1300: Galilean Moons
| Galilean Moons |
 Title text: I'm SO glad I escaped. They almost had me caught in their weird ... thing. |
Explanation
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This explanation may be incomplete or incorrect: Needs further astronomical explanations If you can address this issue, please edit the page! Thanks. |
The four Galilean moons—the largest of the 67 moons orbiting Jupiter—have an unusual orbit, in that the three inner moons, Ganymede, Europa, and Io, have an orbital resonance of 1:2:4, as illustrated in the picture to the right. This comic personifies the moons, with the "MOOOOOON!" interruptions representing the disruptions in their orbits created by the resonance. Io, Europa and Ganymede say "Hi!", "What's your name?" and "MOOOOON!" respectively, when facing Cueball. However, these three moons never actually line up on the same side, but only in the same line on opposite sides (see animation).
The title text describes one of the moons (most likely Callisto, the outermost of the four) escaping from the rest. "Their weird ... thing" ascribes a vaguely sexual nature to the other three moons' relationship, which is extra relevant due to the fact that all four moons are named after lovers of Zeus (Jupiter's equivalent in the Greek pantheon), who often held them captive, much as Jupiter the planet holds the four moons captive.
Transcript
- [Megan approaches Cueball, orbited by four small floating balls.]
- Megan: Check it out!
- Cueball: What?
- Megan: I've got Galilean moons!
- [They are separated before Io can answer. Io stands alone now.]
- Io: Hi!
- [Europa returns to her position near Io, and Ganymede joins them.]
- Io: Hi!
- Europa: What's your—
- Ganymede: MOOOOOON!
- [Io is once again alone.]
- Io: Hi!
- [Europa and Io are together again, this time absent Ganymede.]
- Io: Hi!
- Europa: What's your name?
- Callisto: Ugh.
- [Once more, Europa leaves Io alone before she can answer.]
- Io: Hi!
- Callisto: So annoying.
- [Europa and Ganymede re-join Io.]
- Io: Hi!
- Europa: What's y—
- Ganymede: MOOOOOON.
- [Io is on her own once again. Callisto nudges herself toward Cueball.]
- Io: Hi!
- Callisto: ...Almost...
- Callisto: ...Almoooost...
- [Io and Europa are reunited, Ganymede by himself on the opposite side of Megan. Callisto enters orbit around Cueball.]
- Io: Hi!
- Europa: What's your name?
- Callisto: Yessss!
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"most likely Callisto, the outermost of the four" - seems that it's definitely Callisto, since its drawn with little craters - no? 108.162.219.25 (talk) (please sign your comments with ~~~~)
Hmmm. The animation just added agrees with another animation I've seen, in that the three innermost moons never line up all on one side of Jupiter at the same time. So if "Hi" (Io) and "What's your name" (Europa) conjoin on the right side as we're looking, then "What's your name" and "MOOOON!" (Ganymede) should conjoin on the left side. Not that I'm being critical of course...
Just some guy (talk) 05:39, 6 December 2013 (UTC)
Some javascript application available on the net to see the 4 moons orbits around jupiter
HmmmHmmm (talk) 06:48, 6 December 2013 (UTC)
If the inner moons are tidally locked with Jupiter, can you ostensibly state that they're mooning the outer moons, whenever two such moons line up? lol 108.162.222.209 08:57, 6 December 2013 (UTC)
Even with the resonance, "MOOOOOON!" appears still not to have been able to escape with that effect alone until Cueball's own close approach to Megan brought his own gravity well close enough to hers to give rise to a viable transfer orbit. And appears to be now retrograde, relative to its last orbit. Or possibly on a free-return path, unless Cueball steps back before the return transfer happens or makes an appropriate sideways move to quash the orbital potential. 141.101.99.229 09:34, 6 December 2013 (UTC)
- Hang on... "MOOOOOON!" isn't the "Ugh/So annoying/Almost/Yes!" one. Forgot to note the hint of shading. Still, the above applies to the disgusted/elated moon, clearly not liking either of the Valley Girls or the loudmouth Jock. 141.101.99.229 09:38, 6 December 2013 (UTC)
Is it just me or does "MOOOOOON!" have a subtle "MOON MOON" undertone? 141.101.96.4 12:26, 6 December 2013 (UTC)
Am I the only one thinking that the "MOOOOOON!" is a reference to the "SPAAAAACE!" module from portal 2? 141.101.98.210 (talk) (please sign your comments with ~~~~)
- I saw a possible reference to "Wondermark". 173.245.54.5 15:14, 6 December 2013 (UTC)
I propose a simpler explanation for Ganymede saying "MOOOOOON!". Europa has asked Ganymede the same question, "What's your name?", every time they go by each other for eons. Ganymede is yelling the answer before it is even completely asked, exasperated at having to repeat it for the umpteeen gazillionth time. --uhillard (talk) 17:05, 12 December 2013 (UTC)
Ganymede interrupts Europa, reminding me of the knock-knock joke, "interrupting cow," "interrupting cow wh..." "MOOOOOO". Ganymede is an interrupting moon. ~~charles
Maybe moons converse with Cueball, not between them itself? 173.245.53.180 13:14, 6 December 2013 (UTC)
Or with Megan, when opposite to her face? 173.245.53.180 13:39, 6 December 2013 (UTC)
- I think the moons are clearly conversing with Cueball. Remember that Io executes a full orbit between every panel. --BlueMoonlet (talk) 17:27, 6 December 2013 (UTC)
- Animation is incorrect
The current animation has the wrong speed of the outermost moon, which is currently orbiting at a 5:1 ratio to the innermost. They should all line up along a vertical line once every four rotations. In fact the current animation never lines up all three moons at the same time (at least, not on the same side of the planet). -Greg 108.162.215.10 16:06, 6 December 2013 (UTC)
- The animation is correct. If you look closely at only Europa and Ganymede, you'll see that they are also in a 2:1 resonance, with conjunctions always taking place at the "6 o'clock" position. Io and Ganymede are in a 4:1 resonance, with conjunctions taking place at 12 o'clock, 4 o'clock, and 8 o'clock. The comic is incorrect in having all three moons on the same side of Jupiter at the same time. That never happens in the actual system, though I don't mind it in the name of artistic license. --BlueMoonlet (talk) 17:27, 6 December 2013 (UTC)
- The innermost orbit completes 5 rotations for each 1 of the outermost. How is that a 4:1?
