Ida and Dactyl: Asteroid and Moon . ... Credit Copyright: Galileo Project , JPL , NASA Explanation: This asteroid has a moon ! ... The second asteroid it photographed, Ida, was discovered to have a moon which appears as a small dot to the right of Ida in this picture. ... Dactyl is the first moon of an asteroid ever discovered. The names Ida and Dactyl are based on characters in Greek mythology. Do other asteroids have moons? ... U. Based on Astronomy Picture Of the Day ...