Posted on by Nancy Atkinson

Where In The Universe #55

Are you ready for another Where In The Universe Challenge? Take a look and see if you can name where in the Universe this image is from. Give yourself extra points if you can name the spacecraft responsible for the image. As usual, we’ll provide the image today, but won’t reveal the answer until tomorrow. This gives you a chance to mull over the image and provide your answer/guess in the comment section. Please, no links or extensive explanations of what you think this is — give everyone the chance to guess.

UPDATE: The answer has now been posted below. Don’t peek before you make your guess.

What you are seeing here is the dark side of Saturn’s moon Titan, with sunlight filtering through the moon’s hazy atmosphere. And obviously, the Cassini spacecraft is responsible for this image.

An airless satellite would appear in this viewing geometry only as a lit crescent. But Titan’s thick atmosphere scatters light around all edges of the planet to create a ring of light.

This view looks toward the Saturn-facing side of Titan. North on Titan is up and rotated 45 degrees to the left. The images were acquired at a distance of approximately 1.8 million kilometers (1.1 million miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 157 degrees. Image scale is 11 kilometers (7 miles) per pixel.

Nice job, everyone! Check back next week for another WITU challenge!

13 Replies to “Where In The Universe #55”

  1. This is Titan, black-lit by the Sun and shot by Cassini. There’s no mistaking that great atmosphere!… 🙂

    (And yay! It’s been a while since I’ve been the first to comment on WITU…) 🙂

  3. Titan, likely taken by the Cassini probe (or, perhaps, Huygens on its way in, but I don’t think so); however it could also be one of the best Voyager images, reprocessed (no way to tell if 1 or 2, unless you can remember which of the two made the closest pass to Titan).

  4. I would concur this looks like Titan. There is also a high altitude halo around the body colored blue. This is a signature of methane.

    I am a bit puzzled about why the lit part of the body is nearly a ring. I suppose this might be due to light reflected off Saturn. This almost looks like a planet being eclipsed by a large and close moon. There is nothing in the solar system which is like that.

    Lawrence B. Crowell

  5. PS, I think it more likely that solar photons are being Mie scattered through the thick atmosphere, which gives this ringy type of appearance.

  7. Oops. I wrote “black lit”?! I meant “back lit”.

    Lawrence, your PS hit the bullseye. The Earth’s atmosphere does the same, although in Titan that effect is more pronounced tue to a much higher atmosphere thickness : body size ratio.

  8. Easiest challenge yet. And yes, it’s Titan. Anyone who has ciclops.org bookmarked has seen the atmospheric layers of this moon many times.

  13. It’s an eclipse of the sun. The eclipsing body is Titan. Spaceship is Cassini.

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