Dinosaur-killer asteroid was a cosmic mudball, study

A recent study suggests that the asteroid responsible for the mass extinction of dinosaurs was a giant mudball, composed mainly of clay and ancient solar system materials. 

Published in Science, the research analyzed a global clay layer from the extinction period and identified its chemical signature as matching that of a carbonaceous chondrite—a rare type of asteroid rich in water and organic compounds. 

The mudball, roughly 6 to 9 miles in diameter, struck the Yucatan Peninsula 66 million years ago, vaporizing upon impact and creating a dust cloud that blocked sunlight and drastically cooled the planet for years.

The event led to the extinction of 75% of animal species, including most dinosaurs.