A 100-meter asteroid triggered a wierd affect occasion in Antarctica 430,000 years in the past

The effects of the impact of ancient asteroids on Earth can still be seen from the multitude of impact craters on our planet. And from the 2013 event in Chelyabinsk, when an asteroid exploded in midair over a Russian city, we know how devastating an “airburst” event can be.

Now researchers in Antarctica have discovered evidence of a strange intermediate event – a combination of impact and blast of air. The event was so devastating that its effects can still be seen, even though it happened 430,000 years ago.

The researchers found small black spheres in the Sør Rondane Mountains in East Antarctica, indicating an unusual “touchdown” event in which a jet of molten and vaporized meteoritic material hit the ground at high speed. This impact was the result of atmospheric entry and an air blast from an asteroid between 100 and 150 meters wide.

Scanning electron backscatter images of the spheres found in Antarctica. Photo credits: Matthias van Ginneken et al.

Research, led by planetary scientist Matthias van Ginneken of the University of Kent in the UK, described the event as larger than a puff of air but smaller than an impact crater event. While the density of the evaporated material was too low to form an impact crater, the tiny spheres of igneous rock signal an energy-rich event.

The team’s paper, published in Science Advances, shows that the evaporation of the asteroid as it entered the atmosphere would have created a cloud of superheated gas, from which the alien spheres would have hurled the ground at high speeds, perhaps several kilometers per second.

This picture of a contrail was taken about 200 kilometers from the meteorite event in Chelyabinsk, about a minute after the house-sized asteroid entered the earth’s atmosphere. Credits: Alex Alishevskikh

The Chelyabinsk incident, the largest witness to a blast of air (except perhaps the Tunguska incident of 1908, which flattened trees for miles), exploded over Hiroshima at a height of only 14 miles with 20 to 30 times the force of the atomic bomb. Before exploding into thousands of mostly gravel-sized meteorites and dust, the researchers estimated that the incoming meteorite was about 20 meters wide and about the size of a five-story building. The shock wave from the explosion shattered windows and damaged buildings, injuring nearly 1,500 people.

The new findings in Antarctica point to a far more dangerous influence than the events in Tunguska and Chelyabinsk. The researchers said this underscores the importance of reassessing the threat posed by medium-sized asteroids, as it is likely that similar touchdown events would produce similar particles and be destructive over a wide area. Such an event could create a landscape of hell between the hot gas and the jet of hot material that pelts the ground.

“While touchdown events may not jeopardize human activity in Antarctica,” said van Ginneken, “they would take place over a densely populated area and cause millions of casualties and serious damage over distances of up to hundreds of kilometers. ”

Van Ginneken said his team recommends that future studies focus on identifying similar events on different targets around the world – on shallow ocean floors, for example – as this would indicate how many times such events might have occurred in the past.

Sources: Science Advances, University of Kent

Caption: Mocked illustration of the impact of Touchdown on Antarctica by Mark A. Garlick

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