Asteroid's Moons Show Its Nature

Like the ancient Egyptian queen it was named for, the asteroid Kleopatra has birthed twins — a pair of moons that have helped scientists learn that the huge space rock is a rubble pile rather than a chunk of solid rock.

These two moons, named Alexhelios and Cleoselene after the twin children of the queen, were discovered in 2008. Now, astronomers studying their orbits have deduced that their parent asteroid is a jumble of loosely held rocks.

"That's the point of looking for triple and binary asteroids," study co-author Franck Marchis of the University of California, Berkeley told SPACE.com. "They're the only ones that allow us to measure the mass of the system."…

See SPACE.com for links to further info.