An international team of researchers led by scientists from the University of Kent and Imperial College London has discovered extraterrestrial particles in Antarctica that indicate a medium-sized asteroid impact on the continent. Researchers believe the effects occurred about 430,000 years ago and the particles were discovered on the summit of Walnumfjellet Mountain in Queen Maud Land in East Antarctica.
The discovered particles are known as condensation spheres and suggest that an asteroid with a diameter of at least 100 meters hit the ice at high speed 430,000 years ago. The impact caused an explosion that created a jet of molten and vaporized meteorite material that scattered and settled over the Antarctic ice sheet. The research paper authors say this is an important discovery for geological record as there is little evidence of this type of event.
The lack of evidence is mainly due to how difficult it is to identify and characterize impact particles. Researchers say they’re pretty sure that human ancestors didn’t see the explosion. Study co-author, Doctor Matthew Genge, says that the explosion of an asteroid or comet just a few tens of feet tall at low altitude can resemble a nuclear explosion with energy measured in megatons. Asteroids that explode at low altitude in the atmosphere are more common than those that form craters but are the most difficult to spot in advance.
In this case, debris was examined from the mountain by analyzing extremely small amounts of various chemical elements. The researchers discovered high nickel content and unique oxygen signatures in the rubble that enabled them to pinpoint an approximate date of impact and highlight the extraterrestrial nature of the recovered particles. The team’s scientists also believe the study highlights the importance of reassessing the threat posed by medium-sized asteroids. An effect of this size would be extremely destructive over a large area.