Five Saturn Moons Stun In Cassini Spacecraft Archival Image

This picture is from a couple of years ago, but still worth the extra look. The Cassini spacecraft — busily circling Saturn and gathering data on the ringed planet and its moons — managed to grab five of Saturn’s 62 known moons in one shot. The European Space Agency highlighted the picture on its home page this week.

From left to right, you can see Janus, Pandora, Enceladus, Mimas and Rhea. Don’t be fooled by the rings near Rhea; those are actually Saturn’s rings. Rhea is just blocking the view of the planet from Saturn’s perspective during this picture portrait, which was taken on July 29, 2011.

The cornucopia of moons around Saturn is part of what makes that particular planet so interesting. Titan, the largest, is perhaps the most well-known because of its strange orange haze that intrigued astronomers when the twin Voyager spacecraft zoomed through the system in the 1980s. Cassini arrived in 2004 and revealed many more moons to science for the first time.

Color-composite of Titan made from raw Cassini images acquired on April 13, 2013 (added 4/17) NASA/JPL/SSI. Composite by J. Major.
Color-composite of Titan made from raw Cassini images acquired on April 13, 2013 (added 4/17) NASA/JPL/SSI. Composite by J. Major.

“The dozens of icy moons orbiting Saturn vary drastically in shape, size, surface age and origin. Some of these worlds have hard, rough surfaces, while others are porous bodies coated in a fine blanket of icy particles. All have greater or smaller numbers of craters, and many have ridges and valleys,” NASA wrote on a web page about Saturn’s moons.

“Some, like Dione and Tethys, show evidence of tectonic activity, where forces from within ripped apart their surfaces. Many, like Rhea and Tethys, appear to have formed billions of years ago, while others, like Janus and Epimetheus, could have originally been part of larger bodies that broke up. The study and comparison of these moons tells us a great deal about the history of the Saturn System and of the solar system at large.”

And new discoveries are coming out all the time. Earlier this year, for example, astronomers said that the moon Dione could have had active geysers coming from its surface, such as what is likely happening on Enceladus.

Shepherd Moon Face-Off!

Raw Cassini image acquired on Dec. 18, 2012 (NASA/JPL/SSI)

Two of Saturn’s shepherd moons face off across the icy strand of the F ring in this image, acquired by the Cassini spacecraft on December 18, 2012.

In the left corner is Pandora, external shepherd of the ropy ring, and in the right is Prometheus, whose gravity is responsible for the subtle tug on the wispy ring material. (Please don’t blame the moon for any recent unsatisfying sci-fi films of the same name. There’s no relation, we promise.)

Similar in size (Pandora is 110 x 88 x 62 km, Prometheus 148 x 100 x 68 km) both moons are porous, icy, potato-shaped bodies covered in craters — although Prometheus’ surface is somewhat smoother in appearance than Pandora’s, perhaps due to the gradual buildup of infalling material from the F ring.

Check out some much closer images of these two moons below, acquired during earlier flybys:

Here’s Pandora, as seen by Cassini on September 5, 2005:

False-color image of Pandora (NASA/JPL/SSI)

…and here’s Prometheus, seen during a close pass in 2010 and color-calibrated by Gordan Ugarkovic:

 Prometheus casting a shadow through F ring haze (NASA/JPL/SSI/Gordan Ugarvovic)

The external edge of the A ring with the thin Keeler gap and the wider Encke gap can be seen at the right of the top image. Both of these gaps also harbor their own shepherd moons — Daphnis and Pan, respectively.

These moons keep their gaps clear, as well as maintain the crisp edge shapes of the nearby rings — hence the term “shepherd.”

Image credit: NASA/JPL/Space Science Institute

Extremes in the Saturn System

It’s just one extreme to another in this image from the Cassini spacecraft. Of course, you can’t miss the ginormous Saturn. But do you see three of what appear to be eentsy, tiny moons of the ringed planet?

Tethys (660 miles, or 1,062 kilometers across) is on the right of the image, below the rings. Smaller Enceladus (313 miles, or 504 kilometers across) is on the left of the view, below the rings. Pandora (50 miles, or 81 kilometers across) is also present in this view but is barely visible. It appears as a small grey speck above the rings on the extreme left edge of the image. Pandora has been slightly brightened by the imaging team by a factor 1.2 relative to the rest of the image.

