By Rosa Prince, New York
5:50PM GMT 28 Feb 2012
While the object has the potential to wipe out millions of lives if it landed on a city, it is far smaller than the nine mile wide asteroid which is believed to have led to the extinction of the dinosaurs 65 million years ago.
Scientists have only been able to observe half of 2011 AG5’s orbit, and are hoping to obtain more information about the asteroid’s course between 2013 and 2016, when it will be possible to monitor it from the ground.
This will allow them to decide whether action needs to be taken to attempt to alter the course of the object.
NASA has said that options include deflecting the asteroid by attaching a probe to it and using the extra gravity this would create to steer it away from Earth over the course of millions of light years.
Nuclear weapons could also be used to break up the asteroid, although this would probably create a potentially deadly shower of rocks.
According to sky scans carried out by NASA, there are around 19,000 “mid-sized” asteroids of between 330 and 3,300 feet wide within 120 million miles of Earth. All have the potential to destroy an area the size of a city were they to strike.
The Aphophis asteroid, which is the size of two and a half football pitches, is on course to pass close to the Earth in 2036, coming within 18,300 miles of this planet. Scientists expect that it will be visible from most of Europe, Africa and Asia.