explain xkcd - User contributions [en]

Talk:1300: Galilean Moons

2013-12-07T03:45:11Z

DaveC426913:

"most likely Callisto, the outermost of the four" - seems that it's definitely Callisto, since its drawn with little craters - no? {{unsigned ip|108.162.219.25}}

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...

[[User:Just some guy|Just some guy]] ([[User talk:Just some guy|talk]]) 05:39, 6 December 2013 (UTC)

Some javascript application available on the net to see the 4 moons orbits around [http://www.skyandtelescope.com/observing/objects/javascript/jupiter jupiter]

[[User:HmmmHmmm|HmmmHmmm]] ([[User talk: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 [[Special:Contributions/108.162.222.209|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. [[Special:Contributions/141.101.99.229|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. [[Special:Contributions/141.101.99.229|141.101.99.229]] 09:38, 6 December 2013 (UTC)

Is it just me or does "MOOOOOON!" have a subtle [http://knowyourmeme.com/memes/moon-moon "MOON MOON"] undertone? [[Special:Contributions/141.101.96.4|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? {{unsigned ip|141.101.98.210}}
:No {{unsigned|Sian}}
*I saw a possible reference to [http://www.wondermark.com/302 "Wondermark"]. [[Special:Contributions/173.245.54.5|173.245.54.5]] 15:14, 6 December 2013 (UTC)

Maybe moons converse with Cueball, not between them itself?
[[Special:Contributions/173.245.53.180|173.245.53.180]] 13:14, 6 December 2013 (UTC)

Or with Megan, when opposite to her face?
[[Special:Contributions/173.245.53.180|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. --[[User:BlueMoonlet|BlueMoonlet]] ([[User talk: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
[[Special:Contributions/108.162.215.10|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. --[[User:BlueMoonlet|BlueMoonlet]] ([[User talk: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?
::[[Special:Contributions/108.162.215.10|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. --[[User:BlueMoonlet|BlueMoonlet]] ([[User talk: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. [[User:Wwoods|Wwoods]] ([[User talk:Wwoods|talk]]) 19:42, 6 December 2013 (UTC)
::If it was five to one the planets would line up every other orbit of Ganymede [[Special:Contributions/173.245.54.67|173.245.54.67]]
Did someone change the animation? Because when I watch it, they all line up on the right side.
[[Special:Contributions/141.101.79.13|141.101.79.13]] 22:44, 6 December 2013 (UTC)

Hard to tell exactly which moon was which, until I plotted their cyclic orbits.

[[File:moons.gif]]

Talk:1300: Galilean Moons

2013-12-07T03:43:57Z

DaveC426913:

File:moons.gif

2013-12-07T03:42:16Z

DaveC426913: