The look of a Titanic moon

By Phil Plait | April 12, 2012 9:30 am

Astronomical imaging is an interesting process. The most common question I get when I show a picture is, "Is this what it would look like if you were actually there?"

That’s a tough question to answer in many cases, because our eyes see in a different way than cameras take pictures. We have receptors in our eyes that are sensitive to red, green, or blue light, and they send signals to the brain which then constructs a "true color" image from that. In astronomy, we use filters to mimic that, but they don’t actually perfectly represent the way our eyes see. And even after you get the picture, there are adjustments in contrast, brightness, and so on that can alter a photo.

A few months ago, the folks at Cassini released a really cool picture of Saturn’s moon Titan. It’s a great shot, have no doubt, but amateur astrophotographer Gordon Ugarkovic — who has some experience putting together color pictures from Cassini images — felt that processing the image in a different way might represent natural color better. So he reprocessed it, producing this amazing image:

[Click to encronosenate.]

All by itself, that’s a stunning shot. Titan is larger than Mercury, but still dwarfed by the gigantic planet it orbits. Titan has a thick atmosphere, and you can see some details in it, like the "polar hood" over its north pole. Also, a really neat effect is on Saturn itself. You can see the rings, as well as the shadow of the rings on Saturn’s cloud tops (below the rings themselves). Near the edge of Saturn, the shadow dips downward, hooking down a bit. That’s a product of several effects, including refraction; the bending of light as it passes through the atmosphere (similar to why a spoon looks bent in a glass of water).

It’s interesting to compare Gordon’s version to the one released by Cassini as well (shown here; click to embiggen). Both are beautiful, interesting, and show a lot of detail. The "official" release is darker, a bit, which is the most obvious aspect. Gordon’s shows details in Titan’s polar hood better, but I see more subtle variations in Titan’s atmosphere overall in the official shot, and perhaps better detail in the ring shadows, too.

So which one is better? Neither! They both are amazing, and show slightly different things. One might appeal to you more in an aesthetic sense, or in a scientific sense, or because you’d rather see details in Titan versus Saturn, or whatever. But in my opinion, it’s OK to like both or neither or one over the other for whatever reason you prefer.

In astronomical imaging — something I did professionally for over a decade — the image is never really what you’d see if you were there, because the instant you use a camera and a telescope you’re already two steps removed from real vision. You can try to get as close to what the human eye would see as you can, but I think in most cases that’s a conceit, something that’s interesting to our minds but perhaps not our eye.

And like all photography, this is art. If you want to display an astronomical object and are being true to what you are showing, then it’s OK. These images done for press releases or simply for their own sake are meant to inspire our imagination, fire up our curiosity, and see their beauty.

Beauty that is, at the very least, in the mind’s eye of the beholder.

CATEGORIZED UNDER: Astronomy, Pretty pictures

Comments (26)

Links to this Post

  1. Are Astronomical Images All Faked? « Galileo's Pendulum | April 17, 2012
  1. Fantastic image, but they needed to photoshop a monolith in to really complete the picture.

  2. Blargh

    That. Is. Awesome.
    I love how Titan’s atmosphere looks!

  3. Gary

    It might seem pedantic, but I do get annoyed at sci-fi movies that show space-scapes festooned with vivid brightly-coloured nebulae when these are only visible to us because they have been photographed using very long exposures, and therefore would not be so apparent to the naked eye in space. I also get irate at movies that have spacecraft playing ‘hide and seek’ in nebulae (like in the Wrath of Khan) when they are barely less tenuous than a vacuum and therefore offer no places to hide at all. I still long for realistic sci-fi, and was gutted when I read that James Cameron was going to do a TV adaptation of Kim Stanley Robinson’s amazing Mars trilogy but gave it up. Rant over!

  4. Titan is a lot closer to the edge of Saturn in the re-processed shot…

  5. Wrong Planet, Brett. The monolith was around Jupiter.

  6. @Timechick, In the Special Edition of 2001: A Space Odyssey, the monolith orbits Saturn and shoots first! ;-)

  7. Kevin Kirby

    The Monolith was on Iapetus in the 2001 novel.

  8. Wonderful post as always Phil. As an editor who covers astrophotography in another magazine, I avoid the term “true color” because every single person experiences color differently. In this respect, there is no such thing as true color. Therefore, I prefer the term “natural color”.

  9. reidh

    its so toxic there, and so stupid to want to BE there, that I wish you were there, right now.
    Imagine that!

  10. Roberto

    Why Saturn rings look over imposed on the left edge of Titan?. I’m sure there´s a very interesting scientific explanation for that, despite the fact it looks like bad shopping.

  11. HvP

    Roberto,

    Looks like a combination of two things concerning the rings impinging on Titan’s left limb.

    First, the rings appear bright enough that they shine through the thinner layers of Titans outer atmosphere causing them to appear to cut into part of the mist above the moon.

    Second, there is an optical illusion happening that causes the segments of Titan right next to the ring intersection to appear darker than the rest of Titan’s limb, but only because they are juxtaposed against the relative brightness of the nearby ring segments.

    Take your thumb or a thick piece of paper and cover up the rings right up to the edge of Titan. The illusion goes away and Titan’s limb looks consistent again.

  12. Rafael

    @reidh: if I were there, I’d die with a very big smile.

    (sorry for bad english, bad astronomers)

  13. CharonPDX

    Ah geeks. Yes, Timechick, in the original novel, it was on Iapetus, a moon of Saturn. They went with Jupiter for the movie because they thought it would be easier to do the special effects on. Both are “correct”, as both were done by Clarke. And in the book of 2010, he went with the movie version of 2001 as the base, putting it around Jupiter.

  14. Brad

    Y’know. I always found it annoying when sci fi movies produced these beautiful, colorful, space-scapes in their movies, too. But how can you blame them when NASA does it, too. I’ve always wondered what these places would look like to naked eye. Yeah, it might be boring, but that’s for ME to determine. I think it’s disingenuous to release these worked up photos.

  15. This is true of ordinary photography, too. What you see is seldom what you get. In court, a photograph is only admitted in evidence if someone (usually the photographer) is there to testify that it is a true representation. A picture is a picture, it is not reality. We have no way of knowing, either, if my monitor shows the same colors yours does, let alone whether my eyes and brain process them the same way. So Phil says “I see” and I look at the image on my monitor, and “see” if I “see” the same thing. So, it is a very silly (though typically human) question to ask, “is this what it would look like if you were actually there?”

    Good comments, everyone!

  16. HvP

    Jen,

    Very true. Once I started working with RAW image files in photography it became clear that there are hundreds of different permutations of a picture that are all at least as valid as anyone’s subjective idea of the scene might be.

    Also, I had an epiphany after reading an article that pointed out that we have no way of knowing what any particular color looks like in the mind of anyone else. My brain happens to apply a sensation of color that I call “red” to the signals for long wavelengths and blue to shorter ones. As far as I know you could be imagining a color for blue that if I could see into your mind I might call red instead.

    Just imagine, we could perceive the world as a negative image of each other and we’d never know it.

  17. Ralfp

    Well, if we are going for sci-fi visions, there is one where Titan is old story…

    Welcome to the Spraw, mr. Isaac Clarke.

  18. Nigel Depledge

    Timechick (5) said:

    Wrong Planet, Brett. The monolith was around Jupiter.

    Jupiter in the movie. Saturn in the book.

    If what I heard is correct, they changed the planet to Jupiter because the special effects crew couldn’t “do” the rings of Saturn.

    Edit – Aw, CharonPDX (13) beat me to it.

  19. Nigel Depledge

    Jen Deland (15) said:

    This is true of ordinary photography, too. What you see is seldom what you get.

    All too true.

    Landscape photography might sound simple (point the camera at the view and press the button) but it is all too easy to get foreground elements underexposed while getting some of the sky appearing “true”, or to get the sky burnt out while getting foreground elements to come out looking “true”. There is a specific filter you can get (an ND grad) to counteract this effect – the filter reduces the amount of light reaching the camera across a part of the field of view without tiniting it. Alternatively, you can use a post-processing technique known as HDR (high dynamic range) but only if you took your original shots at several exposure levels using a tripod (or some other means of fixing the camera in place for all 3, 4 or 5 shots).

    But that’s an awful lot of work to get a photograph of a landscape to look the way it did look to the photographer on the day.

  20. browolf

    how does one “put(ting) together color pictures from Cassini images” ?

  21. DJCinSB

    I do find the glow on the dark side of Titan in the retouched image a bit annoying. It shows off the sphere of the moon, but is way overdone for my taste. But both are great images!

  22. Gordan

    DJCinSB Says: “It shows off the sphere of the moon, but is way overdone for my taste.”

    It’s not “overdone”, it’s light from Saturn in the background forward-scattered through the haze just like sunlight is at high phase angles giving the moon that “diamond ring” look. I didn’t invent that glow just to make the globe visible, the effect *is* physically there.

  23. labcad

    Ahhh, BA, I see what you did, working “Titanic” into the headline. All those folks searching for information on the ship will be coming here. Not bad.

  24. DJCinSB

    Gordon Says: “It’s not “overdone”, it’s light from Saturn in the background forward-scattered through the haze just like sunlight is at high phase angles giving the moon that “diamond ring” look. I didn’t invent that glow just to make the globe visible, the effect *is* physically there.”

    Interesting. I was looking at the tif image, and the Saturn glow is much less pronounced there (nearly invisible in the linux viewer that I was using then). The jpeg image at the Cassini site makes it more apparent. I was NOT trying to say it was added to or retouched on the image at all. All I was trying to say — perhaps rather poorly! — was that it looked too enhanced for my taste, though overall, I like the image.

    No accounting for taste – at least mine! :-)

  25. Jebediah S.

    “Embiggen” is a perfectly cromulent word.

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