PLEASE NOTE:


*

CCNet, 32/2003 -  20 March 2003
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"Legend has it that when two people get together and er... bond, the Earth will move - at least in a metaphorical sense. Likewise, it takes two heavenly bodies, an impactor and a target, to come together with Earth-shattering force to form a crater. There's nothing dreamlike about this: it happens, frequently, throughout the solar system. Impact catastrophes are routine."
--Graeme Addison, Popular Mechanics, 18 March 2003


"If we were faced with the threat of an asteroid impact, I expect we could rise to the challenge. There is nothing inherently 'impossible' in the context of present technology."
--Alan Harris, Space Science Institute, 18 March 2003


(1) AVERTING KILLER ASTEROIDS
    The Boston Globe, 18 March 2003

(2) VERY LARGE METEORITE FELL DOWN IN SIBERIA
    Pravda, 18 March 2003

(3) HAVE NO FEAR, A TSUNAMI WILL NOT APPEAR
    Astronomy.com, 18 March 2003

(4) HEAVENLY BODIES STIR UP ROUTINE CATASTROPHES
    Popular Mechanics, 18 March 2003

(5) AND FINALLY: MEMES OF SUPERSTITION
    Tech Central Station, 19 March 2003


===========
(1) AVERTING KILLER ASTEROIDS

>From The Boston Globe, 18 March 2003
http://www.boston.com/dailyglobe2/077/science/Averting_killer_asteroids+.shtml

>From nuking to nudging, researchers plan to save the planet

By Larry O'Hanlon, Globe Correspondent, 3/18/2003

Whether or not an asteroid threatens Earth any time soon, there are people already thinking up schemes to nudge, nuke, slam, sling, vaporize or paint -- yes, paint -- the chunks of cosmic debris off track and save the planet.

Moving huge hunks of rock in space into safer orbits is actually a sort of specialty among asteroid and comet researchers who are determined that humanity not go out with a tremendous bang, as the dinosaurs did 65 million years ago.

We have an advantage the dinos didn't: We can see it coming. There are at least 10 astronomical surveys around the world actively hunting down near-Earth asteroids, or NEAs -- those having orbits that occasionally bring them into the space near Earth's orbit. Estimates in a February report by the National Optical Astronomy Observatory put the number of globally catastrophic NEAs -- those a half-mile or more in diameter -- at between 900 and 1,230 out of a total population of perhaps a million NEAs. So far, about 2,225 NEAs have been found ranging from 30 feet to about 20 miles across.

"We're looking to see if there are any 21st-century hazards out there," MIT asteroid researcher Richard Binzel explained. And, if astronomers find any on hazardous courses, he said, it is more than likely we'll have decades to prepare to respond to the threat.

Just what our response will be depends a lot on the asteroid. The one thing that is certain is that we probably will not be able to destroy one. We just don't have the firepower to pulverize a cosmic Mount Everest. The widely accepted alternative is to nudge the asteroid into a slightly new orbit many years before it's a danger, so that, by the time it reaches Earth's vicinity, it's way off course and misses. For asteroids of about a half-mile in diameter -- the lower end of the globally threatening asteroid scale -- a nuclear nudge might work.

"That solution has its merit," said Joseph Spitale, a scientist at the University of Arizona's Lunar and Planetary Laboratory. But there are a lot of downsides, he said. For one thing, nobody is keen on launching nuclear weapons, and it's not likely they'd be very accurate or effective. "My current feeling is that a buried explosion would be needed if one were going the nuclear route," said Alan Harris, senior scientist at the Space Science Institute. "That requires a rendezvous -- just zipping by and `nuking' it on the fly won't do."

As in any approach to nudging asteroids, there is the danger of knocking one into an even more perilous course. That's why better tracking data is needed than what telescopes offer, Harris said. "Ordinary optical tracking with a telescope is adequate to certify that an asteroid is not even going to come close for the next century. But if the answer is that it will come close, maybe even hit, then much more precise tracking is needed.

"If one were to land a radio beacon on the asteroid, then precision tracking would be about the same as tracking spacecraft, which is easily accurate enough for the job."

A far-less-spectacular approach for moving NEAs is to have them move themselves, which can be done by changing their color. It turns out that the dark surfaces of most asteroids absorb a lot of solar energy, which is radiated back out into space as heat. That heat radiation actually produces thrust -- like a very weak rocket engine -- and influences an asteroid's orbit. The effect is known as the Yarkovsky effect, and explains the anomalous orbits of some artificial satellites.

It's been suggested wrapping an asteroid in a thin film, Spitale said, or perhaps coat or paint it with reflective material to turn off the Yarkovsky effect. Done early enough, it might be enough to alter an asteroid's orbit and save the planet.

Unfortunately, the Yarkovsky effect is too weak to move asteroids larger than a half-mile in diameter unless you have centuries of time to work with, said Jay Melosh, also of the University of Arizona's Lunar and Planetary Laboratory. The dinosaur-killing, 6-mile-wide asteroids out there require more punch than even nuclear bombs or the Yarkovsky effect can pack, Melosh said.

"I have a proposal out to deflect an asteroid by means of a solar reflector," Melosh said. His plan works a lot like a kid using a magnifying glass in the sun to roast ants. Melosh proposes using a lightweight, reflective Mylar-like material called Kaptan to focus sunlight on a small area on the asteroid surface. With a large enough Kaptan reflector, it would be possible, he said, to continuously heat a spot on the surface so that it shoots out a jet of vaporized rock. That jet would work like a rocket engine, pushing the asteroid in the opposite direction.

Melosh said his proposal is often confused with a plan known as the solar-sail approach. That idea would have astronauts attach a giant solar sail to a tumbling asteroid to catch the steady torrent of particles coming from the sun known as the solar wind. The gigantic sail would turn an asteroid into a very large, odd, and sluggish interplanetary sailing ship. It's a neat idea, Melosh said, but just how to rig a constantly tumbling rock with a sail that can stay aligned to catch the solar wind makes the idea fiendishly complicated.

Yet another plan is what's called the mass driver. It would involve building a magnetic rail on an asteroid's surface that could be continuously loaded with rocks mined from the asteroid itself. Those rocks would be shot down the rails and flung into space, Melosh said. All that flinging would gradually push the asteroid in the opposite direction and change its course. It would take a lot of work, but it's within the realm of possibility, he asserted.

About the only idea that has been totally discredited is what might be called an asteroid tugboat. That's a giant rocket ship with lots of fuel from heck knows where. The ship would fly to the asteroid, put its nose to the stone, and push it out of harm's way. Unfortunately, "it's just plain stupid," Melosh said. The size and cost of such a ship would be immense, and the amount of fuel that would be needed to propel a mountain in space is just staggering. "You'd be better off," he said, "running the rocket into the asteroid," and transferring the momentum of the ship to the asteroid.

Melosh argued that his solar reflector asteroid deflector avoids a lot of complications because it doesn't even require landing on the asteroid, or fuel to power it. What it does entail, however, is a massive manned space program to build the ships and technology to fly to the asteroid, build the reflector, and to maintain it.

The bottom line, Harris said, is that there are many possible ways of avoiding the dinosaurs' fate so long as we detect the danger in time and can reach the asteroid. "Any other means one might contemplate, say mass drivers or whatever, would also demand rendezvous and landing on the asteroid," he said. "All these are major engineering challenges, even if we have the needed technology. It's more than just keeping a couple of spare ICBMs around; it's a really major technological project, likely bigger than the Apollo moon program."

There is no reason to lose heart, however. "If we were faced with the threat of an asteroid impact," Harris said, "I expect we could rise to the challenge. There is nothing inherently `impossible' in the context of present technology."

This story ran on page C21 of the Boston Globe on 3/18/2003.

© Copyright 2003 Globe Newspaper Company.

=============
(2) VERY LARGE METEORITE FELL DOWN IN SIBERIA

>From Pravda, 18 March 2003
http://english.pravda.ru/society/2003/03/18/44571.html

The falling of the meteorite is still mysterious. Scientists say that it might weigh 60 tons

The night was rather dull in the north-east of the Russian Irkutsk region on September 25, 2002. All of a sudden, night turned into day. A very bright glow covered the sky, it was hard to look at it. Those people, who happened to be outside at 2 a.m., saw a ball of fire that was flying very fast across the sky. Weird rusting sounds could be heard. A few seconds later the glow disappeared in the north-east. A little bit later, there was a powerful blast from the distance, where the ball fell.

People learned of the Vitimsky meteorite only a week after it fell down 700 kilometers off the Siberian city of Irkutsk. The bright polar streamer in the sky made people think that the woods were shining with radiation. Local residents sent a facsimile message to the Irkutsk Institute of Sun and Earth physics of the Russian Academy of Sciences. People asked scientists to explain the strange phenomenon that happened in their region. Gely Zherebtsov, the director of the institute, made inquiries at EMERCOM departments.

Rumors about the mysterious glow above the Siberian forest could be read in almost every local newspaper for a month after that. A couple of weeks later it was reported that an American spy satellite detected the meteorite. The satellite registered the space object at the moment of its brightest luminescence. The meteorite was flying 62 kilometers above the ground. The satellite lost the object at the height of 30 kilometers. The satellite also determined the position data of the object as well. According to the information from Canadian scientists, it was the largest event of the kind that occurred above the land in the year 2002. The Irkutsk Institute of Sun and Earth physics decided to send an expedition to the spot, where the meteorite fell down. The idea was supported at the Irkutsk State University as well. A small group of Irkutsk scientists left for the settlement of Mama - the center of the area, above which the meteorite flew.

Eyewitnesses said that they saw very interesting and unusual things. People said that lamps turned on in their houses for several seconds, although there was absolutely no electric power that night. This means that the Vitimsky meteorite can be categorized as an electrophone one. Its flight generated a very powerful, albeit alternating, electric field in the atmosphere. Those people, who saw the meteorite flying across the sky, said that they had an incredible impression of it. Someone fell down on the ground on account of horror, someone thought that the doomsday came.

The expedition reached the second spot, which was registered with the satellite. It was not possible to find anything, except several pine trees with broken tops. Explorers came to conclusion that there was no blast over there - the meteorite fell down somewhere farther. Unfortunately, the initial velocity of the meteorite was not known. The committee for meteorites of the Russian Academy of Sciences calculated that the meteorite could weigh 60 tons, if it had the minimum initial velocity of eleven kilometers per second. If it was really so, the meteorite, which fell down in the Irkutsk region was even more powerful than the one, which fell down on the Earth in 1947. The falling of the meteorite in 1947 was considered to be one of the largest phenomena in the 20th century.

Of course, scientists are not 100% sure of that. If the meteorite had a greater speed, for example, 25 kilometers per hour, it is possible to assume that there were only several kilograms left of the space object. The falling of the Vitimsky meteorite posed a lot of questions. First of all, all space monitoring means of the world failed to detect a huge meteorite that was rushing towards planet Earth. The meteorite fell down in the area, where no one lived, so there was absolutely no damage caused. However, things might have turned out totally different, if the falling took place in the densely populated Europe. It seems that Russian observing facilities turned out to be totally helpless. This means that the humanity is supposed to make certain conclusions about it.

Now the area of the meteorite's falling is covered with a thick layer of snow. Irkutsk scientists plan to go to that place again in order to takes some snow samples. The expedition is going to happen in the nearest future, for if the snow melts, spring waters will wash away the space dust forever.

NASA specialists said that the Shuttle of Columbia was going to film the area of the meteorite's falling, although the tragic crash of the shuttle brushed that opportunity aside. If scientists determine that it was a stone meteorite (up to 95% meteorites are referred to that class), spring waters might change the properties of the ancient space substance. Irkutsk scientists can not afford renting a helicopter and examining the area from above. Every large meteorite is extremely valuable for the abstract science, for the world outlook, for developing measures to struggle with the danger of asteroids.

Copyright 2003, Pravda

============
(3) HAVE NO FEAR, A TSUNAMI WILL NOT APPEAR

>From Astronomy.com, 18 March 2003
http://www.astronomy.com/Content/Dynamic/Articles/000/000/001/255onqhj.asp

Old research that has recently surfaced eases worries that a relatively small extraterrestrial impactor could cause a devastating tsunami.

by Vanessa Thomas

For the past decade, many scientists have worried that an asteroid or comet could slam into one of Earth's oceans and create a huge tsunami that would destroy coastal communities. While kilometer-sized impactors could pose such a threat, a recently declassified government defense study suggests objects a few hundred meters wide do not.

