December 1999
============
(2) NEO-CATASTROPHISM & PLANETARY FORMATION
From Andrew Yee <ayee@nova.astro.utoronto.ca>
Department of Public Affairs
University of Toronto
CONTACT:
Janet Wong
U of T Public Affairs
ph: (416) 978-6974, e-mail: jf.wong@utoronto.ca
Researchers chart out early lives of planets Earth-like objects
may be
relatively rare in universe
By Janet Wong
Dec. 8, 1999 -- Interaction between massive planets and the disks
of
gas and dust from which they formed are vital in determining the
shape
of planetary systems, suggest two former U of T researchers.
In a paper to be published in the December 9 issue of Nature,
Philip
Armitage and Brad Hansen, formerly of U of T's Canadian Institute
of
Theoretical Astrophysics, studied how early planet formation
triggered
the formation of other planets in developing solar systems.
"We're suggesting that it's the mass of the disk that
influences the
formation of planetary systems," says Armitage. "If the
disk is
lightweight, planet formation occurs fairly slowly -- over 10
million
years or so -- and the result could look something like our own
solar
system. For a heavyweight disk, more violent processes can occur
more
quickly and lead to a very different-looking system of
planets."
Using computer simulations, the researchers tested how a massive
planet the size of Jupiter would interact with a massive disk, 10
times larger than the disk thought to have given rise to our own
solar
system. They found the extra gravitational force from the planet
would
cause parts of the disk to collapse and fragment into other
planets. The
resulting planets would also be gigantic, but would be mostly
gaseous
rather than solid like that of Earth.
According to Armitage and Hansen, their research indicates that
there
is an upper limit to the amount by which planets can grow. If the
planets
formed close together, the planetary system would become
violently
unstable -- some planets would be ejected from the system and the
remaining ones would be left with eccentric orbits.
"The paper provides a new way to understand how multiple
planets could
form in a relatively short space of time, roughly the first
million years
after the birth of the solar system," says Hansen. "The
rapid creation of
additional planets will result in competition during planet
growth and
so may explain why there appears to be a maximum mass for planets
around other stars."
Whether habitable Earth-like planets can form and survive in such
harsh
environments and allow life to develop and grow remains unknown,
say
the researchers.
"This work, along with other theoretical explanations of
planetary
systems, suggests that planet formation can sometimes involve
violent
and chaotic processes that are different from those of our own
early
solar system," says Armitage. "We now know that the
existence of
planets themselves are common. However, conditions suitable for
forming habitable planets -- at least ones like the Earth --
could
still be rare."
Armitage is currently completing post-doctoral work at the
Max-Planck-Institut for Astrophysik in Germany. Hansen is a
Hubble
post-doctoral fellow at Princeton University in the United
States.
[Janet Wong is a news services officer for the Department of
Public
Affairs.]
===========
(3) DID JUPITER GIVE BIRTH TO URANUS & NEPTUNE?
From the BBC Online News, 8 December 1999
http://news.bbc.co.uk/hi/english/sci/tech/newsid_555000/555473.stm
By BBC News Online Science Editor Dr David Whitehouse
New suggestions that the planets in our Solar System have not
always
been in their current orbits have been put forward by two teams
of
astronomers.
This work, along with recent speculation that Jupiter may have
formed
much further from the Sun than its current position, and the
discovery of other planetary systems orbiting other stars, is
forcing
a reappraisal of our understanding of how the planets were
formed.
Writing in the journal Nature, researchers from Queens University
in
Kingston, Canada, propose that all of the giant planets in our
Solar
System formed in a narrow region of the gas and dust cloud that
surrounded the early Sun. They suggest that they ended up in
their
present orbits as a result of violent and chaotic scattering.
This would mean that when Jupiter, our Solar System's largest
planet,
formed, it triggered the birth of other giant planets nearby. In
a
way, Jupiter was the "midwife" of the Solar System.
Rocky cores
The four major planets in our Solar System are classified into
two
"gas giants" (Jupiter and Saturn), that have a small
rocky core
surrounded by a large hydrogen and helium atmosphere and also two
"ice giants" (Uranus and Neptune), that have icy
mantles around their
cores and only a thin atmosphere.
