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Tuesday, February 18, 2014

Ganymede Geology: Cup Bearer (of GanyMead?) to the gods

     Before we head to the largest moon of Jupiter, Ganymede, and leave earth's Iceland, this 1 minute and 13 second BBC clip shows the divergent (pulling apart) sea-floor spreading we discussed last Tuesday:

     The three margins described on earth in the concept of plate tectonics: (1) divergent (seen above), (2) convergent (mountain building or orogeny) and (3) transform or strike-slip often associated with earthquakes, may also play a role in the geologic formation of Ganymede.

      Ganymede, discovered by Galileo in January, 1610, has surface area that is greater than half of the surface area of the land mass on earth. The moon was named for Ganymede, the pretty boy who was taken by Zeus to be cup bearer to the gods (Had they been geologists it may well have been mead in those cups :-) ). Ganymede may be seen this month with binoculars:

      NASA released a geologic map of Ganymede this week, the first complete geologic map of Jupiter's seventh moon. The "cup bearer" stands out quite well with a blue, dark green, and purple body and green "crater head" on the right side of the first image:

     The geology of Ganymede is especially interesting to geologists because it appears there were times of tectonic movement on this icy moon. These grooves and ridges point to a similar origin to the earth's plate tectonic movement:

     In addition, periods of intense crater impacts are seen in the geologic history:

     One of the more interesting features on Ganymede are palimpsests, derived from the word meaning to write over older writing (similar to pentimento overpainting in art). [The word palimpsest is from the Greek for to scrape]:

   Similarly, older craters are "overwritten" by younger ones as the older crater margins are eroded through time:

         There were (and are) quiescent times on this frozen, icy moon (quiescently frozen :)) as well.

          There is also evidence for some cryovolcanism (eruption of  volatiles like ice and water, methane, and ammonia from volcanoes) on Ganymede.

      The link to the NASA article contains a 37 second animation so you can also see the "Dark Side of the Moon" (The Pink Floyd song turns 40 next month!):

       Looking forward to discussing Ganymede geology, nomenclature, great music, and some planetary geology jokes and puns. Do you have a favorite?

Palimpsestially,(thanks, Lego)

Word Woman (aka Scientific Steph)


  1. Thanks to a reader in Philly, PA, for the blog topic suggestion this week.

    1. Lego, hope you have not been snowed in. We have missed you here and over there. ;-)

    2. SS,
      It is so satisfying the way PEOTS segues seemingly seamlessly from topic to topic from week to week. (Maybe the physics of two-wheeled, solo-stand-up-passenger locomotion is the subject of a future PEOTS; way, way far in the future!)

      As I viewed the BBC clip two words came to mind: potholes and potholders.

      I’ll pass on the golden Ganymedian opportunity to scope out Jupiter’s largest moon this month. Peering at a “pretty boy” (or even his namesake) through binoculars just kinda creeps me out.

      Two wonderful words: I’m impressed with the superlative palimpsest, and (anagram alert!) I LOVE pentimento, an Italian word not listed in my MW Collegiate Tenth). These words value rough drafts, celebrate preservation of the creative process. We can inspect the exed-out adjective Keats rejected, scrape and unveil the hues Monet chose to lose. Composing/creating in our cut-paste-delete processed-word world is like writing with invisible ink/painting with Etch-A-Sketch.

      “Dark Side of the Largest Moon of Jupiter” is not quite so catchy as “DSOTM.” PF’s 1974 mega-selling album was OK (with “Us and Them” its best tune, IMO) but their best album is 1971’s “Meddle” with its sonically glorious “Fearless.”
      The album cover (pictured) is a close-up shot of an ear underwater.


  2. The gas giants and their moons sure are interesting places. I like the images of volcanic plumes on the limb of Io. And that, while Clarke wrote the final scene of 2001 to be set near Iapetus, a moon of Saturn, Kubrick changed it to a Jovian moon, because he thought Saturn's rings would be too hard to shoot convincingly.

    I will forego the usual Uranus jokes.

    Funny you should mention mead; I recently contributed to the Kickstarter campaign of a friend who's starting NJ's first meadery.

    1. Yes, those gigantic volcanic plumes on Io are amazing too, jan. I didn't know that about Kubrick changing from a Saturn moon to a Jovian one. The happy influence of jovial Jupiter may contribute to our jollity this month. Perhaps that and a cup of mead. . .

      Exciting about the first NJ meadery! I am sure it is a honey of a deal. What's the name? Will there be a GanyMead? Granny Mead? Bee Positive Mead? Oh, the creative fun of naming meads!

      And I appreciate your restraint on the Uranus jokes. The way you tell jokes, you may have wrecked 'em anyway ;-).

    2. It's Melovino. They know their Latin roots, I guess.

      Kubrick was a character, according to a relative who knew him. He got married wearing galoshes over his brown shoes, because he didn't own a black pair, apparently. And I heard he was afraid of flying, and used to travel cross-country by train.

    3. I checked out Melovino's web page. Looks like a hit! I wonder if global bee decline is making the honey source harder to find. I would be willing to forgo a spoonful in my tea for the good of the cause ;-)

      Funny Kubrick didn't want to fly but directed 2001: A Space Odyssey. . I always liked his views about keeping a movie secret until its release. Today's film trailers tell way too much. Not sure what to make of the black galoshes though.

  3. A segue to segue, Lego. I like it!

    I agree with you about palimpsest and pentimento, beautiful words for the preservation of first-draft words and hues in writing and painting. Extending it to geologic crater landscapes is quite delightful too.

    Fearless is quite a delightful ear full. Thank you for the link. And I rechecked Dark Side of the Moon; it is forty-wonderful in March. And not a pretty boy in sight. ;-)

    Potholes and potholders: works for me...and not just because I live in Colorado.

  4. Thought of this blog when I saw Wikipedia's Picture of the Day today.

    1. Wow. An amazing panorama. What a glow on the person's face also.

    2. jan and Steph,

      Malovino, should also market "Runnymead, the beverage for those on the go!" (Okay, close to a Uranus joke.) Should sell well to the Brits: "Runnymead, by MaLOOvino."

      Love Kubrick's flicks. What range! Spartacus, Lolita (though Nabokov did not approve), Dr. Strangelove, 2001..., A Clockwork Orange, Full Metal Jacket, The Shining, and even the underrated Barry Lyndon.

      I initially read "limbs of Io" on your post as "Limbs of Lo." (A novella penned by Humbert Humbert?)

      "Palimpsestally" is nice, but I prefer "palimpsestially," rhyming with "celestially." (As usual, my contributions to PEOTS are more wordy than worldly and scientific.)


    3. That's "Melovino". "Malovino" would be applejack, I guess. Or, if you parse it differently, "bad sheep"?

    4. Melo for melon, especially apple-shaped. It is also an archaic name for the Nile River so surely it will be a fertile endeavour. This is my favorite Latin translation site:

      Applejack: very funny, jan. Bad Sheep: Honey, I shrunk ewe?

    5. No, that melo for honey, or sweet. As in diabetes mellitus, which causes an increase in sweet-tasting urine, as opposed to diabetes insipidus, which causes an increase in tasteless, or insipid, urine. (Yum!)

  5. Oh, and since we have been talking about flight, here's a favorite picture of the day featured in The Atlantic :


    1. I've seen planes in flight on Google maps before, never with that 3-color scanner effect, tho. Note that not all "satellite" imagery on Google is actually from satellites, some is plain aerial photography.

      Speaking of Google & planes, I find it curious that Google takes pains to blur the image of car and truck license plates in Street View, but not airplane registration numbers. E.g., you can "go" to the Princeton, NJ, airport and read the N numbers off the planes on the ramp, and check for the owner info on a site like

    2. That is wild. Even if we built subterranean houses, Google would likely create a "Dig to China" View.

    3. The ultimate transparency!

      I'd love to see those cores from 7.5 miles into the earth's crust! Hmmmm, wonder if the Russians will share (or have shared...)

  6. Funny how these things seem to appear non-randomly: Both Ganymede and amygdala showed up on the final round of the Jeopardy! College Championship on Friday.

    1. Interesting. How did they tie together Ganymede and amygdala in a final question?

      No good segue: Here's a great sand dune photo from Mars published this week:


    2. Not tied together, just 2 separate questions.

    3. I think whoever wrote the caption for the photo of Martian dunes missed an Opportunity (couldn't resist that pun): That image, taken on February 14, must be upside-down... those dunes aren't V-shaped, they're heart-shaped!


    is an interesting article about Archimedes Palimpsest.