"I think it is currently an overrated hazard," University of Arizona planetary scientist H. Jay Melosh stated Monday at the 34th Lunar and Planetary Sciences Conference in Texas. Melosh explained that the concern first arose at a 1993 conference in Arizona discussing the hazards of comets and asteroids, where scientists from Los Alamos National Laboratory proposed that ocean-impacting objects as small as 100 meters in diameter could produce waves tens or hundreds of meters high a thousand kilometers away.

While other researchers have repeated the warnings of impact-induced tsunamis and agree that objects a kilometer in size or larger are a major worry, Melosh has remained skeptical about the tsunami-creating capabilities of smaller objects. He presented his position at a 1995 conference and afterward was approached by tsunami expert William Van Dorn. In 1968, Van Dorn told Melosh, the U.S. Office of Naval Research asked him to summarize decades of research into the wave hazards induced by TNT or nuclear explosions in the ocean. However, the details of his work were still classified at the time.

Late last year, Melosh and some colleagues began a hunt for Van Dorn's report. An Internet search provided them with the title, "Handbook on Explosion-Generated Water Waves," and a University of Arizona librarian helped the team track down a copy at a college library in San Diego.

The 173-page report is based on data from actual nuclear tests at Bikini Atoll and TNT tests at California's Mono Lake. In it, Van Dorn concludes that "no catastrophe or damage by flooding could result from explosion waves" and wrote in the manuscript that "this goes for bolide impacts, too," said Melosh.

According to Melosh, one of Van Dorn's most important points is that explosions produce waves with periods unlike that for any other type of wave we're familiar with. Storm waves that surfers ride have periods from 5 to 20 seconds, while earthquake-induced tsunamis have periods of 100 seconds to an hour. Explosion waves have periods that are in between. Thus, Melosh writes in a conference abstract, "our intuition from ordinary surf or earthquake tsunami is not a good guide to the behavior of these waves."

Van Dorn also reported that large impact-generated waves would break on the continental shelf. "They don't get to shore," Melosh emphasized Monday. However, Melosh added that parts of Van Dorn's report seem to be missing because there isn't a full explanation behind this "Van Dorn effect," as it's called in the defense community.

For Melosh, these and other points in the Van Dorn report should dispel worries that impactors only a few hundred of meters wide could cause coastal devastation for humanity. The hazard, he said, "is probably greatly exaggerated," and that "we are not looking at a major hazard" from such small impacts.
 
Melosh continued to downplay impact-related doomsday scenarios in a second talk (given on behalf of his collaborator, Russian scientist Boris Ivanoff, who was unable to obtain a visa for this week's conference). In this talk, the Arizona scientist stated that impacts do not initiate volcanic eruptions, as has been postulated by many since the 1960s. A previous argument was that a large object could strike a "hot spot" on Earth that was on the verge of volcanism. "The trouble is that large impactors are rare and hot spots are not that prevalent," Melosh said. "So there are not a lot of hot spots waiting to be hit and not a lot of impactors waiting to hit them." Therefore, the probability of this kind of impact-induced volcanism is quite low, he concluded.
 
Copyright 2003, Astronomy.com

==========
(4) HEAVENLY BODIES STIR UP ROUTINE CATASTROPHES

>From Popular Mechanics, 18 March 2003
http://www.iol.co.za/index.php?click_id=143&art_id=iol1047987020904C323&set_id=1
 
By Graeme Addison

Legend has it that when two people get together and er... bond, the Earth will move - at least in a metaphorical sense. Likewise, it takes two heavenly bodies, an impactor and a target, to come together with Earth-shattering force to form a crater. There's nothing dreamlike about this: it happens, frequently, throughout the solar system. Impact catastrophes are routine.

Just over two-billion years ago, a chunk of asteroid at least the size of Table Mountain struck the landmass that is now South Africa. It hurtled in at a speed in excess of 55 000km/h, or about 160 times the speed of Shumacher's Ferrari in full cry.

Welcome to the realm of cosmic uncertainty and sudden impacts. More specifically, an impact that changed the face of primeval South Africa.

