An icy Titanic encounter

By Phil Plait | November 8, 2011 11:30 am

This morning, I wrote about some pictures of Saturn’s moon Enceladus I found rummaging through NASA’s Cassini raw images archive. Enceladus is a small icy moon that may have an ocean of liquid water under its surface. It’s a fascinating world, and is one of those objects that cannot seem to take a bad picture; every shot of it is dramatic and intriguing.

Even so, as I clicked through the raw images from the distant spacecraft, I got a jolt when I stumbled on a series of pictures depicting the tiny disk of Enceladus with the gigantic visage of Titan sliding past! I quickly grabbed the images and made a short animation showing the scene, with a description:

[It helps to watch full-screen and in hi-res; I recorded it in 1080p. The images from Cassini look pretty good that way.]

Nifty, eh? I’ll note that in between some of the frames of the animation Cassini was programmed to change filters. That’s most obvious by looking at Titan itself; when the blue filter was used the atmospheric layers become more obvious — an upper level haze layer is dark in blue colors. Here’s one of those images using the blue filter:

You might wonder why the picture isn’t blue if a blue filter was used. That’s because the detectors used on spacecraft (and most telescope) cameras don’t really detect colors, they only detect light. Astronomers use filters to block out or isolate certain colors of light, say red, green, or blue. Each of those individual images is really just an array of numbers, so an individual filtered image can only be displayed as a grayscale picture like the one above. It’s when you add the three images together that true color emerges. The actual process is pretty detailed, but that’s the boiled-down version.

And you can do this too, if you want. The raw images are freely available to anyone, and it’s fun to poke around the archive. For these specific shots, go to the archive, search on "Narrow Angle", set the target to Enceladus, and look between the dates 09/17/2011 to 09/20/2011. You’ll find ’em. But you can find amazing things if you widen the search parameters, too. Find the shots of Hyperion to get a real dose of weird… Also, the folks at Hubble have a great tutorial on how to assemble individual images into a color picture.

There are astonishing shots in there, and if you’re American your tax dollars paid for them. But they belong to all of humanity now, as well they should. There are scientific treasures in there, and I know people will be mining that data for decades to come.

Image Credit: NASA/JPL/Space Science Institute

Related posts:

Watch out, Titan! Vader’s onto you!
Midnight on a ringed world
A hidden world revealed: Titan
A window into Titan
Saturn weather forecast: rings, with light rain from Enceladus

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures
MORE ABOUT: Cassini, Enceladus, Saturn, Titan

Comments (23)

  1. Suuure, those black lines are merely artifacts… So says the NASA-shill!!!

    Admit it, there are fleets of very thin, long-winged spacecraft that are going to destroy the world!!


  2. andy

    This brings out the massive difference between the albedos of the moons: Enceladus is very reflective, Titan substantially less so.

  3. I have become addicted to all the photos and videos you post. My inner astronomer has a field day with these! Thank you!

  4. Chris

    Radius Titan = 2576 km
    Radius Enceladus = 252 km

    ~10 x difference

    diameter of a dime = 0.705 inches
    so you’d need a ball ~ 10x bigger, so something a little smaller than a basketball

    But you’d also need to increase the distance to keep things to scale.

  5. Douglas Cox

    Great animation! And great info as well, as usual.

    But what bothers me is the ad.

    Google puts ads on Youtube videos, and the one on this one makes me shake my head. It’s for “Quantum Jumping,” a website that sets off all sorts of skeptical alarms in my head. I haven’t looked into it at all, but is sure sounds like a lot of pseudoscientific gibberish.

    Just thought you should know what’s being advertised on your videos.

  6. Michael Swanson

    @1. Katherine Lorraine, Chaton de la Mort Says:

    “…there are fleets of very thin, long-winged spacecraft that are going to destroy the world!!”

    Well, it makes perfect sense that they would have very long wings. There are gases in space, of course, but the atoms are so thinly spread that it would take enormous wings to get any kind of lift for a spaceplane. It’s all perfectly scientifical.

    (Of course, the wings have got nothing on the propeller!)

  7. JonB

    I notice that Enceladus seems to wobble a bit as Titan passes. Is that just some artifact of the image processing, motion introduced by Cassini bobbing around, or is it a visible sign of Titan’s and Enceladus’ gravitational effects on each other?

  8. DrFlimmer

    You know, Phil, what’s most amazing?

    You grab a relatively boring subject, make a text or even a video out of it, and the result is a completely fascinating and passionate statement for and of science. I mean, c’mon, that were just some bodies passing each other… and yet you (are able to) present it as if it were the greatest thing on earth… no… in the solar system!

    And you know what? That IS amazing! More people like you are totally needed. Good work!

    I hope that in the future I learn to show this passion about astrophysics and science to other people (especially laymen), as well. I don’t know, if I will ever be able to do it like you do. But I’ll try.

    Btw: Was that a tennis ball OF SCIENCE? 😉

  9. James

    I would have found that video much more comfortable to watch if it was rotated 90 degrees.

    My Earth evolved brain just expects planets to move in that way relative to the orientation of my head. In the same way that the horizon is horizontal instead of vertical.

  10. Zyggy

    @ 5. Douglas Cox – I’ve never seen an ad here. I use Firefox and a plugin called adblock. I see *maybe* 1% of the ads out there. Not much gets through.

    back on topic.

    Being a Photoshop geek, I followed some of the links to combining the filtered images to create full color images. The process is slightly more involved than I expected, but pretty straight-forward. That’s going to be an endless source of amusement for me.

    Also, for those without Photoshop, you don’t necessarily need it anymore! The business end of the software used to be a filter, but it’s now a standalone program that can be downloaded for free.

    Off to discover some new artwork for my office walls…


  11. arcblast

    now THAT was awesome. loved your little presentation, too. very informative. well done :)

  12. Grand Lunar

    Nice fine, Phil!

    Now, throw in some appropiate music, grab a lot more sequences, and you can make something like Chris Abbas did. 😀

  13. Tardis_42

    @5. Douglas Cox

    I had an even dumber ad –

    “3-Minute Chakra test
    Take the Free Chakra Test to Find Out Which of Your Chakras Are Weak”

    Some people!

  14. Pete Jackson

    Watching this movie gave me an amazing insight: billiards in three dimensions would be a rather tough game!

  15. @ ^ Pete Jackson : How about 3D Chess a la Star Trek original series that Spock used to play? 😉

    Great animation BA. Nicely done. Cheers for that. :-)

    BTW. Was that impromptu model – dime Enceladus, tennis ball Titan – approximately to scale? If so, then what would represent Hyperion and Saturn respectively?*

    (Tries to recall how big a US “dime” is versus Aussie currency – looks like about the size of our ten cent coin?)

    * Lemon seed for Hyperion? Large inflated beach ball for Saturn maybe?

  16. Tara Li

    Wouldn’t this have been a lot more bandwidth friendly as an animated greyscale GIF of the important part, and your discussion in text?

  17. Mephane

    @14 Pete Jackson:

    It’s been depicted Jeffrey Carver’s book “Neptune Crossing” – it’s called “EineySteiney” there and basically is just that – billiards in three dimensions, with the addition of simulated gravity between objects and “black holes” to put the balls into (one version of the game uses textures for the balls that look like the planets of the solar system, too).

  18. Nigel Depledge

    The BA said:

    There are astonishing shots in there, and if you’re American your tax dollars paid for them.

    Actually, since Cassini is a joint NASA / ESA / ISA mission, Europeans’ tax Euros also paid for them.

  19. Peter B

    JonB @ #7 asked: “I notice that Enceladus seems to wobble a bit as Titan passes. Is that just (A) some artifact of the image processing, motion introduced by Cassini bobbing around, or (B) is it a visible sign of Titan’s and Enceladus’ gravitational effects on each other?”

    Lock in A, Eddie. (Sorry, Australian TV reference.)

    I’m fairly sure Titan’s gravitational effect on Enceledus wouldn’t manifest itself by making the E moon wobble.

  20. Definitely a teachable moment twice over. Not only is it science education, but also it’s a class on making science fun and how to make a video. You have to bottle this approach and sell it.

    One question: as the two moons pass so close to each other, wouldn’t their respective masses and gravity tug on the other and play around with the perception of a smooth transit by a third object? Is it possible Cassini is making their transits smoother because of its motion?

  21. dw

    That was amazing. But is Cassini orientated so that its “laying on its side” so the orbits appear to be vertical? Or do images appear turned 90 degrees due to processing?

  22. CR

    Cool images, as always (I could lose myself for days–weeks even–at that site), and of course, nifty animation you threw together. I echo the other compliments to you about your making science so accessible. I try to keep accessibilty at the fore when talking to people (especially school kids on the occasional astronomy presentation I give at the local school), but have not made any vidoes.

    To anyone else interested in spreading the word (about astronomy or any other science-y topic): keep it relatively simple and fun, and have some handy, eye-catching visuals if you can. Phil’s use of everyday objects is great, and can always be supplemented with more ‘advanced’ things like posters or books. The audience can get hooked by the simple presentation and shown the small sample of what else is available, and hopefully be inspired to do a little investigation on their own. (In my case with the school astronomy presentations, I also had a few models of both real spacecraft and sci-fi spaceships to help attract attention while showing the difference between reality & fiction.)

    An aside… is anyone else interested in the cool-looking artwork Phil always seems to have adorning his walls? I bet I could get lost in his house for days just going through his collected stuff…


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