Do scientists know what the Tunguska event actually was 100 years ago?”
http://en.wikipedia.org/wiki/Tunguska_event The Tunguska Event, or Tunguska explosion, was a powerful explosion that occurred near the Podkamennaya (Lower Stony) Tunguska River in what is now Krasnoyarsk Krai of Russia, at around 7:14 a.m. on June 30, 1908 Although the cause of the explosion is the subject of debate, it is commonly believed to have been caused by the air burst of a large meteoroid or comet fragment at an altitude of 5–10 kilometres (3–6 miles) above the Earth’s surface. Different studies have yielded varying estimates of the object’s size, with general agreement that it was a few tens of metres across.[ Although the meteor or comet burst in the air rather than directly hitting the surface, this event is still referred to as an impact. Estimates of the energy of the blast range from 5 megatons to as high as 30 megatonsof TNT, with 10–15 megatons the most likely—roughly equal to the United States’ C
