For today’s 103rd anniversary of the Tunguska Event, an image I pulled from my iPhoto library, taken at the Tucson offices of the Planetary Science Institute. This is a section of a telegraph pole standing in Siberia on the morning of 30 June 1908 when something — a piece of a comet, an asteroid, a black hole, or maybe a UFO — exploded several miles above the Earth, releasing the energy equivalent to about 1000 Hiroshima atomic bombs. But it left no crater, leading to speculation that whatever it was saw complete destruction well above the impact site. The energy of the explosion was directed downward and then radially outward once the fireball reached the ground, flattening on order of 80 million trees in the process; these trees were still laid down some 19 years later when the first Russian expedition to the area arrived. It’s not clear in the photo, but the orientation of this particular telegraph pole relative to the fireball is clear: one side of it is as black as charcoal while the other side is essentially pristine. I don’t know how far away from ground zero it was located.
The tag reads “Tunguska ‘Telegraph Pole’ - Portion of a tree used to support a telegraph line singed by the Tunguska explosion. Siberia, 30 June 1908.”