CCNet 143/2002 - 10 December 2002
"Meteor showers are supposed to come from comets. But 3200 Phaethon
doesn't act like a comet, says Cooke. "3200 Phaethon doesn't sprout a
tail when it comes close to the Sun. It doesn't have a halo or a
coma ... in fact, based on its orbit and the way it reflects sunlight, it
seems much more like an asteroid." Perhaps, he speculates, it's a little bit
of both. An asteroid, a comet, a comet corpse? The meteors are lovely no
--NASA News, 9 December 2002
"After the years of research that followed upon the discovery, the
lake in Prati del Sirente is now proposed to be the first known impact
crater in Italy.... Radiometric carbon dating of material in one of the
cores from the rim gave that the elevated rim is formed by overturned
material in a way typical for impact crater rims, and that the age of
formation could be set to the 4th or early 5th century AD."
--Jens Orm÷, Angelo Pio Rossi, and Goro Komatsu, Tumbling
Stone, November 2002
"A remarkable aspect of astrobiology, or xenoscience if you prefer,
is that nobody really knows anything."
--Kenneth Silber, Tech Central Station, 9 December 2002
(1) YOUNG IMPACT CRATER FIELD DISCOVERED IN ITALY (4Th-5TH CENTURY AD)
Tumbling Stone, November 2002
(2) THE DARK AGES: WERE THEY DARKER THAN WE IMAGINED?
Universe, September 1999
(3) FIREBALL FRAGMENTS MAY BE SCATTERED ACROSS COUNTY
The Montrose Daily Press, 9 December 2002
(4) METEORS FROM THE TWILIGHT ZONE
NASA News Service, 9 December 2002
(5) FEATHERWEIGHT JUPITER MOON IS LIKELY A JUMBLE OF PIECES
(6) EXTRATERRESTRIAL INFLUENCES ON MANTLE PLUME ACTIVITY
Dallas H. Abbott and Ann E. Isley
(7) COSMIC PRO-LIFERS
Tech Central Station, 9 December 2002
(8) AND FINALLY: THE TECHNOPHOBES
Yahoo News, 5 December 2002
(1) YOUNG IMPACT CRATER FIELD DISCOVERED IN ITALY (4Th-5TH CENTURY AD)
>From Tumbling Stone, November 2002
The discovery of the Sirente Crater Field
by Jens Orm÷, Angelo Pio Rossi, and Goro Komatsu
In the Prati del Sirente plain in the heart of the Abruzzo mountains, a
small circular lake is clearly visible. A prominent ridge encircles the
lake. The peculiar appearance of the lake drew the attention of this papers
first author (Jens Orm÷) when working in Pescara between 1999 and 2002. Jens
did at that time a European Union Marie Curie post-doc as an impact
geologist at the International Research School of Planetary Sciences
(IRSPS), Universita d'Annunzio. After the years of research that followed
upon the discovery, and which we will describe in this article, the lake in
Prati del Sirente is now proposed to be the first known impact crater in
The discovery of the Sirente crater was a pure coincidence, but nevertheless
shows the importance of mobility of researchers with different experiences.
People with different backgrounds look at things with different eyes.
While preparing for a weekend hike in the mountains Jens saw a photo in a
guide book of the Sirente Regional Park. It showed a high plain in the
Sirente massif with a small circular lake at the centre. Small lakes are
common in the Abruzzo mountains, but this one is encircled by an elevated
rim, which makes it exceptional. A study group was formed with the
colleagues Angelo and Goro. A first reconnaissance trip to the lake gave
that the lake was larger than first expected and that it showed a striking
resemblance to small impact craters known from other areas in the world.
Due to the geological setting of the lake and its voluminous elevated rim it
was soon clear it is not a karstic feature.
After ruling out some other alternative causes of formation based on the
local geology (e.g. volcanic), only three plausible alternatives remained:
periglacial feature (i.e. Pingo), a man-made water reservoir, or an impact
Due to fact that the rimmed lake is formed entirely in soft sediments, no
breccias (see. dict.) or other rocks typical for impacts into solid targets
occur. The work had to be focused primarily on a detailed description of the
morphology and the age of formation.
The morphology was studied by detailed levelling of the elevated rim and
close surroundings. This gave that the elevated rim rises about 2.2 m above
the surrounding plain and that it is 15 m wide. It was also evident that the
lake was slightly oval with a maximum rim-to-rim diameter of 140 meter. The
studies continued with core drillings, one near the centre of the lake (7
meters in length) and two on the elevated rim (3 meters and 5 meters in
length). The core drillings confirmed that the lake depression is developed
entirely in soft sediments. Radiometric carbon dating of material in one of
the cores from the rim gave that the elevated rim is formed by overturned
material in a way typical for impact crater rims, and that the age of
formation could be set to the 4th or early 5th century AD.
At this point the periglacial alternative was ruled out, mainly due to the
young age of formation. We also discovered that the morphology of the crater
rim corresponded exactly to what can be expected at an impact crater in this
specific target material. At a crater formed in solid rock, the ejected
material at the rim rests on a surface that has been uplifted due to
brecciation of the rock (volume expansion) and displaced material below the
rim. In a target consisting of wet clays, however, the shock will cause a
compaction of the target (volume decrease). This has been noted at both
experimental craters and impact craters. At Sirente this is visible as a
depression along sections of the crater rim as well as in the drill cores.
Theoretically, an impact crater of the size of the Sirente lake depression
cannot exist alone. It must be surrounded by a field of small craters. This
is due to the fact that small cosmic objects that approach the Earth would
fragment during the passage through the atmosphere. A common velocity of
such objects (e.g. asteroids and comets) when they impact the Earth is about
20 km/second. It is more than 20 times the velocity of a bullet from a
high-velocity rifle. The collision with the atmosphere generates so high
stresses in the object that it breaks apart. Only objects forming craters
larger than about 1 km in diameter can survive the passage through the
atmosphere as reasonable coherent bodies. Hence, the study at Sirente
continued with a survey of the surrounding plain. It was soon clear that the
lake was the largest crater in a field of craters. The crater field covers
an area somewhat less than a square kilometre, which is the correct
dimensions compared to what has been calculated for impact crater fields
based on the dynamics of atmospheric break-up. The probability for the
remaining alternative formation, a man-made construction, decreased
drastically with the discovery of the crater field.
