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Apocolypse Now (Or At Least Pretty Soon Anyway) Part 1

Rob West
Rob West

Bill Bryson’s engrossing book, A Short History of Nearly Everything, is an extremely long and amusing essay on the history of the universe (yeah I know, the title kind of gave that one away right?!). It details the gradual stages of scientific discovery that lead to our current understanding of the universe and includes some pretty amazing facts. The next few blogs are going to outline some of the more dramatic.

The first is a real classic crowd pleaser: Meteorites.


Not only is the likelihood of the Earth getting hit by a meteorite big enough to change the entire planet enough to wipe us all out a lot higher than you might expect but unlike the films such as Armageddon and Deep Impact show, we would not get any warning.
Asteroids lie in a vast belt between Mars and Jupiter where they will normally be no closer together than 1.5 million kms. The first scary thing is that there are so many of these huge rocks that no one knows how many there are though by 2001 26,000 had been identified. Multiply that by almost 40 million and that is when you reach conservative estimates of the total asteroids in the sky. Bryson states that out of these, around a hundred million (these are only the ones bigger than about ten metres) cross the orbital path of the earth. All of these are incredibly difficult to track as they are small, unpredictable and move extremely fast. The task of an early warning system is thus totally out of the question so Bruce Willis wannabes can put down there drills and head home to sulk.
He claims, though emphasises the guesstimation techniques used, that some two thousand asteroids big enough to “imperil human existence” cross our paths regularly. Even one much smaller than this, of which the numbers are running much higher, could destroy cities and landscapes.
The first really near miss recorded was in 1991. Inventively named 1991 BA, it cruised past at a distance of 170,000 kilometres, a hairs breadth astrologically. The crazy thing is, is that we didn’t notice it till it had already past (honestly by this point I was getting slightly loose in the sphincter area).
The next recorded miss was only two years later and came even closer and again wasn’t noticed till it had past. Some reckon that these near misses go on all the time, maybe every week, but just don’t get noticed.
The most renowned of the big collisions is the dinosaur extinction meteorite. This hit Mexico, but interestingly is by no means the only large impact site on earth. We are crater pocked, not quite to lunar standards but maybe to the extent of an acne imbalanced teen. The gradual and sometimes huge processes of geology have just hidden them from view. These impact sites have been studied and release a heap of information for the scientists on the energy released and allows them to create models of scenarios. The brief one that follows is from a crater in Iowa, USA.
Because the asteroid would hit at such a high velocity the air beneath it would not be able to move out of the way and thus would heat rapidly to ten times the surface temperature of the sun and evaporate everything in it’s path. A second after entering the atmosphere, it would hit the earth and vaporise though not before it had sent 1000 cubic kilometres of rock, earth and super heated gases flying up into the sky. Everything in a 250 km radius would die from the blast radiating outwards at almost the speed of light. For those further afield a flash of light brighter than any seen by human eyes would be followed by a huge cloud of debris rushing at thousands of kmph. The blast would kill, maim and destroy things up to around 1500 km away in every direction. Volcanoes going off, earthquakes and tsunamis would occur next on a global scale and a cloud of debris and dust would cover the planet. Estimates put the death toll at a billion and a half by the end of the first day. The sun would be blotted out, nothing would grow and there would be nothing for life to cling onto for months or years. The effect of the impact would still be being felt 10,000 years in the future.
Out of a clear sky this could come and even if we did know about it there is literally nothing that can be done. Scary eh?!

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