Moon's Bulge Explained

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.'"

Re:Wait a minute...

[Kelson]

The radius at the equator is slightly longer than the radius at the poles. It's not quite a perfect sphere.* Sort of like if you took a rubber ball, set it on the floor, then pushed down slightly.

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.

Re:Missing energy

[Jazzer_Techie]

Actually, circular orbits are the lowest energy state. Thus, tidal forces cause the system to gradually lose energy until it settles into a circular orbit. When you add up the 1/r potential of gravity and the repulsive 1/r^2 centrifugal potential, you get a function with a nice minimum which is the radius of a circular orbit. The reason that elliptical orbits occur is because the period of the orbit exactly matches the period of oscillations around the minimum potential. Thus when you go around once, you end up right back where you started and get a closed, elliptical orbit. (Note that this is true only for Newtonian mechanics. Once you take General Relativity into account, the periods aren't the same and orbits precess. We can directly observe this in the orbit of Mercury as a perhelion shift of 43 arcseconds/century.)

Re:Come on people, give the moon a break...

[isellmacs]

http://en.wikipedia.org/wiki/Luna_(moon) [wikipedia.org]

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.

More verbose

[5937]

http://www.space.com/scienceastronomy/moon_mechani cs_0303018.html [space.com]

Enough already

[midkay]

Isn't that enough of the "Because it's fat!" and "Because it's horny!" comments? If I knew how to mod all of you "Redundant", make no mistake, I would!

I don't think so

[npietraniec]

The moon is actually a spaceship. http://www.theforbiddenknowledge.com/hardtruth/moo n_spaceship.htm [theforbidd...wledge.com]

Re:Missing energy

[joeljkp]

A more straightforward way of visualizing it may be to imagine a satellite around Earth in a highly elliptical orbit. At the nearest points to Earth, it's getting a little bit more resistance from the atmosphere, the magnetic field, etc. This extra resistance means it can't get as far out the next go-around, leading to a decrease in eccentricity, or a circularization of the orbit.

Re:Eccentric vs. Circular Orbit

[Anonymous Coward]

While you have a very interesting theory, I think it is more likely due to the fact that circular orbits are the lowest energy state. Thus, tidal forces cause the system to gradually lose energy until it settles into a circular orbit. When you add up the 1/r potential of gravity and the repulsive 1/r^2 centrifugal potential, you get a function with a nice minimum which is the radius of a circular orbit. The reason that elliptical orbits occur is because the period of the orbit exactly matches the period of oscillations around the minimum potential. Thus when you go around once, you end up right back where you started and get a closed, elliptical orbit. (Note that this is true only for Newtonian mechanics. Once you take General Relativity into account, the periods aren't the same and orbits precess. We can directly observe this in the orbit of Mercury as a perhelion shift of 43 arcseconds/century.) . . . more or less.

Re:Come on people, give the moon a break...

[Shadow Of The Sun]

In the Norse mythos, the moon is masculine and the sun is feminine.

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."

Re:I don't think so

[Daniel_Staal]

He is informative: He's informing us of a crackpot theory that most haven't heard of. So we can all laugh at it.

Re:Come on people, give the moon a break...

[Neurotoxic666]

The moon has always in the human mind been female, for basically every known religion.

Wrong. Die Sonne, der Mond. In Germanic/Northern mythologies, the Sun was female and the Moon was male.