The world-famous Vredefort Dome - centred on a tiny northern Free State dorp and now billed as the oldest and biggest asteroid impact site on the planet - was finally accepted as a blast site by the majority of scientists only in the mid-1990s. It is now being proposed as a World Heritage Site (South Africa's fifth, after Lake St Lucia, Robben Island, Sterkfontein Caves and the Drakensberg).

Despite its obvious significance, there is still much speculation about Vredefort. Today leading geologists are disputing whether the impactor set the Earth's crust on edge or not - whether there is a shear zone as if a mighty fist had punched a hole in the crust, leaving shards of it standing upright. Yes, say the crust-on-edge supporters; but there are others who say there is no real discontinuity in the underlying rock formations.

Why does it matter? Well, knowing how impacts have shaped the Earth's crust could explain many things that remain puzzling, and perhaps aid in deep-level geological exploration. Although a great deal is now known about crater formation, and the Vredefort site is increasingly being studied and modelled, much remains speculative.

The impact took place a very long time ago when the Earth was just over half its present age, and yet it has primary modern significance for mining. South Africa's vast semicircle of goldfields follows the outline of the Vredefort ring. Coincidentally, the impact area largely covered the earlier Witwatersrand basin where gold-bearing strata had been laid down by archaic rivers.

Experts differ about exactly how the gold came to be concentrated so highly in this area, but the energy released by the impact certainly had something to do with it. The strata appear to have been thrown on edge, and erosive processes finally exposed them as the well-known Reef at the highest point in Johannesburg. The world's deepest mines are to be found near Carletonville, where Anglogold is probing to a vertical depth of 3,5km in search of the deep veins of ore that were buried so long ago.

Few South Africans are aware of this geological wonder in the very heart of their country. Yet it has always fascinated those in the know - the geologists, minerologists and astrophysicists who pay attention to large rocks falling from the sky, and who warn that it could happen again. Here they share something with local mystics who believe the Dome is a sign from heaven portending the worst.

According to prophecy, fire will once again rain from the sky (or erupt from the bowels of the Earth), and we are all doomed to burn to extinction. This might sound alarming or merely funny depending on your view of fate. But it could indeed happen again. Scans of our immediate environs show that dangerous Near Earth Objects (NEOs) quite frequently stray into Earth's neighbourhood. Some have narrowly missed in recent years, and more are predicted.

Calculations based on the observed number of asteroids suggest that we should expect about three craters of at least 10km in diameter be formed on the Earth every million years. Very big impactors are rare, but if one the size of Vredefort should hit us, it would probably spell the end of life as we know it.

Colossal fires and tidal waves would sweep away landmarks, killing millions if not billions immediately. Ejecta and dust thrown from the impact zone would do the long-term damage, darkening the skies and chilling the seas for centuries, putting an end to agriculture and possibly disrupting the atmospheric processes from which we draw our air.

This is what seems to have caused the mass extinction of the dinosaurs. About 65-million years ago, an asteroid ploughed into what is now the Yucatan peninsula of Mexico, setting in motion the chain reactions that killed off Earth's dominant species in a few short years. Known as the Chicxulub crater, this is regarded as the world's third-largest.

The second largest is at Sudbury in Ontario, Canada - thought to have been caused by a large comet. According to one study, Sudbury produced about 31 000 cubic kilometres of impact melt, approximately six times the volume of lakes Huron and Ontario combined, and nearly 70 percent more than the melt at Chicxulub.

Defending Earth against these roving destructors is becoming a political issue in the leading Western nations. Public funds are committed to searching for NEOs and designing possible weapons to deflect them - although it is doubtful at this stage whether the largest and fastest could be stopped in time.

At any rate, worldwide interest in impactors (otherwise known as bolides) has focused attention on the Vredefort Dome and is starting to bring international tourists to the town of Parys, on the banks of the Vaal about 120km from Johannesburg. This type of feature is known as an "astrobleme" - a wonderfully evocative word for an eroded impact crater.

As with many old craters, appearances are misleading. The centre of the Vredefort Dome (also known as the Ring) looks merely like a small- to medium-sized crater.

