Saturn lies in the outer Solar System, ten times farther away from the Sun than Earth is. It's best known for its fabulous ring system, but it also has an amazing system of moons including ring shepherds and the smallest natural round body in the Solar System.

10 Amazing Facts about Saturn's Moons

Rhea was Saturn's wife in classical mythology. Rhea the moon zips around Saturn in four and a half days. Although it has an oxygen atmosphere, we won't be moving there anytime soon. Even in direct sunlight, it's -281 degrees Fahrenheit and the "atmosphere" is similar to a vacuum on Earth.

Rhea - Moon of Saturn

Titan was a mystery for three and a half centuries. It's a giant moon shrouded in impenetrable clouds, and has only recently begun to share its secrets. Why do scientists say it's like Earth? Is it time to book a vacation to visit the lakes and mountains of Titan?

Titan Titan - Planet-sized Moon of Saturn

Last month Cassini imaging showed red streaks on the moon Tethys. You can see it in the enhanced-color image. What are the streaks? There are various guesses, but no one knows.

Christina Sng has the answer to the mystery of the red streaks on Tethys. She's supplied Astronomers without Borders a little poem: Found on Tethys

Hi Mona,

It is so frustrating! Pin Interest won't let you read anything unless you belong or whatever. I am not a friend of these types of companies that force membership to access material.

Is there another way you can show the info or another site Dr Google will help with?

Anyway.

Cheers

Lestie, you're quite right about Pinterest. So annoying. I don't know when it took up doing this, but a friend alerted me to it only recently. Since then I've tried to use direct URLs in the forum, but slipped up here.

Unfortunately, my article links are all to Pinterest - because it was a way of ensuring that the links didn't break every time NASA and others reorganised their websites. (I'm not sure what to do now.)

Anyhow Found on Tethys by Christina Sng looks as though it meant to be a haiku, but It seems to be slightly oversyllabled, if so.

FOUND ON TETHYS
OLD MOON GRAFFITI
FROM TITAN'S LAST VISIT
FORGOT THE WASHABLE MARKER

This is superimposed on the picture of red streaks on Tethys.

This is a recent Cassini image of Saturn's moon Dione. The trailing hemisphere is distinguished by bright ice cliffs, some of them several hundred meters high.

This view of Saturn's icy moon Dione is of the leading hemisphere, and it's quite different to the terrain in the image I linked to in the previous post. You can also see Saturn and its rings in the background. The photo was taken just as Cassini was about to make its final close approach to the moon a few days ago.

If you look to the lower right, you can see an impact basin with several rings around it. It's 350 km (220 mi) wide. To the lower left is Padua Chasma, which is on the edge of the bright terrain of ice cliffs shown in the post I did yesterday. The canyons reach into the darkness along the lower left edge.

It's a mosaic made from nine visible light images. (Credit: NASA/JPL-Caltech/SSI, released 2015-08-20)

It was 226 years ago yesterday (August 28, 1789) that William Herschel discovered Saturn's moon Enceladus.

Enceladus was a mythical giant, but this moon is no giant - it's only 500 km in diameter. NASA's Cassini probe took this image, showing a cryovolcanic eruption.. Instead of hot lava, it shoots out icy water with some gases mixed in.

It was William Herschel's son John - a prominent scientist in is day - who named the moons of Saturn.

Saturn's moon Rhea was discovered by Giovanni Cassini on December 23, 1672.

A view from Cassini toward the unilluminated side of Saturn's rings from somewhat below the ring plane. You can see Mimas (the larger moon) and Pandora. Mimas has enough mass that its gravity has pulled it together into a spherical shape. Little Pandora, on the other hand, has an irregular shape.

Credit: NASA/JPL-Caltech/Space Science Institute

NASA’s Cassini spacecraft captured this incredible view of Saturn moons, Enceladus and Tethys, in perfect alignment with the planet’s rings.

Photograph by NASA/JPL-Caltech/Space Science Institute

This is a near-true color image of Iapetus, taken by Cassini using different filters. The use of color on Iapetus is particularly helpful for discriminating between shadows (which appear black) and the intrinsically dark terrain (which appears brownish).

Iapetus is Saturn's two-toned moon, though this image is only of the northern part of dark Cassini Regio and the transition zone to a brighter surface, all on the dark side. It doesn't include any part of the bright hemisphere.

Credit: NASA/JPL/Space Science Institute

Saturn's moon Tethys seems to float between two sets of rings in this view from NASA's Cassini spacecraft, but it's just a trick of geometry. The rings, which are seen nearly edge-on, are the dark bands above Tethys, while their curving shadows paint the planet at the bottom of the image.

looks like a golfball

It looks a bit like a family portrait - except no one is making funny faces. Cassini sent this picture of Enceladus, Tethys and Mimas and the rings. Enceladus (504 km across) is just below center and Mimas (396 km across) is below left of Enceladus. The third moon, just above the rings, is Tethys (1062 km across).

This is Saturn's little moon Phoebe in a mosaic of 6 images taken by the Cassini spacecraft.

Although Phoebe is one of the darkest known bodies in the Solar System, there is also some very bright material thought to contain ice. The moon's topography is quite irregular and it's heavily cratered. It

Image Credit: NASA/JPL/Space Science Institute

Awesome!

Saturn's little moon Mimas transits Saturn's northern latitudes over shadows of the planet's rings. Saturn usually looks yellow, but it has a blue hue at the northernmost latitudes. This occurs for the same reason our own sky looks blue - it has to do with the way light is scattered at different angles.

Mimas is the smallest known body that has enough mass for its own gravity to pull it into a spheroid.

Image credit: Michael Benson using data from NASA's Cassini spacecraft in 2005.

Atlas, Daphnis and Pan are small, inner, ring moons of Saturn, shown at the same scale in this montage of images from the Cassini spacecraft.

Daphnis was discovered in Cassini images from 2005. Atlas and Pan were first sighted in images from the Voyager 1 and 2 spacecraft. Flying saucer-shaped Atlas orbits near the outer edge of Saturn's bright A Ring, while Daphnis orbits inside the A Ring's narrow Keeler Gap, and Pan within the A Ring's larger Encke Gap. The curious equatorial ridges of the small ring moons could be built up by the accumulation of ring material over time. Even diminutive Daphnis makes waves in the ring material as it glides along the edge of the Keeler Gap.

Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA

It was 228 years to the day - well actually, to the day +2 - that William Herschel discovered Saturn's moon Enceladus. It was August 28, 1789 and he was using his new telescope which was then the largest in the world. William didn't name any of his discoveries, but his son John Herschel suggested names for the moons of Saturn. Enceladus was one of the mythological giants related to Cronos, the Greek equivalent of Saturn.

Image: NASA/JPL/SSI

Even with all of the time Cassini spent studying the Saturnian system, many questions remain unanswered. One of the puzzles is the moon Dione - is it active? There was some inconclusive evidence of cryovolcanism, probably related to the Janiculum Dorsa mountain region where the crust is bent.

A recent paper suggests that Dione could have a subsurface ocean like Enceladus and Jupiter's moon Europa.

Certainly if Dione is - or was in the past - active, it doesn't match the activity visible on Enceledus.

Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA
Description: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)