Massive Asteroid Flyby on Monday Reveals Surprising Discovery

The massive asteroid that buzzed Earth on Monday didn't come alone. Scientists working with NASA's Deep Space Network antenna found that the asteroid was so large that it had its own small moon.

The asteroid itself made its closest approach to Earth on Monday, Jan. 26, 2015. Called asteroid 2004 BL86, its closest distance was about 745,000 miles, or 3.1 times the distance from Earth to the moon. The asteroid itself was about 1,100 feet across, and the small moon was about 230 feet across. That's massive in terms of the near-Earth population of asteroids; only about 16 percent of these asteroids are about 655 feet across are or larger and are binary.

This asteroid was first discovered on Jan. 30, 2004 as part of NASA's Lincoln Near-Earth Asteroid Research (LINEAR) survey. NASA actually places a high priority on tracking asteroids in order to protect Earth from potential collisions. To date, U.S. assets have discovered over 98 percent of the known near-Earth objects (NEOs).

In fact, NASA already plans to launch a robotic probe to one of the most potentially hazardous of the NEOs in 2016. The OSIRIS-Rex mission to asteroid (101955) Bennu will be a pathfinder for future spacecraft designed to perform reconnaissance of any newly discovered threatening objects.

While this latest asteroid was harmless, there is potential for one to actually one day cause a threat to Earth. That's why NASA continues to work on its Asteroid Redirect Mission (ARM), which will show scientists a bit more about asteroids in general.

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