Many people who visit the area think that a horseshoe of low mountains called the "Bergland", lying to the north west of the Vaal River between Parys and Potchefstroom, is the crater rim. It isn't: the mountains are merely what remain of a central "upheaval dome" that formed at the core of the crater.

The truth is far more impressive, though harder to see from the ground. What is most likely the outermost concentric ring of the crater itself runs from the Mondeor heights south of Johannesburg along the ridges of the West Rand to Welkom in the Free State - a diameter in excess of 300km. An inner ring is also visible: it's called the Gatsrand, and you cross it when driving on the N1 through the Grasmere tollgate.

In mistaking the Bergland for the crater rim, early estimates put the size of the Vredefort impact zone at less than 100km. This merited inclusion in the top league of big craters, but as time passed and geologists explored the features of this unique area, the truth began to dawn: this was a crater of earth-shattering proportions, and possibly the largest on record.

Recent Landsat pictures put the minimum diameter at 250km, although there are still scientists who say the crater is no more than 107km wide.

There has never been any shortage of hot debating topics in the realm of meteorites and comets. In the past, the Vredefort "structure" was thought to have been an ancient volcano. There was even an oddball theory that the Moon had pulled away from Mother Earth at this point, sucking up molten rock from below the crust, but the age of the Moon (4,5-billion years) and its size quickly ruled out this possibility.

Vredefort is newer and smaller than any feature that might have been left by the departing Moon. In fact, evidence in the rocks points to an impact by a space invader. With no meteoritic fragments present after such a long passage of time, other evidence is invoked to prove impacting. "Shock metamorphism" - or changes in the rock due to high pressures not found in volcanic eruptions - is a sure sign.

Imagine a stone hitting a window: the glass shatters in myriads of splinters. In the case of impacted rocks, these "shatter cones" appear along with melt rocks and other signatures in zircons, quartz and feldspar grains. In the Vredefort area, so-called pseudotachylites - melted black seams in the rock having the false appearance of volcanism - are a sure giveaway.

The crater was blasted out of the Earth by a wandering asteroid that detonated in the atmosphere with the explosive force of millions of nuclear bombs and melted the crust instantly to a depth of up to 30km.

The low dome of granite in the middle was once viewed as the plug of cooled molten matter that had welled up from the magma surrounding Earth's core, and the rings were described as successive volcano rims.

Until about three decades ago, almost every large impact site on Earth was thought to be volcanic rather than extraterrestrial in origin. Then along came American geologist Eugene Shoemaker and his wife Carolyn, who pains-takingly documented crater after crater, from America to Australia and even on the Moon. They were convinced that many terrestrial and lunar craters were due to asteroidal impacts rather than volcanoes, but were sidelined by research authorities and scientist peers.

The big breakthrough came when Shoemaker and a colleague, David Levy, correctly predicted that a newly discovered comet, Shoemaker-Levy 9, would impact Jupiter in June 1994 - and impact it did, in 21 spectacular fragments. Clearly, major impacts could and did occur throughout the solar system.

A meteorite is any rock that remains after an impact. The impactor may vaporise, however, and leave no meteorite. Large asteroids from the belt of Asteroids lying between Mars and Jupiter are likely to vaporise when colliding with Earth, though the smaller ones would leave a meteorite. Meteoroid is the word to describe any solid body migrating through space on a collision course with other bodies. Some of these take the form of smaller swarms of bits of rock crossing the solar system.

The Vredefort impact was certainly not the biggest in Earth's history of punishment by heavenly bodies, either. Between three and four- billion years ago, Earth weathered a period of heavy bombardment by passing rock fragments, large and small. Then or perhaps later, comet "storms" also struck the earth; comets - which are lumps of ice and dust - have been credited with delivering liquid water in such abundance that the seas were formed.

Comets, too, have generated their share of scientific dispute. British astronomer Sir Fred Hoyle suggested that life on Earth may have been seeded by comets that transported the essential molecular materials from outer space.

Dubbed "panspermism", this idea - supported by the discoverer of DNA, Francis Crick - is still hotly debated.

The status of Vredefort as the oldest and biggest known impact site on Earth has recently been challenged by Dr Gary Byerly of Louisiana State University in the US. He and his team found evidence of an even bigger blast in the Barberton area - crossing over to the Pilbara Block in Western Australia (the two land masses were once joined).

