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One image, five moons

Five of Saturn's moons in one image

Five of Saturn's moons appear in this single image taken by NASA's Cassini spacecraft.

NASA’s CASSINI SPACECRAFT snapped this image showing part of Saturn’s rings edge-on, and with five of the giant planet’s moons in the same frame.

The moon Rhea (1,528 kilometres in diameter) dominates the image, and is in the foreground of the tableau. Below it and appearing to sit on the rings, is Dione (1,123km wide). Dione is actually far in the background.

Just to the right of Dione is what looks like a small bump in the rings. This is actually Prometheus (86km wide), a “shepherd moon” that orbits Saturn along the inner edge of the F ring.

The tiny dot off to the right of the rings is Epimetheus (113km wide), and the larger moon right on the edge of the image is Tethys (1,062km wide). Epimetheus is very interesting, as it shares almost exactly the same orbit as another moon, Janus. In fact, their orbits are different by a factor of only 50 kilometres. And every now and then they come close together and swap positions!

Cassini was about 61,000 kilometres from Rhea when it took this image on January 11, 2011. Detail can be seen on Rhea down to about 2km per pixel.

Just so that you know what each of the moons looks like close up, here are images of them, also taken by Cassini.

Saturn's moon Rhea.

Saturn's moon Rhea.

Saturn's moon Dione.

Saturn's moon Dione.

Saturn's moon Prometheus.

Saturn's moon Prometheus.

Saturn's moon Epimetheus.

Saturn's moon Epimetheus.

Saturn's moon Tethys.

Saturn's moon Tethys.

Adapted from information issued by NASA/JPL/Space Science Institute.

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Moons with a view

NASA’s Cassini spacecraft has been orbiting Saturn since July 2004. The ringed planet has more than 60 moons, and Cassini has taken numerous images of them.

Sometimes, when the angles are just right, Cassini’s camera can fit more than one moon into its field of view—with one moon in the background and one in the foreground.

Many of the moons orbit near or within the planet’s famous rings, so the rings often appear in the images too.

Here’s a selection of recent shots showing some of Saturn’s natural satellites, large and small.

Rhea, Prometheus and Saturn's rings

In this view, the moon Rhea (1,530km wide) is on the far side of the rings. Much smaller Prometheus (86km wide) is on the nearside, orbiting between the main portion of the rings and the thin outer F ring. Camera distance to Rhea: approx. 1.6 million km. Camera distance to Prometheus: approx. 1 million km.

Dione and Titan

The cratered and cracked moon Dione (1,120km wide) seems to hang suspended in place in front of Titan (5,150km wide) in the background. Camera distance to Dione: approx 1.8 million km. Camera distance to Titan: approx. 2.7 million km.

Tethys and Dione

Dione, in the foreground of this image, appears darker than the moon Tethys (1,070km wide). Tethys appears brighter because it has a higher albedo than Dione, meaning Tethys reflects more sunlight. Camera distance to Dione: approx. 1.2 million km. Camera distance to Tethys: 1.8 million km.

Epimetheus and Janus

Saturn's moon Epimetheus (86km wide) moves in front of the larger moon Janus (179km wide) as seen by the Cassini spacecraft. Camera distance to Epimetheus: approx. 2.1 million km. Camera distance to Janus: 2.2 million km.

Janus and Prometheus

In this image, Janus is on the far side of Saturn's rings. Prometheus is on the nearside, orbiting in the gap between the main rings and the outer, thin F ring. Camera distance to Janus: approx. 1.1 million km. Camera distance to Prometheus: 1 million km.

Images courtesy of NASA / JPL / Space Science Institute.

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Rings and moons

Cassini spacecraft image of Rhea, Prometheus and Saturn's rings.

Cassini spacecraft image of Rhea, Prometheus and Saturn's rings.

  • Rhea & Prometheus
  • Saturn’s rings seen edge-on
  • Images by the Cassini spacecraft

From just below the plane of Saturn’s thin rings, the Cassini spacecraft took this image of the rings edge-on with the planet’s second largest moon, Rhea, beyond.

Although Rhea may appear to be in the foreground of this image, it isn’t. The rings are closer. The small moon Prometheus, orbiting between the A ring and the thin F ring, is also visible within the rings near the upper middle of the image.

This view looks toward the Saturn-facing side of Rhea (1,528 kilometres wide) and the leading hemisphere of Prometheus (86 kilometres wide). This view looks toward the southern, unilluminated side of the rings from just below the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on January 31, 2010. The view was obtained at a distance of approximately 2.5 million kilometres from Rhea and approximately 2 million kilometres from Prometheus. Image scale is 15 kilometres per pixel on Rhea and 12 kilometres per pixel on Prometheus.

Adapted from information issued by NASA / JPL / Space Science Institute.