30 June, 1908. Thousands of square km of trees were burned and flattened.
Scientists have always suspected that an incoming comet or asteroid lay behind the event - but no impact crater was ever discovered and no expedition to the area has ever found any large fragments of an extraterrestrial object.
The explosion, equivalent to 10-15 million tones of TNT, occurred over the Siberian forest, near a place known as Tunguska.
An atmospheric shock wave circled the Earth twice. And, for two days afterwards, there was so much fine dust in the atmosphere that newspapers could be read at night by scattered light in the streets of London, 10,000 km (6,213 miles) away.
So what was that?!






















