One day we will only be able to see the Moon from one side of the Earth?

I found this quote during a tour of the moon, courtesy of the BBC

http://www.bbc.co.uk/science/space/solarsystem/earth/moon.shtml

So my question is how long will it take until the earth’s spin will be completely in synch with the Moons orbit? Also, when the earth has fully slowed down to that point, it would in theory have a day that would last almost a month long, what possible affects would that have on the Earth?

http://www.aoc.nrao.edu/~smyers/courses/astro11/L12.html

So don’t buy that moon-view property just yet. First, wait about 5 billion years to see if the sun swallows up both the earth and the moon when it turns into a red giant. Then BUY BUY BUY!

It should be noted that the frictional force slowing the Earth down is not constant. Over the eons, the amount has varied depending on several factors, including the orientation of continents on Earth.

However, this does not change the essential point that toadspittle made: it’s going to be several sagan[sup]1[/sup] years before the Earth slows down that much.
[sup]1[/sup]1 sagan = billions and billions

Well then, we’ll just have to bring the moon down to a geosynchronous orbit. (About ten times closer than it is now.)

Some people will lose their satellite-dish TV, and the monstrous tides will take some getting used to, but all that is a small price to pay for a lovely geosynchronous moon.

Doesn’t everyone agree?

Once the moon is in geosynchronous orbit won’t the tides be a lot lower?

Wouldn’t they be pretty much nonexistant? The tide would be permanently high towards the moon and permanently low on the other side.

I can move further inland, but keep your moon lovin’ hands off my satellitle dish!

Gee, this is sort of like a really, really long super-duper-gigantic roulette game. Can you just imagine how property values will shift as the moon settles into its “spot.” I can see it now: “Paris may have the Eiffel Tower, New York the Statue of Liberty, but only Wake Island has the Moon!”

Not quite - solar tides are nearly as important as lunar ones. If the Earth’s rotation does get the chance to lock with the Moon, then the whole system will still rotate every month and there will still be a solar high tide twice during that month.
The month in question will however be longer than the current one.

In the interest of fighting ignorance, Sagan claims to have never said this until his final book where he wrote it out of a “there, I said it, now shut up about it” sense of frustration.

I know that, it comes from Johnny Carson’s spoof of Cosmos. That didn’t stop Usenet denizens from making it sort of a standard joke years ago. But I wrote it wrong – it should be “beelyuns and beelyuns” or something like that.

Someone has already pointed out solar tides. But there’s another error in this. The moon raises tides on both the side nearest it and the side furthest from it. Low tides are at the points halfway in between. So if the moon were moved to a geostationary orbit, the tides would be permanent and much, much higher (modulo solar tides) at those places.

I came here to fight ignorance, and it was I that learned something.

[QUOTE=dtilque]
I know that, it comes from Johnny Carson’s spoof of Cosmos. That didn’t stop Usenet denizens from making it sort of a standard joke years ago. But I wrote it wrong – it should be “beelyuns and beelyuns” or something like that.
QUOTE]

WTF? My BF has the Cosmos series on DVD and he MOST CERTAINLY DOES say “beelyuns and beelyuns”!! I heard it for myself! :confused:

Since the moon is spirling out won’t it leave us long before that?

No. The reason that it’s orbit is increasing is because tidal friction on the Earth is slowing it’s daily rotation. As that rotational energy is transfered to the Moon, it gradually moves to a higher orbit. However, even all of the energy stored in the rotation of the Earth wouldn’t be enough to allow the Moon to reach escape velocity. The end point of this process is therefore what’s been discussed above: the Earth locks with the Moon, though the Moon will be further away than it is currently.

Wait a sec, if an orbital object is slowed down it will ‘lower’ it’s orbit. The moon is indeed leaving us and I don’t think the tides will slow it donw enough. Someone has to look at the math more carefully here.

The Earth is slowing down (in its rotation). The Moon is the one gaining energy and hence moving to the higher orbit.

It pre-dates Usenet - the earliest reference I can recall is in a Bloom County cartoon (the “Penguin Evoloution Trial” story?) Sagan is called as a witness, and the court reporter is frustrated with the correct spelling of “beeylions”. That would be mid-80s.

But on the other hand, if you raise an object, that’ll slow it down. So if you want to bring something from a fast circular orbit to a slow one, you first need to speed it up to put it into a transfer orbit, then speed it up again to re-circularize it, at which point it’ll be going slower than it was originally. This may sound paradoxical, but the key is that in between your two “speed it up” steps, gravity is slowing it down more.

Usenet was invented in 1979. Google archives it back to 1981.