Ida is an asteroid in the belt between Mars and Jupiter. It was the 243rd to be discovered. It is the only asteroid with a moon. Ida was visited by the Galileo probe on its way to Jupiter. Ida rotates once every four hours and fifty minutes, which is 5 times for every orbit of Dactyl, which is 23 hours and 10 minutes. Before the discovery of Dactyl, scientists weren't aware that asteroids could have moons.