
100 years ago today, local people in Shepard, Texas, were rocked by a massive explosion as a meteor smashed through the roof of a house in the town. Luckily that was all the damage there was, and no one was killed. On June 30 a year later, the Tunguska event took place, which was a very much bigger event altogether.
The 1908 Tunguska event has always been mysterious and intriguing because there were no known witnesses, and it has been difficult to fully understand what caused the explosion that flattened more than 2000 square kilometres (800 square miles) of Siberian forest (pictured). However, recent research by Michael Kelly of Cornell University has confirmed that the cause was almost certainly a comet exploding in the atmosphere.
Kelly saw that weather events after Tunguska were similar to those after several Space Shuttle launches, when water vapour from the Shuttle’s exhaust caused bright night-time clouds. This is similar to conditions after Tunguska, when nights were so bright that you could read a newspaper at midnight across much of Europe. Kelly has concluded that the only source that could provide such a huge amount of extra water vapour in 1908 would have been the head of a water-ice comet, flashing to instant steam as it hit the atmosphere at anything up to 72 km/sec (45 miles/sec).
Are we in danger of a repeat Tunguska event? It’s impossible to say absolutely, but there are no known dangerous comets or asteroids presently visible in the skies. Still, rocks from space make a great plot for an end-of-the-world drama, as Bruce Willis showed in the 1998 Hollywood sci-fi drama Armageddon, directed by Michael Bay of Transformers fame. Dubious science aside, it was a good humoured romp that deserved its box office success. Enjoy the trailer!








































