Close Encounters Of The Fourth Kind

As every visitor to that little Gaulish village circa 50 BC knows, Vitalstatistixs only fear is that the sky may fall on his head. But, by Toutatis, it hasnt happened yet. But the asteroid Toutates itself nearly fell on our heads just about three months ago passing a galactic hairsbreadth from the Earth in its eccentric orbit. Thus the speculations of a collective scientific community of geologists, astron-omers,chaoticists,paleontologists and science fiction writers were confirmed by experimental verification as the closest asteroid strike of recent history occurred.

Back in the 40s, Velikovsky popularised a Catastrophism Hypothesis for the development of human life, the extinction of dinosaurs, the ice age cycles etc. At that time it was dismissed as merely speculative. By the 90s, with new information and the sharing of interdisciplinary information, scientists have veered around to believing that cometary and asteroid strikes are indeed the likeliest explanation for the current state of spaceship earth and the solar system.

 

This collaboration by the well known popular science team is an entertaining and well documented account of the recent dramatic changes in our view of the solar system and the frightening, if logical, consequences.

What were the developments that forced scientists to reconsider standard evolutionary and astronomical models? First of all, geologists kept finding huge quantities of iridium at layers of datum that corresponded closely to the extinction of dinosaurs 65 million years ago. They also found similar iridium deposits in earlier layers that corresponded closely to other extinctions. At the same time, paleoentologists discovered that there was a pattern to extinction cycles which recurred every so many million years. Iridium is a very rare metal in the earths crust whereas it is far more common in asteroid and comets.

Meanwhile, astronomers simultaneously discovered there were more comets in the outer solar system than there were stars in the Milky Way. They also used the orbit-modelling techniques of Chaos Theory to work out that huge numbers of these had unstable eccentric long-period orbits that brought them close to the earth and in some cases, even closer to the sun at perihelion. Physicists used the data garnered from nuclear explosions to develop nuclear winter simulations wherein temperatures dropped to Ice Age levels. These were confirmed incidentally by Mt Pinatuba which forced world average temperatures down by around 2 degrees Celsius with its dust cover.

By 1994, Nobel-winning physicist Luis Alvarez and his team had worked out the probabilities of large impacts on the earth. Using H-bomb explosion data they had also worked out the likely size of the impact craters required to trigger the level of planetary catastrophe that would cause extinctions. Then comet Shoemaker-Levy had its spectacular collision with Jupiter and impact craters of the right era notably one in Yucatan (Mexico) were discovered. Astronomers also observed similar unmistakable impact activity and debris across the entire solar system.

The data from the Tunguska impact of 1908 and also the 17th and the 5th centuries AD also fit the catastrophic scenario. Assuming cosmic impacts, destr-uctions such as Sodom and Gom-orrah make sense. A 5th Century Northern European crash drove nomads south to invade Rome. A February 1994 atmospheric explosion nearly sparked off nuclear reaction from a jittery US military. Toutates recently added the icing on the cake.

Comet Swift-Tuttle will be a high probability contender for the title of the Doomsday asteroid as it will make close approaches over the next 10,000 years. A stratospheric Hiroshima occurs every year or so. The current odds on a 20 kiloton explosion is once every 5 years, while a 700 kt bang comes every 350 years. There is a one in 10,000 chance of a 2 km object hitting the earth in any given century. This would wipe approximately 2 billion people out.

The risk of megadeath from cometary impact is greater than the combined risk of death from storms, forest fires and volcanic eruptions. Its around one in 20,000 for most of us. Scary? Yes, and there are less than 12 people worldwide on permanent watch for such objects and there isnt much science could do to even limit damage.

Its a fascinating subject for a book not least because of the cooperation between scientists from different disciplines. While there is no point in hanging Armageddon placards out with the Diwali greetings it should also help concentrate readers minds wonderfully. Please note this is not fiction, its hard fact reluctantly conceded by scientists who dislike the implications just as much as you do.