The moon of Asteroid Ida. Image taken by the Galileo spacecraft showing Dactyl, the tiny moon of Asteroid 243 Ida, previously known as 1993(243)1. This image was the first conclusive evidence that an asteroid could have a satellite. The moon is roughly egg-shaped, about 1.5km in diameter, and is thought to orbit about 100km from Ida's centre. More than a dozen impact craters over 80m diameter are seen in this image, the largest (near the terminator) is about 300 metres across. This image was gathered on August 28th, 1993, at a distance of 10,870km from Ida, but was relayed to Earth on June 8th, 1994.