THE Tunguska blast that flattened a huge swathe of remote Siberian forest one morning in 1908 might have come from within the Earth rather than from outer space.
Although the mysterious explosion didn't leave a crater, trees over an area of 2100 square kilometres were burnt and flattened. Most researchers agree that the devastating incident was caused by some kind of celestial body disintegrating a few kilometres above the ground,and say the only serious debate about Tunguska is now whetherit was a fragment of a comet or a stony meteorite.
Yet scientists are still arguing over certain unexplained events and the fact that no samples of the impacting object have ever been found. "If a group of experts cannot agree for almost a hundred years, it's probably a third option," says Wolfgang Kundt, an astrophysicist from the University of Bonn in Germany.
That third option is a high-pressure gas explosion, ...
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