Byerly says five separate rock layers containing debris ejected from an ancient impact have been discovered and dated at 3,47-billion years old. They didn't manage to find a crater - preserving, for now at least, Vredefort's claim to fame.

However, none of the asteroidal or cometary impacts compares with the biggest ever, which occurred right near the beginning of Earth's existence, some 4,5 billion years ago. It is now thought that the Moon was formed when a huge lump of coalescing matter - large enough to be another planet in the process of formation - collided with the proto-Earth. From the loose agglomeration of the two bodies, some lighter crustal matter spun off to create the Moon.

The story of Vredefort is just one chapter in the epic of planetary formation in our solar system, and many others.

As gravity pulls drifting dust together to create stars and planets, the leftovers circulate as clouds of comets, belts of asteroids and random rock fragments. As these bodies continue to fall inwards towards us, they result in grand and terrifying catastrophes. It will happen again - but we hope not soon.

Graeme Addison lives in Parys and is writing a popular scientific book about the Vredefort impactor. He is the author of The Hidden Edge: South Africa's Quest for Innovation, and White Water: the World's Wildest Rivers.

This article originally appears in the March issue of the South African edition of Popular Mechanics

Copyright 2003, Popular Mechanics

=============
(5) AND FINALLY: MEMES OF SUPERSTITION

>From Tech Central Station, 19 March 2003
http://www.techcentralstation.com/1051/envirowrapper.jsp?PID=1051-450&CID=1051-031903B

By Sallie Baliunas
 
"Meme" is a term invented by Richard Dawkins (The Selfish Gene, 1976) based on a concept outlined by anthropologist F.T. Cloak in 1973, and it may now inform the current debate over global climate change.

In a deliberate parallel to genes and biological evolution, Cloak and Dawkins have argued that information-containing entities - memes (pronounced "meem," like dream) - much as genes, reproduce as they are transferred among humans and mutate as ideas change.

Memeticists are still searching to identify a meme with a physical substrate to complete the analogy with genes. An organism's genes are carried as instructions by four special molecules (called nucleotides) arranged in pairs and connected across two strands built of sugar and phosphate molecules that twist into a helix-shaped molecule called deoxyribonucleic acid (DNA). Some neuromemeticists speculate that the meme is the electrical impulse of a thought, although that is too vague a description for scientific rigor. Others (and for now I favor this camp) argue that memes are external to the human mind (e.g., W. L. Benzon, Beethoven's Anvil, 2001).

In any event, memes can be viewed as the sum of ideas that describe human culture. And so being, they have consequences - positive, neutral or negative - that can be repeated in history.

Let's examine some important memes related to science and weather.

Good Memes

By the latter half of the 16th Century the scientific revolution was well underway in Europe. Nicolaus Copernicus gave it impetus when he published De Revolutionibus, in 1543, reviving a meme that had been forgotten for 17 centuries - the one in which Aristarchus (280 BCE) had crazily imagined that the Sun, not the Earth, was the center of the solar system.

In 1545, the Italian mathematician Niccolò Cardano used mysterious negative numbers to represent something as real as debt. In 1572, Tycho Brahe, by observing a supernova in the constellation Cassiopeia, discovered that the celestial vault evolved - thus challenging the assumed, eternal immutability of the heavens. Brahe proved that comets soared beyond the moon's realm, and constructed a catalogue of the precise positions of about 1,000 stars. (Besides creating some beneficial memes, Brahe was a memorable character. He lost part of his nose in duel at the University of Rostock in 1566 and had a prosthetic fashioned of a gold, silver and copper alloy to cover the injury. Brahe also had a pet moose named Rix who died after accidentally imbibing too much purloined beer.)

In 1582, the Bavarian astronomer Christoph Clavius and Pope Gregory XIII established the Gregorian calendar to correct errors that had accumulated over centuries because the assumed value of the length of the day had been wrong.

In 1586, Dutch mathematician Simon Stevin wrote fractions in decimal notation, making their manipulation easier.

And in 1590, Dutch optician Zacharias Janssen invented the concept of the microscope.

All of these were and are consequential and beneficial memes for society.