Scientists have always been slightly puzzled by the positions of
Uranus and Neptune because in their present locations it would
have
taken longer than the age of the Solar System for them to form.
The scientists from the University of Kingston suggest that the
four
giant planets started out as rocky cores in the Jupiter-Saturn
region, and that the cores of Uranus and Neptune were tossed out
by
Jupiter's and Saturn's gravity.
In the simulations, the ejected planets went into highly chaotic
orbits for a few hundred thousand years after which they settled
down
and gradually migrated to their present, nearly circular
orbits.
Stable orbits
Another group of scientists, also writing in Nature, from the
University of Toronto, have simulated how planets such as Jupiter
may
have formed in the first place.
They found that gas and dust circling the early Sun that starts
to
accumulate to form a proto-Jupiter creates a spiral density
pattern
in the surrounding disk material. The proto-planet accretes mass
rapidly through the spiral arms but when the planetary mass
reaches
four-to-five-times Jupiter's mass, the disk rapidly fragments
into
smaller proto-planets.
Over hundreds of thousands, or millions of years the proto-Uranus
and
proto-Neptune would be flung outwards by the now smaller
proto-Jupiter's gravity.
Not too long ago, scientists regarded the orbits that the planets
circle our Sun as being the ones they were born in. Now they are
realising that this is not the case. Uranus and Neptune may have
migrated outwards and Jupiter may have come in from the outer
cold.
One of the questions scientists would like to answer is
whether the Earth has always been where it is now?
Copyright 1999, BBC
============
(4) NEW EVIDENCE OF CATACLYSMIC VOLCANIC EVENT
From Andrew Yee <ayee@nova.astro.utoronto.ca>
News Office
Massachusetts Institute of Technology
Cambridge, Massachusetts
CONTACT:
Deborah Halber, MIT News Office
(617) 258-9276
dhalber@mit.edu
WEDNESDAY, DECEMBER 8, 1999
Team finds surprising volcanic clues to Indian Ocean formation
By Deborah Halber, News Office
An MIT researcher co-led a team of 25 international scientists in
a recent
ocean-floor drilling expedition to the Kerguelen Plateau in the
southeast
Indian Ocean. The researchers discovered clues in this huge
sunken island
complex that may shed light on exactly how Antarctica, Australia
and India
broke up into separate land masses about 130 million years ago.
On December 13 at the annual meeting of the American Geophysical
Union
in San Francisco, Fred Frey, professor of geochemistry at MIT and
co-chief
scientist on the drilling expedition, will report on the results
of several
drilling forays up to 200 meters into the plateau's
"basement." The
researchers retrieved black volcanic rock that holds clues about
how the
Earth evolved.
Professor Frey will give an IAP talk on "Study of Submarine
Volcanic Magma:
The Kerguelen Plateau," January 7, from 12-1:30pm in Rm
54-915.
The Kerguelen Plateau was formed by one of the most cataclysmic
volcanic
events in the Earth's history. So much magma spewed forth that it
covered
a land mass one-third the size of the continental United States
with a
20-kilometer-thick layer.
"This makes Mount Pinatubo look like a pinhead,"
Professor Frey said. "The
major objective of our drilling program was to retrieve rocks
that would
enable us to more precisely constrain the eruption ages.
Regardless of the
exact time of the eruption, production of this much magma clearly
is a
major geologic event."
An earlier ocean-drilling expedition uncovered evidence that the
Kerguelen
Plateau was above sea level during its intense volcanic period.
Sediments
on top of the cooled magma had trapped wood, seeds, spores and
other
organic matter indicating that the plateau was high and dry.
Professor
Frey said the land mass forming the Kerguelen Plateau existed
above sea
level for several million years before it cooled, shrunk and
sank. Now only
a few small islands rise above sea level: the Kerguelen
archipelago owned
by France and the smaller Heard and McDonald islands, which
belong to
Australia.
