Ice moon, ghost moon

By Phil Plait | May 10, 2012 8:55 am

One of my favorite things to do is take a gorgeous astronomical image and pierce down into it, finding some detail not discussed in press releases and other articles.

On the other hand, sometimes I’ll post a picture because it’s so, so cool:

[Click to encronosenate.]

That’s a shot of Saturn’s rings and moons by the Cassini spacecraft, taken in mid-April 2012. Cassini was nearly in the same plane as the rings, so they look like a knife cutting across the image. The bright moon is Enceladus, tiny and icy, almost but not quite full as seen from this angle.

But the scene stealer is Titan, the moon as big as a planet — bigger than Mercury, actually — looming in the background, nearly invisible. This image, taken using a filter that only lets through green light, shows just how much darker Titan is than Enceladus. The bigger moon is shrouded in a thick, hazy atmosphere, and reflects about 1/5th of the sunlight that falls on it. Enceladus, on the other hand, is covered in ice, and reflects nearly all the light that falls on it. So the brightness ratio you see here is real: Titan really is far darker then Enceladus.

… and there you go. I drilled down a bit into the picture’s science anyway. I guess I had to. It’s in my nature; when it comes to science, I’m reflective too.

Image credit: NASA/JPL-Caltech/Space Science Institute

Related Posts:

An icy Titanic encounter
Enceladus fires on Alderaan
Incredible quadruple transit on Saturn!
The scale of Saturn

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures

Comments (14)

Links to this Post

  1. Lovely universe, ennit? | ***Dave Does the Blog | May 10, 2012
  1. Two of the most fascinating moons in that system posing with one of the most interesting features of the main planet. I’m starting to think that Cassini is a professional supermodel photographer!

  2. Keith K

    Lately, I’ve been seriously considering finally getting a tattoo, now that I’ve been inspired.

    This is conceptually what I want: Enceladus mistaken as Titan’s moon, as both orbit Saturn.

    Unfortunately the scale is a factor that I haven’t been able to get beyond. Deliberation continues.

    In the meantime: Soooooooooooo pretty!

  3. donna taylor

    Agreed. Cassini must be a supermodel photographer. Makes me want to go paint something!

  4. MichaelT

    Phil, what distances would be in play here? That is, how far (close?) is Cassini from Enceladus, the Rings, and from Titan? This is indeed a great shot.

  5. Rod

    Could anyone tell me where Cassini is here in relation to Saturn? Is it flying between the rings and the planet or is it outside the whole system altogether (say, Saturn is to the right of the picture or something like that)?


  6. Dennis

    After admiring all the incredible shots Cassini has taken over the years, I found myself wondering –
    Does Cassini compose and make these shots autonomously, or is there a very talented person back on Earth directing it remotely?

    I did a brief Google search but couldn’t find the answer.

  7. Jay Fox

    What is the spatial relationship between the three objects in this photo? Obviously, Titan is the farthest away, but I am confused as to where Enceladus actually lies. Is it between the camera and rings, or between the rings and Titan? Knowing the locations relative to each other would go a long way towards understanding the size difference between the two moons.

  8. Will


    At the time of the photograph, Cassini (C) is not far outside the orbit of Enceladus (E), looking back toward Saturn (S)(which is out of frame not far to the right). The rings (R) orbit inside Enceladus, and then beyond them, looping way out on its more distant orbit is Titan (T).

    Maybe this helps…looking from the top of the image down. View is in the -> direction.
    C ->E — R/S ——–T

    with everybody orbiting S in a counterclockwise direction if north poles are up in the image (which I think they are based on the date given).

  9. Grant

    Such a beautiful pic!

  10. Ori Vandewalle

    @Jay Fox:

    Wiki says Titan is about 10 times as wide as Enceladus. It looks to me like you can fit roughly 4 Enceladuses (Enceladi?) across Titan in that picture, which makes Titan roughly 2.5 times as far away from Cassini as Enceladus is. I think.

  11. Jamie

    Does anyone else get the illusion that Enceladus is moving while reading the text (moving from left to right)?

  12. Crudely Wrott

    Pictures like this, along with the videos that Phil posts for our edification make me turn a bit wistful sometimes as I remember the images in my young mind years ago. The Mercury Seven were still being chosen. Asimov and Sturgeon were inspiring me. Now, after waiting so long, I feel like this:

    Beauty is where you find it.

    You find it by looking with your eyes and seeing with your mind.

    When your eyes are insufficient, you create new ones that can see even farther and more clearly. You chose what light to see. You send these new eyes out upon paths that tread a greater sky to find the better vantage.

    Your mind, which really does the seeing, becomes so richly informed that imagination burgeons to the point that more wonderful and more real things are conceived.

    Learning is joy. Wonder is the fuel. Curiosity reinforces imagination to forge a formidable tool of discovery.

    All this from a few pounds of jelly that lives in the darkness within a vault of bone.

    This, in itself, is a thing of beauty. We are immersed beauty. All that is needed to see it are eyes and brains and taking delight in their use.

  13. Messier Tidy Upper

    Great image. :-)

    Cheers to (#8.) Will, (# 10.) Ori Vandewalle & ^ Crudely Wrott for their informative and poetric comments above. :-)

    @11. Jamie :

    Does anyone else get the illusion that Enceladus is moving while reading the text (moving from left to right)?

    Yeah, I get that slightly too. :-)


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