City-sized asteroids ‘regularly’ smashed Earth in its early years

The early solar system was a violent place, and ancient Earth was pummeled by a bevy of asteroids for millions of years. Now, a new study shows this period of heavy bombardment was 10 times greater than previously believed.

An asteroid impact 66 million years ago wiped out much of life on Earth, ending the Age of Dinosaurs. Between 3.5 and 2.5 billion years ago, impacts the size of this Chicxulub event or larger would have struck Earth every 15 million years or so, this new study finds.

Weather wears away on impact craters through erosion, making older impact craters disappear over the ages.

However, impacts also kick up pellets of molten glass, which land back on Earth. More massive impacts kick pellets further, with the most massive events capable of producing a global debris field.

Credit: Simon Morris/Flickr