Asteroid AG13 narrowly misses earth

While everyone was asleep in their beds early on Tuesday morning, an asteroid the size of a 10-storey building came very close to earth.

The new asteroid, dubbed 2017 AG13, was first discovered on Saturday by the University of Arizona's Catalina Sky Survey.

If the asteroid had of hit earth, it would have created around ten times more energy than the atomic bomb that hit Nagasaki.

The space rock is estimated to be between 10 and 33 metres wide and it came within half the distance that the moon is from Earth, according to Slooh.

"This is moving very quickly, very nearby to us," astronomer Eric Feldman said during a live broadcast of the flyby. "It actually crosses the orbits of two planets, Venus and Earth."

"This one has a particularly elliptical orbit which means it has a stretched out rubber band-like shape versus more of a circular shape."

"This rock out of space it is actually moving about 16km/s," he said.

Possible impact

Researchers at Purdue University have created an "Impact Earth" simulator to calculate the possible impact of asteroids.

Had a porous rock asteroid the size of AG13 hit Earth at a 45-degree angle, the simulator found, it would have exploded into smaller fragments.

The blast would release around 800 kilotons of energy  around 10 times more powerful than the atomic bomb detonated over Nagasaki.

Because the impact would have occurred as the asteroid entered the atmosphere, it would have shattered into smaller pieces and the boom would have sounded like heavy traffic from the ground.

However if you heard that sound and went outside to see what the chaos was, you would already be too late. It would take over a minute for the sound of the impact to reach the ground.

Realistically, Purdue estimates this type of asteroid is only likely to hit the earth every 145 years.