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Using Shadows To Measure the Geysers of Enceladus

Posted by Soulskill on from the easier-than-breaking-out-the-yardstick dept.

The Bad Astronomer writes "A lot of folks are posting about the amazing new pictures of the icy moon Enceladus returned from the Cassini spacecraft. However, one of them shows the shadow of the moon across the geyser plumes. This has been seen before, but I suddenly realized how that can help determine the geysers' locations, and I thought Slashdot readers might be interested in the general method."

27 comments

  1. Uh oh by Esteanil · · Score: 1, Informative

    http://www.ciclops.org/view_media/36124/Tethys_Rev_164_Raw_Preview_1

    That's no moon. It's a space station!

    --
    I'm a dreamer, the world is my playpen. But hey, I'm a serious person, I can't dream all the time.
    1. Re:Uh oh by Cazekiel · · Score: 1

      Looks more like the DS' graphics of Yavin and its moon with the R-R-Rebel base.

      --
      You want to know how to help your kids? LEAVE THEM THE F*&K ALONE. --George Carlin
    2. Re:Uh oh by Chris+Burke · · Score: 1

      I vote Mimas for being no moon.

      --

      The enemies of Democracy are
  2. News for nerds... by overbaud · · Score: 1, Insightful

    by nerds... " I’ve written about Enceladus about thirty two bajillion times, because it’s fascinating, and photogenic as heck" given just how nerdy this is no doubt it will have fewer responses than more mainstream non nerdy articles on slashdot.

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    Users... the only thing keeping 1st level support from being the bottom feeders.
    1. Re:News for nerds... by Qzukk · · Score: 1, Offtopic

      given just how nerdy this is no doubt it will have fewer responses than more mainstream non nerdy articles on slashdot

      Sadly, this is probably true, but at least some of us nerds will have clicked it. And possibly even RTFA'd.

      --
      If I have been able to see further than others, it is because I bought a pair of binoculars.
  3. Nerdy-purdy! by Cazekiel · · Score: 3, Informative

    Icons of this. It shall be done.

    Gorgeous, gorgeous.

    --
    You want to know how to help your kids? LEAVE THEM THE F*&K ALONE. --George Carlin
  4. I want my 5 minutes back by Rosco+P.+Coltrane · · Score: 0, Flamebait

    This has been seen before, but I suddenly realized how that can help determine the geysers' locations, and I thought Slashdot readers might be interested in the general method.

    Hmm, at first, this looks like you're just a Slashdot whore. But I may be wrong, you may be on to something. So I follow the link, read your masterpiece, thinking "this is bloody obvious", then TFA arrives grandiosely at this:

    In reality itâ(TM)s tougher than this, but in essence itâ(TM)s doable. In fact, Carolyn told me this has been done in Enceladus images before!

    So, in essence, you just had a brainfart and wanted to share it with us?

    --
    "A door is what a dog is perpetually on the wrong side of" - Ogden Nash
    1. Re:I want my 5 minutes back by Anonymous Coward · · Score: 4, Insightful

      Here's your five minutes back. The balance of eternity is for people that understand how wondrous this is.

      By the way, you are wrong about the "Slashdot whore" part, just so you know. Sites like "Bad Astronomy" qualify as being one of the main reasons Slashdot was created.

    2. Re:I want my 5 minutes back by jd · · Score: 4, Insightful

      No, he CAN'T have his five minutes back - you know the rules, no refunds on Slashdot except through the complaints department.

      "The Bad Astronomer" has been around long enough, and has enough credibility, that anyone who claims he's a karma whore is de-facto neither a nerd nor a geek and should gerroff our collective lawns.

      Obvious Geometry is indeed Obvious. This guy, Euclid, wrote some of the Obvious Geometry down and used it as a teaching manual. Nobody had done that before. Everyone in his time knew the rules he was describing (Archimedes regarded them as insultingly simple), but few had understood the fundamentals (what was axiomatic, what was derivative) and absolutely nobody had thought of actually explaining things before. The result of him doing so caused the number of mathematicians and their skills to explode. The learning curve had become dramatically shallower.

      This is really no different. Sure, it's basic but the learning curve of WHY it works, HOW it works and WHEN/WHERE it can be used is NOT common knowledge. This makes teaching the relationship of maths and astronomy a cakewalk. I have no objections to more people seeing why geometry and maths are relevant (a common complaint is that they aren't ever used anywhere, but that's because nobody explains why, yes, they are). I regard it as the sole opportunity for turning the world into people who can think for themselves.

