# One day we will only be able to see the Moon from one side of the Earth? **URL:** \ **Category:** Factual Questions\ **Created:** [April 6, 2004, 3:53pm UTC](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567 "2004-04-06T15:53:36Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![kuwatto](https://avatars.discourse-cdn.com/v4/letter/k/6a8cbe/32.png) [@kuwatto](https://boards.straightdope.com/u/kuwatto)\ **Post date:** [April 6, 2004, 3:53pm UTC](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567/1 "2004-04-06T15:53:36Z")
> [@](#): > > Gradually the Earth is slowing down. One day, the length of time the Earth takes to spin round its axis will be the same as the Moon takes to orbit us. When that happens, 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](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? ---
**Author:** ![toadspittle](https://avatars.discourse-cdn.com/v4/letter/t/c0e974/32.png) [@toadspittle](https://boards.straightdope.com/u/toadspittle)\ **Post date:** [April 6, 2004, 4:09pm UTC](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567/2 "2004-04-06T16:09:01Z")
[http://www.aoc.nrao.edu/~smyers/courses/astro11/L12.html](http://www.aoc.nrao.edu/~smyers/courses/astro11/L12.html) > [@](#): > > The friction induced by the stresses combined with the Earth’s rotation relative to the Moon is slowing down the Earth’s rotation by the tiny amount of **1.6 ms (or 1.6 x 10^-3 sec) per century!** Thus, about 450 million years ago, the day was only 22 hours long. At this rate, it will take about **146 billion years** to slow the Earth enough to lock with the Moon’s orbit of 27 days. 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! ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [April 6, 2004, 6:30pm UTC](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567/3 "2004-04-06T18:30:41Z")
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 ---
**Author:** ![Bytegeist](https://avatars.discourse-cdn.com/v4/letter/b/9dc877/32.png) [@Bytegeist](https://boards.straightdope.com/u/Bytegeist)\ **Post date:** [April 6, 2004, 9:24pm UTC](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567/4 "2004-04-06T21:24:25Z")
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? ---
**Author:** ![gazpacho](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@gazpacho](https://boards.straightdope.com/u/gazpacho)\ **Post date:** [April 6, 2004, 9:28pm UTC](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567/5 "2004-04-06T21:28:45Z")
Once the moon is in geosynchronous orbit won’t the tides be a lot lower? ---
**Author:** ![kuwatto](https://avatars.discourse-cdn.com/v4/letter/k/6a8cbe/32.png) [@kuwatto](https://boards.straightdope.com/u/kuwatto)\ **Post date:** [April 6, 2004, 9:44pm UTC](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567/6 "2004-04-06T21:44:41Z")
> [@](#): > > 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. ---
**Author:** ![Mr.Blue\_Sky](https://avatars.discourse-cdn.com/v4/letter/m/d26b3c/32.png) [@Mr.Blue\_Sky](https://boards.straightdope.com/u/Mr.Blue_Sky)\ **Post date:** [April 6, 2004, 9:45pm UTC](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567/7 "2004-04-06T21:45:58Z")
> [@Bytegeist](#): > > 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? I can move further inland, but keep your moon lovin’ hands off my satellitle dish! ---
**Author:** ![stuyguy](https://avatars.discourse-cdn.com/v4/letter/s/ec9cab/32.png) [@stuyguy](https://boards.straightdope.com/u/stuyguy)\ **Post date:** [April 6, 2004, 9:50pm UTC](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567/8 "2004-04-06T21:50:49Z")
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!” ---
**Author:** ![bonzer](https://avatars.discourse-cdn.com/v4/letter/b/45deac/32.png) [@bonzer](https://boards.straightdope.com/u/bonzer)\ **Post date:** [April 6, 2004, 10:20pm UTC](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567/9 "2004-04-06T22:20:52Z")
> [@kuwatto](#): > > Wouldn’t they be pretty much nonexistant? The tide would be permanently high towards the moon and permanently low on the other side. 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. ---
**Author:** ![FordPrefect](https://avatars.discourse-cdn.com/v4/letter/f/e99b99/32.png) [@FordPrefect](https://boards.straightdope.com/u/FordPrefect)\ **Post date:** [April 6, 2004, 11:02pm UTC](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567/10 "2004-04-06T23:02:41Z")
> [@dtilque](#): > > [sup]1[/sup]1 sagan = billions and billions 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. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [April 7, 2004, 4:49am UTC](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567/11 "2004-04-07T04:49:59Z")
> [@FordPrefect](#): > > 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. > [@kuwatto](#): > > Wouldn’t they be pretty much nonexistant? The tide would be permanently high towards the moon and permanently low on the other side. 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. ---
**Author:** ![FordPrefect](https://avatars.discourse-cdn.com/v4/letter/f/e99b99/32.png) [@FordPrefect](https://boards.straightdope.com/u/FordPrefect)\ **Post date:** [April 7, 2004, 7:29pm UTC](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567/12 "2004-04-07T19:29:05Z")
I came here to fight ignorance, and it was I that learned something. ---
**Author:** ![OneYogini](https://avatars.discourse-cdn.com/v4/letter/o/b9e5f3/32.png) [@OneYogini](https://boards.straightdope.com/u/OneYogini)\ **Post date:** [April 7, 2004, 8:12pm UTC](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567/13 "2004-04-07T20:12:23Z")
[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! 😕 ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [April 7, 2004, 10:29pm UTC](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567/14 "2004-04-07T22:29:12Z")
Since the moon is spirling out won’t it leave us long before that? ---
**Author:** ![bonzer](https://avatars.discourse-cdn.com/v4/letter/b/45deac/32.png) [@bonzer](https://boards.straightdope.com/u/bonzer)\ **Post date:** [April 7, 2004, 11:29pm UTC](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567/15 "2004-04-07T23:29:46Z")
> [@kanicbird](#): > > 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. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [April 8, 2004, 12:22am UTC](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567/16 "2004-04-08T00:22:51Z")
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. ---
**Author:** ![bonzer](https://avatars.discourse-cdn.com/v4/letter/b/45deac/32.png) [@bonzer](https://boards.straightdope.com/u/bonzer)\ **Post date:** [April 8, 2004, 12:39am UTC](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567/17 "2004-04-08T00:39:28Z")
> [@kanicbird](#): > > 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. ---
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [April 8, 2004, 3:00am UTC](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567/18 "2004-04-08T03:00:45Z")
> [@](#): > > =dtilqueI 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. 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. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 8, 2004, 3:08am UTC](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567/19 "2004-04-08T03:08:04Z")
> [@](#): > > Wait a sec, if an orbital object is slowed down it will ‘lower’ it’s orbit. 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. ---
**Author:** ![CurtC](https://avatars.discourse-cdn.com/v4/letter/c/ce73a5/32.png) [@CurtC](https://boards.straightdope.com/u/CurtC)\ **Post date:** [April 8, 2004, 5:20am UTC](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567/20 "2004-04-08T05:20:56Z")
> [@](#): > > _Northern Piper wrote:_ > It pre-dates Usenet - the earliest reference I can recall is in a Bloom County cartoon… That would be mid-80s. Usenet was invented in 1979. Google archives it back to 1981. [Next page](https://boards.straightdope.com/t/one-day-we-will-only-be-able-to-see-the-moon-from-one-side-of-the-earth/238567.md?page=2)