Bad Memes

In the same period of these enlightened memes, though, society also became infected with a destructive one that led to the torture and death of thousands of women. Their pain and deaths were the response of ignorance and uncertainty to a deterioration in the weather. To stave it off, people in Europe engaged in a type of precautionary principle for the climate with human sacrifice.

What was going on?

Nearly one million years ago, the Earth's climate entered an ice age, which had not been seen in some 250 million years. That ice age has meant roughly 100,000-year-long periods of global cold and advancing glaciers between short periods of warmth and retreating glaciers.

The last major glaciation receded into the current, warm relief over 10,000 years ago. And that warm spell has propelled tremendous human advances in population and culture. Between the 9th and 12th Centuries, especially mild climate occurred over many regions of the world (although not simultaneously), in a period called the Medieval Optimum or Medieval Warm Period. Some areas were warmer then than in the 20th Century.

But by the 14th Century, the coldest period of the last 10,000 years seeped across much of the world. Again, it was neither uniform nor was it everywhere, but this brown climate - the Little Ice Age - did not recede in some regions until the 19th Century.

According to climatologist Hubert H. Lamb, the decline in climate in central and northern Europe during the Little Ice Age tended to produce lower temperatures in all seasons and increase fluctuations of extreme conditions, such as heat waves. The realm of Arctic sea ice expanded southward. The frequency of severe storms, windstorms and floods increased.

How did this end up sacrificing women?

Weather conditions were poorest in much of Europe during the latter half of the 16th Century and persisted through most of the 17th Century. For example, the frequency and intensity of floods of the Pegnitz River in Nuremberg rose in that time, becoming five times more frequent than in the 20th Century, a Czech geographer and colleagues recently noted.

That acute period's generally wetter summers, harsher winters, frequent storms and wild fluctuations in weather brought such blights as crop failures, marshland expansion, pasture and farmland destruction, starvation and disease leading to animal and human deaths. According to Lamb, England, France and the Netherlands in the 17th Century suffered wheat prices that were factors of three to five times higher compared to the average across the 13th through 16th centuries. One severe frost in May 1626 froze lakes and rivers, decimated crops and wild vegetation and was characterized by climate historian Christian Pfister as the worst in 500 years.

The seeming reappearance of winter in the late spring of 1626 was unusual. But to contemporary experts it was something even worse - unnatural. And once the extreme weather was labeled unnatural, prevailing memes drew upon fanaticism, superstition and demonology to address climate change. Authorities of that age insisted that sinners, primarily women, working in concert with the Devil, could corrupt the benign weather into hyperstorms and superfrosts with unseen, unknowable and undetectable powers; in short, witchcraft.

While burning people alive for witchery had been practiced for centuries in Europe, witch burnings for climate crimes escalated in response to ignorant, mob demands on compliant authorities, who espoused with theological certainty that only torture and institutional murder would atone for the storm-wielding moral reprobates.

University of York historian Wolfgang Behringer (Witchcraft Persecutions in Bavaria, 1997) documents societal panic triggered by catastrophic weather in the depths of the Little Ice Age. In Germany the severe frosts that decimated crops in 1626 were followed by human sacrifices: Behringer notes that 600 victims were immolated in Bamberg, 900 in Wurzburg, 900 in Electorate Mainz and 2,000 in Cologne.

That history of how destructive memes of superstition can coincide with a time of advance in science ought to inform the debate about climate change in this era.

Memes Today

The severe weather of the late Middle Ages has moderated as the 20th Century banished much of the cold of the Little Ice Age. Meanwhile, the meme that held that human sacrifice would prevent mercurial weather demons in extreme weather is also mostly gone, in part owing to science. But not entirely.

Some modern authorities who believe in catastrophic anthropomorphic global climate change claim the intense storms and floods in central Europe in the summer of 2002 were related to human burning of fossil fuels.

The facts, though, are that there was nothing unusual or unnatural about Europe's weather, especially compared to periods during the Little Ice Age. And computer simulations of climate give no clear evidence that recent or future storms would increase as a result of fossil fuel and energy use.

Recent weather catastrophes are ever-present and naturally-occurring, and to cope with them requires economic resources - which rely upon energy use. That, plus the meme that respects scientific facts.

Copyright 2003, Tech Central Station


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