Eclipsing Moons

The Cassini Spacecraft orbiting Saturn continues to give us unique views of the Solar System. Today's exhibit is a unique eclipse of Saturn's Moon Mimas (also known at the Death Star Moon) by the Moon Enceladus.

You don't see Enceladus...just its shadow! Enceladus is off the screen. This animations was made from 7 images snapped 30 seconds apart, so the event didn't last long at all. Cassini was about 800.000 miles away when it snapped this sequence of images.

These eclipses can only occur near Saturn's equinox. Most of the time the orbits of Saturn's Moons are tilted with respect to the Sun so their shadows will pass above or below each other. Only near the equinox (which occurs in August for Saturn) will they line up just right so they can eclipse each other. Neither of the Voyager Spacecraft passed Saturn close to an equinox so this is the first time we have been able to see events such as this.

You can find some nice animations of the shadhows of Moons cast on Saturn's rings as well.

Reprinted with permission from the Half-Astrophysicist Blog.