The gigantic rock, named 2004 BL86 by astronomers, will sweep safely past Earth on January 26.
A Nasa spokesman said: “It will be the closest asteroid 2004 BL86 will get to Earth for at least the next 200 years.
“And while it poses no threat to Earth for the foreseeable future, it’s a relatively close approach by a relatively large asteroid, so it provides us a unique opportunity to observe and learn more.”
Amateur astronomers with small telescopes and strong binoculars should be able to see the asteroid from the evening of January 26 into the morning of January 27.
The asteroid will whizz past in front of the constellations Hydra, Cancer and Leo.
The asteroid, which is about a third of a mile wide, will pass about 745,000 miles from the Earth’s surface. For comparison, the moon is about 240,000 miles from Earth.
The flyby is notable because 2004 BL86 will be the closest of any known space rock this large until asteroid 1999 AN10 flies past Earth in 2027.