Asteroid Explosion Over Antarctica 2.5 Million Years Ago, Study Finds

A recent study suggests that an asteroid exploded over Antarctica over 2.5 million years ago, based on analysis of rock fragments found in the ice of the continent. Published in Earth and Planetary Science Letters, this finding marks the oldest documented midair detonation in the geological archives, with only two other ancient airbursts recorded, dating back 480,000 and 430,000 years.

While asteroids or comets striking the Earth’s surface typically leave visible craters, some objects disintegrate in the atmosphere before impact, leaving no such marks. These airburst events are challenging to detect, but their potential for significant destruction is well-known, with shockwaves and thermal radiation released into the atmosphere upon explosion.

According to Matthias van Ginneken, a cosmochemist at the University of Kent, the energy from an asteroid explosion is dispersed through shockwaves and heat in the atmosphere. Past events like the Chelyabinsk meteor in 2013 and the Tunguska event in 1908 highlight the destructive power of such airbursts.

Van Ginneken and his team analyzed minuscule rock particles from Antarctica, determining their composition and age. The rocks, dominated by olivine and spinel minerals consistent with ordinary chondrite asteroids, suggest an airburst occurred 2.3 to 2.7 million years ago. The oxygen isotopes present in the rocks further confirm their origin from an airburst interacting with ice before landing.

Jason Pearl, a physicist not involved in the study, remarked on the frequency of such events, estimating occurrences every 50 to 500 years. Van Ginneken believes there are more instances of airbursts yet to be discovered in the geological record, indicating ongoing research in this field.