The Many Moons of Saturn
Saturn has many moons and Cassini has been taking some wonderful pictures of them.  Here is a selection, which is being added to as more of them are received.  More Images - September 2012
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Titan, a mosaic of eight separate images taken during a close fly-by on Oct. 26, 2004. This colour image of Titan shows redder areas where atmospheric methane absorbs light and blue areas caused by high atmosphere and detached hazes.  Dione, taken on December 14th, 2004. To the surprise of Cassini imaging scientists, the wispy terrain does not consist of thick ice deposits, but rather the bright ice cliffs created by tectonic fractures. This image of Dione was taken on Sept. 20, 2005, through a filter combination sensitive to polarized green light. It was acquired at a distance of about 2.1mm Km and resolution is 12Km per pixel.
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With a diameter of 1,528km, Rhea is Saturn's second largest moon. One hemisphere is covered with bright, wispy streaks which may be water frost Iapetus, with a diameter of 1,436 km, about one third that of our own moon.  This visible light image was taken on July 3, 2004, from a distance of 3 million km. This dazzling view looks beyond gigantic storms near Saturn's south pole to the small disc of Tethys 1,060km in diameter. A huge chasm is visible on the icy moon And this close up of Tethys shows the surface detail much more clearly
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A later image of Tethys, taken in December 2005 Phoebe, an ice rich body overlain with a thin layer of darker material. This image was taken on 11th June, 2004 Mimas, seen against the cool, blue-streaked backdrop of Saturn's northern hemisphere. Shadows cast by the rings arc gracefully across the planet, fading into darkness on Saturn's night side This view of the shepherd moon Prometheus, 102 km across, shows the F ring resolved into five separate strands, with potato-shaped Prometheus connected to the ringlets by a faint strand of material
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Another superb view of Prometheus and the ring system, which extends thousands of kilometers into the distance.  A notable brightening of the F ring material is visible ahead of Prometheus in its orbit, near the right side of this image. The month of January is named for the Roman god Janus, who guarded the gate of heaven. This image of the heavily cratered, irregularly shaped, 181Km diameter moon shows vague hints of it's surface morphology. A superb closer view of Janus taken in October 2006 Irregularly shaped Epithemius, seen against the backdrop of the planet's rings, which are nearly edge-on in this view. Some of the moon's larger geological features can be seen here. Epimetheus is 116 kilometers (72 miles) across
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Epithemius again, from 34 degrees above Saturn's equatorial plane. The two largest craters visible here are the only officially named features on this moon. At the left (at about the 9 o'clock position) is Pollux; and at lower left (containing a string of several smaller craters) is Hilairea. Pandora  - 84 kilometers (52 miles) across, orbiting just beyond the outer edge of the F ring. Several bright areas are visible within the F ring. In the main rings, the Keeler gap and the Encke gap, with a bright ringlet, are also visible Another lovely view of Pandora, crisp and sharp against the background of Saturn Tethys (at the right, 1,071 kilometers across) and Mimas (near the centre, 397 kilometers across) are captured here against the planet's turbulent atmosphere.  Observe the structure of the entire main ring system in its shadow on the planet - from the C ring at the bottom to the faint F ring at the top.
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The icy moon, Enceladus, imaged from a distance of approximately 1,180 kilometers (730 miles). Enceladus is one of the most reflective objects in the solar system and its surface resembles freshly fallen snow. A full view of Enceladus.  This shot was Astronomy Magazine's 6th Picture of the Day, one of several APOD's won by Cassini And a more recent image, taken as Cassini passed through water ice plumes seen being ejected from Enceladus at 1,300kph.  The two large overlapping craters are called Ali Baba and Aladdin.  Click here for a high resolution image. Enceladus is a small, icy body (this is it's size relative to the UK), yet volcanic activity has been detected.  In a body this small, and according to all known theories, vulcanism should not be possible on Enceladus
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Mimas (398 kilometers, or 247 miles across) at right, Pandora (84 kilometers, or 52 miles across) near centre and Janus (181 kilometers, or 113 miles across) in the lower left corner. Mimas is in fact 34,000 kilometers (21,000 miles) more distant than Janus. Telesto (24 kilometers, or 15 miles across) shares the orbit of Saturn's moon Tethys (1,071 kilometers, or 665 miles across), leading the larger moon in its path by 60 degrees. Similarly sized Calypso (22 kilometers, or 14 miles across) trails Tethys by the same amount. These positions, called Lagrange points, are dynamically stable. Saturn's moon Dione occults part of Saturn's distant rings while Tethys hovers below. Dione is 1,118 kilometers (695 miles) across, while Tethys is 1,071 kilometers, 665 miles) across. Hyperion has an unusual shape with dimensions of 164 by 130 by 107 kilometers (102 by 81 by 66 miles).  
It is one of the large, low-density objects that orbit Saturn. and is close to the size limit where, like a child compacting a snowball, internal pressure due to the moon's gravity will begin to crush weak materials like ice, closing pore spaces and eventually creating a more spherical shape.

Preliminary density estimates show that it is only about 60 percent as dense as solid water ice. This suggests that much of its interior (40 percent or more) must be empty space.
The Mother Planet
Saturn and its rings completely fill the field of view of Cassini's narrow angle camera in this earlier natural colour image taken on March 27, 2004. This is the last single 'eyeful' of Saturn and its rings achievable with the narrow angle camera on approach to the planet. After this point and until orbital insertion, Saturn and its rings are larger than the field of view of the narrow angle camera.  Of particular note for us is the striated pattern on the upper planet as the sun shines through the rings, and also the fact that you can see the planet through the rings.  Spend a while to fully absorb the splendour of this amazing picture.

Colour variations between atmospheric bands and features in the southern hemisphere of Saturn, as well as subtle colour differences across the planet's middle B ring, are very distinct. Colour variations generally imply different compositions. The nature and causes of any compositional differences in both the atmosphere and the rings are major questions to be investigated by Cassini scientists as the mission progresses.

The bright blue sliver of light in the northern hemisphere is sunlight passing through the Cassini Division in Saturn's rings and being scattered by the cloud-free upper atmosphere.

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