Does the moon rotate, if not, why not?

The Great Apple said:
Doesn't the moon appear larger and moonrise and moonset as well?

Probably. I've never heard it explicitly stated, but it makes sense.
 
Truronian said:
Incidentally, when moons are not syncronised with their planet's rotation, this usually results in volcanic activity eg Io

No, that's caused by Io being slowly pulled apart by Jupiter, Europa and Ganymede (Callisto is too far away to have much effect). Because it's between the large moons and Jupiter, and because Europa and Ganymede both orbit more slowly than Io (Europa at half the speed and Ganymede at a quarter times the speed), Io is constantly being stretched, which causes heating due to friction between its rocks.
 
Cuivienen said:
No, that's caused by Io being slowly pulled apart by Jupiter, Europa and Ganymede (Callisto is too far away to have much effect). Because it's between the large moons and Jupiter, and because Europa and Ganymede both orbit more slowly than Io (Europa at half the speed and Ganymede at a quarter times the speed), Io is constantly being stretched, which causes heating due to friction between its rocks.

Oops :blush:. I need to learn to stop trusting my physics teachers.
 
Bozo Erectus said:
The moon is slowly receding and escaping the Earths pull, and will eventually break free completely, iirc. Supposedly a billion years or so ago, the moon would have been much larger in the sky because it was closer.
The moon is receeding, but it won't break free entirely. Ultimately, it will look the earth's rotation, and recession will cease.

It was indeed larger in the past. Back when the world was young, it will have loomed huge in the sky, as in this artist's rendering of the Hadean Eon (~4 Ga BC):

HadeanLandscape.jpg
 
The Last Conformist said:
Hadean Eon (~4 Ga BC):

Would that be 4 gazillion years ago?
 
The Last Conformist said:
The moon is receeding, but it won't break free entirely. Ultimately, it will look the earth's rotation, and recession will cease.
But Im sure long before then whoever is here on Earth, will have to deal with the changing tides, plate tectonics, volcanism, and all the other fun stuff that will take place with a receding moon.
 
The Great Apple said:
4 gazillion 2 thousand and 6...
Your precision will be helpful in my planning...
 
The Great Apple said:
Doesn't the moon appear larger and moonrise and moonset as well?

It does just as the sun does, but it's an opitcal illusion, produced by the context of visible objects such as houses and trees, try holding up an object that actually matches the moons diameter at moonrise and follow it through the sky, you'll clearly see it never decreases nor grows in size, our brain merely thinks it does.

The Great Apple said:
Never trust physics teachers...

Trust them but always cut the cards before being dealt a hand :D
 
Isnt it actually the atmosphere acting as a lens which causes the moon to appear larger?
 
Bozo Erectus said:
But Im sure long before then whoever is here on Earth, will have to deal with the changing tides, plate tectonics, volcanism, and all the other fun stuff that will take place with a receding moon.

A receding moon will make things quieter. Fewer volcanic eruptions, slower plate movements, less extreme tides. That's a good thing in the long run.
 
Cuivienen said:
A receding moon will make things quieter. Fewer volcanic eruptions, slower plate movements, less extreme tides. That's a good thing in the long run.

Longer day... though, then again, is that neccessarily a bad thing?
 
Birdjaguar said:
Would that be 4 gazillion years ago?
G=giga=10^9, a=annum=year. So 4 Ga=4 billion years.

Also, just to be obnoxious, I gave the date as a Before Christ date, not a Before Present one. Of course, a couple millennia here or thither doesn't matter one jot in context.
 
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