Tunguska Blast is 100 years old today June 30, 2008Posted by jcconwell in Asteroid, Astronomy.
Tags: comet, meteor, Tunguska
On June 30th, 1908 a giant blast near the Podkamennaya Tunguska river leveled some 500,000 acres of forest, over 2000 square kilometers. The blast was originally estimated to be between 10 to 20 Megatons of TNT, 1000 times more powerful than the Hiroshima bomb, about the size of the largest H bomb in the world’s arsenals.
Because of the remote location, the political upheaval of the first world war and the Russian revolution, the first expedition did not reach the area until 1927. A blast area of radius 15miles, with felled trees pointing away from the center of impact was found , but no crater.
The lack of a crater has lead to the theory that an airburst of either a comet or meteor at an altitude of approximately 5 miles caused the destruction. The exact nature of the body whether comet or meteor is still a matter of debate. The excess amount of nickel and iridium in trees, both common in meteors, favors a rocky or iron meteorite. Also the number of Earth crossing asteroids is far larger than the number of comets. This has lead most scientists to favor the meteor rather than the comet being the impact object. The debate however is not settled.