NationStates Jolt Archive

Alright, so the Earth's moon plays a large roll in the creation of our ocean's tides. Now, how would a larger moon change the tides? A smaller one? How would the ocean act under the influence of multiple moons? If there were no moons, would there still be any sort of tide?

I have no earthly idea, but does anyone else think it'd be wicked awesome if we had two (or more!) moons? And maybe an extra sun or two?

Alright, so the Earth's moon plays a large roll in the creation of our ocean's tides. Now, how would a larger moon change the tides? A smaller one? How would the ocean act under the influence of multiple moons? If there were no moons, would there still be any sort of tide?
Lemme see here:

Larger moon: Depends on where the moon is in relation to the Earth. It could be larger than our current moon, but out far enough that the effects are the same. A larger moon in the Moon's current position would produce stronger tides.

Smaller moon: See above on position, smaller tides if in the current position.

Two: Depends on where they are and how big they are.

No moon(s): Earth would have a small tide due to the rotation of the planet (Think of spinning a water balloon and watch it wobble and bludge), but nothing like the current large tide system.

I have no earthly idea, but does anyone else think it'd be wicked awesome if we had two (or more!) moons? And maybe an extra sun or two?

Any extra suns would totally change the gravitational alignment of the solar system. Very likely, there'd be no life on Earth.

More moons? Same thing on a much smaller scale: it'd make some weird tides for sure!

Any extra suns would totally change the gravitational alignment of the solar system. Very likely, there'd be no life on Earth.

More moons? Same thing on a much smaller scale: it'd make some weird tides for sure!

Oh pfft - I didn't mean it in an academic sense - just think how awesome it'd look! Honestly man you have no soul, no imagination! :D

Couldn't we also get a large enough moon that our orbit around the sun would be affected? I mean, if the moon just suddenly became larger, it wouldn't go in the same orbit around the Earth. And... I'll stop there as my physics knowledge is truly horrible. ;)

Lemme see here:

Larger moon: Depends on where the moon is in relation to the Earth. It could be larger than our current moon, but out far enough that the effects are the same. A larger moon in the Moon's current position would produce stronger tides.

Smaller moon: See above on position, smaller tides if in the current position.

Two: Depends on where they are and how big they are.

No moon(s): Earth would have a small tide due to the rotation of the planet (Think of spinning a water balloon and watch it wobble and bludge), but nothing like the current large tide system.

Oh right! I forgot the distance variable, even though I HAD been thinking about that earlier.

I'm guessing that with multiple moons you'd probably have a series of multiple tides of different magnitudes depending on where the moons were in relation to eachother, and in relation to the sun?

Hmm... Let's take a moon somewhat large than our moon and slightly further away, and a second moon, 3/4 to 1/2 the size of our moon and closer. Is the speed of a moon dependent on size/distance in relation to its planet? Anyone want to help me puzzle out a tide system for such a system?

Yes, you have to consider masses, distances, and alignment. Bear in mind that in a three-body system, the common centre of gravity and motion abot it, will present a non-trivial problem. The tide severity on any one of the worlds would be quite a bumpy curve, but a periodic one for a stable system. One extreme consequence of tidal forces is tidal locking of an orbiting body so it always presents the same face to another body, with varying degrees of libration. The libration could be a complex pattern in itself in a multiple-body system.

It is also fun to imagine a resonance situation catapulting a body out, and/or scattering the rest into a new (and possibly unstable) configuration. But that's not likely in an already stable system unless disturbed. Orbital mechanics are cool, but a real headache.

No moon(s): Earth would have a small tide due to the rotation of the planet.

Well, the sun does play a role in tides, too. About 1/3 the role of the moon, I think.

http://www.mddavis.homestead.com/files/astrog4.gif

...time to git 'r done!! :D

Yes, you have to consider masses, distances, and alignment. Bear in mind that in a three-body system, the common centre of gravity and motion abot it, will present a non-trivial problem. The tide severity on any one of the worlds would be quite a bumpy curve, but a periodic one for a stable system. One extreme consequence of tidal forces is tidal locking of an orbiting body so it always presents the same face to another body, with varying degrees of libration. The libration could be a complex pattern in itself in a multiple-body system.

It is also fun to imagine a resonance situation catapulting a body out, and/or scattering the rest into a new (and possibly unstable) configuration. But that's not likely in an already stable system unless disturbed. Orbital mechanics are cool, but a real headache.

Yay headaches! That does sound cool....Resonance catapults....hehe...

Tidal forces are interesting things. I had a BS in physics and I don't think we ever covered the actual equations in any class. You can increase the mass, but distance plays a far greater significant factor. (Which is why the sun, which is far larger than the moon has less of a tidal impact than it does a gravational impact on the earth.) When tidal forces reach a critical level, a planet or moon can literally be torn apart.

The restricted three body problem (planet and two moons) would produce oscilating tides. In effect the earth is a three body problem only the Sun being so far away produces only a minor impact on the tides. (Creating stronger tides when during full or new moons and weaker tides during half moons.) A three body langrange point problem sounds like a fascinating bit of useless trivia as well.

Well, the sun does play a role in tides, too. About 1/3 the role of the moon, I think.
You know, I remembered that after I had posted and gone to class. Jesh, and I used to remember this stuff. *sighs* Been too long since I last sat down and devoured a good book on this.

I would like to present the following situation:
Moon One: Slightly larger than our moon and slightly farther away.
Moon Two: Between 3/4 and 1/2 the size of our moon and slightly closer.

The two moons follow similar paths around the planet, and I'm going to go out on a limb and say that the smaller one orbits faster than our moon and the large moon, while the large moon orbits at the same speed as our moon or slower. Somebody correct me if it wouldn't work like this.

Given this situation, and ignoring the Sun for now, take the following positions:

The two moons in alignment on one side of the planet: Two extreme high tides, two extreme low tides?

The two moons at right angles to eachother: Would this create four very small high tides, with no real low tides, the higher tides on the sides in line with the large moon? Or would there only be two high tides in line with the large moon, without much tide at all in line with the smaller moon? Something else?

The two moons in alignment on opposite sides of the planet: Would this work the same as them aligned on the same side of the planet? Would the tides be greater? Less?

At any other locations: Four high tides, four low tides, with the largest in line with the big moon and lesser ones in line with the smaller moon?

Or am I completely wrong on all of these, and don't understand tides at all? I suppose I should break down and study tides. Ah world-building, you demand so much from me...

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I say we get someone to program this for us...

I say we get someone to program this for us...

That would be amazingly cool.

I read in a science book that the friction of the tides on the earth's surface slows the earth's rotation by something like 1/1 000 000 every hundred years, so that by the time the earth is destroyed by the sun, a day will be 48 hrs long

I read in a science book that the friction of the tides on the earth's surface slows the earth's rotation by something like 1/1 000 000 every hundred years, so that by the time the earth is destroyed by the sun, a day will be 48 hrs long

1/1000000 whats?

0 moons-earth wobbles on axis. Climate change becomes too radical for surface life.
larger moon and/or closer moon=stronger tide

On an interesting note about tides, I read a study they did somewhere about some species of clams, they opened up at the start of high tide and closed again at the end. So a bunch of scientiststook em out of their natural habitat and plonked them in a fishtank 1,000km inland. Surprisingly, the clams still opened up at high tide, but not at high tide where they used to be but rather where high tide WOULD have been if there was ocean underneath them. This also worked for the ones they kept out of the tank on dry land.

Anyway, I just thought it was interesting. And sorry, I read it in a newspaper not a website, so I cant find it.