Asteroid Zips by Earth with Moon in Tow
May 31, 2013
A large asteroid that is swinging past Earth today is bringing along a surprise companion–a moon. Asteroid 1998 QE2 will make its closest approach to Earth at a comfortable distance of 3.6 million miles (5.8 million kilometers) at 4:59 p.m. Eastern Daylight Savings Time. That distance is about 15 times as far as the orbit of Earth’s moon, so there’s no chance that the asteroid could crash into us.
Scientists have been tracking the asteroid since its discovery on August 19, 1998, by the Massachusetts Institute of Technology Lincoln Near Earth Asteroid Research program in Socorro, New Mexico. Radar images of the asteroid suggest that it is about 1.7 miles (2.7 kilometers) in diameter. The moon is an estimated 2,000 feet (600 meters) across, more than 15 times the length of a football field. Only about 16 percent of asteroids larger than 655 feet (200 meters) in diameter belong to systems with two or more objects.
A series of radar images show asteroid 1998 QE2 as it appeared when it was about 3.75 million miles (6 million kilometers) from Earth. The small white dot at lower right in the images is the asteroid's moon. (NASA/JPL-Caltech/GSSR)
Scientists at NASA’s Jet Propulsion Laboratory in Pasadena, California, began observing the asteroid and its moon on May 29 using two radar telescopes—the Deep Space Network antenna at Goldstone, California, and the Arecibo Observatory in Puerto Rico. The radar observations, which will continue until June 9, will allow the scientists to determine the size and shape of the asteroid and its moon and to study the objects’ surface features. The first radar images of the asteroid revealed dark areas that may be impact craters or another kind of depression in the surface.
NASA’s Near-Earth Object Program identifies and tracks comets and asteroids that move around the sun near Earth’s orbit. These comets and asteroids are called near-Earth objects or NEO’s. The major role of the program is to determine if any NEO’s could strike Earth. By the end of 2008, the program had discovered and tracked more than 90 percent of the NEO’s larger than 0.62 mile (1 kilometer). The program is now focusing on finding 90 percent of NEO’s larger than 450 feet (140 meters). As of mid-2013, the program had found 9,858 NEO’s. At least 860 of them have a diameter of approximately 0.62 mile.
Additional World Book articles:
- Dawn
- Eros
- Vesta
- When Worlds and Comets Collide (a special report)
- What Has Caused Mass Extinctions (a special report)
