very fascinating especially given the knowledge that a comet will intersect earth at some point in the future… perhaps not in our lifetime but within a few hundred years.

the event, known as the tunguska event or tunguska explosion, was a powerful mysterious explosion in 1908 that occurred near the tunguska river in what is nowkrasnoyarsk krai in russia. although the cause of the explosion is the subject of debate to this date, it is commonly believed to have been caused by the airburst of a large meteoroid or comet fragment at an altitude of 5–10 kilometers above the earths surface. the explosion registered on seismic stations across eurasia. in some places the shock wave would have been equivalent to an earthquake of 5.0 on the richter scale. it also produced fluctuations in atmospheric pressure strong enough to be detected in great britain. more recent discoveries here. by dd

“why can’t I see them now?” is the daughter’s question that’s said to have inspired edwin land to devise the instant camera eventually produced by his polaroid corporation. the camera was announced in 1947 and hit the market in 1948. sixty years later (2008) the company stopped production of its film-based cameras and then of its self-developing film. the last polaroid film expired on October 9 2009. by bh