Hildebrand, who along with Brown heads the Prairie Meteorite Search Project, said ample evidence of these atmospheric explosions can be found on the planet Venus. If Tunguska was of a similar low density, it too would have broken up in the atmosphere. (Last year, an team of Italian scientists said they had found a crater at the bottom of nearby Lake Cheko.)ĭecades after the first expedition, as theories in physics advanced and the time gap between the actual event and subsequent research grew, a host of other ideas were postulated, everything from an antimatter explosion to the impact of a tiny black hole.īut meteors like Tagish Lake and earlier Canadian examples, such as the 1965 impact near Revelstoke, B.C., have shown that low-density meteors do break up in response to atmospheric pressure, and that when they do, they can still pack a punch. And it was Tunguska's apparent lack of an impact site that puzzled expeditions visiting the region. Usually, when people think of the threat of a comet hitting the Earth, there is an actual impact and with a crater left behind. "That, and the huge detonations, of course."Īnd yet, for all of Tagish Lake's pyrotechnics, the energy released during the detonation was about the equivalent of one kilotonne of TNT. "That certainly made an enormous impression on people," he said. As a result, the dust trail left by the meteor hung in the air like an "ethereal glowing cloud," said Brown, who spent three months in Tagish Lake with University of Calgary associate professor Alan Hildebrand collecting evidence of the event. The sun was also just on the verge of rising above the horizon, so objects in the sky were illuminated in what would normally have been a twilight sky. It reportedly lit up the nearby landscape with a blue-green light that was as much as ten times brighter than daylight. Streaking across the dark morning sky at a shallow trajectory, the meteor broke apart in an explosive fireball seen by different witnesses for hundreds of kilometres. The Tagish Lake meteor, as it's now known, fell to Earth on January 18, 2000, and was the largest impact over land anywhere in the world in the last decade, Brown said. To put in perspective how spectacular Tunguska must have been, consider a similar atmospheric flameout of a meteor near Tagish Lake in northern B.C. "Tunguska was the mother of all recorded impacts in human history." Tagish Lake a firecracker by comparison "There's never been an event of this magnitude before and since that has been as well-documented," said Peter Brown, a University of Western Ontario associate professor and a member of the Western Meteor Physics Group. Remarkably, there were only two reported human deaths. So it would be another two decades before an actual scientific expedition could travel to the site to piece together what happened.Īccording to the best estimates, a chunk of space rock - possibly an asteroid or comet estimated to be about 50 metres in length - exploded in the atmosphere at an altitude of six to 10 kilometres above sea level, sending a blast of heat and a shockwave with a likely energy equivalent of about 10 to 15 megatonnes of TNT, or about 1,000 times more powerful than the blast from the bomb dropped on Hiroshima during the Second World War. Russia was a nation in upheaval, just recovering from one revolution in 1905 with another on its way in 1917. There were even reports of brighter than usual nights across Europe.īut Siberia in the early 20th century was not an easy place to reach. Eyewitness accounts from the sparsely populated region reported a sky split apart by fire, accompanied by sounds like explosive thunderclaps. ((Soviet Academy of Science))Īn estimated 80 million trees covering more than 2,150 square kilometres were flattened. Trees were found knocked down and burned in the Tusguska region of Siberia in this photo taken during a 1927 Soviet Academy of Science Expedition.
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