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Originally posted by Zicsoft:
How can you form any judgment about how big these objects are if you don't know how far they are? And vice versa?

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Originally posted by LivingImpaired:
Yeah, yeah, yeah... these are all good points. But we're getting away from the important point: It looks pretty.

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Originally posted by LivingImpaired:
Yeah, yeah, yeah... these are all good points. But we're getting away from the important point: It looks pretty.

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"I love to see a young girl go out and grab the world by the lapels. Life’s a bitch. You’ve got to go out and kick ass." —Maya Angelou

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Originally posted by LivingImpaired:
Yeah, yeah, yeah... these are all good points. But we're getting away from the important point: It looks pretty.

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Originally posted by Delvo:
Thinking there's a problem with this is SERIOUSLY off-track from real-world physics and geometry. Where did such an idea even COME from?

For one thing, that gas giant (the big planet) looks almost exactly like a NASA simulation I've seen of how Saturn would look from one of its moons (I don't remember which).

Second, where did this idea of gravity ripping planets apart if they get too close come from? Stars do that, but they have much stronger gravity and are GAS. Planets can have very close orbits and not be damaged; a collision, not an orbit, is where there'd be trouble.

Third, multiple moons of big planets ROUTINELY pass close to each other. So all we're looking at here is a coincidence on the level of a "blue moon" (something that happens once every few months or years).

Fourth, haven't you ever seen the photographs of something with the moon behind it with the moon looking much too large? All you need to do is back off a bit with the camera, and presto, the foreground objects shrink in your viewfield and the distant ones like moons don't.

Also, the moon is currently drifting away from the Earth at a rate that puts it less than half as far away a few billion years ago. So it would have taken up four times as much of the sky. And the only nasty horrible consequence was that there'd be a bit more vertical difference between high tide and low tide. Closer yet would have been possible; there's no reason to think not.

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Originally posted by Delvo:
Thinking there's a problem with this is SERIOUSLY off-track from real-world physics and geometry. Where did such an idea even COME from?

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And please read up on on the Roche Limit.

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And please read up on on the Roche Limit.

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But, in the end, like LivingImpaired said, all that matters is that it looked pretty.

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Originally posted by Zicsoft:
Math can be pretty too!

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Originally posted by Haken:
Take a look at this from the 'The Train Job'



I'm guessing the largest one in the background is a planet. The other two are moons. One seems to be terraformed. The one Malcolm is on must be a moon as well because there's just no way for two planets to be that close together.

But how the heck do you explain all these terrestial objects being so close together in distance without gravity ripping everything apart? There's just no way.

A bit overzealous with the cut and paste I think.

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Originally posted by Zicsoft:

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And please read up on on the Roche Limit.

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Aha! I had forgotten about that. Nice simple model for planet break-upage. Here's a page with a slightly simpler description, accesible to anybody with a little basic math:

http://curriculum.calstatela.edu/courses/builders/lessons/less/les1/mo
ons/roche.html

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Originally posted by Zicsoft:

The Roche limit of two bodies of the same size and density is 2.43 radiuses. Earth's radius is a little over 6,000 km, so two earth-like bodies start destroying each other when the get within about 15,000 km of each other. (If you're metrically challenged, that about 9300 miles.) The terraformed moon in the picture is obviously not that close -- it'd fill the sky if it was.

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Originally posted by Zicsoft:

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But, in the end, like LivingImpaired said, all that matters is that it looked pretty.

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Math can be pretty too!


JOSS, WHERE'S MY CHECK???!!!

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