Scientists have found evidence that an asteroid at least a hundred meters in diameter exploded at low altitude in Antarctica 430,000 years ago. Particles of extraterrestrial nature have made it possible to establish this large-scale phenomenon.
It was at the top of Walnumfjellet Mountain, located in Queen Maud’s Land in eastern Antarctica, that an international team of researchers led by the University of Kent and Imperial College London found impact particles from an asteroid. The latter exploded at low altitude at this location 430,000 years ago. The pebble, with a diameter of at least one hundred meters, left “condensation spherules” on the spot.
An explosion that melted the surrounding ice
After chemical analysis, these particles revealed a high concentration of nickel coming from space, as well as oxygen: over time, the spherules interacted with the ice of Antarctica. This is the reason why geologists can conclude that the asteroid exploded very close to the ground, because the shock wave melted and vaporized the surrounding ice: the oxygen contained in the ice then mixed with the asteroid particles.
The researchers say this discovery is important in the history of geology because evidence for these events is scarce and complex to find. It is indeed difficult to identify such spherules. Low altitude asteroid explosions are more common than those that create craters, however they are less obvious to detect.
The explosion caused by the meteorite must have been felt for thousands of kilometers, but not by our ancestors: according to scientists, they could not have witnessed it. This does not detract from the likely power of such an impact. An asteroid of ten meters which explodes not far from the surface of the Earth has the force of an atomic bomb of several megatons.