# Moon Question **URL:** \ **Category:** Factual Questions\ **Created:** [August 7, 2017, 7:39am UTC](https://boards.straightdope.com/t/moon-question/792982 "2017-08-07T07:39:29Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [August 7, 2017, 3:35pm UTC](https://boards.straightdope.com/t/moon-question/792982/21 "2017-08-07T15:35:14Z")
> [@Princhester](#): > > Not how I’ve heard people use the term, and clearly not how the OP meant it. We are here to fight ignorance after all. The dark side is the side that is non-illuminated, and the far side is the side that we never see. These sometimes coincide. Of course the far side is metaphorically ‘dark’, as in ‘hidden’, but we needed to establish what the OP was talking about. From the responses in posts #12, 13 and 14 it seems the OP is interested in all sides of this question, not just the tidal locking. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [August 8, 2017, 12:43am UTC](https://boards.straightdope.com/t/moon-question/792982/22 "2017-08-08T00:43:44Z")
> [@eburacum45](#): > > We are here to fight ignorance after all. The dark side is the side that is non-illuminated, and the far side is the side that we never see. These sometimes coincide. In the interest of fighting ignorance, can you provide any evidence of your assertion that the phrase “dark side of the moon” is not exactly equivalent to “far side of the moon”? ---
**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:** [August 8, 2017, 12:52am UTC](https://boards.straightdope.com/t/moon-question/792982/23 "2017-08-08T00:52:22Z")
Simple: The English word “dark” does not mean “far”. The word “dark” means “not light”, and the portion of the Moon that’s not light does sometimes face the Earth. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [August 8, 2017, 1:05am UTC](https://boards.straightdope.com/t/moon-question/792982/24 "2017-08-08T01:05:06Z")
> [@Chronos](#): > > Simple: The English word “dark” does not mean “far”. The word “dark” means “not light”, and the portion of the Moon that’s not light does sometimes face the Earth. But “dark” does mean “unknown” (sometimes), and the far side was the unknown side (until the Russian probe took pictures of that side). I haven’t find any headlines from 1959 on the Internet (yet), but I suspect some of them said “dark side.” ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [August 8, 2017, 1:37am UTC](https://boards.straightdope.com/t/moon-question/792982/25 "2017-08-08T01:37:43Z")
> [@abashed](#): > > Why don’t we ever see the dark side of the moon from earth? This has been answered (tidal locking). Interestingly, given enough time, there will come a day when the earth is tidally locked to the moon so that only one side will face the moon. Essentially the moon will seem to hover in one spot over the earth. That will take maybe 50 billion years (long past the death of the sun) but if the earth/moon are not destroyed when the sun expands at the end of its life it may happen. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [August 8, 2017, 2:53am UTC](https://boards.straightdope.com/t/moon-question/792982/26 "2017-08-08T02:53:06Z")
> [@Chronos](#): > > Simple: The English word “dark” does not mean “far”. The word “dark” means “not light”, and the portion of the Moon that’s not light does sometimes face the Earth. What does that have to do with the way English works? A phrase often contains words with specialized meanings. The far side of the moon was named its dark, i.e. unknown, side because nobody could know what it looked like until a camera could be sent there. Exactly as dark matter and dark energy use dark in the same sense of unknown. Is there any body of usage that contradicts or modifies this? Can you point to usage that involves the dark side as the unlit portion of the seeable side? I don’t believe that any such body of usage exists outside of this thread. Note that body of usage is not a few people getting it wrong or making unsubstantiated claims like eburacum45. I checked Google Books for usage in the 20th century before the Pink Floyd album and found only a couple of hits that refer to the dark side as unlit, and those are more references to the area rather than a common phrase. By contrast, I. S. Shklovskiĭ and Carl Sagan’s classic _Intelligent Life in the Universe_ (1965), which I hope you have because you would enjoy it, makes specific note that “there is an unfortunate tendency to call the far side of the Moon the ‘dark’ side of the Moon…” That’s how idiomatic phrases work in English. Idioms do not have to make either semantic or grammatical sense. They simply get weight by repetition. As do mistakes, unfortunately, which is why we should be fighting them. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [August 8, 2017, 3:20am UTC](https://boards.straightdope.com/t/moon-question/792982/27 "2017-08-08T03:20:53Z")