"We found that most of the plateau is formed of basalt, a
magma type
that erupts relatively 'quietly,' but that near the end of the
plateau
growth, there is strong evidence of highly explosive
eruptions," Professor
Frey said. "This is significant because explosive eruptions
input more
material into the atmosphere and are more likely to have
environmental
consequences."
Core from one of the drilling holes included a rock that is found
only on
continents. Almost as soon as the rock was recovered on the deck
of the
143-meter scientific research vessel JOIDES Resolution, Professor
Frey
said, "It was apparent that we had a spectacular and
unexpected result.
That's not an oceanic rock, yet it was sitting in the middle of
the ocean."
The core will shed light on the continental drift that led to the
formation
of the Indian Ocean.
Graduate student Kirsten Nicolaysen reported at a recent annual
international geochemical meeting that the rock is a continental
fragment
as much as 900 million years old. "The surprise is that the
Indian Ocean is
less than 200 million years old," Professor Frey said.
"Apparently, when
India, Australia and Antarctica broke up to form the Indian Ocean
around
130 million years ago, a fragment of these continents was broken
off and
incorporated into the newly forming Indian Ocean."
The ocean-drilling program is funded by the National Science
Foundation
with contributions from several participating countries.
===============
(5) NAMN - NASA 1999 GEMINID CAMPAIGN
From Mark Davis <MeteorObs@charleston.net>
Due to the success NAMN enjoyed during our recent Leonid
campaign, we
have been asked by NASA to team up with them on the upcoming
Geminid
meteor shower. The overwhelming response NASA received from their
"Leonids Live" web project promoting meteor observing
will be repeated
with a similar site for the Geminids. The web site,
http://www.geminids.com,
will attempt to keep the public informed of
what is taking place with frequent updates. NAMN observers have
been
asked to provide a large majority of the observations.
Reaching a maximum on December 14th, Geminids are visible from
around
December 7th to 17th and appear to come from the constellation
Gemini.
With the favorable moon conditions this year, the campaign will
extend
from December 10th to the 17th.
Membership in NAMN is not required to participate. However,
observers
should report their observations to meteorobs@charleston.net
as soon as
possible as updates to the web site will be made daily. No
special
reports are needed, you may use one or more of the existing forms
we
have in place to send in your observations. Reports will also be
forwarded to the International Meteor Organization as usual.
Questions about the campaign, and requests for forms or
instructions
may be sent to me at the above address. Observing forms as well
as
general information on meteor observing can also be found at the
NAMN
home page:
http://web.infoave.net/~meteorobs
The results of our Geminid campaign will be published in a future
issue
of "NAMN Notes" while the uncorrected observing periods
will be posted
at our web site.
I encourage everyone to participate with us in this effort to
promote
not only science, but meteor science in particular. I look
forward to
hearing from you, and wish everyone clear skies this month!
Happy Holidays!
Mark Davis
NAMN Coordinator
MeteorObs@charleston.net
===============
(6) HOW 2000 PEOPLE CONQUERED THE WORLD
From San Jose Mercury News, 7 December 1999
http://www7.mercurycenter.com/premium/scitech/docs/emigrant07.htm
Studies: Earliest human emigration east out of Africa, not north
BY NICHOLAS WADE
New York Times
TWO genetic surveys of human populations bring new evidence to
bear on
a pivotal event in prehistory, the first dispersal of modern
humans
from Africa.
One study, based on analysis of people in East Africa and India,
suggests that the first emigration of modern humans was eastward,
toward Asia, and not northward through the eastern Mediterranean.
A second, Stanford University research that draws on DNA data
from 50
ethnic groups around the world, concludes that the ancestral
population
from which the first emigrants came may have numbered as few as
2,000
people.
Both studies point to the most recent common ancestor of the
emigrants
as having lived 60,000 to 40,000 years ago.
Previous genetic studies have suggested 100,000 years or so for
the
most recent common ancestor, and about 10,000 for the ancestral
population size.
The younger date of around 50,000 years seems to tally much
better with
an emerging synthesis of the archaeological data relating to
human
origins.
"A combination of fossil and genetic evidence locates the
ancestral
population in Africa, and archaeological discoveries imply an
initial
dispersal out of Africa about 50 ky years ago," writes Dr.
