Thursday, June 30, 2016

Tonight's Sky for June 30: the Tunguska Event (1908)

It was on this date in 1908 that the biggest impact from a celestial body in recorded history took place over the remote Tunguska region of Siberia, Russia. 

June 30, 1908 dawned a normal morning in Siberia. Then, just past 7am, a blinding fireball as bright as the Sun came through the sky and exploded. Shock waves knocked people off their feet and windows were broken hundreds of miles away. For the next few days, nights as far away as London were as bright as day. Something extraordinary had happened, but the world would have to wait almost 20 years for scientists to pick up the case when Russian Leonid Kulik finally penetrated the vast wilderness in search of a meteorite crater and/or pieces of the space rock. He came up empty but found over 1,000 square miles of forest flattened, save a small area near the center of the region. Thanks to political instability and then WWII, the world would have to wait almost a generation for further investigation.
In the 1950s and 60s, a new generation of scientists entered the Tunguska forest in search for clues. Recalling damage patterns brought upon by nuclear weapons testing, the Russians theorized that the vast devastation was caused not by a meteor or comet impacting the Earth, but by one exploding above the Earth. Using models with match sticks on springs standing in for trees and small explosive charges for the impactor, the scientists determined that the impacting body, whatever it was, exploded about 5 miles above the Earth while coming in at an angle of around 30 degrees inclination from the horizon. The proof? Scientists were able to recreate the famous butterfly, complete with standing "trees" right above the detonation.
As for what caused the explosion in the first place, there is still lively debate in the scientific community on the asteroid vs. comet theories, with both sides having very valid arguments to support their ideas.

Perhaps the only thing that can be agreed upon is this: Tunguska serves as a stark reminder that the detection of near-Earth objects and the development of technologies to divert them from hitting the Earth should be a very pressing scientific undertaking.


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