Kleopatra is an unusual object. Its odd shape was revealed by adaptive optics on the ESO 3.6m telescope at La Silla. By bouncing radar signals off the asteroid, a team of astronomers at the Arecibo radio telescope in Puerto Rico were able to develop a more detailed computer model of its shape, which confirmed the dog-bone like shape. A favored explanation is that Kleopatra is a contact binary: two similarly-sized asteroids that have hit and stuck together instead of breaking apart.