Richard G.
Klein of Stanford University in the latest edition of his book
"The
Human Career." The term 50 ky means 50,000 years ago.
Klein believes an important distinction can be discerned in the
archaeological record between what he calls anatomically modern
humans
and behaviorally modern humans. Though the fossil remains of each
type
look the same, a more advanced set of stone tools appears with
human
remains dating back to 50,000 years or so.
Modern human sites older than this have a more primitive set of
stone
implements, similar to those used by archaic humans like the
Neanderthals.
Klein and others believe that some major genetically based
neurological
change, such as the development of language, occurred around
50,000
years ago. This transformation, he infers, was the spur that led
behaviorally modern humans to innovate their characteristic suite
of
more advanced stone implements, develop the first forms of art,
and
spread throughout the world.
Remains of modern humans dating to about 100,000 years ago have
been
found at a well-known archaeological site called Skhul in Israel.
The
finding has been interpreted as evidence of the first human
migration
out of Africa, and it fitted with the old genetic data of a
modern
human origin at this time.
But the Neanderthals occupied Europe and the eastern coast of the
Mediterranean at this time, and they or the cold climate may have
blocked any further advance in this direction.
Klein's data suggests that the humans of 100,000 years ago,
anatomically modern but not like modern people in their behavior,
did not in fact spread out of Africa at this time.
First dispersal
A new genetic study, by Silvana Santachiara-Benerecetti of the
University of Pavia and colleagues, confirms the view that the
first
dispersal of modern humans was not until about 50,000 years ago,
and
that the direction was eastward toward Asia.
The study, published in Nature Genetics last week, is based on
mitochondrial DNA, the genetic material of the small
energy-producing
organelles inside every cell. Because mitochondria are inherited
with
the egg, from the mother alone, their DNA escapes the shuffling
that
occurs in sexual reproduction, and any changes reflect the
occasional
random mutation in the DNA.
On the basis of these mutations, biologists can construct a
family tree
of mitochondrial lineages and, by estimating the mutation rate,
figure
out the time that has elapsed since the mutation at the root of
the
tree.
Santachiara-Benerecetti and her colleagues studied a particular
pattern
of mitochondrial DNA which is well-known in India. They found an
earlier form of the pattern among people in Ethiopia, suggesting
that
East Africa was its place of origin.
Signs of the pattern also exist among many people in Saudi
Arabia, but
not among inhabitants of the eastern Mediterranean. This provides
the
first genetic evidence, the Italian biologists say, that the
human
migration route out of Africa was from eastern Africa along the
coast
toward Southeast Asia and Australia.
Another new genetic study, by Marcus Feldman of Stanford
University and
others, makes an interesting counterpart to the Italian study
because
it is based on a different kind of DNA but reaches similar
conclusions.
Y chromosome indicator
Feldman and his colleagues looked at segments of the Y
chromosome,
another part of the human genome which escapes the usual
shuffling of
the reproductive process. Studying Y chromosomes from around the
world,
they conclude that the most recent common ancestor of all these
Ys was
carried by a man who lived only 40,000 years or so ago.
Even though all Y chromosomes can be traced back to a single
individual, this does not mean a single Adam was the species'
only
male representative. The founding population from which the
world's
present population is derived consisted of about 2,000
individuals,
according to the new data, Feldman said. One Y chromosome in such
a
population will eventually dominate in the descendants after all
the
other Y lineages are brought to a halt, whether because their
owners
have no children or beget only daughters.
The 40,000 year date, which has a large range of uncertainty, is
much
more recent than others, in part because these earlier estimates
were
forced to assume, quite unrealistically, that the size of the
human
population has remained constant throughout prehistory.
Exponentially expanding
Feldman assumed an exponentially expanding population, which
yields a
more recent date of origin. His study is published in the current
issue
of the journal Molecular Biology and Evolution.
The two new studies represent a convergence of the genetic and
archaeological data bearing on modern human origins, said Luca
Cavalli-Sforza, a leading population geneticist at Stanford
University.