- 108.162.215.10 18:16, 6 December 2013 (UTC)
- I think you need to count more carefully. Start when both moons are at "12 o'clock". In the time it takes for Ganymede to get back to that position, I see Io go around 4 times. --BlueMoonlet (talk) 18:19, 6 December 2013 (UTC)
- You're probably counting from 1 to 5, instead of from 0 to 4. I.e. When they're lined up to start, you could call that conjunction #1, but they've done 0 orbits. Wwoods (talk) 19:42, 6 December 2013 (UTC)
- If it was five to one the planets would line up every other orbit of Ganymede 173.245.54.67
Did someone change the animation? Because when I watch it, they all line up on the right side. 141.101.79.13 22:44, 6 December 2013 (UTC)
- Not the animation I've been seeing. Starting at an arbitrary point:
- Io@12, Europa@12, Ganymede@3 (I+E Conjunction)
- Io@8, Europa@10, Ganymede@2 (I+G Opposition)
- Io@12, Europa@6, Ganymede@12 (I+G Conjunction, E Opposed)
- Io@4, Europa@2, Ganymede@10 (I+G Opposition)
- Io@12,Europa@12, Ganymede@9 (I+E Conjunction)
- Io@8, Europa@10, Ganymede@8 (I+G Conjunction)
- Io@12, Europa@6, Ganymede@6 (E+G Conjunction, I Opposed)
- Io@4, Europa@2, Ganymede@4 (I+G Conjunction)
- ...then repeat
- That's one cycle of Europa and Ganymede, two cycles of Io and Europa (relative to each other, alone) four cycles of Io and Ganymede (likewise).
- There are two 'in-line' conditions, when Ganymede is in conjunction with one of the other moons, the remaining one in opposition, with Ganemedes other Io conjunctions having Europa off at an angle and the other Io/Europa conjunctions having Ganymede off at a right-angle. If I've managed to note all that down correctly. (Note, this is nothing to do with the following plot regarding the XKCD motions, which I quite admire!) 141.101.99.229 08:09, 7 December 2013 (UTC)
Hard to tell exactly which moon was which, until I plotted their cyclic orbits.
-- DaveC426913 (talk) (please sign your comments with ~~~~)
"You may also notice at the animated picture that, unlike in the fifth and ninth panels of the comic, the three moons are never on the same side of Jupiter at the same time." The animated picture doesn't match this text. In the animated picture it looks like the three moons are on the same side of Jupiter at least twice for each cycle of Ganymede. -- 199.27.128.109 04:26, 7 December 2013 (UTC)
- It means they are never lining up on the same side of Jupiter. 108.162.231.53 23:53, 7 December 2013 (UTC)
- That picture, which is very helpful, confirms that the three moons are all in conjunction with each other in panels 5 and 9 of the comic. In the animation, Io and Europa have their conjunctions at 12 o'clock, so (if the comic were correct) this picture would imply that Ganymede should sometimes also be at 12 o'clock during an I+E conjunction. In fact, the animation shows that Ganymede is always at either 3 o'clock or 9 o'clock during an I+E conjunction. --BlueMoonlet (talk) 18:25, 12 December 2013 (UTC)
Also note that "Io" looks like "Lo" in many fonts, so Io saying Hi is a probably a little Lo-Hi (Low High) pun. And Io passes 10 times, a Io-10 pun. And Europa saying "what's your name" is maybe a pun on Europa sounding like "You Are" a bit? 108.162.231.244 14:42, 10 December 2013 (UTC) Martin.
- Animation is correct
Randall's Moon Meetings are just a part of the joke, all four Galilean Moons never would meet in that way in reality. Randall does not present science publications here, but just comics, playing with real things. --Dgbrt (talk) 22:28, 12 December 2013 (UTC)
Is it possible that a person having moons is a reference to Ioun Stones? 162.158.38.214 (talk) (please sign your comments with ~~~~)