> [@eburacum45](#): > > We are here to fight ignorance after all. The dark side is the side that is non-illuminated, and the far side is the side that we never see… > [@Chronos](#): > > Simple: The English word “dark” does not mean “far”. The word “dark” means “not light”, and the portion of the Moon that’s not light does sometimes face the Earth. No, I’m with **Exapno** on this. > **[Far side of the Moon](https://en.wikipedia.org/wiki/Far_side_of_the_Moon)** > > The far side of the Moon is the lunar hemisphere that always faces away from Earth, opposite to the near side, because of synchronous rotation in the Moon's orbit. Compared to the near side, the far side's terrain is rugged, with a multitude of impact craters and relatively few flat and dark lunar maria ("seas"), giving it an appearance closer to other barren places in the Solar System such as Mercury and Callisto. It has one of the largest craters in the Solar System, the South Pole–Aitken bas... > [@](#): > > The idiomatic phrase “dark side of the Moon” does not refer to “dark” as in the absence of light, but rather “dark” as in unknown: until humans were able to send spacecraft around the Moon, this area had never been seen. While many misconstrue this to think that the “dark side” receives little to no sunlight, in reality, both the near and far sides receive (on average) almost equal amounts of light directly from the Sun. However, the near side also receives sunlight reflected from the Earth, known as earthshine. Earthshine does not reach the area of the far side which cannot be seen from Earth. Only during a full moon (as viewed from Earth) is the whole far side of the Moon dark. The word “dark” has expanded to also refer to the fact that communication with spacecraft can be blocked while on the far side of the Moon, during Apollo space missions for example. One can certainly argue that this idiomatic usage “dark side” is misleading, and that the term “far side” is preferable. But even if we accept that “dark side” is a poor term for the side permanently facing away from the earth, that does not imply that the term should mean (or has ever meant in common usage) the side transiently facing away from the sun. Either accept the idiomatic usage, or choose to abandon the term altogether. But it is almost willfully confusing to decree that it means something else. ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [August 8, 2017, 3:46am UTC](https://boards.straightdope.com/t/moon-question/792982/28 "2017-08-08T03:46:17Z")
Whether on the Earth or on the Moon, if the sun is not in the sky we could say we are on the night side, otherwise the day side. ---
**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:** [August 8, 2017, 3:52am UTC](https://boards.straightdope.com/t/moon-question/792982/29 "2017-08-08T03:52:38Z")
If it’s an idiom, then it doesn’t make sense, by definition. But who says it’s an idiom? If I refer to the left side of my body, then I mean the side of my body that’s on the left. If I refer to the top side of a blanket, I mean the side of the blanket that’s on the top. And if I refer to the dark side of the Moon, I mean the side of the Moon that’s dark. That’s not how idiomatic speech works, but it is how ordinary, non-idiomatic speech works, which is relevant because I’m not using an idiom. ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [August 8, 2017, 3:59am UTC](https://boards.straightdope.com/t/moon-question/792982/30 "2017-08-08T03:59:01Z")
I’m pretty sure Roger Waters has seen the Dark Side of the moon. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [August 8, 2017, 4:01am UTC](https://boards.straightdope.com/t/moon-question/792982/31 "2017-08-08T04:01:26Z")
> [@Chronos](#): > > If it’s an idiom, then it doesn’t make sense, by definition. But who says it’s an idiom? If I refer to the left side of my body, then I mean the side of my body that’s on the left. If I refer to the top side of a blanket, I mean the side of the blanket that’s on the top. And if I refer to the dark side of the Moon, I mean the side of the Moon that’s dark. That’s not how idiomatic speech works, but it is how ordinary, non-idiomatic speech works, which is relevant because I’m not using an idiom. I’m not sure about the fuss over this. Perhaps colloquialism is better. Usage of the phrase goes back to the 1750’s so this is not new. It is fine to point out that there is no such thing as the “dark side of the moon” but I think most people understand immediately that the phrase is meant to mean the far side of the moon (as seen from earth). ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [August 8, 2017, 4:20am UTC](https://boards.straightdope.com/t/moon-question/792982/32 "2017-08-08T04:20:30Z")
