
Image: Geochemistry, Geophysics, Geosystems
(Phys.org) — Early on the morning of June 30th, 1908, a huge explosion occurred in a remote part of Siberia near the Podkamennaya Tunguska River. So great was the blast that trees were knocked down in neat rows for nearly a thousand square miles and the sky lit up from parts of Asia to Great Britain. What caused that explosion has never been firmly settled. Most researchers agree that it was the result of either a comet or meteoroid, with most leaning towards the former due to the lack of both an impact crater and meteoroid fragments. Now however, a research team from Italy says that they have found proof that it was in fact a meteorite that struck the Earth and that a nearby lake is the impact crater. They have published the results of their findings inGeochemistry, Geophysics, Geosystems.
For years, amateurs and professionals alike have debated the cause of the Tunguska Event, as it’s come to be known as. Some suggest it was the work of extraterrestrials while others say it was god’s way of getting our attention. Serious scientists, on the other hand, have suggested its most likely cause was a comet melting and then vaporizing as it hit, leaving no real evidence behind
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http://phys.org/news/2012-05-team-evidence-lake-cheko-impact.html











Is Lake Cheko an impact crater? Hardly so. This idea was put forward as long ago as 2007 (see: Gasperini, L., et al. “A possible impact crater for the 1908 Tunguska Event.” Terra Nova, 2007, Vol. 19, 245–251). But here is an article, in which this question is discussed in detail and the authors’ answer is definite “no”:http://www.univie.ac.at/geochemistry/koeberl/publikation_list/312-Lake-Cheko-not-impact-crater-Terra-Nova-2008.pdf (G. S. Collins et al. “Evidence that Lake Cheko is not an impact crater”). Also, I must add that the problem of the Tunguska explosion is rather complicated. For more information about this problem I would recommend the following books: “The Tungus Event or The Great Siberian Meteorite,” by John Engledew (Algora Publishing, ISSN 9780875867809), “The Tunguska Mystery,” by Vladimir Rubtsov (Springer N.Y., ISSN 9780387765730) and, with some reservations, “The Mystery of the Tunguska Fireball,” by Surendra Verma (Totem Books, ISSN 9781840467284). After reading these books I doubt that the “impactor” will soon be excavated from the lake bottom.