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NASA Video Reveals New Views of Asteroid with Small Moon

A new video from NASA reveals a sharper look at a large asteroid zipping through space while a small moon orbits it.

New images from NASA and the National Radio Astronomy Observatory clearly show a tiny moon circling Asteroid 2004 BL86 when the cosmic objects made their closest flyby of Earth on Jan. 26. During its closest approach, the asteroid flew about 800,000 miles (1.3 million kilometers) from Earth.

Asteroid 2004 BL86 is a big space rock that measures about 1,100 feet (325 meters) in diameter. The asteroid's moon, at about 230 feet (70 m) wide, is relativly small. The moon is, however, proportionally large when compared to the size of its parent asteroid. The moon is about , and  Roughly 16 percent of asteroids come as a pair (binary system) or a triple system, NASA officials said.

NASA's 230-foot-wide (70 m) Deep Space Network antenna at Goldstone, California and the NRAO's 328-foot (100 m) Green Bank Telescope in West Virginia obtained a series of radar images that led to the moon's discovery.

Moons are somewhat rare among asteroids, but according to NASA, there are at least 150 known examples in the solar system. The first, Dactyl, was discovered orbiting the asteroid Ida in 1993.

Many scientists think that asteroids are leftovers from the solar system's formation. While most of them are located between the orbits of Mars and Jupiter, there are many "near-Earth asteroids" that cross the planet's orbit.

NASA and other space agencies have monitoring programs in place to predict the motions of these objects, and each regularly issue advisories telling the public when a big space rock is expected to safely pass by our planet.

From time to time, however, one does impact the atmosphere – illustrating the long-term danger of these objects. A recent example is a bolide that broke up over Chelyabinsk, Russia in 2013, causing extensive property damage and thousands of injuries (mainly from broken glass).

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Elizabeth Howell

Elizabeth Howell is a contributing writer for who is one of the few Canadian journalists to report regularly on space exploration. She is the author or co-author of several books on space exploration. Elizabeth holds a Ph.D. from the University of North Dakota in Space Studies, and an M.Sc. from the same department. She also holds a bachelor of journalism degree from Carleton University in Canada, where she began her space-writing career in 2004. Besides writing, Elizabeth teaches communications at the university and community college level, and for government training schools. To see her latest projects, follow Elizabeth on Twitter at @howellspace.