Asteroid (216) Kleopatra has been interesting to astronomers for a long time because its brightness is highly variable, but it seems to get more interesting every time somebody looks at it with a new instrument. In 2000 it was found to be “dog-bone” shaped; in 2008 it was discovered to have two moons.
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.
There are a number of smaller asteroids throughout the solar system that are loose, gravitationally bound piles of rock rather than solid objects.
But to find one in such a large system is surprising. At about 135 miles (217 km) in length, Kleopatra is among the largest of these rubble pile asteroids discovered over the past few years, topped only by 174-mile (280 km) 87 Sylvia.
Credit: UC Berkeley NewsCente/Nola Taylor Redd