A meteorite exploded in the air above Antarctica 430,000 years ago

A micrograph of impact particles from the Sør Rondane Mountains, Antarctica, is shown here.

(CNN)Tiny particles recovered from the summit of a mountain in Antarctica are clues that a meteorite more than 100 yards wide exploded in the sky 430,000 years ago, sending a fireball of vaporized extraterrestrial material to the icy surface, according to new research.

Such "airbursts" are thought to occur more frequently than falling meteors or much larger asteroids that leave craters in the ground -- such as the one that killed off the dinosaurs 66 million years ago. Identifying these space rocks, however, is much harder because they leave few traces in the geological record.
"Asteroids must be sufficiently massive to make it through the atmosphere and reach the ground with enough speed to form an impact crater. Smaller objects, which are much more abundant, explode in the atmosphere and do not form a crater," said Mark Boslough, a researcher at the University of New Mexico, who has studied meteorite explosions but wasn't involved in this latest study.
    Matthias van Ginneken, a research associate from the University of Kent's School of Physical Sciences, collected the 17 dark black particles -- all smaller than 1 millimeter and invisible to the naked eye -- while on an expedition to the Sør Rondane Mountains, Queen Maud Land, in East Antarctica, where the Belgian Princess Elisabeth Antarctica station is based.
      "I first noticed that some of them looked like they had been stuck together, which would have had to have happened when they were molten. It would have meant lots of them interacting with each other when they were at a very high temperature. The only sensible way to explain this was a huge impact," said van Ginneken, the lead author of the study that published in the journal Science Advances on Wednesday.
      This is an artist's rendering of a touchdown impact event over Antarctica.

      'Touchdown impact'

      He and a team of international scientists were able to piece together what happened when the ancient meteorite entered the Earth's atmosphere by analyzing the microscopic particles. Their chemistry and high nickel content suggested they originated in outer space.
      The researchers compared them with similar particles found in two cores of ice, which serve as archives of past geological conditions. The samples, dated to 430,000 years ago, were taken from other locations in East Antarctica. Numerical modeling looking at the distribution and density of the particles suggested that the meteorite would have been between 100 meters and 150 meters wide.
      While the meteorite didn't create a crater, it would have wreaked havoc on the ground.
      "It was a touchdown impact. Like an explosion in the atmosphere that's creating this very hot cloud of gas that travels very fast toward the ground," van Ginneken said.
      He said if a meteor event like that took place above a densely populated area, it would result in millions of casualties and severe damage over distances of up to hundreds of miles.