Monday's Fly-by Asteroid Has Its Own Moon

You probably heard about it. Last Monday morning, amateur stargazers and professional astronomers alike looked to the heavens to watch the asteroid known as 2004 BL86 glide by Earth. And while NASA's near-Earth object (NEO) tracking program had long known that this brief visitor was no threat to our planet, it still was a fascinating subject of study.

Now, NASA's Deep Space Network antenna at Goldstone, Calif., have released the first radar images of the asteroid, revealing that it was so massive that it boasts its own tiny moon.

The NASA images were first taken when 2004 BL86 was approximately 800,000 miles from Earth. The hulking asteroid - estimated to be about 1,100 feet (325 meters) across - actually drew 55,000 miles closer, reaching to about three times the distance our Moon is from Earth.

"Monday, January 26 [was] the closest asteroid 2004 BL86 will get to Earth for at least the next 200 years," Don Yeomans, the manager of NASA's Near Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif., said in a recent statement.

"At present, we know almost nothing about the asteroid, so there are bound to be surprises," Lance Benner, the principal investigator for the Goldstone radar observations had announced prior to the event.

He wasn't disappointed. (Scroll to read on...)

The asteroid's somewhat "close" flyby allowed experts to gain some telling information about the asteroid - namely that it is accompanied by a small natural satellite (approximately 230 feet, or 70 meters, across).

Interestingly, even for large near-Earth asteroids like this drive-by visitor, boasting a tiny moon is pretty rare. NASA reports that only about 16 percent of large asteroids that fly around or within our solar system's asteroid belt - the first ring of giant chunks of space rock, ice and dust that separates the orbits of Mars and Jupiter - can be considered a binary or even triple (two moons) system.

Far beyond Neptune, there remains a larger and more mysterious valley of asteroids known as the Kuiper Belt, where this may be more common; however, that is purely speculation.

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