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Record Meteorite Hits Norway
equex256 writes "Early Wednesday morning, a meteorite streaked across the sky in northern Norway, near Finland and Russia. A witness (Article in Norwegian) went up the mountain to where it hit and reported seeing large boulders that had fallen out of the mountainside, along with many broken trees. Norwegian astronomer Knut Jørgen Røed Ødegaard told Aftenposten, Norway's largest newspaper, that he would compare the explosive force of the impact with the Hiroshima bomb. This meteorite is suspected to be much larger than the 90-kilo (198-pound) meteorite which hit Alta in 1904, previously recognized as the largest to hit Norway. From the article: 'Røed Ødegaard said the meteorite was visible to an area of several hundred kilometers despite the brightness of the midnight sunlit summer sky. The meteorite hit a mountainside in Reisadalen in North Troms.'"
Of course the meteor would not have had any noteworthy radioactivity and was not in a populated area. I don't remember exactly how often it's estimated to happen and I can't find any sources, but meteors of this size hit the earth a lot more often than most people realize...something like between once a year and once a decade. The comparison to Hiroshima really is about the energy of the impact, not the destructiveness. Little boy had a yield equivalent to approximately 15,000 tons of TNT.
Whenever the topic of meteors comes up, someone has to post a link to the University of Arizona impact effects calculator. Play with the numbers, see if you can destroy the earth.
Also worth checking out along the Lucifer's hammer line of thought is How to Destroy the Earth
I tried a quick reverse engineering of the meteor with the calculator. An iron meteor 4.5 meters in diameter moving 20 km/s hitting crystalline rock at 45 degrees will have a yield of 18 kilotons...slightly higher than the atomic bomb detonated over Hiroshima. The average interval of an impact of this size on earth is about once every 5 years. Most go largely unnoticed. The earth is a big place.
Actually, I saw a paper presented back in the late 90's that fairly convincingly made the case for a mostly iron meteor. The author's contention was that the object slowed due to air resistance, it would heat up. As is heated, the metal would have softenned. As it softenned, the metal would start to pancake like a dum-dum bullet. As it pancakes, its air resistance increases, causing it to slow down even more and heat up even faster, causing it to pancake even more... until you get an airbirst at an altitude with on the order of magnitude suggested by the tree angles at Tunguska. If you acept his hypothesis about the meteor's composition, there were no major contradictions in the evidence.