Tiny ‘Spherules’ Reveal Details About Earth’s Asteroid Impacts

Researchers are learning details about asteroid impacts going back to Earth’s early history by using a new method for extracting precise information from tiny “spherules” embedded in layers of rock.

The spherules were created when asteroids crashed into Earth, vaporizing rock that expanded into space as a giant vapor plume. Small droplets of molten and vaporized rock in the plume condensed and solidified, falling back to Earth as a thin layer. The round or oblong particles were preserved in layers of rock, and now researchers have analyzed them to record precise information about asteroids impacting Earth from 3.5 billion to 35 million years ago. (Photo Credit: Oberlin College photo/Bruce M. Simonson)

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