spaceSpace and Physics

Cassini Snaps Images Of Weird "Ravioli Moon" Pan Orbiting Saturn


Jonathan O'Callaghan

Senior Staff Writer

NASA/JPL-Caltech/Space Science Institute

There are some odd moons in the Solar System, such as Iapetus with its two-toned surface, or Hyperion with its sponge-like appearance.

But Saturn’s moon Pan looks like it’s about to jump up the weird scale, as new images from the Cassini spacecraft reveal its bizarre shape. We’ve actually known it had this shape for quite a few years, but these latest snaps show just how weird it is.


Images from the spacecraft show the moon, which is about 34 kilometers (21 miles) wide, has a large equatorial bulge. This might be built up from material in Saturn’s rings, with Pan orbiting in a gap within them known as the Encke Gap. The images were taken from 24,572 kilometers (15,268 miles) away and are the closest images ever of Pan.

The bizarre shape of Pan has drawn similarities to ravioli or even a flying saucer. The ridge is several kilometers high, with an oddly smooth surface compared to the rest of the moon.

NASA/JPL-Caltech/Space Science Institute

It’s location within Saturn’s A ring makes Pan a shepherd moon, as it clears debris away from the gap by either pulling it onto its surface or pushing it away.


Back in 2007, Cassini imaging lead Carolyn Porco and colleagues first hypothesized how Pan might get its ridge. They came up with the idea that it was taking in particles from the rings on both sides of its orbit, which impacted the moon and stayed there, accumulating over time.

“As a result of Pan’s (almost) circular orbit, ring particles reach Pan’s surface with low relative velocities,” Porco et al noted in a paper published in the journal Science in 2007.


Sadly, we won’t be getting new images like this from Saturn for too much longer. The Cassini mission is coming to an end, with the spacecraft due to enter Saturn’s atmosphere on September 15, where it will be destroyed, having entered orbit in 2004.

This is because it’s running out of fuel, and scientists don’t want it to accidentally crash on and contaminate one of Saturn’s potentially habitable moons, Titan or Enceladus.


At the moment, Cassini is performing some ring-grazing orbits, which are taking it around the outer edge of Saturn’s rings. In April, it will move into its Grand Finale phase, skimming between the planet's clouds and the inner rings.

That phase of the mission should be rather glorious, giving us some of our closest views of Saturn and its rings yet. It should be a fitting end to what has been an incredible mission.


spaceSpace and Physics
  • tag
  • nasa,

  • Saturn,

  • cassini,

  • moon,

  • Pan,

  • ravioli