Late yesterday, NASA turned the 230-foot (70-meter) Deep Space Network antenna at Goldstone, California towards Asteroid 1998 QE2 as it was heading towards its closest approach to Earth, and they got a big surprise: the asteroid is a binary system. 1998 QE2 itself is 1.7 miles (2.7 kilometers) in diameter, and the newly found orbiting moon is about 600 meters in diameter. The radar images were taken were taken on May 29, 2013, when the asteroid was about 3.75 million miles (6 million kilometers) from Earth. “Radar really helps to pin down the orbit of an asteroid as well as...