Don’t laugh. Sooner or later, it will happen again.
* * *
The above note was composed, believe it or not, on Christmas Day 1985; for as long as I can remember I have escaped to my office as soon as the compulsory festivities are over. Since then, there have been a few more developments.
Halley’s Comet, to the surprise of everyone except Sir Fred Hoyle and Dr Chandra Wickramesinghe (who used the observations to support their controversial theory that comets may harbour bacteria and other life-forms), turned out to be very black indeed. It was not, as expected, a ‘dirty snowball’ – but a ‘snowy dirtball’. However, it certainly did contain vast quantities of ice, and my thesis still stands. It has now received support from several unexpected directions. On 13 August 1984 a report came from Moscow headlined, FROZEN GAS METEORITE HITS RUSSIAN HOLIDAY CAMP; part of it reads:
A Russian holiday camp supervisor who narrowly missed being struck by a block of ice falling from a cloudless sky has provided Soviet scientists with their first sample of an ‘ice meteorite’. Anatoly Kozhukhov heard a whizzing noise and jumped out of the path of the chunk of ice which thudded into the sand two paces away from him at a holiday camp near Kazan on the River Volga. He put the strange object in his refrigerator and called Moscow scientists, who sent a team of researchers. Their conclusion was that the camp had been struck by the remnants of frozen gas meteorites which had penetrated the atmosphere. Ice meteorites had landed on earth before but melted before scientists could analyze their chemical composition, Tass said.
Thank you, Tass; just what I’ve been saying. But the final remark isn’t quite correct. In our Mysterious World programme scientists in England and the USA actually analyzed ice-falls that had been saved. And the Chinese had got hold of a sample a year earlier than the Russian one, for on 11 April 1983 a 100 lb (40 kilo) ‘cake’ of ice dropped out of the sky and splintered on the pavement in the East China city of Wuxi. By an ingenious piece of detective work the Chinese scientists were able to make its meteoric origin virtually certain. On a picture taken seventeen minutes later by the US metsat NOAA-7, they discovered a dark line running across the clouds towards the impact point! They believe it was the track made by the meteor (original mass probably about a ton) as it entered the atmosphere.
Artificial satellites may also have contributed another clue to this continuing story. Astrophysicist Louis Frank of the University of Iowa has discovered that ultra-violet images of the upper atmosphere made by Dynamics Explorer 1 show numerous black spots, lasting a few minutes which he believes are produced by water vapour from incoming ‘ice comets’. If this is confirmed it may throw new light on both planetary and biological evolution. The ice comets – if that’s what they are – arrive at a rate of over 1,000 an hour, and average 100 tons each. If this has been going on for the whole of geological time, it’s enough to account for all the oceans of the earth! This will upset a lot of theories; no wonder that a good deal of arm-waving is going on among Dr Frank’s sceptical colleagues.
Perhaps they feel that all this is uncomfortably reminiscent of the ‘cosmic ice’ theories put forward early in this century by eccentric Germans like Fauth and Hoerbiger, who believed that most of the universe was made of ice and that, for example, lunar formations were carved by glaciers. (Though I wouldn’t swear to it, I seem to recall that one genius constructed a cosmology in which even the sun was made of ice!) Such pseudo-science flourished – briefly -under the Nazis; how ironic if it turns out, after all, to contain an element of truth.
Further Thoughts on Tunguska
The weight of scientific opinion now favours the idea that it was a comet which exploded above Siberia in 1908, laying waste to around 800 square miles of forest. Indeed, in the summer of 1986 the American Geophysical Union held a special session in Baltimore, Maryland, designed to alert the world, in that year of Halley’s return, to the catastrophic implications of another comet arriving and colliding with the earth.
The geophysicists have a special nightmare. Rocks and boulders – the debris of space – are swirling round the earth all the time, running into our atmosphere and disintegrating. On average, a 1,000-ton boulder bumps into us each month. Frequently, especially in June, there are spectacular displays of shooting stars at night as fragments burn up in the upper atmosphere. But what the geophysicists fear is the arrival of a really large body weighing perhaps 100,000 tons or more. They envisage its sudden appearance, unanticipated, in the upper atmosphere.
There would be a tremendous fireball, brighter than the sun; then a cataclysmic explosion. If this took place over a populated area, the destruction and loss of life would be enormous. Worse, it might well be assumed that the explosion was a thermonuclear weapon, with the consequent horror of retaliation and holocaust. Hopefully the sensor systems of the superpowers are, or soon will be, discriminating enough to tell the difference.
However, in September 1986 another natural disaster occurred which, some scientists felt, might shed light on the mystery of Tunguska. In Yaounde, capital of the West African state of Cameroon, the authorities started to receive reports that in an area around Lake Nios in the interior, hundreds of people had just fallen down dead. Officials who quickly arrived on the scene were confronted with an apocalyptic vision.
The rolling green countryside was strewn with the carcasses of cattle, pigs and wild animals. Along the roads and tracks leading to the lake lay the corpses of people who had apparently been struck down as they walked or bicycled along. In the villages themselves around the lake, people had died by the hundred in their houses and gardens. In total, more than 1,700 people died, as well as herds of animals. It was soon apparent that a great cloud of poisonous gas was responsible. It had rolled down from the crater lake, fatally enveloping everything in its path.
In 1984 a geologist, A.R. Crawford of the University of Canterbury, New Zealand, suggested that a great gas cloud from within the earth might have been the cause of the Tunguska explosion. Tunguska, he wrote, ‘might be a wholly terrestrial phenomenon … Rather than being the only well-argued-for cometary impact on Earth, it may be the only modern example of a sudden very voluminous hot gaseous effusion.’ Crawford noted that such gases were associated with diamond-bearing kimberlite pipes, a belt of which lie across Siberia.
Crawford belongs to a school of geologists which believes that the earth may be expanding, even pulsating like a heart, and that this may account for some of the fractures associated with plate tectonics. From these fractures in the earth’s crust may emerge gouts of lethal and explosive gases.
Sixty years of research on the Tunguska site have still failed to come up with any convincing residue of extraterrestrial material, though there are plenty of exotic minerals in the little glass globules found in the Tunguska soil. It is a frightening but plausible concept that the big bang, which could have laid waste a city the size of Paris, might simply have been the biggest gas explosion the modern world has ever seen.
Arthur C. Clarke comments:
The Tunguska event will soon be eighty years in the past. Imagine our surprise, therefore, at receiving this report in 1985 from Mr Samuel Sunter of Victoria, Canada. Mr Sunter was a boy of nine, living in Northumberland, England, when the explosion took place. This is what he told us:
I saw, looking north east, on June 30th 1908, a large red ball of fire, about three times the size of a full moon. It looked just like a hole in the sky. On the other side of the hole, it looked like flames, just like looking into the fire box of a locomotive. But what made me afraid was a solid beam of light which reached right down to where I was standing. This made me afraid and I ran into the house, so I do not know how long it lasted after I first saw it. Even today I have a very vivid memory of it.
Could Mr Sunter have indeed seen the Tunguska explosion from 4,000 miles away across the roof of the world? It seems improbable; but if his memory of the date is correct, he almost certainly witnessed some of its effects.
The whole subject of meteor – or cometary – impact has now become of great scientific and, surprisingly, political importance. On the scientific side, it is now widely believed that the extinction of the dinosaurs (as well as a vast range of other creatures) some sixty-five million years ago was due to the impact of an asteroid or comet about 5 miles in diameter. Quite apart from the colossal immediate danger, the resulting smoke and airborne debris darkened the earth for months, killing off much of the planet’s vegetation and the chains of life that were based upon it.