The two independent lines of evidence support the idea that
behaviorally modern humans arose in Africa around 50,000 years
ago from
their anatomically modern forebears.
These behaviorally modern humans "had three big improvements
in culture
-- language, boats or rafts, and Aurignacian technology,"
Cavalli-Sforza said, referring to the more sophisticated stone
implements. Shortly after they had acquired these innovations,
they
burst forth to inhabit the rest of the globe.
Copyright 1999, San Jose Mercury News
================================
** LETTERS TO THE MODERATOR **
================================
(7) LARGE METEOROIDS
From Duncan Steel <D.I.Steel@salford.ac.uk>
Dear Benny,
I have read with interest the recent postings regarding the
apparent
optical detection of substantial Leonid meteoroids striking the
moon,
and congratulate all those who have contributed.
Here I would merely like to remind readers that there are reasons
to
expect that meteoroid streams will contain large objects, not
merely
the tiny fragments one detects as visual meteors in the
atmosphere.
And these large objects are *not* necessarily like the meteorites
(assumedly largely or entirely of asteroidal origin) which reach
the
ground intact.
Over the decades meteor observations in the optical region have
shown
clear evidence of fragmentation events on atmospheric entry.
Radar
data - often very difficult to interpret - have also shown
evidence
of fragmentations occurring, and this facet has been elucidated
by
recent pencil-beam radar observations reported by Taylor, Elford
&
Steel (ACM 1996 = COSPAR Conference Proceedings #10).
Those are disruptions in the atmosphere, however. There is also
evidence of (i) Fragmentation just prior to atmospheric entry, as
shown by multiple meteors with short time delays/parallel paths
substantially separated; and, significant here, (ii)
Fragmentation of
circa. 1 tonne very low density (cometary?) meteoroids close to
Earth
as evidenced by swarms of impacts upon the HEOS-2 satellite. The
investigators (Fechtig & Gruen) suggested that these were due
to very
weak structures being disrupted by electrostatic charging upon
transit through the magnetosphere/Van Allen belts, producing
clouds
of co-moving micron-scale grains which then impacted the
spacecraft
in groups, but only when it was near Earth (see Hugo Fechtig's
chapter in Comets, ed. L. Wilkening, University of Arizona Press,
1982).
Such objects, if present in the Leonid stream, might explain the
lunar impact phenomena observed recently, and yet *not* produce
the
phenomenal Leonid fireballs which would otherwise be expected
upon
atmospheric entry. An additional part of the explanation could be
that such bodies are largely composed of organic chemicals, so
that
they would ablate (either having already been split into myriad
smaller particles or not) high in the atmosphere and at a
temperature
too low to produce any optical emission (cf. D. Steel, 'The
Leonid
meteors: compositions and consequences,' Astronomy &
Geophysics, 39,
24-26, 1998).
Just some ideas to chew on.
I finally note that the work done on modelling the optical
emission
produced by Leonid meteoroids striking the lunar surface has to
some
extent already been carried out elsewhere/elsewhen, for example
by
various authors arguing for the non-existence of LAFOs (Lou A.
Frank
Objects, as designated by Al Harris).
Duncan Steel
===============
SOME CORRECTIONS ON PHAETHON, HERSCHEL & INTELLIGENCE TESTS
From Duncan Steel <D.I.Steel@salford.ac.uk>
Dear Benny,
Please could I make a few corrections and comments on recent
items carried on CCNet.
(a) Firstly, in the recent NASA Science News item concerning the
Geminid
meteor shower link with asteroid 3200 Phaethon it was stated
that:
>Years of searching proved to no avail until finally, in 1983,
NASA's
>Infrared Astronomical Satellite discovered a curious object
moving in
>the same orbit as the Geminid meteoroid stream.
One might note the following:
(1) IRAS was a joint US-UK-Netherlands project;
(2) I believe that 3200 Phaethon (= 1983 TB) was actually
identified
in amongst the images by Simon Green (an English
astronomer, then
at the University of Leicester but now at the
University of Kent);
(3) I believe that the first published notice of the similarity
of the
orbits of 1983 TB and the Geminid stream was by Fred
Whipple (the
great U.S. comet/meteor astronomer), in the IAU
Circulars;
(4) Instruments don't discover things: people discover things,
through
the intelligent usage of the data from the
instruments they have
constructed and deployed.
