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There’s a Cerulean Storm Swirling on Saturn’s North Pole

RGB color-composite of Saturn from raw images acquired on Feb. 13, 2017. (NASA/JPL-Caltech/SSI/Jason Major)

RGB color-composite of Saturn from raw images acquired on Feb. 13, 2017. (NASA/JPL-Caltech/SSI/Jason Major)

Like some giant beast’s great blue eye Saturn’s north polar vortex appears to glare up at Cassini’s wide-angle camera in this image, a color-composite made from raw images acquired in red, green, and blue visible light wavelengths on February 13, 2017.

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The “Front” Side of Tethys

Color-composite image of Tethys from Feb. 1, 2017 (NASA/JPL-Caltech/SSI/J. Major)

Color-composite image of Tethys from Feb. 1, 2017 (NASA/JPL-Caltech/SSI/J. Major)

This is a color image of Saturn’s moon Tethys I made from raw images acquired by Cassini on Feb. 1, 2017 in visible-light color channels. It shows the moon’s sunlit leading side—the face that aims in the direction that it moves in its orbit around Saturn. (Click image for a larger version.)

While this icy moon is mostly monochromatic—appearing quite grey even in a color image—there are some subtle variations over large parts of its surface. Here you can just make out a slightly darker bluish band that runs across Tethys’ equatorial region. This is the result of surface weathering by high-energy electrons within Tethys’ orbit. The pale pinker regions to the north and south of the band are thought to be a coating of small ice particles that have been expelled from nearby Enceladus.

Also visible along the terminator is part of the 1,200-mile long, 60-mile-wide Ithaca Chasma, an enormous and ancient canyon system that runs almost all the way from Tethys’ north to south poles.

Tethys is 662 miles (1,065 km) in diameter and composed mostly of water ice and rock. It orbits Saturn at a distance of 183,000 miles (295,000 km) and takes 45.3 hours to complete one orbit. Read more about Tethys here.

And the Award for Leading Trojan Moon Goes To…

Raw image of Telesto from Cassini's narrow-angle camera on Jan. 14, 2016. (NASA/JPL-Caltech/SSI)

Raw image of Telesto from Cassini’s narrow-angle camera on Jan. 14, 2016. (NASA/JPL-Caltech/SSI)

Drumroll please… the little moon Telesto! (You like it, you really like it!) This image, captured by Cassini on Jan. 14, 2016, shows Saturn’s moon Telesto – a “leading trojan” of the much larger satellite Tethys.

A trojan moon is one that orbits a parent body within the same path as a more massive satellite, positioned at the Lagrangian points L4 and L5… usually at 60º ahead and behind within the orbit relative to the overall center (which, in the case of Tethys, is Saturn.)

The irregularly-shaped, 15-mile (24-km) -wide Telesto rides around Saturn ahead of Tethys, making it the moon’s “leading” trojan. Its slightly larger sister Calypso follows behind Tethys as the trailing trojan. All three orbit the ringed planet at a distance of over 183,000 miles (294,000 km).

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Once you realize what this Cassini image is showing, you’ll love it.

Go ahead, take a look. Let it sink in…..waaaait for it…… there. I told you.

Still wondering what it is you’re looking at? That’s ok, you’ll love it even after I tell you.
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