Asteroid 2004 BL86 will fly by Earth on Jan. 26, passing at a range of 1.2 million kilometers [three times the distance between the Earth and the moon]. It will be the asteroid's closest approach to Earth for the next 200 years, according to NASA scientists.
Asteroid 2004 BL86 is nearly 1,800 feet (549 meters) in diameter, but there is no risk of it hitting the Earth when it fly by. The next asteroid of similar size to come near Earth will be the asteroid 1999 AN10, which will make its closest approach in 2027, according to the NASA statement.
Astronomers will track asteroid 2004 BL86 with dish shaped radars at NASA's Deep Space Network in Goldstone, California, and the Arecibo Observatory in Puerto Rico. These radio dishes will beam microwave signals at the asteroid, which will then bounce off the target, and return to Earth.
The resulting radar "echo" looks like a sonogram and can reveal details about the asteroid's three-dimensional shape, its rotation and even its internal density.
Astronomers first detected the asteroid on Jan. 30, 2004, with the 1-meter LINEAR telescope in New Mexico.