Bennu has a shape that looks a bit like a spinning top. It is roughly 500 meters (1,640 feet) in diameter and orbits the sun once every 1.2 years, or 436.604 days. Every six years or so, it comes very close to Earth — about 0.002 AU, according to the University of Arizona. (... well within the orbit of Earth's moon.) Bennu is part of a small class of carbonaceous (dark) asteroids that likely have primitive materials in them. Called a B-type class, Bennu and other asteroids like it have materials such as volatiles (compounds with a low boiling point),...