It is known that when an object strikes the ground with such a high velocity
that it generates a crater of the size of the Sirente lake depression, most
of the object would melt and vaporise. However, the broken off fragments may
get their velocities so reduced by atmospheric friction that they merely
penetrate into the ground without disintegrating. The process can be
compared with the impact of a high-velocity rifle bullet, although the
larger size of the fragments and the still high velocity (about 5-7
km/second) generate craters a few meters in diameter. These fragments would
be responsible for the smaller craters in the Sirente crater field.
Meteorites often have a magnetic signature that is different from the
present Earth magnetic field. This can generate distinctive magnetic
anomalies. To investigate if any of the smaller craters contains meteoritic
fragments, a magnetic survey of the crater field was performed together with
colleagues from the Istituto Nazionale di Geofisica e Vulcanologia in Rome.
Preliminary results from this survey indicate sources of magnetic anomalies
at some meters depth in most of the small craters, but the evaluation of the
data is not yet concluded.
Two adjacent small craters in the crater field were excavated to about 9
meters deep in order to investigate the source of the magnetic anomalies and
to reveal the subsurface morphology. The excavation did not retrieve any
macroscopic meteoritic fragments, possibly due to that it did not reach deep
enough. It is estimated that any meteoritic fragments would be at least 12
meters below the surface. Instead soil samples were obtained for geochemical
analyses. These analyses are not yet finished. In addition, several other
discoveries were made during the excavation, which gave further support to
the formation by a meteoritic impact.
It is very unlikely that any meteoritic material is exposed on the ground
surface at the Sirente crater field. Due to the soft target, any meteoritic
fragments would have penetrated too deep to be recoverable. In the large
crater that contains the small lake, the meteorite exploded and vaporised at
impact. Thus, there is no large meteorite hidden below the lake.
Detailed results from the studies of the Sirente main crater and the crater
field will be published in the November issue of the international
scientific journal Meteoritics and Planetary Science. The studies of the
Sirente crater field are a continuous project and previous results are
constantly being updated by new data. The results from the latest
excavations mentioned above are not yet published.
The morphology of the main crater and its relation to a crater field
strongly supports a meteoritic impact origin. The research is now focused on
finding geochemical traces of the meteorite, which would provide unequivocal
evidence for a meteoritic impact.
The Sirente crater field is of great value for the researchers, and to the
Sirente-Velino Regional Park. We would like to express our gratitude to the
former park director Edoardo Alonzo who gave a great support to our studies
in the park. Due to the soft material of the crater it is very sensitive for
erosion, especially the elevated rim. Only the this grass cover protects the
craters from being destroyed by rain wash and wind. We would like to advice
any visitors to be very careful not to damage the grass cover.
There are about 155 known impact craters in the world. Many of them are
millions of years old and very eroded. Due to the geologically young age of
Italy no impact craters have been found until today. The Sirente main crater
and its adjacent smaller craters are very small compared to most the other
impact craters in the world. However, due to the young age, the craters are
very well preserved. They provide a rare, and valuable, example of an impact
into a soft target.
For more information please contact:
Dr. Jens Orm÷ (email: firstname.lastname@example.org), Principal Investigator of the Sirente
Angelo Pio Rossi (email: email@example.com) and Dr. Goro Komatsu (email:
Copyright Tumbling Stone 2002
(2) IS ITALIAN IMPACT CRATER FIELD LINKED TO THE FALL OF THE ROMAN EMPIRE?
>From Universe, September 1999
THE DARK AGES: WERE THEY DARKER THAN WE IMAGINED?
By Greg Bryant
Any history text will say that the Dark Ages refers to the period after the
fall of the Roman Empire in the middle of the 1st Millennium (it was not
sponsored by the International Dark Sky Association). It was a time when
European civilisation stagnated - even that term is a generous description
of the living standards and social setting of the next few centuries. In a
broader sense, however, "Dark Ages" can be applied to a few eras of social
upheaval over the last several thousand years, which fits in nicely with
what you're about to read - stay with me, as the possible astronomical
implications will soon become apparent.
Physical Aspects Of The Dark Ages
Let's first look at the onset of "the" Dark Ages in the sixth century AD.
The Roman Empire was finished, nothing was happening in the sciences, and
worse was happening in nature. The Italian historian Flavius Cassiodorus
wrote about conditions that he experienced during the year AD 536 :
"The Sun...seems to have lost its wonted light, and appears of a bluish
colour. We marvel to see no shadows of our bodies at noon, to feel the
mighty vigour of the Sun's heat wasted into feebleness, and the phenomena
which accompany an eclipse prolonged through almost a whole year. We have
had a summer without heat. The crops have been chilled by north winds, [and]
the rain is denied."
Other writers of the time described similar conditions :
Procopius : "...during this year a most dread portent took place. For the
Sun gave forth its light without brightness...and it seemed exceedingly like
the Sun in eclipse, for the beams it shed were not clear."
Lydus : "The Sun became dim...for nearly the whole year...so that the fruits
were killed at an unseasonable time."
Michael the Syrian : "The Sun became dark and its darkness lasted for
eighteen months. Each day it shone for about four hours, and still this
light was only a feeble shadow...the fruits did not ripen and the wine
tasted like sour grapes."
Was this a local phenomenon? According to the book "Volcanoes of the World",
Dr. Timothy Bratton has noted that there was a small eruption of the volcano
Mt. Vesuvius in AD 536. Could this be the cause? It may well have
contributed to the scene (although the eruption was much smaller than the
big one of AD 79), but it can not really account for the similar conditions
that were experienced around the world.
In China, "the stars were lost from view for three months". Records indicate
that the light from the Sun dimmed, the expected rains did not eventuate,
and snow was seen in the middle of summer. Famine was widespread, and in the
midst of the turmoil, the Emperor abandoned the capital.
Bad luck tends to get bunched together, and thus came the plague. The
Justinian Plague, named after the Byzantine Emperor of the time, is reported
to have begun in central Asia, spread into Egypt, and then made its way
through Europe. By some accounts, it was as bad as the Black Death which
"plagued" Europe in the Middle Ages.
