What If the Moon Dropped?

I’m looking at the full moon hanging low over the Brooklyn Bridge and wondering, “What would be the immediate effects on Earth if all of a sudden the moon “dropped out of sight” and disappeared below the horizon, never to be seen again?”

Cecil handles this (or something very similar) in http://www.straightdope.com/columns/001027.html

Tides! If the moon is put into a geosynchronous orbit on the other side of the planet, the water would be drawn to that side of the earth… drought and famine on our side, floods on the other side…

Hmmm, sorry, that’s not quite right. We have two high tides a day, one under the Moon (roughly) and one on the opposite side of the Earth from the Moon. So if the Moon stayed on one side of the Earth, the other side would have high tides too, not low ones. Anyway, there wouldn’t be flooding any more than we have now at high tide. I have a web page describing tides.

Well, some poor sap over the horizon would be hit in the eye, as with a big pizza pie.

Is that the same sap who is standing on top of the pot of gold at the end of the rainbow?

How instantly karmic. Discover a pot o’ gold… get whacked by a rapidly falling Moon.

It wouldn’t be instantly karmic, even if it would be right in the face. 'cause the moon, and the stars, and the sun must all shine on.

And I guess the question would be, do you mean the moon runs away from Earth entirely (cf. Cecil’s column), or that it just begins to orbit in such a way that it is no longer visible from Brooklyn?

…or falls out of the sky and comes crashing to the Earth?

Of course, I hope you realize that the Moon is a whole other world and not just a shiny plate hanging just over the edge of the world, right? :wink:

[Tom Servo]Scientists say: “That’s Amore!”[/Tom Servo]

I just heard that the moon is slowly getting further and further away, so the Earth is turning a little faster every year so we lose a milli-half-quarter (?!) of a millisecond every year. They say millions of years ago a year used to last 44 months and the tides were huge (tsunami like) and our tides now are getting smaller and smaller.
It will take million of years, we certainly won’t be there anymore!, but what’s gonna happen if the earth turns faster and faster… two-days years?

Carine, you have some details wrong.

Through the mechanism of the tides, the Earth is transfering some angular momentum to the Moon. As a result of this, the Earth spins slower, about 2 milliseconds/century.

The additional angular momentum moves the Moon into a higher orbit. Because of the way orbital mechanics work, this means the Moon actually takes longer to go around the Earth, so the month is slowly getting longer, too.

Eventually, the Earth will slow so much that it will be tidally locked to the Moon. That is, the period of the Moon’s orbit will be the same as the period of the Earth’s rotation (both something like 40 or 50 of our current days). The Moon will still be tidally locked to the Earth, so you will have one side of the Moon always facing the same side of the Earth.

But that’s in the distant future. If the Earth even lasts that long which it probably won’t. The time frame for this to happen is estimated at 50 billion years or more.

A couple billion years ago, the Earth rotated faster (maybe 20 hours in a day) and the Moon was closer to the Earth and the months were shorter and the tides larger. As the Moon gets further away, the changes have slowed down as the tidal forces get weaker. Also about 1 billion years from now, the sun will get hotter and the oceans will evaporate, thereby decreasing the tidal effects. Not eliminating them, since there are tides in the ground too.

There’s several places on the web you can find to discuss tidal drag. Here’s one of them: http://astro.isi.edu/notes/tides.html

Another: http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980421b.html

Just thought I’d point this out: The Earth/Moon system has no bearing on the length of a year (well, I’m sure there’s some transferal of angular momentum like with the Earth and Moon, but it’s insignificant enough to ignore for now) so if the Earth turns faster and faster, the year gets longer and longer, sorta. It will just be there are more days in a year, but a year will still be the same length. For a 2 day year, the Earth would have to rotate Reeeeeeeeeaaaaaaal slow…

In his column Cecil asked “How are you going to do this?”.

That seems to be the big question. The moon just isn’t going to run out of juice and drop.

Another question is where is it going to drop to?

Did you know by any chance that the world isn’t flat?

Not flat? I REALLY should get a new atlas! :slight_smile:

Thanks dtilque and MattTheCroc to enlight me on this subject. That was intersting. I am very bad at science…! But I could swear they said on this show that the Earth was going faster and faster because the attraction to the moon is less and less as its moving away from us… Weird… Oh well, i trust my Dopers!
Thanks!

In my previous post above, I have a description of tidal evolution of the Earth/Moon system too. That might help.

And here I thought I was the only one to wonder why Dean compered the moon to an eel.

d