meteorite was left by an asteroid that formed a fireball and exploded over the russian city of chelyabinsk was the biggest one to hit the earth in a century. most asteroids orbit the sun in a region between jupiter and mars known as the master. royd out there debris left over from the early solar system. this animation shows the orbits of all 600000 known asteroids new ones are discovered every month the earth has been struck throughout its history and the moon shows how often and violently lunar impact craters aren't worn away by wind and waves so the moon serves as a kind of archive over the last 290000000 years the frequency of impact on earth has risen because large asteroids have collided producing many tiny fragments. some of these space rocks caused massive destruction when they hit the earth like one that struck 66000000 years ago. an asteroid measuring 10 kilometers in diameter landed in mexico and the cataclysm that ensued wiped out the dinosaurs and many others feel she's not even much smaller asteroids can cause deadly damage that's why telescopes constantly survey the sky to d