Saturn's Crisscrossed Rings Hide Tiny Moon

Saturn's Criss-crossed Rings Hide Tiny Moon

It seems that whenever we look at a new picture of Saturn by NASA’s Cassini mission, there’s always something unique. And often, there’s hidden gem.

Captured on Feb. 11, this observation, at first, doesn't make a whole lot of sense. We already know that Saturn sports hundreds of distinct rings, but they all occupy the same plane. How did Cassini see rings that are criss-crossed?

Actually, this observation only shows one ring plane, but behind are the shadows of each ring being cast on Saturn’s upper atmosphere, creating the illusion there are 2 sets of rings.

At first glance, Saturn's rings appear to be intersecting themselves in an impossible way. In actuality, this view from NASA's Cassini spacecraft shows the rings in front of the planet, upon which the shadow of the rings is cast. And because rings like the A ring and Cassini Division, which appear in the foreground, are not entirely opaque, the disk of Saturn and those ring shadows can be seen directly through the rings themselves.

But while you digest the scene and work out which lines are rings and which are shadows, you’re probably overlooking tiny moon Pan, a 17 mile (or 28 kilometre) wide satellite occupying a gap in the rings (just below the middle of the photo).

Many of the gaps in Saturn’s rings possess small moons whose gravity keeps these rings clear of debris as they orbit. Pan occupies the famous Encke Gap, for example. Many other gaps, however, don’t appear to have moons, so their nature is a little more mysterious. Some theories on ring dynamics suggest some of these gaps may have formed through resonances with Saturn’s larger moons.

The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

Regardless of how they were formed, Cassini continues to capture their beauty, constantly reaffirming Saturn as the jewel of the solar system.