We must give credit where credit is due: in all respects.
(b) The above shows that getting the history right is
significant,
so one might also note that the ESA announcement in which it was
written that:
>Eta Carinae, in the constellation of the same name in the
southern
>hemisphere, has puzzled scientists ever since the famous
>nineteenth-century British astronomer William Herschel
noticed
...is a little off the mark. The Herschel concerned must have had
short-lived fame. Sir William Herschel, the discoverer of Uranus
in
1781, died more than two decades earlier than observation of the
Eta Carina outburst, having done most of his major work in the
18th
century. I imagine than the report was intended as a reference to
his son (Sir) John Herschel. I might also note that JH's son
Alexander
Herschel was a prominent meteor astronomer in the latter half of
the
19th century.
I also note on the Herschel front that the use of this as a first
name
seems to stem from this family. Charles Babbage, a close friend
of JH,
may have started the trend, naming his eldest son Benjamin
Herschel
Babbage. Nowadays there are many males given that name: in the
astronomical/astronautical connection the most prominent might be
taken
to be John Herschel Glenn.
(c) John Lewis wrote (quite correctly):
[NEO impacts] "present us with an intelligence test of
the highest order, with the highest possible stakes for
the human race."
Australia should be congratulated on winning the Rugby World
Cup, the Netball World Cup, the Cricket World Cup, and most
recently the Davis Cup (that's tennis, folks). Next year it
will host the Olympic Games, and its athletes will win many
gold medals, leading to a swell in nationalistic pride.
Unfortunately it failed the NEO intelligence test. In American
parlance one might say that this makes it a nation of jocks.
And Ivy League universities are not judged on their success as
universities on the basis of how well their sports teams perform.
Duncan Steel
(an Australian citizen)
==============
LUNAR CRATER GIORDANO BRUNO
From Michael Paine <mpaine@tpgi.com.au>
David,
Re your query about crater Bruno. I too have been searching for
more
information about the event witnessed by monks. All the
information
I have gathered is at
http://www1.tpgi.com.au/users/tps-seti/spacegd2.html#bruno
If the 1178AD event did produce the crater Giordano Bruno (note
the
full name has been important for some database searches) then it
has
significant implications for the NEO hazard on Earth. This is
because
the crater is about 22km in diameter and an impactor somewhere
around
1km in diameter would be required (I should get 'round to
checking Jay
Melosh's crater calculator for this). I would expect the average
interval between such events on the Moon to be in the 100s of
thousands,
maybe millions, of years.
My web page also has a little information about seismic readings
taken
by Apollo instruments. It seems to me that the Moon would make an
excellent NEO impact detector - the curtailment of the Apollo
experiments was indeed short-sighted.
Michael Paine
==================
REFERENCE TO WATCHFUL CLERICS
From Rolf Sinclair <rolf@santafe.edu>
"Does anyone know of a Web (or other) reference to an
account of the
large impact observed by Canterbury monks in 1178..."
Hi David --
The first such reference I believe is J. B., Hartung (1976)
Meteoritics Vol. 11, 187-194. There have been subsequent papers
arguing with the conclusions.
Rolf
===================
IN DEFENSE OF MILANKOVIC'S ICE-AGE THEORY
From Steve Drury < s.a.drury@open.ac.uk
>
The oddest thing about the climate of the last 2.5 million years
is
that it reveals shifts in the volume of water stored as ice on
the land
surface that have a first-order cyclicity. This is revealed by
the
oxygen isotope variations in shells from ocean-floor
sediments.
Evaporation favours light oxygen-16 in water vapour, so if water
is
transferred from the oceans to semi-permanent storage in ice
masses on
land, in chemical isolation from sea water, the remaining sea
water
becomes enriched in the heavier oxygen-18. Tracing the variation
of
ocean-water O-18 by measuring its relative contribution to the
oxygen
in shell carbonate is therefore a proxy for fluctuations over
time in
the volume of continental ice caps.