A Different Branch Of The Picture
Mike Baillie is Professor of Palaeoecology at Queens University, Belfast,
Northern Ireland. He is an authority on tree rings and their use in dating
ancient events (every year, a tree adds a "ring" to its trunk as it grows -
good years are represented by thick rings while bad years are represented by
thin rings). He conducted a complete (and continuous) review of annual
global tree growth patterns over the last 5,000 years and found that there
were five major environmental shocks that were witnessed worldwide. These
shocks were reflected in the ring widths being very thin. Wanting to know
more, he turned to human historical records, and found that the years in
question (between 2354 and 2345 BC, 1628 and 1623 BC, 1159 and 1141 BC, 208
and 204 BC, and AD 536 and 545) all corresponded with "dark ages" in
The minimal growth of trees around 2350 BC has been associated in the past
with the eruption of a volcano in Iceland. Yet, the period in question is
also associated with floods, the creation of new lakes, and even the start
of Chinese history. Furthermore, Marie-Agnes Courty, an archaeologist from
France, has claimed new data regarding a catastrophe said to have occurred
in the Middle East. Samples from three separate regions all appear to
contain a calcite material found only in meteorites, and analysis of debris
show what seems to be a combination of "a burnt surface horizon and air
Indeed, some 40 cities throughout North Africa, the Middle East, Europe, and
Asia are thought to have been devastated, or even disappeared, about the
same time in a series of catastrophes.
The twelfth century BC is associated with the "Greek Dark Ages", the end of
the Hittite civilisation in the Near East, the end of Bronze Age Israel, and
the end of the Bronze Age Shang dynasty in China. Ancient Chinese history
has the notion of "mandate from heaven", where the rulers were essentially
subject to the whims of the sky above. Strange sights in the sky would not
be seen as good news for Chinese Emperors. Indeed, around this time, Chinese
records speak of:
"...many gods and spirits were annihilated in this battle, and several
stellar dignitaries were replaced by newcomers to the celestial domains."
What could cause such global shocks? A likely answer, which has a good fit
to the evidence, was what the European and Chinese observers described at
the time as "dragons in the sky" - comets! We're not talking about an intact
large comet (if that had hit in the last several millennia, we would not be
here today), but rather fragments from a disintegrating comet or asteroid
(small pieces like that which hit Tunguska in 1908). These would throw up
dust that would envelope the world and dim our view of the Sun and skies.
All this sounds like an interesting theory, but is there any evidence "above
us" that fits in with the scenario. How do we account for so many impacts
over the last several millennia when the consensus today in astronomy is
that impacts causing global consequences (mild as well as major) are very
Enter The Astronomers
Independently of Baillie's studies, British astronomers were putting
together an explanation of the Taurid meteors that we see. The Taurids are
related to comet Encke, as first shown by Fred Whipple, best known for
proposing the "dirty snowball" model of comets. Mark Bailey, Victor Clube
(brother of my rugby coach at school!), and Bill Napier put forward the
theory that Encke and the Taurid meteors originated from a giant comet that
fragmented some 40,000 years ago after entering the inner Solar System. The
idea of a comet splitting up into smaller pieces is nothing new (witness
Shoemaker-Levy 9 in 1994 and the return this year of the fragmented periodic
comet Machholz 2), and indeed Dr. Brian Marsden of the Smithsonian
Astrophysical Observatory is the originator of the idea that the bulk of
sungrazing comets we see come from a large comet that perhaps originally
split a few centuries before Christ, and has split again - this family of
comets is known as the Kreutz sungrazers.
The astronomers noted that Chinese records of meteor observations over the
last two thousand years revealed significant surges in the number of meteors
observed every few centuries. These tended to be observed at the same time
every year - we now know of them as the Taurids, which has a nighttime
display in October/November (the Taurids South and Taurids North - see the
end of the article), and a daytime appearance in June (Beta Taurids). Both
meteor showers are linked. The Taurids South and Taurids North are what
Earth encounters as the Taurid meteor stream heads towards perihelion,
whilst the Beta Taurids are encountered as the meteor stream heads away from
Unlike the most prominent annual meteor showers, the Taurids are not known
for being spectacular because the stream is too broad. Whatever caused the
Taurids must have been huge, as it was suggested many years ago as the
primary source for dust in the inner Solar System. It is argued that comet
Encke itself is a fragment of this larger, inactive comet.
Such a scenario implies that there are other objects in the Taurid stream,
much larger than dust, that are unobserved because they are inactive. Is
there any evidence for large objects in the Taurids hitting Earth in recent
history? Consider the following :
In late June, 1178, an English monk reported the observation by five men of
what is believed to have been an impact on the Moon. The American
astronomer-geologist Jack Hartung has argued that this reported impact
created the Giordano Bruno crater, known to be one of the youngest craters
on the Moon. The timing of this event, late June, is consistent with the
In his book "Rogue Asteroids and Doomsday Comets", former AAO astronomer
Duncan Steel describes the fall of a meteorite on 25th June, 1890 near
Farmington, Kansas. Besides its obvious timing with the Beta Taurids, the
meteorite is most notable for being the youngest meteorite known (in terms
of exposure to space). Dating of the meteorite has revealed it was separated
from its parent less than 25,000 years ago (a factor of ten younger than the
next youngest meteorite).
Tunguska : On 30th June, 1908, a fragment believed to be less than 100m in
diameter exploded over the Tunguska river in Siberia. It is the most
well-known impact we know of in modern times. It is generally believed that
the timing of the impact is consistent with it originating from the Beta
When the astronauts went to the Moon, they placed seismometers on the Moon's
surface. At the end of June, 1975, they registered their major series of
lunar impacts. The impacts were detected only when the nearside of the Moon
(where the astronauts landed) was facing the Beta Taurid radiant. At the
same time, there was a lot of activity detected in Earth's ionosphere, which
has been linked with meteor activity.
Obviously, given the presence of comet Encke, and the additional fact of
various known Apollo-class asteroids which are observed to have orbits that
resemble those of the Taurids, there is more in the Taurid meteor stream
than just dust. According to Duncan Steel, some of the discovered
Apollo-class asteroids that are in the Taurid meteor stream have diameters
in excess of one kilometre. How many other Tunguska-type bodies are in it?
