It was a meteorite that crashed in Siberia in 1908! No, it was a comet! No, it was a bomb! No, it was a UFO crash! No, it was a methane explosion! No, it was a visit by an angry Evanki god called Ogdy! No, it was …
Something packing the force of what has been described as 185 Hiroshima bombs hit a fortunately deserted area of Siberia near the Tunguska River in 1908 – destroying an estimated 80 million trees over an area of 2,150 sq km (830 sq miles) – but the space rock or bomb or whatever caused it has never been identified, especially since there’s no impact crater or reliable eyewitnesses. An air burst from a meteor disintegrating in the atmosphere generally gets the most votes, but it’s far from unanimous. Now, new research suggests a similar yet different cause for the Tunguska Event … and that cause may still be around. Should we be worried? Is this the winner? Don’t place your bets … yet.
“We have studied the conditions of through passage of asteroids with diameters 200, 100, and 50 metres, consisting of three types of materials – iron, stone, and water ice, across the Earth’s atmosphere with a minimum trajectory altitude in the range 10 to 15 kilometres.”
In the journal Monthly Notices of the Royal Astronomical Society, Dr. Sergei Karpov and fellow researchers at the Kirensky Physics Institute in Krasnoyarsk, Siberia, focused their attention on a select group of asteroids or various sizes, composed of what they believe the Tunguska rock might have been and traveling at a trajectory estimated to be the same as the event-causer. The model generated what each size and composition would have on 1908 Tunguska.
The icy space rock was eliminated early because it would have melted before achieving maximum destruction. The stone space rock would have come closer, but it still would have disintegrated and left a trail of debris and a possible crater. That left the brick house built by the third little pig … sorry, the iron space rock. After manipulating the sizes, the researchers delivered their verdict and Science Alert reported it:
“According to the team’s calculations, the most likely culprit is an iron meteorite between 100 and 200 metres (320 to 650 feet) across that flew 3,000 kilometres (1,800 miles) through the atmosphere.”
But wait … there’s more! The Siberian Times explains:
“The meteor passed over 3,000 kilometres (1,865 miles) of the planet’s surface at the lowest altitude of 10 to 15 kilometres (6.2 to 9.3 miles), they believe. It travelled at a phenomenal 20 kilometres per second speed (12.4 miles per second) before exiting into the outer space shredding about half of its over 30 million tonnes weight on the way.”
That’s right – the model concludes that the Tunguska Event was caused by the shock wave of a 200-meter-wide iron asteroid that ripped through the atmosphere, losing half of its mass along the way … but not all of it. The 100-meter-wide asteroid blasted back into space, explaining why it left no impact crater in Siberia. What about all of the iron chunks and shavings it lost in its flight through the atmosphere? That is explained by its incredible speed and altitude, says Science Alert:
“It would never have dropped below 11.2 kilometres per second (7 mps), or below an altitude of 11 kilometres.”
“The lack of iron debris is also explained by this high velocity, since the object would be moving too fast, and would be too hot, to drop much. Any mass lost would be through the sublimation of individual iron atoms, which would look exactly like normal terrestrial oxides.”
Those oxides would have remained behind in the higher atmosphere and explain the bright glow witnessed that same night across Europe.
If this sounds similar to the Chelyabinsk Event of 2013, you’re right. However, that one exploded before it could escape and, while destructive, caused far less damage than found in Tunguska.
Is it time for bookies to pay those with “Iron asteroid which went back into space” bets? The researchers are still hesitate to credit their model with an indisputable answer. Are we in any danger of this killer iron asteroid coming back? You’re probably more likely to be done in by an iron deficiency or tripping over an anvil.