Tag Archives: Daphnis

A Saturn moon makes waves

Daphnis makes waves

Cool image time! The image above, taken on January 16, 2017 during one of Cassini’s ring-grazing passes as it enters its last year at Saturn, has been reduced and cropped to post here. It shows clearly the waves caused by the gravity of the moon Daphnis as its travels within a gap in the rings of Saturn.

Daphnis (5 miles or 8 kilometers across) orbits within the 42-kilometer (26-mile) wide Keeler Gap. Cassini’s viewing angle causes the gap to appear narrower than it actually is, due to foreshorteneing. The little moon’s gravity raises waves in the edges of the gap in both the horizontal and vertical directions.

The image also shows many details about Daphnis itself, including a ridge at its equator that is thought to be an accumulation of material gathered from the rings.

The strangeness of Saturn’s rings is well illustrated here. Though made up of many solid particles, as a group the rings act almost like liquid. Note for example the ring on the far side of Daphnis. Its edge gets pulled out slightly as the moon goes by, but then the gravity of the rest of the ring pulls it back.

The universe is a wonderful place, as it is. No need to make up stuff (such as faces on Mars or fake civilizations on the Moon), as our imagination is probably insufficient to match the weirdness that is really out there.