Are they isolated, or do they exist in swarms?
Meteor streams orbit the Sun, like the planets, but their orbits tend to be
perturbed by the planets. The astronomers calculated how the orbit of the
Taurids has changed over the centuries.
In "Lessons from Jupiter" (Southern Sky magazine, January/February 1995),
Clube and David Asher wrote :
"Calculations based on an orbit related to that of P/Encke reveal
intersections with the Earth's orbit around AD 600 and before that AD 400,
so that a swarm would have been near the Earth's orbit for a duration of a
few centuries around that epoch, the time of the European Dark Age. This
then is a critical extended period when we might well expect several multi
megaton [explosive] events, indeed a great many if we consider the globe as
a whole. The perspective is evidently one in which we expect the Roman
Empire to have gone into decline owing to multiple-Tunguska bombardment
causing great tracts of land to be deserted and whole communities or nations
to be suddenly dislocated. Of necessity, the period becomes one of barbaric
Chinese historical records of AD 540 say :
"Dragons fought in the pond of the K'uh o. They went westward....In the
places they passed, all the trees were broken."
The calculations for the Taurids suggest that we pass through the core of
the meteor stream approximately every 2,500 years - today, we are passing
through the outer edges. The last two occasions when we passed through the
core were in 2200 - 2000 BC and in AD 400 - 600. The epoch around AD 3000
looks like being a fun time too - the Y2K doomsayers can always say they
just got the millennium wrong.
In 1983, the orbiting IRAS infra-red satellite discovered cometary "trails"
(not tails), representing debris along the path of various short-period
comets. These trails consist of debris, most of which would be microscopic
in size, but how many large objects are there in the trails? If there are
many large objects in these trails, then Duncan Steel notes in his
above-mentioned book :
"A large fraction of the objects on Earth-crossing orbits, of all
dimensions, are the daughter products from the break-up of a giant comet
some time during the past 100,000 years, dynamical studies suggesting around
20,000 years as likely. All that is suggested here is a break-up similar to
that undergone by P/Shoemaker-Levy 9 in 1992, except by a comet at least 100
kilometres across and in an orbit crossing from Jupiter to the Earth.
The core of the complex...evolves to have a node near 1 AU every millennium
or so, at which time the Earth is bombarded by many [large] objects in
episodes at certain times of year. It is these events that dominate the
hazard to humankind. Such an episode would last for a century or two."
Ben Rudder, an anthropologist who reviewed in New Scientist magazine a
recently published book by Baillie on the subject, wrote:
"If Baillie is right, history has overlooked probably the single most
important explanation for the intermittent progress of civilisation. Worse,
our modern confidence in benign skies is foolhardy, and our failure to
appreciate the constant danger of comet "swarms" is the result of a myopic
trust in a mere 200 years of "scientific" records."
Baillie himself notes that :
"There is, I feel, a strong case for the contention that we do not inhabit a
benign planet. This planet is bombarded relatively often. If this story is
correct, we have been bombarded at least three times - and probably five
times - since the birth of civilisation some 5,000 years ago. And each time,
the world was changed."
In their book "The Origin Of Comets", Bailey, Clube, and Napier write :
"the destruction and chaos accompanying the fate of the Roman empire [midway
through the First Millennium] was all but total, the almost complete
breakdown of the old order leading to a loss of the accumulated knowledge
and wisdom of antiquity which was far from temporary."
Some of these ideas you may have heard of before. In the 1950s, Immanuel
Velikovsky published a number of books, in particular "Worlds In Collision",
which suggested that a huge comet had come near to Earth, and had indeed
settled into an orbit around the Sun between Mercury and Earth. Velikovsky
was claiming that Venus was a large comet!
Naturally, his ideas were rubbished. They had no scientific foundation. The
problem today, as Duncan Steel notes, is that astronomers have become so
entrenched in their rightful criticism of Velikovsky's nonsense, they are
rejecting today's scientifically-founded discoveries that the myths and
records of ancient civilisations may contain important information about
what was happening in the sky.
Only now are we seriously contemplating the view that "near-Earth space" is
anything but safe. Is it possible that the ancients were not entirely
ignorant in their beliefs of the appearance of comets being a bad omen?
Fragments hitting the ground would cause earthquakes and blast damage, as
well as start forest fires (fire storms?) and perhaps volcanoes - which in
turn would amplify the environmental effects through the release of soot
into the air. Fragments hitting the water would generate tsunamis which
would flood coastal and inland regions. Would it surprise you to learn that,
according to Baillie, the ancient Celtics had an oath which translates as :
"We will not move from this place until the stars fall from the sky, the
earth quakes and the sea comes over the land."
In "Lessons from Jupiter", Clube and Asher wrote :
"We do not of course deny a general background of [Earth-crossing asteroids]
from the asteroid belt but it is these meteoroidal streams, harbouring
swarms of super-Tunguska debris, which are now perceived as the source of
high-level dust veils and low-level airbursts in the atmosphere, essentially
controlling climate and extinction on Earth and punctuating the course of
If our eyes weren't opened to the danger of fragmenting bodies after we saw
Shoemaker-Levy 9, they should be now. Observatories are conducting surveys
of the sky to discover and track near-Earth asteroids. The consensus of the
astronomical community, however, still remains that the threat to Earth
comes from random asteroids and comets. The idea of the inner Solar System
being different now to from what it was 50,000 years ago has not been widely
accepted. Nevertheless, more astronomers are open to the dangers associated
with an object (currently known or to be discovered) that fragments in the
future. Dealing with any incoming fragments, however, still remains a
problem. You might think that "planetary defence" is a recent idea. Yet,
readers of the poetry of Lord Byron might be interested to know that in
1822, when he was living in Pisa, he wrote :
"Who knows whether, when a comet shall approach this globe to destroy it, as
it often has been and will be destroyed, men will not tear rocks from their
foundations by means of steam, and hurl mountains, as the giants are said to
have done, against the flaming mass? And then we shall have traditions of
Titans again, and of wars with Heaven."
An Observing Postscript
Although Comet Encke is only visible every 3.3 years (it returns next year),
we can observe the Taurid meteor stream every year. As mentioned above, they
have a broad display rather than a well-defined peak. Although their
activity spans the period 1st October to 25th November, there are two
separate maxima. The Taurids South maximmum lasts for about a week around
5th November, while the Taurids North maximum similarly lasts for about a
week around 12th November - the two virtually overlap each other to produce
The rates aren't high (at best, about 5 per hour) but they are easily seen,
slow moving, and they have a reputation for producing very bright fireballs
- a fact that has apparently been observed for thousands of years! The
Taurids are visible during this period from late evening onwards, and with
New Moon occurring on Monday 8th November, there will be no moonlight
interference - the shower is well timed for the Society's monthly star party
at Wiruna. Regardless of whether you're at Wiruna or elsewhere, if the
weather is good, why not step outside and keep an eye on the sky - it will
only be a week or two before the Leonids.
One thing is for certain: debris from the Solar System does hit Earth. If it
didn't, we wouldn't see meteors every night! The astronomical community (in
particular, those who specialise in comets and/or asteroids) is not yet
convinced as a whole about the notion of the inner Solar System currently
suffering from periodic bombardment from the remains of a fragmented giant
comet. Nevertheless, David Morrison, principal author of NASA's Spaceguard
Survey Reports in 1992 and 1995, and a critic of the British viewpoint, does
admit that :
"While I believe that the British neo-catastrophists are wrong about the
threat to Earth, their work is science, not pseudoscience. They are making
their case to other scientists, and time will sort out who is right and who
Regardless of whether the specific theories referred to in this article turn
out to be correct, observing comet debris hitting Earth's atmosphere now
seems to take on a whole new perspective in our "enlightened ages".
Copyright 1999, Universe
MODERATOR'S NOTE: See also "Tree Rings challenge History"
(3) FIREBALL FRAGMENTS MAY BE SCATTERED ACROSS COUNTY
>From The Montrose Daily Press, 9 December 2002
MONTROSE -- A meteor that lit up the night sky Nov. 28 may have weighed up
to a ton and broken up over western Colorado, researchers from the Denver
Museum of Nature and Science have found.
Montrose and Gunnison counties "are likely locations" to find meteorites
from the meteor, which broke up while plummeting through the atmosphere,
according to a report from the museum.
The museum has been gathering data on the event, which produced hundreds of
sightings and was captured by a camera atop Montrose High School.
"The eyewitness reports are especially helpful in determining the track of
the fireball," said Jack Murphy, curator of geology and head of the museum's
meteorite research team. "Due to all the sightings lately, there's a
curiosity factor that has prompted people to watch for meteors, and that
will help our research."
The meteor may have left more than a memory of a lifetime for Western Slope
residents, Murphy said. The fireball may have scattered meteorites
throughout Montrose and Gunnison counties.
"Researchers are determining the object's orbit through the solar system,"
the report says. "Meteorites recovered after a big fireball such as this are
found to originate from a parent body in the asteroid belt, a well-known
region between Mars and Jupiter."
The images captured at Montrose High School, which is part of the museum's
All Sky network of cameras, show the meteor breaking up in the atmosphere
about midway through its descent, the report says.
Copyright 2002 The Montrose Daily Press.
(4) METEORS FROM THE TWILIGHT ZONE
>From NASA News Service, 9 December 2002
December 9, 2002: The Geminid meteor shower has begun.
It started on Saturday, Dec. 7th, when our planet entered a cloud of dusty
space-debris. The meteor rate is low now, because we're still in the
outskirts of the cloud, but it will increase as Earth penetrates the debris
field. "We expect to see more than 100 meteors per hour when the shower
peaks on Saturday, Dec. 14th," says Bill Cooke of the NASA/Marshall Space
"The Geminids are one of the best annual meteor showers," says Cooke.
Geminid meteors are bright, plentiful, and sky watchers can see them from
both hemispheres. And that's not all...
"I enjoy the Geminids because they come from the Twilight Zone," he laughs.
Meteor showers are supposed to come from comets. "Comets are big chunks of
ice mixed with some amount of dust and rock," explains Cooke. When they
swing by the Sun, the ice evaporates; clouds of dust and gas spew into
space--"that's why comets have tails," he says.
The source of the Geminid shower is an object called 3200 Phaethon.
Discovered in 1983 by NASA's Infrared Astronomical Satellite, Phaethon
shares its orbit with the Geminid meteoroids. Furthermore, it is about the
right size to be a comet. So far, so good...
But 3200 Phaethon doesn't act like a comet, says Cooke. "3200 Phaethon
doesn't sprout a tail when it comes close to the Sun. It doesn't have a halo
or a coma ... in fact, based on its orbit and the way it reflects sunlight,
it seems much more like an asteroid."
Perhaps, he speculates, it's a little bit of both.
"It has become quite obvious in recent years that our nomenclature in
astronomy is not keeping pace with our discoveries. We like to place objects
in neat well-defined categories even though Mother Nature makes no such
distinctions. For instance, is Pluto a planet or a Kuiper-belt asteroid?
When does a Jupiter-like planet become a brown dwarf?"
Likewise, he asks, "after a comet has gone around the Sun so many times that
its ices are exhausted, so that it no longer has a tail or a coma, is it
still a comet? Or do we re-classify it as an asteroid?"
Phaethon may well be a "Twilight Zone" object--intermediate between
asteroids and comets. "That's my opinion," says Cooke. "3200 Phaethon was
once an active comet, but about 1000 years ago the last of its ices
evaporated." Indeed, dynamical studies by Bo Gustafson and colleagues at the
University of Florida show that Geminid meteoroids are about 1000 years old.
"Now," he adds, "all that's left is a rocky comet corpse."
An asteroid, a comet, a comet corpse? The meteors are lovely no matter what.
Geminid meteors stream out of the constellation Gemini--hence their name.
Try looking for them any clear night this week after 10 p.m. local time,
when Gemini is well above the horizon. The best time to watch, says Cooke,
is actually around 2 a.m. local time. "That's when the Moon sets and when
Gemini is highest in the sky," he explains.
This year's Geminid shower is expected to peak between Friday evening, Dec.
13th, and Saturday morning, Dec. 14th. This is true no matter where you
Friday evening is also a good time to look for Geminid earthgrazers.
Earthgrazers are disintegrating meteoroids that fly over the horizon nearly
parallel to the atmosphere. They have remarkably long and colorful tails.
