Photo is a freeze frame of a YouTube video from Russia of a meteorite falling in the Chelyabinsk region
WASHINGTON (AP) - Scientists say the threat of space rocks smashing into Earth is bigger than they thought.
Three studies published in the journals Nature and Science say up until February's terrifying meteor that exploded without warning over a Russian city, scientists thought such an event would occur only once every 150 years.
The Russian meteor injured 1,600 people.
The Associated Press