A rare event has given astronomers a great view of a binary asteroid system. Tonight, asteroid 2008 BT18 passed 1.4 million miles from Earth, shining like a 13th magnitude star. Before July 7th, astronomers believed 2008 BT18 was “just another” near-Earth asteroid, but then the Arecibo radio telescope obtained a “delay-Doppler” image of the asteroid … Continue reading "Binary Asteroid Glides Past Earth"