At http://phys.org/print280132683.html … and again at http://phys.org/print280123324.html … we have further on the Russian meteor. Phys Org are making a meal of it today and we learn that NASA say they have detected 9500 celestial objects of various sizes that have a trajectory that cross the path of the Earth – but they also think the real numbers are ten times this (90,000 or so).
At http://phys.org/print280137867.html … an image of Meteor Crater in Arizona is used to introduce the Tunguska comsic mystery, of 1908. No fragments of a meteor or comet have ever been found – which has led to the idea it skipped through the atmosphere and back out again and may be still out there with the possibility of a return visit. Other theories, apart from alien spacecraft, are an explosion of methane leaking out of the ground (is this a projection of global warming theory?) for example. The problem here is that the region is swampy and remote and expeditions there were delayed until almost 20 years after the event. Even then, early expeditions were hampered by the environment and the weather but more recent expeditions have also failed to come up with anything definitive.
At http://phys.org/print280137656.html … we have a fourth page on the subject, in a single day, which locates the meteor passing over the Ural Mountains. Soothing words ooze from scientists but a mineralogist from the University of Munster is more objective. He says there are around ten per year similar meteors – mostly falling on uninhabited areas or into the ocean. The damage from the meteor in Russia was caused by blast – the release of energy. However, it exploded several miles above the surface of the Earth – which is just as well.