The image was taken with the Cassini spacecraft wide-angle camera on Dec. 7, 2011 using a spectral filter sensitive to wavelengths of near-infrared light centered at 752 nanometers. The view was obtained at a distance of approximately 1.3 million miles (2.1 million kilometers) from Saturn. Image scale is about 77 miles (124 kilometers) per pixel.

Image caption: Saturn and three small moons. Credit: NASA/JPL-Caltech/Space Science Institute


Moons Large and Small


It may be one of the best images from Cassini yet this year! Cloud-covered Titan and tiny Prometheus (can you see it just above the rings on the right?) are literally dwarfed by their parent Saturn in an image captured on Jan. 5, 2012.

Prometheus’ pinpoint shadow can also be seen on Saturn’s cloud tops, just inside the thin, outermost F ring shadow at bottom left.

The two moons themselves couldn’t be more different; Titan, 3,200 miles (5,150 km) wide, is wrapped in a nitrogen and methane atmosphere ten times thicker than Earth’s and is covered with vast plains of dark hydrocarbon dunes and crisscrossed by rivers of liquid methane.

Prometheus imaged by Cassini in Dec. 2009.

Prometheus, on the other hand, is a potato-shaped shepherd moon 92 miles long and 53 miles wide (148 x 53 km) that orbits Saturn just inside the narrow, ropy F ring. While it doesn’t have an atmosphere, it does create some impressive effects on the icy material in the ring!

Another moon, Pandora, casts its shadow onto Saturn just outside the F ring shadow at bottom center. 50 miles (80 km) wide, Pandora shepherds the outer edge of the F ring but is itself not visible in this image. Watch an animation here.

This image was featured on the Cassini Imaging Central Laboratory for Operations (CICLOPS) website on Feb. 28, 2012. The view looks toward the southern, unilluminated side of the rings from about 1 degree below the ringplane.

Image credit: NASA / JPL / Space Science Institute.

Cassini’s Majestic Saturn Moon Quintet


Check out this gorgeous new portrait of a Saturnian moon quintet taken by Earths’ emissary – NASA’s Cassini Orbiter. The moons are majestically poised along a backdrop of Saturn’s rings, fit for an artist’s canvas.

Janus, Pandora, Enceladus, Mimas and Rhea are nearly lined up (from left to right) in this view acquired by Cassini at a distance of approximately 684,000 miles (1.1 million kilometers) from Rhea and 1.1 million miles (1.8 million kilometers) from Enceladus.

The newly released image was taken by Cassini’s narrow angle camera on July 29, 2011. Image scale is about 4 miles (7 kilometers) per pixel on Rhea and 7 miles (11 kilometers) per pixel on Enceladus.

Cassini will stage a close flyby of Enceledus – Satarn’s geyser spewing moon – in about two weeks, swooping within 99 km

Moon Facts from JPL:
Janus (179 kilometers, or 111 miles across) is on the far left. Pandora (81 kilometers, or 50 miles across) orbits between the A ring and the thin F ring near the middle of the image. Brightly reflective Enceladus (504 kilometers, or 313 miles across) appears above the center of the image. Saturn’s second largest moon, Rhea (1,528 kilometers, or 949 miles across), is bisected by the right edge of the image. The smaller moon Mimas (396 kilometers, or 246 miles across) can be seen beyond Rhea also on the right side of the image.

This view looks toward the northern, sunlit side of the rings from just above the ring plane. Rhea is closest to Cassini here. The rings are beyond Rhea and Mimas. Enceladus is beyond the rings.

The simple graphic below shows dozens of Saturn’s moons – not to scale. So far 62 have been discovered and 53 have been officially named.

Saturn’s moons. Click on link below to learn more about each moon. Credit: NASA/JPL

Learn more about Saturn’s moons at this link

List of Saturn’s officially named moons:
Aegaeon, Aegir, Albiorix, Anthe, Atlas, Bebhionn, Bergelmir, Bestla, Calypso, Daphnis, Dione, Enceladus, Epimetheus, Erriapus, Farbauti, Fenrir, Fornjot, Greip, Hati, Helene, Hyperion, Hyrrokkin, Iapetus, Ijiraq, Janus, Jarnsaxa, Kari, Kiviuq, Loge, Methone, Mimas, Mundilfari, Narvi, Paaliaq, Pallene, Pan, Pandora, Phoebe, Polydeuces, Prometheus, Rhea, Siarnaq, Skadi, Skoll, Surtur, Suttung, Tarqeq, Tarvos, Telesto, Tethys, Thrym, Titan and Ymir.