This isotopic proxy reveals about 50 periods of ice-cap growth in
the
last 2.5 million years, with intervening, shorter episodes of
their
decline; a repetition of glacial and interglacial periods. The
cycling
has remarkable regularity, which is revealed by frequency
analysis of
the oxygen-isotope record. For the last 0.7 million years this
has been
dominated by a 100 thousand-year periodicity. For times between
2.5 and
1.2 million years the dominant frequency was 40 thousand years.
In the
1.2 to 0.7 million-year period signals for 100, 41, 23 and 19
thousand
years emerge clearly from the frequency analysis. The four
periodicities are exactly those calculated my Milutin Milankovic
for
controls over insolation by the changing orbital and rotational
properties of the Earth, themselves induced by interactions
between the
gravitational fields of massive planets orbitting in the Solar
System.
Whether or not the shifts in insolation that result from
astronomical
behaviour of the Earth are large enough directly to cause climate
shifts of the scales involved - and the present dominant forcing
by 100
thousand-year fluctuation of orbital eccentricity is certainly
far too
small - Milankovic's tune is the one to which the Earth's climate
has
danced for the entire history of human evolution. Indeed, its
recording
extends back far beyond that, though there is scant evidence for
major
ice caps in the northern hemisphere before 2.5 million years ago.
This remarkable coincidence between empiricism and prediction
leaves
little room for random controls over climate by tangible and
essentially random events of extraterrestrial or interal origin,
such
as the effects on atmospheric chemistry by bolide impacts, that
Hoyle
and Wickramasinghe demand, or major episodes of volcanism once
favoured
by others.
No doubt there have been random impacts, large and small in the
last
2.5 million years. However to implicate them in deglaciation
demands
evidence. Such is the precision of the oxygen-isotope for the
sudden
shift from full glacial conditions at the end of the last ice
age, and
likewise for the sharp descent into and then emergence from the
lesser
though nonetheless chilly Younger Dryas - possibly decadal events
-
that we know exactly where and when to seek evidence. A 10e13 kg
bolide
and a 'rain-out' of 10e17 kg displaced water vapour would leave a
signal in the delicate near-continent, ocean-floor sedimentary
record -
most likely signs of increased influx of terrigenous sediment
through
continental erosion. But that is not the point. Impacts
approximating
Gaussian distributions of period and energy, and regular
glacial-interglacial shifts do not sit well together.
Most climatologists, perhaps even mercenary 'renegade scientists'
- the
metaphor of wagon trains carrying guns to Crazy Horse and Sitting
Bull
before Little Big Horn is difficult to avoid - eschew notions
that
Milankovic's processes alone force glacial cyclicity. That
the
land-ice record parallels the insolation shifts for the northern
hemisphere more or less knocks that one on the head. Nor is it
likely
to be some atmospheric blocking effect that 'turns on' and 'shuts
off'
the rhythm. Current views are moving towards changes in deep
ocean
circulation - the halt and re-establishment of equatorward
movement of
North Atlantic Deep Water, which draws warm surface water
polewards
during the present interglacial, and probably did in previous
warmings.
Contrary to Hoyle and Wickramasinghe's unique notion that
"Melt water
from arctic glaciers has gradually filled the lower ocean with
water
close to freezing", it is the sinking of dense cold brines
left over by
the formation of sea-ice - which has very low salinity - that
presently
drives high-latitude warming in the North Atlantic. The
sensitivity of
this to the salinity of surface water and to the formation or not
of
sea-ice in a restricted area around Iceland appears to be the
key. The
balance seems exquisitely sensitive, as there is evidence for
shifts to
'on' and 'off' for deep circulation within the last glacial that
relate
to purges of fresh water from the ice caps.
Climatologists still do not agree on what it is that superimposes
the
tiny Milankovic insolation cycles on the vastly more energetic
oceanic
circulation, and those of water vapour and heat in the
troposphere.
Albedo shifts undoubtedly play some role in 'hardening' glacial
trends
when established, but more those associated with snow and ice
mass than
with ice-crystal scattering. Its function seems synergistic
rather than
some mechanical determinant as Hoyle and Wickramsinghe claim.
