A Shepherd’s Shadow

Prometheus casts a shadow through smoky F-ring particles

Inner shepherd of Saturn’s ropy F-ring, Prometheus casts a long shadow through the ring’s icy haze in this beautifully reworked Cassini image by Gordan Ugarkovic.

Discovered by Voyager in 1980 Prometheus completes a tumbling orbit around Saturn every 14.7 hours, regularly dipping into the F-ring in a scalloped path and pulling out streamers of icy particles every time it emerges. At 92 miles long, the potato-shaped moon is only 62 miles across at its widest.

See this image and lots more on Gordan’s Flickr album.

Image: NASA/JPL/SSI/Gordan Ugarkovic.


  1. Gordan says:

    The shadow really adds a nice touch, IMO. The scene required some heavy processing due to noise induced by Saturn’s radiation belts, though. Also note that blob in the lower right corner – it’s not an artifact, it’s real. I wonder if it’s one of those F-ring clumps or a proper smallish moon?


    1. J. Major says:

      It does IMO too. Places it in space very nicely. And that little dot….I suppose it could be a moon! Giving a little tug on the ring there…I mean, why not! Not that there’s a limit to how many moons Saturn can have!


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