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Moon's Bulge Explained
Posted by
Zonk
on Thu Aug 03, 2006 06:36 PM
from the put-some-cream-on-that dept.
from the put-some-cream-on-that dept.
anthemaniac writes "The moon has an unexplained bulge that astronomers have been trying to find a source for since 1799. Finally, an apparent answer: The equatorial bulge developed back when the developing moon was like molasses (and you thought it was cheese!) and, rather than today's nearly circular orbit, it 'moved in an eccentric oval-shaped orbit 100 million years after its violent formation.'"
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no (Score:5, Funny)
Re:no (Score:2, Funny)
Re:no... I thought it was just (Score:3, Funny)
Re:no (Score:2)
Re:Eccentric vs. Circular Orbit (Score:3, Informative)
Well (Score:2, Insightful)
Re:Well (Score:2)
Uh huh (Score:4, Funny)
Wait a minute... (Score:2, Insightful)
Re:Wait a minute... (Score:4, Informative)
The same is true of the Earth, though I believe it's generally attributed to the Earth's rotation.
* Yes, I know that craters and such interfere with it being a perfect sphere too. No need to get pedantic, people of Slashdot. Well, no more than usual.
Parent
Re:Wait a minute... (Score:5, Insightful)
Parent
Re:Wait a minute... (Score:2)
Like a dinosaur (Score:5, Funny)
It's thin at one end, much much thicker in the middle, and thin again at the other end.
I have another theory, you know...
Parent
Re:Wait a minute... (Score:5, Insightful)
Don't all circular/spherical objects bulge around the middle?
If they are planets and they are spinning, yes. Just look at pics of the Jovian worlds, especially Saturn. And the Sun has a definite bulge. Of course, for most of the planets, the bulge is pronounced because they are still elastic to some degree. The Earth bulges owing to the fact that the continents are riding around on their crustal plates, which ooze on molten material, and the Moon is tugging on them as it goes aroudn us. The Moon's is more fascinating because it is a geologically dead world, so the bulge happened some time in the past and then got frozen in place.
Parent
Come on people, give the moon a break... (Score:5, Funny)
Re:Come on people, give the moon a break... (Score:5, Funny)
YOU do that, fat-ass!
Parent
Re:Come on people, give the moon a break... (Score:2)
Re:Come on people, give the moon a break... (Score:2)
(Wait, the moon IS a chick, isn't it?)
Re:Come on people, give the moon a break... (Score:5, Informative)
http://en.wikipedia.org/wiki/Selene [wikipedia.org]
I'd say "Her" would be appropriate, as the name Luna (the name of our moon) comes from the Roman Goddess of the Moon.
Parent
Re:Come on people, give the moon a break... (Score:3, Interesting)
I always found that mythology better.
The sun is a woman, and the moon loves her!
Re:Come on people, give the moon a break... (Score:4, Interesting)
If that is true, it is a baaad mythology. The moon has always in the human mind been female, for basically every known religion. It was a good long while since I studied this, so I apologise if I make any mistakes.
In most (almost all I think) mythologies there exists a goddess that is identified with the moon (and a god that is identified with the sun, although he is rarely as important). For instance in greek mythology, it's Artemis, the goddess of the new moon. See, it has everything to do with phases. That's a funadmental theme in many religions, the cycle of birth-life-death-rebirth. The moon is the perfect symbol for this, first being very small (new moon), to becoming brilliant (full moon) to eventually dying (dark moon), and then being reborn (new moon again). This is closely tied to another classic mythological motif (a favourite of mine), that of the descent to the underworld. This one is everywhere in mythology and literature, Inanna does it, Jesus does it, Gandalf does it (when he fights the Balrog), frickin' Harry Potter does it. The motif is basically where a "hero" (Inanna/Jesus/Gandalf/Harry!) descends to the land of the dead (sumerian underworld/hell/beneth the mines of Moria/the Chamber of secrets), on the way he/she gets "undressed", either metaphorically or literally (Inanna loses her armour i think/Jesus is whipped and put on a cross/Gandalf skipped that part of the mythology/Harry loses both Ron and Hermione), faces the dark side of himself/herself (Erishkigal/the Devil/the Balrog/Voldemort), dies and is reborn (Inanna comes back/Jesus gets resurrected/Gandalf becomes Gandalf the white/Harry is resurrected by the Pheonix). Anyway, this is a tangent, back to the point.
This montly cycle does not only symbolize life and death, but also a decidedly more feminine cycle (if you can't guess what it is, I ain't gonna tell ya). While this connection is rarely explicit, it is certainly present. The moon also symbolizes many aspects that we as humans connect with femininity, such as darkness, magic, mystery and death, wheras the sun symbolizes typically male attributes such as ligth, reason, strength and life (it's so sexist that I can barely type without gagging, but that is the way the archetypes work). Therefore, the moon is often assigned to a female deity. Infact, because of the phases thing, it is sometimes assigned several. Artemis is the virgin goddess of life, the hunt and rebirth, and is the goddess of the new moon. Hecate, the dark witch-queen of sorcery is essentially the dark side of Artemis, is the dark moons goddess. One interpretation of this is that once a month, the beautiful, lively, and wonderful goddess (=a woman) turns into a raging witch-queen (=a bitch). (I'm telling you, this is so god-damn sexist, I want to vomit!) This female connection with the moon is the reason that many dark and mysterious concepts are frequently connected to women, such as intuition. You never hear anyone mention male intuition, do you? This is also why there are much more witches than warlocks in mythology and literature.
Anyway, I've been rambling on for a while now, and I should stop. The point is, if Tolkien chose to make the moon male, he made the wrong choice. In the human mind the moon is, and has always been, female.
Parent
Re:Come on people, give the moon a break... (Score:4, Informative)
And almost everything that Tolkien wrote is based off of the Norse mythos. For example, the Norse term for the Earth is Midgard. Midgard means "Middle Earth."
Parent
Re:Come on people, give the moon a break... (Score:3, Informative)
Wrong. Die Sonne, der Mond. In Germanic/Northern mythologies, the Sun was female and the Moon was male.
Re:Come on people, give the moon a break... (Score:3, Interesting)
Re:Come on people, give the moon a break... (Score:5, Funny)
Hmm. So beautiful it inspires poetry, so attractive it pulls the sea, and men feel compelled to spend more than they can afford just to walk all over it. Oh, and let's not forget, every 28 days it swells and causes dogs to howl.
I think you're on the right track.
Parent
Re:Come on people, give the moon a break... (Score:2)
Re:Come on people, give the moon a break... (Score:2)
It's *not* orbiting that's the hard bit.
The answer is apparent. (Score:5, Funny)
Oblig... (Score:2, Insightful)
Re:Oblig... (Score:2)
It's a big-a pizza pie!
sometimes... things come to mind... (Score:3, Funny)
Excellent... (Score:4, Funny)
scientific explanation debunked (Score:4, Funny)
Monolith? (Score:4, Funny)
Missing energy (Score:5, Interesting)
Re:Missing energy (Score:5, Informative)
Parent
More verbose (Score:2, Informative)
Re:Missing energy (Score:4, Interesting)
The only tidal forces I can see in this problem are evinced in the deformation of the earth or the moon, their atmospheres, and the ocean of the earth. Wikipedia has this to say about tidal locking:
There is a tendency for a moon to orient itself in the lowest energy configuration, with the heavy side facing the planet. Irregular shaped bodies will align their long axis to point towards the planet. Both cases are analogous to how a rounded floating object will orient itself with its heavy end downwards. In many cases this planet-facing hemisphere is visibly different from the rest of the moon's surface.
The orientation of the Earth's moon might be related to this process. The lunar maria are composed of basalt, which is heavier than the surrounding highland crust, and were formed on the side of the moon on which the crust is markedly thinner. The Earth-facing hemisphere contains all the large maria. The simple picture of the moon stabilising with its heavy side towards the Earth is incorrect, however, because the tidal locking occurred over a very short timescale of a thousand years or less, while the Maria formed much later.
I'll have to try to work out how tidal forces within one astronomical body might lead to a circular orbit. It might be a well-known effect, but it's not obvious to me.
Parent
thanks for explaining! (Score:2)
It's quite simple actually... (Score:2, Funny)
shapes (Score:4, Funny)
Enough already (Score:2, Informative)
Re:Enough already (Score:2)
mmmm.... (Score:5, Funny)
I don't think so (Score:4, Informative)
Re:I don't think so (Score:3)
Re:I don't think so (Score:3, Informative)
How did Laplace find it? (Score:3, Insightful)
Was it a "simple" measurement of the shape of the Moon or something more sophisticated via his favorite mathematic tricks? Considering it is Laplace, he must have measured its eccentricity fairly accurately. I wonder what he used to do that in 1799.
Fondue (Score:3, Funny)
Iapetus (Score:3, Interesting)