Cosmic Wildcard Tunguska Turns 100

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It's a planetary smoking gun and the body has still not been found so the jury remains well hung. One hundred years after the event, definitive explanation for what caused a blast which levelled 80 million trees over an area of 2,000 square km (800 square miles) in remote Siberia remains elusive.
One cloudless late June day in 1908, the few eyewitnesses in this remote area of heavily forested Siberia noticed strange doings in the sky. A brilliant fireball resembling a "flying star" was ploughing across the cloudless morning sky at an oblique angle. The plume of hot dust trailing the fireball gave rise to descriptions of a "pillar of fire", which was quickly replaced by a giant cloud of black smoke rising over the horizon.

The blast was 1,000 times more powerful than the atomic bombs dropped on Hiroshima and Nagasaki and generated a shock wave that knocked people to the ground 60km from the epicentre.

Sounds like some kind of cosmic object smashing into the earth but as that obvious explanation has yet to be determined, Tunguska remains rich ground for scientific research and UFO speculation.

The current front runner theory is that it was one huge meteorite which penetrated the earth's atmosphere largely intact and and smacked into Siberia.
Cool but still no body, no crater. Not a single fragment of any sort of cosmic object has turned up nor has an impact site been found for the Tunguska "meteorite".

An aesthetic oddity is that an aerial view of the sire reveals the flattened trees were angled away from the epicentre of the explosion over a 50km-wide zone in a definite butterfly shape. Another peculiarity of the blast left trees at ground zero charred and stripped of their branches and bark, but left standing, from tree to telephone pole in a flash.

Last year yielded the best bet so far at locating the body, when an Italian research team published findings concerning little-known lake Lake Cheko The lake does not appear on any maps of the area made before 1908; it also happens to lie North-West-West of the epicentre, on the general path taken by the impactor as it plummeted to Earth. Further, a radar signal from beneath the lake is suggestive of a dense object, possibly part of the Tunguska meteorite, buried about 10m down.

The Italian team is due back at Lake Cheko in 2009 with high hopes of nailing this one once and for all. Maybe. Other researchers are already poking holes in the idea.Gareth Collins and Phil Bland of Imperial College London, cast doubt on the idea Lake Cheko has anything to do with the Tunguska event.

Unimpressed by the map making skills of Czarist Russia, they point to trees older than 100 years which are still standing around the rim of the lake, as more enduring evidence. These trees would have been toothpicks, nor are the geological features of the lake consistent with known impact origin, they insisted to the BBC.

Other contenders include the comet theory, the antimatter theory, the multiple cosmic object collision theory, a colliding black hole and an exploding alien spaceship .

A personal favourite in this category is one which posits the explosion as the result of a spacecraft from Earth's future trying to land on what should be its home base not a dense pine forest.

The Comet Encke theory also has its fans, proposing that the Tunguska object might be the mother fragment of that ball of ice and dust, responsible for the Beta Taurids meteor shower, which falls into Earth's atmosphere in late June and July - the time of the Tunguska event.

To long-term survivalists, unravelling the thing is vitally important.They see the event as a calling card from future past, The biggest space impact of modern times serves as a heads-up to the continuing threat posed to this planet by objects from space.

As humankind expands its range, the odds contract that the next super meteorite to get through will impact on a populated area. If the Tunguska "impactor" had exploded over a major city such as London, the death toll would have been in the millions.
Watch the skies.