spaceSpace and Physics

Cassini Snaps Saturn's Rings Like You've Never Seen Them Before


Jonathan O'Callaghan

Senior Staff Writer

This image shows spiral wave density in Saturn's rings. NASA/JPL-Caltech/Space Science Institute

Yes, we’re all crying that the Cassini mission is coming to an end at Saturn this Friday. But before it goes, we’re getting treated to plenty of amazing images from the little spacecraft that could.

This latest batch is no exception. NASA has released some stunning shots of Saturn’s rings as seen by Cassini, showing wave structures in the ring and their mysterious natural hue.


The first image, which you can see above, was snapped on June 4 when Cassini was 76,000 kilometers (47,000 miles) from the rings, or 16 times the distance from New York to LA.

In the image we can see what’s called a 2:1 spiral density wave in Saturn’s B ring, caused by the moon Janus. It looks like the rings are tilted to the top left in this image, but the upper-left is just as close to the camera as the lower-right.

Instead, what you’re seeing is “wave crests”, where the rings get tighter together in a repeating pattern. This is caused by the moons Janus and Epimetheus switching positions in orbit every four years. As Janus is much larger, however, its effect on the rings is much more noticeable.

“This wave is remarkable because Janus, the moon that generates it, is in a strange orbital configuration,” NASA said in a statement.


“The distance between any pair of crests corresponds to four years' worth of the wave propagating downstream from the resonance, which means the wave seen here encodes many decades' worth of the orbital history of Janus and Epimetheus.”

This means that the wave in the upper-left shows the positions of Janus and Epimetheus when the Voyager spacecraft flew past in 1980 and 1981.

In a second image, below, we get a glimpse of what Saturn’s rings look like in their natural color.

The strange natural hue of Saturn's rings. NASA/JPL-Caltech/Space Science Institute

When looking at the planet through a telescope, the color of the rings is washed out by Saturn, which has a similar hue. This image, the highest-resolution color image of any part of Saturn’s rings, used a red, green, and blue filter to reveal the pale tan color of the rings.


As NASA notes, no one is quite sure what gives the rings this color. They are mostly made of water ice and so should appear white, so it’s hoped observations by Cassini may shed some light on the mystery. This image was taken on July 6 from the same distance as the previous image.

An enhanced color version, below, shows the stark contrast between different portions of the ring. Areas that are redder are thought to be richer in water-ice.

Three days to go. Say it ain’t so.

An enhanced color view of the image above. NASA/JPL-Caltech/Space Science Institute


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