Epimetheus moon: Encyclopedia II - Epimetheus moon - Discovery

Epimetheus moon - Discovery

Epimetheus occupies essentially the same orbit as the moon Janus. Astronomers assumed that there was only one body in that orbit, and accordingly had a hard time figuring out their orbital characteristics; it is obviously impossible to reconcile the observations of two distinct objects as a single object.

Audouin Dollfus observed a moon on December 15, 1966, which he proposed to be named "Janus"[3]. On December 18, Richard L. Walker made a similar observation which is now credited as the discovery of Epimetheus[4]. However, at the time, it was believed that there was only one moon, unofficially known as "Janus", in the given orbit.

Twelve years later, in October 1978, Stephen M. Larson and John W. Fountain realised that the 1966 observations were best explained by two distinct objects (Janus and Epimetheus) sharing very similar orbits. This was confirmed in 1980 by Voyager 1, and so Walker officially shares the discovery of Epimetheus with Larson and Fountain.

The 1980 Voyager discovery was designated S/1980 S 3, and it was officially named "Epimetheus" in 1983. The name Janus was officially approved by the IAU at the same time, although the name had been used informally since Dollfus proposed it a few days after the 1966 discovery.

Adapted from the Wikipedia article "Discovery", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki