This color mosaic shows the asteroid Ida and its moon Dactyl. The images use to assemble this picture were taken by the camera system on the Galileo spacecraft as it was passing through the Asteroid Belt in 1993. Ida is about 52 km in length and, as you can see, is irregularly shaped. The image shows many craters, including quite a few degraded ones, indicating Ida’s surface is older than previously thought.
Dactyl was discovered in the series of images Galileo recorded over an observation period of 5.5 hours during the 1993 flyby of Ida. Dactyl’s longest dimension is about 1.6 km.
Image Credit: NASA