Last week, a large space rock numbered 2012 DA14 missed Earth, but now is not the time for a sigh of relief because there are still thousands of potentially hazardous asteroids in space.

"Scientists have discovered 1,379 potentially hazardous asteroids, and even more than that number of PHAs have yet to be found," said Zhao Haibin, an asteroid researcher at Purple Mountain Observatory under the Chinese Academy of Sciences.

Asteroids with a diameter of at least 100 meters closer than 7.5 million kilometers to Earth, are considered, "potentially hazardous".