On Monday January 26, an asteroid called 2004 BL86 flew past Earth at a distance of 745,000 miles. But the asteroid wasn't alone in its journey through the solar system. Scientists studying radar images of the flyby have discovered that the asteroid has its own mini-moon.
The asteroid itself is quite massive, measuring 1,100 feet wide, which is roughly the size of a mountain. The accompanying moon orbiting the asteroid measures 230 feet in diameter. Radar images captured by NASA's Deep Space Network antenna at Goldstone, California showed the moon as a small blimp of light hovering above the large chunk of space rock. Upon viewing the images, NASA research scientist Lance Benner described how he could see the two distinct objects.
"This is an object that's rounded. It has a moon," Benner said. "Using radar last night we confirmed their observations. We can clearly see two objects."
According to NASA nearly 16 percent of asteroids larger than 655 feet are binary systems and some can even be triple systems with a large primary asteroid and two orbiting moons.
NASA also commented that Monday's close flyby is the closest asteroid 2004 BL86 will come to Earth in another two centuries, and the next large space rock to buzz past Earth, asteroid 1999 AN210, will come in 2027.
"The flyby was the closest approach the asteroid will make to Earth for at least the next two centuries. It is also the closest a known asteroid this size will come to Earth until asteroid 1999 AN10 flies past our planet in 2027."2004 BL86 flew past Earth at a relatively harmless distance on Monday. Although, the gap between Earth and the asteroid was nearly three times the distance from the Earth to the moon, scientists predict that it could travel closer to Earth on its next go around. Using the collected radar data, Paul Chodas of JPL's Near-Earth Object Program predicted that the asteroid will keep getting closer to Earth every time it passes for the next few hundred years.
"And over the centuries, and as far as a millennia, this asteroid will be approaching slightly closer each time. So it's definitely one we'll want to keep our eye on." Chodas remarked.
Considering the fact that a space rock measuring 164 feet, which is nearly ten times smaller than asteroid 2004 BL86, would have devastating effects if it hit Earth, we definitely want to watch out for 2004 BL86 in the future.
NASA's team of scientists in its Near-Earth Object Program are currently studying and monitoring asteroids and comets that orbit a little closer to Earth than we would like.