A massive blast in 1908 is why we have Asteroid Day on June 30th
More than a century ago, something exploded in the sky above Siberia, breaking windows and creating a shining ball of light – but what caused this unusual event?
A new Russian study suggests a very strange alternative.
The Tunguska event, in 1908, is described as the largest impact event in recorded history, destroying 80 million trees over an area of 800 square miles in the Siberian forest.
But mysteriously, no impact crater was ever found, even though there are fragments of rock that could be meteoric in origin, Science Alert reported.
Researchers have suggested that nothing actually hit the ground at all, and instead, a large iron asteroid flew through Earth's atmosphere before flying off into space.
The team, led by Daniil Khrenikov, wrote: "We have studied the conditions of through passage of asteroids with diameters of 200, 100, and 50 metres, consisting of three types of materials – iron, stone, and water ice, across the Earth's atmosphere."
The researchers said it's possible that an iron asteroid could have passed through the atmosphere and continued into space.
They wrote: "The conditions of this passage with a subsequent exit into outer space with the preservation of a substantial fraction of the initial mass have been found.
"The results obtained support our idea explaining one of the long-standing problems of astronomy – the Tunguska phenomenon, which has not received reasonable and comprehensive interpretations to date.
"We argue that the Tunguska event was caused by an iron asteroid body, which passed through the Earth's atmosphere and continued to the near-solar orbit."
In an interview with The Siberian Times, Dr Sergei Karpov, of the Kirensky Physics Institute in Krasnoyarsk, said the theory of an iron asteroid "passing through" answered several unsolved questions.
He said: "At present, there are over 100 hypotheses about the nature of the Tunguska phenomenon. They include the fall of a small asteroid measuring several dozen metres consisting of typical asteroid materials, either metal or stone, as well as ice.
"We calculated trajectory characteristics of space from 50 to 200 metres in diameter, and our modelling shows that it could not consist of rock or ice because, on the contrast with iron, such bodies fall apart quick because of colossal aerodynamic pressure in the atmosphere."