Cassini Focuses In On Two Moons

Article written: 8 Aug , 2011
Updated: 24 Dec , 2015
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In this new image from the Cassini Imaging Team Saturn’s moon Titan looks a little out of focus compared to the sharp, cratered surface of Tethys, seen in the foreground. But that’s only because Titan’s hazy atmosphere makes the moon look blurry. Titan’s current atmosphere is thought to resemble Earth’s early atmosphere, so we could be looking at an analog of early Earth.

And so, the Cassini mission is sharpening our understanding of Saturn and all its moons, but it might help us understand our own planet, as well.

At just over 1,000 kilometers in diameter, Tethys is believed to be almost entirely comprised of water ice, based on density estimates. Titan, at just over 5,000 kilometers in diameter is notable for being the second largest moon in our solar system, as well as having an atmosphere 1 1/2 times thicker than Earth. Titan is also known to have an active “liquid cycle” made up of various hydrocarbons, making Titan the second body in the solar system to have stable liquid on its surface.

The camera view is aimed at the Saturn-facing side of Titan and at the area between the trailing hemisphere and anti-Saturn side of Tethys. Not shown in frame is Saturn, which would be far to the left, from the perspective shown in the image.

The image was acquired with Cassini’s narrow-angle camera, in green visible light, on July 14, 2011. At a distance of roughly 3 million kilometers, the image scale for Titan is 19 kilometers per pixel. With Tethys at a distance of about 2 million kilometers, the image scale is roughly 11 kilometers per pixel.

If you’d like to learn more about the extended Cassini “solstice” mission, you can read more at: http://saturn.jpl.nasa.gov/mission/introduction/

Source: Cassini Solstice Mission Images

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9 Responses

  1. WaxyMary says

    What an interesting picture.

    Mary

  2. Anonymous says

    I thought Tethys resembled the Death Star with Alderaan looming in the background. The large limb crater at 5o’clock (Odysseus?) would be the laser canon I guess.

    (Note Saturn’s moon Mimas[w-Herschel crater] is usually accorded this distinction: http://en.wikipedia.org/wiki/Mimas_%28moon%29#Unusual_resemblances )

  3. Anonymous says

    I thought Tethys resembled the Death Star with Alderaan looming in the background. The large limb crater at 5o’clock (Odysseus?) would be the laser canon I guess.

    (Note Saturn’s moon Mimas[w-Herschel crater] is usually accorded this distinction: http://en.wikipedia.org/wiki/Mimas_%28moon%29#Unusual_resemblances )

  4. Anonymous says

    “For the World Is Hollow and I Have Touched the Sky”…startrek;-)

  5. mk says

    that’s no moon. it’s a battle station

  6. Anonymous says

    Author did not mention this is known as a “mutual event”
    http://www.ciclops.org/view.php?id=5978
    see the link for more info

    • Gregory, I didn’t feel mentioning the technical term for this type of image was terribly necessary. I’ll be sure to consider doing so if I do another write up on this type of image. Thanks for the feedback!

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