Dactyl (moon)
Dactyl (designated (243) Ida I Dactyl) is a tiny asteroid moon which is 1.6 km in diameter and orbits the asteroid 243 Ida in the asteroid belt.[1] It was first imaged by the Galileo spacecraft on August 28, 1993; Dactyl was discovered while examining the delayed image downloads from the Galileo spacecraft on February 17, 1994. It was provisionally designated S/1993 (243) 1. The small moon was named after the mythical creatures called dactyls who lived on Mount Ida according to Greek mythology.[2]
 Galileo spacecraft Dactyl | |
| Discovery | |
|---|---|
| Discovery date | February 17, 1994 |
| Designations | |
Named after | Dactyls (mythology) |
| Dactyl (Ida I) | |
Dactyl orbits the asteroid, Ida, with a period of 1.54 days at an average distance of 108 km, with an inclination of 9° to Ida's equator.[3]
Dactyl was the first asteroid moon discovered. Its discovery settled the long discuss over the existence of asteroid moons.
Origin
The origins of Dactyl are unclear, but two main hypotheses exist. The first is that Dactyl and Ida formed at the same time, and the second is that Dactyl was knocked loose by a later impact.[4][5]