The enduringly popular theory that the Chicxulub crater holds the clue to the demise of the dinosaurs, along with some 65 percent of all species 65 million years ago, is challenged in a paper to be published in the Journal of the Geological Society on April 27, 2009.
Latest research has concluded that the Tunguska explosion was almost certainly caused by a comet entering the Earth's atmosphere. And how researcher Michael Kelly from Cornell University came to that conclusion is quite interesting: He analyzed the space shuttle's exhaust plume and noctilucent clouds.