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07-05-2013, 01:36 AM
Meteoroid, Not Comet, Explains the 1908 Tunguska Fireball (http://blogs.discovermagazine.com/d-brief/2013/07/01/meteoroid-not-comet-explains-the-1908-tunguska-fireball/)
By Breanna Draxler (http://discovermagazine.com/authors?name=Breanna+Draxler) | July 1, 2013 2:10 pm
http://blogs.discovermagazine.com/d-brief/files/2013/07/Tunguska_Ereignis.jpg (http://blogs.discovermagazine.com/d-brief/files/2013/07/Tunguska_Ereignis.jpg)Damage from the 1908 Tunguska impact as documented by Leonid Kulik on his 1929 expedition to the epicenter.
On this day 105 years ago, Russians were reeling from the enormous fireball that streaked through the sky the day before and flattened almost 800 square miles of trees near the Podkamennaya Tunguska River.
<snip>
The burning chunk of rock struck Siberia on June 30, 1908 with a force 1,000 times more powerful than the atomic bomb dropped on Hiroshima. Over a century later, it is still the largest impact event in Earth’s recorded history. The area was uninhabited (luckily) but that did not mean the blazing ball of who-knows-what went unnoticed.
Scientific expeditions over the last century have combed the site and proposed a flurry of hypotheses: some said meteoroid; some said comet. The comet hypothesis was gaining traction by mid-century since such a mass of ice and dust would have vaporized when it hit the Earth’s atmosphere, causing an explosion without leaving any physical trace. But with so little evidence to go on, none of the theories could be proven.
A 1978 expedition came closer when it uncovered minuscule mineral samples embedded in peat at the epicenter of the blast. Researchers determined the samples to be 99.5 percent carbon with inclusions of other trace elements such as troilite and iridium. The amount of pressure required to form such samples suggested that the minerals were contained in a meteorite that smacked into the Earth. But these samples could also have formed when the heat and pressure of the space blast encountered rocks right here on our home planet, so the results were deemed inconclusive.
Read it all: http://blogs.discovermagazine.com/d-brief/2013/07/01/meteoroid-not-comet-explains-the-1908-tunguska-fireball/#.UdYROG3VWM9
By Breanna Draxler (http://discovermagazine.com/authors?name=Breanna+Draxler) | July 1, 2013 2:10 pm
http://blogs.discovermagazine.com/d-brief/files/2013/07/Tunguska_Ereignis.jpg (http://blogs.discovermagazine.com/d-brief/files/2013/07/Tunguska_Ereignis.jpg)Damage from the 1908 Tunguska impact as documented by Leonid Kulik on his 1929 expedition to the epicenter.
On this day 105 years ago, Russians were reeling from the enormous fireball that streaked through the sky the day before and flattened almost 800 square miles of trees near the Podkamennaya Tunguska River.
<snip>
The burning chunk of rock struck Siberia on June 30, 1908 with a force 1,000 times more powerful than the atomic bomb dropped on Hiroshima. Over a century later, it is still the largest impact event in Earth’s recorded history. The area was uninhabited (luckily) but that did not mean the blazing ball of who-knows-what went unnoticed.
Scientific expeditions over the last century have combed the site and proposed a flurry of hypotheses: some said meteoroid; some said comet. The comet hypothesis was gaining traction by mid-century since such a mass of ice and dust would have vaporized when it hit the Earth’s atmosphere, causing an explosion without leaving any physical trace. But with so little evidence to go on, none of the theories could be proven.
A 1978 expedition came closer when it uncovered minuscule mineral samples embedded in peat at the epicenter of the blast. Researchers determined the samples to be 99.5 percent carbon with inclusions of other trace elements such as troilite and iridium. The amount of pressure required to form such samples suggested that the minerals were contained in a meteorite that smacked into the Earth. But these samples could also have formed when the heat and pressure of the space blast encountered rocks right here on our home planet, so the results were deemed inconclusive.
Read it all: http://blogs.discovermagazine.com/d-brief/2013/07/01/meteoroid-not-comet-explains-the-1908-tunguska-fireball/#.UdYROG3VWM9