Around 8:00 p.m. local time at mid-northern latitudes, Gemini will be
hanging low above the eastern horizon--ideal geometry for earthgrazing
meteors. "You might not see many, because they're rare," says Cooke. "But
earthgrazers are beautiful, so it's worth a try."
And finally, don't forget to dress warmly because mid-December nights in the
northern hemisphere are likely to be cold. Bring a reclining chair, suggests
Cooke, or spread a thick blanket over a flat spot of ground. Lie down and
look up. Geminid meteors can appear in any part of the sky.
The shower will quickly wane after Dec. 14th. "Earth exits the debris cloud
on Dec. 17th and the Geminids will vanish until next year," he says. So
catch them now, while you can--the meteors from the Twilight Zone.
(5) FEATHERWEIGHT JUPITER MOON IS LIKELY A JUMBLE OF PIECES
Headquarters, Washington Dec. 9, 2002
Jet Propulsion Laboratory, Pasadena, Calif.
RELEASE: 02-237 (Correction)
FEATHERWEIGHT JUPITER MOON IS LIKELY A JUMBLE OF PIECES
NASA's Galileo spacecraft continues to deliver surprises. Galileo's
seven-year run continued with the discovery that Jupiter's potato-shaped
inner moon, named Amalthea, appears to have a very low density, indicating
it is full of holes.
"The density is unexpectedly low," said Dr. John D. Anderson, an astronomer
at NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif. "Amalthea is
apparently a loosely packed pile of rubble," he said.
The empty gaps between solid chunks likely take up more of the moon's total
volume than the solid pieces, and even the chunks are probably material that
is not dense enough to fit some theories about the origin of Jupiter's
moons. "Amalthea now seems more likely to be mostly rock with maybe a little
ice, rather than a denser mix of rock and iron," said JPL's Dr. Torrence
Johnson, project scientist for Galileo.
This red-tinted moon measures about 270 kilometers (168 miles) in length and
half that in width. Anderson and colleagues estimated Amalthea's mass from
its gravitational effect on Galileo, when the spacecraft passed within about
160 kilometers (99 miles) of the moon on Nov. 5. Dr. Peter Thomas at
Cornell University, Ithaca, N.Y., had calculated Amalthea's volume from
earlier Galileo images of the moon.
Amalthea's overall density is close to the density of water ice, Anderson
reports today at the fall meeting of the American Geophysical Union in San
Francisco. However, the moon is almost certainly not a solid hunk of ice.
"Nothing in the Jupiter system would suggest a composition that's mainly
ice," Anderson said.
Amalthea's irregular shape and low density suggests the moon has been broken
into many pieces that cling together from the pull of each other's gravity,
mixed with empty spaces, where the pieces don't fit tightly together. "It's
probably boulder-size or larger pieces just touching each other, not
pressing hard together," Anderson said.
Johnson said, "This finding supports the idea that the inner moons of
Jupiter have undergone intense bombardment and breakup. Amalthea may have
formed originally as one piece, but then was busted to bits by collisions."
Amalthea does not have quite enough mass to pull itself together into a
consolidated, spherical body like Earth's moon or Jupiter's four largest
moons. The density estimate, obtained from Galileo's flyby, extends an
emerging pattern of finding irregularly shaped moons and asteroids to be
porous rubble piles. What's more of a surprise, Johnson and Anderson said,
is the density estimate is so low that even the solid parts of Amalthea are
apparently less dense than Io, a larger moon that orbits about twice as far
One model for the formation of Jupiter's moons suggests moons closer to the
planet would be made of denser material than those farther out. That's based
on a theory that early Jupiter, like a weaker version of the early Sun,
would have emitted enough heat to prevent volatile, low-density
material from condensing and being incorporated into the closer moons.
Jupiter's four largest moons fit this model, with the innermost of them, Io,
also the densest, made mainly of rock and iron. However, the new finding
suggests, even if Amalthea is mostly gaps, its solid chunks have less
density than Io.
Galileo's flyby of Amalthea brought the spacecraft closest to Jupiter since
it began orbiting the giant planet on Dec. 7, 1995. After more than 30 close
encounters with Jupiter's four largest moons, the flyby was the last for
Galileo. Galileo has been put on course for a mission-ending impact with
Jupiter's atmosphere on Sept. 21, 2003. Galileo's long and successful career
will come to an end on its way to the giant planet.
Galileo left Earth aboard NASA's Space Shuttle Atlantis in 1989. JPL, a
division of the California Institute of Technology in Pasadena, manages the
Galileo mission for NASA's Office of Space Science, Washington. Additional
information about the mission is available online at:
(6) EXTRATERRESTRIAL INFLUENCES ON MANTLE PLUME ACTIVITY
Earth and Planetary Science Letters
Volume 205, Issues 1-2, 30 December 2002, Pages 53-62
by Dallas H. Abbott and Ann E. Isley
We use time series analysis to compare the impact histories of the Earth and
Moon with the record of mantle plume activity. We use events with errors in
their ages of 150 Ma. The terrestrial and lunar impact records, when
smoothed at a 45-Ma interval, correlate at a 97% confidence level. This high
confidence level suggests that we have an adequate sampling of most of the
major impact events on the Earth. We then test the idea that existing mantle
plumes may be strengthened by impacts. When smoothed at a 45-Ma interval,
strong plumes correlate with the terrestrial impact record at better than a
99% confidence level. No time lag is discernible between the data sets,
which is expected given their present error level. When the time series are
smoothed at a 30-Ma interval, there are 10 major peaks in impact activity.
Nine out of ten of these peaks have a counterpart in either or both of the
strong mantle plume or the mantle plume time series. As a result, the strong
mantle plume and the impact time series correlate at the 97% confidence
level. The mantle plume and the impact time series correlate at the 90%
confidence level. Finally, the Deccan plume showed greatly increased
activity immediately after the Chixculub impact. The results of our analysis
suggest that large meteorite and cometary impacts may well increase the
amount of volcanism from already active mantle plumes.
(7) COSMIC PRO-LIFERS
>From Tech Central Station, 9 December 2002
By Kenneth Silber
Questions about extraterrestrial life - whether it exists, what it would be
like, how to look for it - generate very little scientific consensus. Some
scientists enthuse over the Search for Extraterrestrial Intelligence, which
listens for radio signals from alien civilizations. Others propound the Rare
Earth Hypothesis, which states that an array of unusual factors allowed
complex life to arise here, and that any life we find elsewhere would likely
be as simple as bacteria.
Two new books provide some interesting perspective on the debate. Both could
be described as "pro-life" (in the cosmic sense), though they approach the
subject from different angles. What Does a Martian Look Like?: The Science
of Extraterrestrial Life
( http://www.amazon.com/exec/obidos/ASIN/0471268895/techcentralst-20/002-3412712-8345621 ),
by biologist Jack Cohen and mathematician Ian Stewart
(published by John Wiley & Sons), presents a view that alien life is
probably not only common but also truly alien. Cohen and Stewart castigate
scientists for a lack of imagination about the possible forms and habitats
of extraterrestrial life.
Origins of Existence: How Life Emerged in the Universe
( http://www.amazon.com/exec/obidos/ASIN/0743212622/techcentralst-20/002-3412712-8345621 ),
by physicist Fred Adams (Free Press), presents a broad-canvas
picture of a universe that's congenial to at least one type of life (the
carbon-based, water-dependent life that exists on Earth). Adams describes
how the laws of physics give rise to structures such as galaxies, stars and
planets, which are prerequisites for such life. He argues that the
conditions for life do not appear unique to Earth, and may become yet more
widespread in future stellar and galactic evolution.
Both books discuss the apparent "fine tuning" by which our universe's laws
appear to be precisely right for life. If physical constants such as the
mass of the proton or the strength of the electromagnetic force were
slightly different, none of us would be here. This is sometimes presented as
evidence of intelligent design. But it could also mean that there are
multiple universes, or that our conception of life is too narrow, or that
the calculations of what the universe would be like with different physics
are unduly simplistic. Adams emphasizes multiple universes, whereas Cohen
and Stewart focus on the other objections.
Leaving aside the question of what if any life would exist under other
physical laws, there remains the question of what kind of life is possible
in the universe we actually inhabit. Here, Cohen and Stewart are harshly
critical of "astrobiology," the interdisciplinary scientific field that
examines the possibility of extraterrestrial life. They argue that
astrobiologists are too focused on looking for something similar to life on
Earth and fail even to grasp the diversity of past and present terrestrial
life. The authors seek to change not only the focus but the name; they call
for a new field known as "xenoscience."
What Does a Martian Look Like? intersperses synopses of various
science-fiction novels with Cohen and Stewart's own speculations. They
discuss such possibilities as blimp-like creatures floating amid the clouds
of Jupiter, or even more exotic entities such as intelligent magnetic
vortices living on the surface of a star. They criticize assumptions built
into the Rare Earth Hypothesis, such as that life could evolve only in a
narrow "habitable zone" that's not too close or too far from a star. They
note that such habitability could also occur in far-flung planets or moons
that have their own heat sources, or in bodies that orbit close to a star
but do not rotate (there would be a warm region between the hot hemisphere
facing the star and the cold one facing away).
Yet Cohen and Stewart also express skepticism toward the Search for
Extraterrestrial Intelligence. Intelligent aliens, they argue, would be
difficult or impossible for humans to understand, are unlikely to use radio
communication, and probably would be cautious about advertising their
existence. Moreover, any messages the extraterrestrials are sending among
themselves would likely be encrypted to sound like random noise.
A remarkable aspect of astrobiology, or xenoscience if you prefer, is that
nobody really knows anything. Even though Cohen and Stewart's arguments are
often cogent, the Rare Earth Hypothesis might still be correct, or the
Search for Extraterrestrial Intelligence might be on the right track.
Similarly, Adams could be right in his portrayal of a universe basically
friendly to life, but this might also be a universe that just barely
tolerates life. Nonetheless, the subject is compelling and
thought-provoking. And by contemplating what may be out there, we can also
learn more about ourselves.
As Cohen and Stewart point out, extraterrestrial life may have evolved under
conditions humans would find extremely hostile. The converse is true as
well. Aliens might be horrified by an environment dominated by, as the
authors put it, "sleeting electromagnetic radiation, a corrosive oxygen
atmosphere, and that terrible universal solvent, hydrogen monoxide, sloshing
all over the place." But for us, it's just a day on the beach.
Copyright 2002, Tech Central Station
(8) AND FINALLY: THE TECHNOPHOBES
>From Yahoo News, 5 December 2002
By Dan Seligman
A guide to assorted Luddites, labor monopolists, muddled intellectuals and
otherworldly pietists who kept resisting modernity even as it overwhelmed
It is hard to resist technology's endless landslide, but people keep trying.
Why? One discerns four possible reasons:
FIRST CASE: The new technology threatens the material interests of some
groups. An esoteric example, now largely forgotten, arose from the sudden
popularity, early in the last century, of margarine. Based on vegetable
oils, the new spread obviously represented big trouble for butter. The dairy
industry responded by attacking margarine as a threat to healthy diets--this
was before Americans had heard of cholesterol--and, since the new stuff
looked like butter, as an exercise in consumer fraud. Allegedly to forestall
fraud, but actually to make the new competitor seem as weird as possible,
dairy lobbyists persuaded many state legislatures to outlaw yellow
margarine, and so many a consumer had to take home white vegetable fat and
add yellow food coloring on the kitchen counter.
Less esoteric and more pervasive were wars against new technologies that
threatened jobs. A typical union reaction was to demand that new work be
found for the suddenly redundant employees, even if the new work was of no
economic value. So we entered the era in which newspaper publishers were
stuck with typographers whose job was to set "bogus" type. Or sometimes not
even that. Thirty years ago there was a place in the New York Times building
called the Rubber Room. The reference, you will (possibly) be relieved to
hear, was to rubbers of bridge. It seems that members of the printing-trade
union would report for work, play bridge for eight hours, then go home.
The Rubber Room was made possible by two French inventors, RenÚ Higonnet and
Louis Moyroud, who developed a machine, ultimately called the Photon, that
set characters electronically on film. It eliminated the need for the kind
of artisans who had, for the previous 500 years, moved metal type around.
