Janus (moon)

Janus in front of Saturn. Photo taken by Cassini-Huygens.

Janus is a moon of Saturn. It was discovered by Audouin Dollfus in 1966. Astronomers were first mistaken that another moon, Epimetheus, was the same as Janus. Voyager 1 confirmed in 1980 that there were two moons that share the same orbit.

Janus (moon) Media

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  Epimetheus (lower left) and Janus (right) seen on 20 March 2006, two months after swapping orbits. The two moons appear close only because of foreshortening; in reality, Janus is about 40,000 km farther from Cassini than Epimetheus.

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  Rotating-frame depiction of the horseshoe orbits of Janus and Epimetheus

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  Animation of Epimetheus's orbit – Rotating reference frame      Saturn ·       Janus ·       Epimetheus

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  Janus as viewed by Voyager 2 (1981-08-25).

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  Janus and Prometheus lie above and below Saturn's rings (2006-04-29).

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  Janus and Tethys (foreground) near Saturn's rings (2015-10-27).

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  Janus as imaged by Cassini (2008-02-20).

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  Crescent Janus (2008-06-30).