      --
      It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
    3. Re:I want my 5 minutes back by TapeCutter · · Score: 1

      "The Bad Astronomer" has been around long enough, and has enough credibility, that...

      ...my 78yo dad sends me links to his articles. As for this article the explaination is easy to grasp, invariably the hardest part is spotting what is right under your nose and thinking "That's odd?".

      --
      And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
    4. Re:I want my 5 minutes back by Muad'Dave · · Score: 1

      The result of him doing so caused the number of mathematicians and their skills to explode.

      I read that as "The result of him doing so caused the number of mathematicians and their skulls to explode."

      --
      Tiller's Rule: Never use a word in written form that you've only heard and never read. You will end up looking foolish.
    5. Re:I want my 5 minutes back by jd · · Score: 1

      Had the Vikings invented geometry.....

      --
      It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
  5. That sounds familiar... by Anonymous Coward · · Score: 0

    Wasn't The Geysers of Enceladus a Lyle Lovett album?

  6. When I first saw this.... by billybob_jcv · · Score: 0

    ... I thought it was story about geysers of enchiladas....

    1. Re:When I first saw this.... by Anonymous Coward · · Score: 0

      Only morons mispronounce Enceladus to sound like "enchiladas".

  7. Beautiful. by robably · · Score: 2

    Seeing the images, running us through the thought process - lovely. More stories like this, please. It was fascinating and wonderful.

  8. Two serious questions: by Anonymous Coward · · Score: 2, Interesting
    1) What sort of freaky small time window and lighting conditions do they need to get a picture at a range of 185 km, and can they do it consistently? That's insanely close for how fast this spacecraft is traveling across the surface of the moon, and for the lighting conditions.

    2) Unrelated, but what the hell are those things at lower left (and two of them crossing in upper-mid-to-upper-right)this pic from a more more sane 17000 km? Ridiculously long crater chains from ejecta, or something rolling/bouncing "downhill"? Seems weird that it could roll "downhill" through a crater without altering its path, so I'm leaning towards crater chains from ejecta, but they seem pretty wildly extended for crater chains, yet are too varied in direction to suggest faults. Where was this relative to the "tiger stripes"?

    1. Re:Two serious questions: by Muad'Dave · · Score: 1

      They're either lava (ice?) tubes, sealed-over ice fissures, or lairs of the Mole-Men.

      --
      Tiller's Rule: Never use a word in written form that you've only heard and never read. You will end up looking foolish.
  9. OK, then what? by PPH · · Score: 1

    Do we have enough photos of Enceladus' surface (illuminated, from different angles) so that we can look at these locations and see what lies there? Now that could be interesting.

    --
    Have gnu, will travel.
  10. Least comments ever. by DeionXxX · · Score: 2

    This article has the least comments I've ever seen for an article on the homepage. Only 16 comments after 7+ hours. What's happening with Slashdot??

    1. Re:Least comments ever. by 12WTF$ · · Score: 1

      I went to badasstronomy to read the article, but it was slashdotted :(

      --
      Cryonics - Keep cool and carry on.
    2. Re:Least comments ever. by serialband · · Score: 1

      Most of the comments on other articles are opinions. Political articles seem to get the most back and forth comments. This article just presents interesting facts, and simple facts that people accept don't elicit much opinions.

  11. A Challenge! by director_mr · · Score: 1

    So now that we know all this stuff the Bad Astronomer said, I want to lay down a challenge. I noticed the Bad Astronomer included no actual plume information. How tall ARE the plumes? How far away are they from each other? How did you calculate your figures? I won't be able to work on it until after my real work, but lets see if any enterprising Slashdot aficionado can come up with the info, preferably using math, not an online source. Don't make me break out my TI-86 and be the first to come up with the data!

  12. Science Fair by Port-0 · · Score: 1

    A girl in my highschool back in 1988 was used voyager I or II photos (I can't recall which) to calculate the depth of craters on a couple of Jupiter's moons. Which is little different than what the article is describing, but it seems shadows have a lot more information encoded in them. This girl and I ended up winning the science fair and going on to the International science fair, where I felt a bit out of my league. She won a few awards. Apparently at that point no one had thought to do that up to that point. (for those interested, I wired up a photometer to an Apple II and wrote some software to automate variable star photometry, which measures the light from light sources through a telescope over time. It can be used to find the rotation of asteriods, or with a sensitive enough instrument, the change in light from a large planet orbiting a star, stuff like that.)