Published January 10, 2013
The asteroid Apophis has crossed Earth's path. Now, astronomers will return to their calculators to find out what danger it poses in the future.
The 1,000-foot-wide asteroid has made the first in a series of close approaches to the Earth predicted since it was first discovered in 2009.
Scientists ruled out any possibility of a devastating collision this time -- but there remains a small chance the asteroid will smash into Earth in 2036.
This time, Apophis, named after an Egyptian god of destruction, was no closer than around 9.3 million miles.
In 2029, Apophis is expected to come uncomfortably close, brushing past the Earth at a distance of just 18,000 miles. That will put the asteroid inside the orbit of communication satellites.
Current models predict a small but real possibility that Apophis will strike the Earth in 2036 -- but only if the space rock passes through a small "slingshot" region in space when it crosses our orbit in 2029.
This is why scientists are so keen to get exacting measurements of the rocks weight, density, color and shape. All will contribute towards an exact model of the asteroid's orbit.
Scientists at the space agency NASA have calculated that if Apophis struck the Earth it would generate a blast equivalent to more than 500 megatons of TNT.