A Four Cluster Pile-Up


Abell 2744, shown above in a composite of images from the Hubble Space Telescope, the ESO’s Very Large Telescope and NASA’s Chandra X-ray  Observatory, is one of the most complex and dramatic collisions ever seen between galaxy clusters.

X-ray image of Abell 2744

Dubbed “Pandora’s Cluster”, this is a region 5.9 million light-years across located 3.5 billion light-years away. Many different kinds of structures are found here, shown in the image as different colors. Data from Chandra are colored red, showing gas with temperatures in the millions of degrees. Dark matter is shown in blue based on data from Hubble, the European Southern Observatory’s VLT array and Japan’s Subaru telescope. Finally the optical images showing the individual galaxies have been added.

Even though there are many bright galaxies visible in the image, most of the mass in Pandora’s Cluster comes from the vast areas of dark matter and extremely hot gas. Researchers made the normally invisible dark matter “visible” by identifying its gravitational effects on light from distant galaxies. By carefully measuring the distortions in the light a map of the dark matter’s mass could be created.

Galaxy clusters are the largest known gravitationally-bound structures in the Universe, and Abell 2744 is where at least four clusters have collided together. The vast collision seems to have separated the gas from the dark matter and the galaxies themselves, creating strange effects which have never been seen together before. By studying the history of events like this astronomers hope to learn more about how dark matter behaves and how the different structures that make up the Universe interact with each other.

Check out this HD video tour of Pandora’s Cluster from the team at Chandra:

Read more on the Chandra web site or in the NASA news release.

Image credit: X-ray: NASA/CXC/ITA/INAF/J.Merten et al, Lensing: NASA/STScI; NAOJ/Subaru; ESO/VLT, Optical: NASA/STScI/R.Dupke.


Jason Major is a graphic designer, photo enthusiast and space blogger. Visit his website Lights in the Dark and follow him on Twitter @JPMajor or on Facebook for the most up-to-date astronomy awesomeness!


Saturn’s Rings, Moons Line Up in Latest Stunning Cassini Image


This latest offering from the Cassini spacecraft shows a wide-angle view of Saturn, its rings, and a sampling of the planet’s moons in varying sizes. Saturn’s largest moon, Titan, is in the center of the image, with the smaller moon Enceladus on the far right, while appearing just below the rings on the far left beyond the thin F ring is teeny-tiny Pandora. Oh, to have this view out your spacecraft window as you approach the ringed-world for a flyby!

How do the moons shown here vary in size? Titan is 5,150 kilometers, or 3,200 miles, across. Enceladus is 504 kilometers, or 313 miles across, while Pandora is 81 kilometers, or 50 miles across. This view looks toward anti-Saturn side of Titan and toward the northern, sunlit side of the rings from just above the ringplane.

The image was taken with the Cassini spacecraft wide-angle camera on Jan. 15, 2011, from a distance of about 844,000 kilometers (524,000 miles) from Titan. Image scale is 50 kilometers (31 miles) per pixel.

See more info and get a larger version from the Cassini website.

Cassini Takes Images of Growing Storm on Saturn


The white storm on Saturn’s northern hemisphere is growing and expanding. This raw image from the Cassini collection was taken on Dec. 24, 2010, showing the storm getting bigger. You can compare the storm from earlier images taken by amateur astronomer Anthony Wesley.

Below is a color version, as well as other recent raw images showing the “real” moon Pandora is on the line.

A 'quick' colorization of Saturn and its storm by Stu Atkinson.

Here’s a color version sent in by Stu Atkinson, who said he did a “quick” go at adding color to the image. Looks great, Stu!

The moon Pandora lines up with Saturn's rings in this view from Cassini. Image Credit: NASA/JPL/Space Science Institute

See more images at the Cassini website.