Dione was the daughter of Tethys in Greek mythology. In the real world, Saturn’s moons Tethys and Dione are not mother and daughter. They are more like sisters since they’re believed to have formed out of the same disk around Saturn.
Dione is the upper moon in the picture; Tethys is the lower.
Saturn’s moon Hyperion tumbles as it orbits the planet. Hyperion’s 270 km long spin axis has a chaotic orientation in time, meaning that it is essentially impossible to predict how the moon will be spinning in the future. It’s one of a very few known bodies with such chaotic spins.
The changing length of Saturn’s shadow marks the passing of the planet’s seasons. As the planet nears its northern-hemisphere solstice in May, 2017, the shadow will get even shorter. At solstice, the shadow’s edge will be about 45,000 km from the planet’s surface, barely making it past the middle of the B ring.
The white speck in the lower left of the picture isn’t a dust mote on your monitor. It’s the moon Mimas, only a few pixels wide in this image.
Saturn’s moon Tethys’s trailing side shows two terrains that tell a story of a rough past. To the north (up in this picture) is older, rougher terrain, while to the south is new material dubbed “smooth plains” by scientists. The smooth plains are roughly antipodal to the large impact crater Odysseus. Odysseus, which is on the far side of Tethys, is out of view. The leading theory is that the impact that created Odysseus also created the smooth plains, although exactly how this happened is not yet clear.
Saturn’s moon Pan, named for the Greek god of shepherds, rules over quite a different domain—the Encke gap in Saturn’s rings. See the inset at left for a zoomed in view. Pan (28 km across) keeps the Encke gap open through its gravitational influence on the ring particles nearby.
This view looks toward the sunlit side of the rings from about 48 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Christmas Day, 2013, from a distance of approximately 2.3 million km from Pan. The image scale is about 14 km) per pixel.
A couple of years ago, a huge storm occurred in the northern hemisphere of Saturn. This set of images from the Cassini spacecraft orbiting the planet shows the turbulent power of that monster storm. The visible-light image was taken on 25 February, 2011, and shows the turbulent clouds churning across the upper layers of Saturn’s atmosphere. The inset infrared image, obtained a day earlier using Cassini‘s visual and infrared mapping spectrometer, shows water and ammonia ices from deep in Saturn’s atmosphere being churned up to the top layers. This was the first time water ice was detected in Saturn’s atmosphere. The storm was first detected by Cassini‘s radio and plasma wave subsystem in December, 2010, and eventually wrapped around the planet.
No one is sure what lies at the bottom of Hyperion’s strange craters. The Casinni spacecraft has made a couple of passes past the sponge-like satellite of Saturn to gather data. This false color image from the 2005 flyby shows the odd little world strewn with strange craters. Some unknown type of dark material that might be only tens of meters thick in some places at the bottom of the craters. Hyperion is about 250 km across. It rotates chaotically, and its density so low it’s been suggested that Hyperion might have a vast system of caverns inside.