Researchers have suggested that an asteroid that was on course to collide with Earth may have detonated over Antarctica more than 2.5 million years ago, based on their analysis of rock samples retrieved from the continent’s ice.
A report published in Earth and Planetary Science Letters revealed that this asteroid explosion represents the oldest documented midair detonation recorded in the geologic archives. Prior to this discovery, only two ancient airbursts had been recorded, dating back 480,000 and 430,000 years. While asteroids or comets impacting the Earth’s surface typically leave visible craters, some incoming objects disintegrate in the atmosphere before reaching the ground, leaving no trace of impact. However, evidence of such midair bursts has been limited.
The detonation of asteroids can result in significant devastation, typically occurring at altitudes ranging from a few to several tens of kilometres above the Earth’s surface. The immense kinetic energy of the incoming object is transferred into an impact plume, generating a complex mix of shock waves and thermal radiation.
Matthias van Ginneken, a cosmochemist from the University of Kent in England, explained that during such events, “All the energy is released in the atmosphere in the form of shock waves and thermal radiation.” These phenomena contribute to the destructive potential of asteroid explosions in the Earth’s atmosphere.
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