"That orbed maiden, with white fire laden, / Whom mortals call the moon."

February 26, 2012 4:36 AM

""The moon is actually expanding or stretching and being pulled apart in some small areas and by a little bit," [CBC.ca] New evidence suggests that the moon, once thought to be geologically cold and dead, is still stretching and contracting on its surface.
posted by Fizz (27 comments total)

The moon's a balloon.
posted by pracowity at 5:15 AM on February 26, 2012

Very impressive, The Moon, but do you have seasons?
posted by Artw at 5:51 AM on February 26, 2012

It's only a paper moon.
posted by flapjax at midnite at 5:51 AM on February 26, 2012

But seriously... stretch marks? So where's the little moon, then? Already scampering about, getting babysat by the moons of Jupiter?
posted by flapjax at midnite at 5:54 AM on February 26, 2012

a geologically and tectonically active moon

an earthquake on the moon
made a ripple in my cup of tea
an earthquake on the moon
caused a whirlpool in the Caspian Sea
an earthquake on the moon
stirred a little wave on the River Po
an earthquake on the moon
made me write these shaky lines, you know
an earthquake on the moon
an earthquake on the moon
an earthquake on the moon
posted by flapjax at midnite at 6:10 AM on February 26, 2012

How are tidal forces not mentioned in that article?
posted by DU at 6:17 AM on February 26, 2012 [1 favorite]

How are tidal forces not mentioned in that article?

That was certainly my thought before I read the article. "Well, of course it's getting pulled this way and that -- it's very close to a much larger gravity sink, and if it affects our oceans to the extent it does, surely the Earth's mass must be affecting IT in return...."
posted by hippybear at 6:33 AM on February 26, 2012

It was my thought during and after the article as well. It even mentions theories, but neglects to at least discount tides. WTF?
posted by DU at 6:36 AM on February 26, 2012

The article suggests that these fissures on the surface of the Moon might indicate a that the Moon has a molten core, but didn't the recent discovery of dormant volcanos on the back side of the Moon pretty much already prove that?
posted by three blind mice at 6:46 AM on February 26, 2012

once thought to be geologically cold and dead

Nah, we've known about moonquakes since the Apollo missions.
posted by Brandon Blatcher at 6:50 AM on February 26, 2012

That's no moon....
posted by The Whelk at 7:17 AM on February 26, 2012

How are tidal forces not mentioned in that article?

Given that the moon is tidally locked so as always to present the same face to the Earth, I don't see how there could be any "tidal" effect on the moon from the earth's gravity. We're always pulling in the same direction.
posted by yoink at 7:22 AM on February 26, 2012 [1 favorite]

Oh, shit. It's going to hatch.
posted by Faint of Butt at 7:32 AM on February 26, 2012 [10 favorites]

Chewy, I have a bad feeling about this. . .
posted by Danf at 7:40 AM on February 26, 2012

The moon could be expanding (as long a theories are being tossed out)
So, in the Expando Planet model, the continuous stream of energy from the Sun goes not only to the surface of the planets, but also to the center of the planets, where, given the correct conditions, and the existence of an active plasma core (Mars, as an aside, has none, and is therefore, a 'dead' planet), this energy is transmuted into matter.

I'm not going to defend or support the idea.
posted by rough ashlar at 7:44 AM on February 26, 2012

Damn thing goes through four phases a month, easy. How do you get that shit done without a little stretching?
posted by Clyde Mnestra at 8:08 AM on February 26, 2012

yoink: even though the moon is locked, the orbital period at the point closest to earth would still be a smidge different from the orbital period of the farthest point. But the whole moon can only have one orbital period! The differences between the actual orbital period and the orbital periods bits of the moon want to have create stretchy forces within it. See also: Io.
posted by ROU_Xenophobe at 8:19 AM on February 26, 2012

The forces that stretch and compress Io are actually due to interactions between it and the other moons of Jupiter. The Earth's moon doesn't experience like that.
posted by Mitrovarr at 10:20 AM on February 26, 2012 [1 favorite]

I always found the idea of the Masscons fascinating. I also thought there were evidence of the Moons geological deadness.
posted by Artw at 10:22 AM on February 26, 2012 [1 favorite]

The tidal heating of Io are indeed due to the fact that its distance from Jupiter varies due to the fact that its orbit is non-circular. The gravitational interactions with other moons are what keep Io's orbit significantly non-circular, though.
posted by BrashTech at 10:43 AM on February 26, 2012 [1 favorite]

That's a great little article, Artw.

...Theoretical considerations in either case indicate that all the lunar mascons are super-isostatic (that is, supported above their isostatic positions). ...

If the stretchmarks (grabens) tend to point toward the centers of mascons, that would seem to imply they might be the result of the mascons settling-- as they would tend to try to do-- toward their isostatic equilibrium positions, because on the surface of a sphere, pushing in a thick piece would cause the material beneath the edges of the surrounding pieces to have to stretch, leading to a line of collapse on the surface.
posted by jamjam at 10:56 AM on February 26, 2012

BrashTech: The tidal heating of Io are indeed due to the fact that its distance from Jupiter varies due to the fact that its orbit is non-circular. The gravitational interactions with other moons are what keep Io's orbit significantly non-circular, though.

Yes, you're right. I misread the original comment.

Still, there's nothing putting energy into maintaining the moon's orbit as non-circular, as there is for Io (unless there's some kind of resonance with Venus, or the Sun). I can't help but think that the Moon can't possibly derive much tidal energy out of the remaining circularization of its orbit, or else it would have already became circular.
posted by Mitrovarr at 11:27 AM on February 26, 2012

Perturbations from the Sun, Venus, and Jupiter are enough. You'll notice that the Moon isn't as volcanically active as Io. :) Not much energy is being deposited.
posted by BrashTech at 12:18 PM on February 26, 2012

Given that the moon is tidally locked so as always to present the same face to the Earth, I don't see how there could be any "tidal" effect on the moon from the earth's gravity.

The moon does librate a bit, so I guess there'd be a small effect.
posted by stebulus at 12:39 PM on February 26, 2012

The moon ... being pulled apart...

(in accordance with the Thundarr prophecy.)
posted by blueberry at 6:06 PM on February 26, 2012

Given that the moon is tidally locked so as always to present the same face to the Earth, I don't see how there could be any "tidal" effect on the moon from the earth's gravity. We're always pulling in the same direction.

IANA Physicist, but I know that the tides on the Earth's oceans are most influenced by the moon, but also a little bit by the sun. Hence, we have spring tides and neap tides. The moon is tidally locked to the Earth, but it is rotating with respect to the sun. If the sun has a tidal influence on the Earth, then it should on the moon as well. So I'm thinking that this:

Damn thing goes through four phases a month, easy. How do you get that shit done without a little stretching?

...is actually scientifically correct?
posted by polecat at 11:29 PM on February 26, 2012

Wouldn't eclipses be far more significant than phases.
posted by Artw at 12:39 AM on February 27, 2012