Such events were likely common a few billion years ago, when the solar system was young and there were more asteroids roaming and colliding. The meteorites in Sweden provide clues to one of the most modern asteroid collisions known.
In the new study, a chemical analysis of the meteorites reveals they ended up on Earth roughly 100,000 years after their parent asteroids were destroyed in the Asteroid Belt.
That transfer time is surprisingly short, said Philipp Heck of ETH Zurich, a university in Switzerland.
"The transfer times we found provide an additional confirmation that all the fossil meteorites [in the previous Swedish study] are from the same parent body break-up event," Heck told SPACE.com.
The shower of debris lasted at least 1 million years and likely much longer. Unlike a summer meteor shower, which involves comet debris mostly no bigger than sand grains vaporizing in the atmosphere, the asteroid collisions created fragments large enough to create dramatic fireballs in the sky. Some pieces survived their fiery plunge through the air and hit the planet.
Today, random rocks and boulders from space spark fireballs that alarm people and sometimes plow through a roof.
Had there been any humans around 480 million years ago, they would not have noticed any difference on a daily or yearly basis. But on larger time scales, the change was significant.
"Suddenly about a hundred times more often than today bright fireballs would light up Earth´s night sky, at least for the coming million years, or maybe for up to 30 million years," Heck said.
The study is detailed in the July 15 issue of the journal Nature.
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