by Gene Turnbow, station manager

It’s a big one. Roughly the size of a mountain, about a third of a mile (half a kilometer) across, the flying rock has the rather unglamorous name of 2004 BL86. Don’t worry, it’s not going to hit us. The asteroid will safely pass about three times the distance of Earth to the moon today. This is the closest any space rock this big will pass us until asteroid 1999 AN10 flies past Earth in 2027. It will be about 745,000 miles away from us today, and that’s the closest it’s going to get. It won’t get this close again for another 200 years.


This graphic depicts the passage of asteroid 2004 BL86, which will come no closer than about three times the distance from Earth to the moon on Jan. 26, 2015. Due to its orbit around the sun, the asteroid is currently only visible by astronomers with large telescopes who are located in the southern hemisphere. But by Jan. 26, the space rock’s changing position will make it visible to those in the northern hemisphere. Image credit: NASA/JPL-Caltech

The fact that it’s coming this close gives NASA scientists a chance to do a little science. They’re going to bounce microwaves off it. NASA’s Deep Space Network antenna at Goldstone, California, and the Arecibo Observatory in Puerto Rico have been trying to get science data and radar-generated images of the asteroid during its approach to Earth.

“When we get our radar data back the day after the flyby, we will have the first detailed images,” said radar astronomer Lance Benner of JPL, the principal investigator for the Goldstone radar observations of the asteroid. “At present, we know almost nothing about the asteroid, so there are bound to be surprises.”

Asteroid 2004 BL86 was initially discovered on Jan. 30, 2004, by a telescope of the Lincoln Near-Earth Asteroid Research (LINEAR) survey in White Sands, New Mexico.

If you want to see this asteroid for yourself, it’s big enough and close enough that you can probably spot it with nearly any amateur telescope, or a really good pair of binoculars.

“I may grab my favorite binoculars and give it a shot myself,” said Yeomans. “Asteroids are something special. Not only did asteroids provide Earth with the building blocks of life and much of its water, but in the future, they will become valuable resources for mineral ores and other vital natural resources. They will also become the fueling stops for humanity as we continue to explore our solar system. There is something about asteroids that makes me want to look up.”

NASA’s Near-Earth Object Program Office is experiencing its first transition in leadership since it was formed almost 17 years ago. On Jan. 9, after a 39-year-long career at JPL, Yeomans retired, and was replaced by Paul Chodas, a long-time member of Yeomans’ team at JPL. This NASA office¬† detects, tracks and characterizes asteroids and comets using both ground-based and space-based telescopes. Elements of the Near-Earth Object Program, often referred to as “Spaceguard,” discover these objects, characterize a subset of them and identify their close approaches to determine if any could be potentially hazardous to our planet. Think of it as an astronomical neighborhood watch.

JPL manages the Near-Earth Object Program Office for NASA’s Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena.

For more information on asteroids and other near-Earth objects, visit the JPL page at

To get updates on passing space rocks, follow on Twitter.

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