Shadow Caster

Pan casts its shadow onto Saturn's rings

It’s been a while since I posted any moon shadow images but they’re always cool to look at, since they add another dimension to a scene that can sometimes be hard to put into context. This image, taken by Cassini on January 10 and released today, shows the 12-mile-wide shepherd moon Pan cruising along within the Encke Gap, a 200-mile-wide space in Saturn’s bright A ring. Pan’s shadow falls upon the particles along the outer edge of the gap.

The little moon clips along at a good pace, too, completing an orbit of the giant planet every 13.8 hours!

As time passes and Saturn gets further from its spring equinox, which occurred back on August 11, the shadows of the moons nearest the rings will get shorter and eventually no longer strike the rings themselves. This visual phenomenon was a real treat for all Cassini enthusiasts but once the shadows dip below the ringplane we won’t be seeing much more of them for a while…the Cassini mission may have been extended for another seven years but that’s still not enough time for the spacecraft to witness another equinox, since it takes Saturn over 29 years to complete a full trip around the Sun!

For more info on Saturn’s ring system and the Cassini mission click here.

Image: NASA/JPL/Space Science Institute

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