Pan’s remarkable equatorial skirt
Processed image. Photographic montage of Pan’s northern and southern trailing-side views, captured on 7 March 2017. The left and right camera scales were about 147 and 224 metres per pixel, respectively. The central body and narrow equatorial ridge are visible; the paired perspectives do not show growth happening. A separate stereo treatment uses these same observations.
NASA/JPL image-use policy · credited mission imagery, resized to WebP
· Original image source · Image licenceA close encounter reveals a shape hidden in distant ring views.
- World
- Pan
- Case date or period
- Observations · 2009–2017
Look closer
At close range, Pan looks strikingly different from the tiny point seen inside the Encke Gap. A prominent equatorial ridge gives the moon a memorable outline.
Follow the evidence
The companion views place Pan back among the rings and its disturbances. They show context and changing viewing geometry, not evidence that the moon changes shape between frames.
An independent perspective
The Planetary Society traces an unusual discovery history: evidence in ring structure, identification in Voyager imagery and Cassini’s much closer encounter. It is a useful example of old observations gaining meaning through renewed inspection. Compare that history with the actual Cassini images gathered here.
Testing how a ring can build a ridge
Alice Quillen, Fatima Zaidouni, Miki Nakajima and Esteban Wright modelled ring particles accumulating onto small moons. Their calculations constrain how rapidly a ridge can grow without overcoming Saturn’s torque that keeps the moon tidally locked. An eccentric orbit and asymmetric gap could build multiple lobes like Pan’s. Migration or orbital resonance could bring the moon into contact with fresh ring material. These scenarios reproduce aspects of the observed shape; the photographs do not record accretion or uniquely select its history.
Sources & further reading
- Pan Revealed — NASA Image and Video Library / JPL
- Pan In the Middle — NASA Image and Video Library / JPL
- Pan in Action — NASA Image and Video Library / JPL
- The three discoveries of Pan — The Planetary Society
- Accretion of Ornamental Equatorial Ridges — Quillen and colleagues — Original research paper / author archive
- Shadow of Saucer-Shaped Moon — NASA / JPL / Space Science Institute