Iron bodies are much more resistant to fragmentation than rocky ones.Īccording 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. Meteors are thought to explode when air enters the body through small fractures in the meteor, causing a build-up of pressure as it flies through the air at high speed. The rocky body, too, would be less likely to survive. The heat generated by the speed required to obtain the estimated trajectory would have entirely melted the ice body before it reached the distance observational data suggests it covered. The ice body - a hypothesis floated by Russian researchers in the 1970s - was pretty simple to rule out. ![]() The team mathematically modelled the passage of all three asteroid compositions at different sizes to determine whether such an event is possible. 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." "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 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," wrote researchers led by astronomer Daniil Khrennikov of the Siberian Federal University in their paper. Well, it's possible we'll never actually know… but according to a recent peer-reviewed paper, a large iron asteroid entering Earth's atmosphere and skimming the planet at a relatively low altitude before flying back into space could have produced the effects of the Tunguska event by producing a shock wave that devastated the surface. Was it really a bolide? And if it wasn't, what could it be? Later searches have turned up fragments of rock that could be meteoric in origin, but the event still has a looming question mark. It is often referred to as the "largest impact event in recorded history", even though no impact crater was found. The Tunguska event - as it came to be known - was later characterised as an exploding meteor, or bolide, up to 30 megatons, at an altitude of 10 to 15 kilometres (6.2 to 9.3 miles). Geologically young, but not young enough to be the epicenter.Eyewitness reports describe a brilliant ball of light, shattered windows and falling plaster, and a deafening detonation not far from the local river. Core samples drawn by the Russians seemed to indicate that the lake bed was nearly 200 years older than the Tunguska event. ![]() In 2017, a Russian team contested those findings. Dense stony substrate beneath the sediment was likely the remains of the exploded meteoroid, they concluded. ![]() And Lake Cheko’s bed - which is shaped like a crater - was deeper than is typical for the region. The Italian group collected seismic measurements of the crater’s bottom, which showed about 100 years’ worth of accumulated sediment. The study was hotly contested because that crater is located some eight kilometres from the Tunguska event’s supposed epicenter. In 2012, an Italian research team found evidence that pointed to a small 500m crater in Lake Cheko as the point of impact. Others think it was caused by hard impact. Some believe the blast was caused by a mid-air explosion. It is Earth’s largest impact event on record, but scientists have yet to locate its crater. ![]() Experts estimate that the blast decimated some 80 million trees and dispatched at least three human beings. In July 1908, a meteoroid measuring 50-60 metres in diameter plunged through the atmosphere above the Siberian taiga, catalyzing the 12-megaton Tunguska explosion. Photo: Tungussky Nature Reserve The Tunguska event and conflicting research Lake Cheko in Siberia, Russia, close to the epicenter of the Tunguska event.
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