Every year, Earth passes through the tail of the comet Encke - twice. This isn’t unusual. We regularly cross cometary trails of ice and dust. But this one may be different. It could have been the source of the dramatic 1908 Tunguska airburst which flattened hundreds of square kilometres of Russian forest. The 45m wide comet fragment struck on June 30, at the height of the Beta Taurid shower. Was it, in fact, a part of that shower? Astronomer and science advocate Dr Phil Plait says it is possible. Calculations of its trajectory indicate the Tunguska object came from the...