The point that Hoyle and Wickramasinghe miss regarding the
significance
of carbon dioxide vis a vis water vapour as 'greenhouse' agents
is that
of atmospheric residence time. Water's is short whereas that of
CO2 is
longer. The latter can build through anthropogenic emissions, as
it
does. The perverse feature of warming trends, whether natural or
anthropogenic, is not that they might stave off the next glacial
round,
but the opposite. Global warming combined with greater
precipitation
from poleward winds at high northern latitudes, which freshens
surface
ocean water, work to shut down deep-water formation and thereby
the
warming influence of the Gulf Stream - North Atlantic Drift. At
the
very least this would chill the North Atlantic rim, and at worst
hasten
the onset of full glaciation by an increase in high-latitude
albedo due
to increased snow mass.
The misconceptions by the authors are so deep that the essay
seems to
be a polemic not an essay, seeking to maintain the growth of
greenhouse
emissions and the economic circumstances that lie at their root.
The
intricacies of the climate system, and its inherent instability,
threaten to increase rather than decrease the possibility of
catastrophic climatic and social change, should emissions
continue
rising and means of countering past output not be sought.
Steve Drury
Earth Sciences, Open University
==============
NO UNIFORM GLOBAL ICE-AGE
From Alasdair Beal < a.beal@btinternet.com
>
The essay by Fred Hoyle and Chandra Wickramasinghe about ice ages
is
interesting and makes some good points about the likelihood of a
catastrophic explanation but they are surely wrong in insisting
that
the last Ice Age involved solely uniform worldwide cooling. Three
hints that more than just cooling was involved are that
(i) during Ice Age, the present Arctic and places like northern
Siberia were largely unglaciated and
(ii) the location of the centre of the northern ice cap was in
what
is now Hudson's Bay, which is outside the present Arctic Circle.
The odd geography of this ice cap suggests strongly that pole
shift
needs to be considered as an explanation. A shift in the Earth's
poles at the end of the Ice Age (caused presumably by a cosmic
impact
or close encounter) would also explain the remarkably rapid
temperature rises which were experienced - and the fact that
although
most places suddenly got warmer, northern Siberia and the high
Arctic
got colder and have stayed that way ever since.
Yours sincerely,
Alasdair Beal,
Editor, SIS Chronology & Catastrophism Review,
10 King George Avenue,
Chapel Allerton,
Leeds LS7 4LH,
Great Britain
=============
AND FINALLY: HAPPY (332nd) BIRTHDAY, WILLIAM WHISTON
William Whiston
b. Dec. 9, 1667, Norton, Leicestershire, Eng.
d. Aug. 22, 1752, Lyndon, Rutland
From Encyclopaedia Britannica
http://britannica.com/bcom/eb/article/1/0,5716,78831+1,00.html
Anglican priest and mathematician who sought to harmonize
religion and science, and who is remembered for reviving in
England the heretical views of Arianism.
Ordained in 1693, Whiston served from 1694 to 1698 as
chaplain to John Moore, Anglican bishop of Norwich. During
this period he wrote A New Theory of the Earth (1696), in
which he claimed that the biblical stories of the creation,
flood, and final conflagration could be explained
scientifically as accounts of events with historical bases.
After three years as vicar of Lowestoft (1698-1701), he
returned to Cambridge, his alma mater, as assistant to the
mathematician Sir Isaac Newton, whom he succeeded as
professor in 1703.
From the works of early Christian writers, Whiston was led
to Arianism, a doctrine that denied the divinity of Christ.
Deprived of his professorship in 1710 because of his
unpopular notions, Whiston organized a society for the
revival of primitive Christianity, whose members met weekly
in his London home (1715-17). Finally, in 1747, he left the
Church of England to join the General Baptists. Among
Whiston's other works are The Accomplishment of Scripture
Prophecies (1708), Primitive Christianity Revived, 5 vol.
(1711-12), a translation (1737) of the works of the Jewish
historian Josephus, a revision (1745) of the King James
Version of the New Testament, and his own Memoirs
(1749-50).
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