 This asteroid has a moon! The robot spacecraft Galileo, while exploring the Jupiter system, photographed several asteroids. One of them, the asteroid Ida, is shown above, and it clearly has a small moon in orbit around it. Ida itself is only about 60 kilometres long; its tiny moon, named Dactyl, is a mere 1.5 kilometres across. Dactyl is the first moon of an asteroid ever discovered, although other asteroids are now known to have moons too. The Galileo spacecraft took the photo above on August 28, 1993, when it was about 10,500 kilometers from Ida. Photos and information from NASA Picture of the Day |