A day after over 1,000 people were injured after a meteor weighing about 10tonnes exploded over the Ural Mountains in Siberia on Friday, scientists, including NASA's Amitabha Ghosh - the Washington-based Indian who was a part of the Mars mission - warned that humans are sitting ducks for such 'cosmological bullets' because very little is known about them.

"There are millions of such small rocks, which might hit the earth anytime. And the worst part is that we have no information about them," said Ghosh.

Heavy-impact asteroid hits have occurred only around 10 times since the earth was formed. One of them is believed to have wiped out dinosaurs.