Unable to get financing in France, the inventors crossed the Atlantic, and
soon had American newspaper publishers panting to get in on the Photon. The
device could spin out type at least four times faster than the Linotype
machine. It could be operated by inexpensive clerical workers hired off the
street in place of the high-paid members of the International Typographical
Union. The Photon represented disaster for the ITU, and the union's New York
Local 6, run by hardball player Bertram Powers, led a strike from 1962 to
1963 that shut down all New York City newspapers for 114 days and terminated
the life of New York's Mirror. The union ultimately won lifetime employment
contracts for printers, many of whom took up bridge.
SECOND CASE: The new technology is thought to be unhealthy. Here the
paradigmatic examples were DDT and other pesticides, and their principal
adversary was Rachel Carson, author of the 1962 bestseller Silent Spring.
The book inspired the creation of the Environmental Protection Agency and
the environmental philosophy of Al Gore. Carson, a marine biologist by
training, wrote with a kind of poetic power and scared the socks off
thousands of readers with apocalyptic passages like: "One of the most
sinister features of DDT and related chemicals is the way they are passed on
from one organism to another through all the links of the food chain. ...
The breast-fed human infant is receiving small but regular additions to the
load of toxic chemicals building up in his body. ... There has been no such
parallel situation in medical history. No one yet knows what the ultimate
consequences may be."
Fortifying this dreadful storyline was the fact that Carson died two years
after the book's publication--of breast cancer. Many environmentalists think
that toxic chemicals are an important cause of breast cancer. DDT was banned
in the U.S. in 1972.
But today the Carson argument is seriously suspect. DDT has been enormously
successful in wiping out malaria in undeveloped countries worldwide--no
other pesticide does the job as well--and there is no evidence that this
huge benefit has been offset by increased cancer rates. It is not clear that
DDT is carcinogenic to humans, and if it is, the effect is clearly weak. The
World Health Organization has found that "the only confirmed cases of injury
[from DDT] have been the result of massive accidental or suicidal
ingestion." An interesting question is whether Rachel Carson's policy
influence might actually have increased the incidence of cancer. It now
seems clear, at least, that the pesticides she was concerned about had
little if any effect on cancer, while restricting use of pesticides raises
the price and reduces the consumption of fruits and vegetables--which are
important inhibitors of cancer.
Echoes of these 40-year-old arguments may be picked up nowadays in the
worldwide debate over the safety and legitimacy of genetically modified
foods. While few would deny that we need to pursue research on the long-term
health effects of such foods, the evidence thus far plainly shows that the
new technology holds considerable promise of lowering fruit and vegetable
costs, and thus enhancing human health.
THIRD CASE: New technologies are resisted because they are viewed,
correctly, as fostering economic growth, and growth is viewed, incorrectly,
as bad for the human species.
Prominent on the antigrowth track was Lester Brown, founder of the
Worldwatch Institute. Another famous member of the school was Paul Ehrlich
of Stanford, a tireless pessimist who was endlessly arguing, just like
Thomas Malthus (1766-1834), that natural resources are limited but there is
no natural limit to human populations--so it is only a question of time
before we have overcrowding, famine and pestilence. In his 1968 book The
Population Bomb, Ehrlich said it was already too late to prevent huge
worldwide famines in the 1970s. ("The battle to feed all of humanity is
over. In the 1970s and 1980s hundreds of millions of people are going to
starve to death in spite of any crash programs embarked upon now.") Ehrlich
had an equation to prove it: I = PAT. That means the Impact of growth can be
quantified by looking at Population multiplied by Affluence (i.e.,
consumption) and multiplied again by Technology.
The grim Malthusian argument that growth means starvation climaxed in a 1972
book by the Club of Rome, The Limits to Growth, spelling out the timetable
on which the world would run out of this or that essential raw material. It
sold 12 million copies in 37 languages.
But it was all involved nonsense, and Ehrlich had the bad luck to
demonstrate his folly by making a bet guaranteed to get extensive media
coverage. The bet was with economist Julian Simon of the University of
Maryland. Both men agreed that if Ehrlich's model of the problem was valid,
then basic commodities would be increasingly scarce and rising in price.
Simon's data told him that, on the contrary, commodity prices were in
continual decline, and he offered to bet $1,000 that any raw materials one
picked would decline in price (in real, inflation-adjusted terms) over a
period of at least a year. Ehrlich and two of his colleagues sprang for the
deal and said that a "basket" of chromium, nickel, copper, tungsten and tin
would rise in price over a ten-year period. They lost ignominiously: The
real price of every one of the metals declined during the decade. Far worse,
from Ehrlich's point of view if not humanity's, was the subsequent
relentless improvement in living standards worldwide. In place of famine and
death, the global population has seen a steady increase in per capita
calorie consumption (up 24% since 1961 and up 38% in developing countries).
Life expectancy has also grown steadily, from around 30 years in 1900 to 67
FOURTH CASE: The technology is said to offend religious faith. It is always
possible to find a certain number of environmentalists identifying their own
policy prescriptions with God's will, or to find preachers in pulpits with
strong views about our need to embrace the Kyoto Protocol on global
warming. Right now the religion/technology nexus is conspicuously embodied
in a much-hyped coalition of Christian and Jewish groups that is "linking
fuel efficiency to morality," as the New York Times put it, and positing
that Jesus would not drive a sport utility vehicle.
And yet it is possible to point to at least one religious group that has had
a fair amount of success in resisting technology. Not total success, but
definitely above average. The group in question is the Pennsylvania
Dutch--the Mennonites of Lancaster County, and especially the Amish. Back in
1919 the Amish made a fateful decision to turn their backs on electricity
and declined to connect their farms to the power grid. They still do without
electricity, cars or flush toilets, and their principal farm equipment is a
horse-drawn tractor with metal wheels. They resist modernity because easy
access to the outside world could, in the words on an Amish Web site, "lead
to many temptations and the deterioration of church and family life."
The Amish and other Mennonites make up a small fraction of the population,
but a sizable number of people embrace environmentalism with a
quasireligious fervor that opposes technological progress on the theory that
the good old days of horse-drawn sleighs were less sinful. Whether such
believers would be willing to accept 30-year life spans as a price for
turning the clock back is another matter.
Copyright 2002, Yahoo! News
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