> [@Chronos](#): > > If it’s an idiom, then it doesn’t make sense, by definition. I’m not sure what you mean by “doesn’t make sense”. An idiom is a phrase whose precise meaning cannot be deduced from the individual words. But that does not imply that that the meaning _contradicts_ the usual meaning of the individual words. It has been pointed out that the idiomatic phrase is consistent with some meanings of the work “dark”, if not the most common one. > [@Chronos](#): > > But who says it’s an idiom? …if I refer to the dark side of the Moon, I mean the side of the Moon that’s dark. That’s not how idiomatic speech works, but it is how ordinary, non-idiomatic speech works, which is relevant because I’m not using an idiom. Well, whether it’s an idiom is an empirical question. But if it is, then it’s just confusing to use it in a non-idiomatic way and expect to communicate effectively. If two canines are in conflict in your yard, and neither one belongs to you, it might not be particularly helpful to call the police and say “I don’t have a dog in this fight.” ---
**Author:** ![Shinna\_Minna\_Ma](https://avatars.discourse-cdn.com/v4/letter/s/f08c70/32.png) [@Shinna\_Minna\_Ma](https://boards.straightdope.com/u/Shinna_Minna_Ma)\ **Post date:** [August 8, 2017, 7:33am UTC](https://boards.straightdope.com/t/moon-question/792982/33 "2017-08-08T07:33:11Z")
“There is no dark side of the moon really. As a matter of fact, it’s all dark.” ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [August 8, 2017, 8:32am UTC](https://boards.straightdope.com/t/moon-question/792982/34 "2017-08-08T08:32:22Z")
Trouble is, the term 'dark side of the Moon refers to _both_ the far side and the night side. This can lead to confusion in the minds of people who are unacquainted with the sky who might think that the ‘dark side of the Moon’ is actually dark. If you mean the ‘idionatic’ dark side, then it is no more dark than Darkest Africa, which is pretty bright most of the time (except at night). ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [August 8, 2017, 8:36am UTC](https://boards.straightdope.com/t/moon-question/792982/35 "2017-08-08T08:36:57Z")
(Apologies if I’ve put the cat among the pigeons here somewhat, but this thread reminded me of a queston in Stephen Fry’s _QI_ which addressed exactly this ambiguity. Most people found it difficult to differentiate between the ‘far side’, ‘night side’, ‘dark side’ and the side illuminated by the Earth. ---
**Author:** ![abashed](https://avatars.discourse-cdn.com/v4/letter/a/c6cbf5/32.png) [@abashed](https://boards.straightdope.com/u/abashed)\ **Post date:** [August 8, 2017, 10:38am UTC](https://boards.straightdope.com/t/moon-question/792982/36 "2017-08-08T10:38:25Z")
> [@eburacum45](#): > > Nearly all of the moons in the Solar System are tidally locked, so that they always showone particular face to the planet which they orbit. About the only major moon I can think of which is not tidally locked is Hyperion, which tumbles erratically- but probably quite a few of the smaller ones rotate as well. I did not know that, interesting. ---
**Author:** ![abashed](https://avatars.discourse-cdn.com/v4/letter/a/c6cbf5/32.png) [@abashed](https://boards.straightdope.com/u/abashed)\ **Post date:** [August 8, 2017, 10:39am UTC](https://boards.straightdope.com/t/moon-question/792982/37 "2017-08-08T10:39:36Z")
> [@John\_DiFool](#): > > It’s very easy to see Earthshine when the moon is a thin crescent (note that having non-hazy skies helps). Through binocs or a telescope you can actually see the dim outlines of the various maria and major craters. Have to get myself a telescope. 😉 ---
**Author:** ![abashed](https://avatars.discourse-cdn.com/v4/letter/a/c6cbf5/32.png) [@abashed](https://boards.straightdope.com/u/abashed)\ **Post date:** [August 8, 2017, 10:41am UTC](https://boards.straightdope.com/t/moon-question/792982/38 "2017-08-08T10:41:33Z")
> [@Machine\_Elf](#): > > The first reply explains that the moon rotates once per orbit, but it doesn’t explain why. That’s covered here: > > [Tidal locking - Wikipedia](https://en.wikipedia.org/wiki/Tidal_locking) > > Short version: The Earth’s gravitational field distorts the shape of the moon. Back when the moon rotated more than once per orbit, this distortion caused a torque that tended to slow the rotation of the moon. This continued until the moon’s rotation slowed to the point that it always showed the same side to the earth, and the tidally-induced distortion stopped producing that decelerative torque. > > Something similar is happening to the earth. The moon’s gravity distorts the earth, and because the earth is rotating faster than the moon orbits around it, that distortion produces a torque that tends to slow the rotation of the earth (it also tends to increase the orbital speed of the moon, which is gradually moving the moon to a higher orbit). Brilliant! 🙂 ---
**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:** [August 8, 2017, 1:58pm UTC](https://boards.straightdope.com/t/moon-question/792982/39 "2017-08-08T13:58:30Z")
If you use an idiom (or something that your audience thinks is an idiom) non-idiomatically, you’ll cause some confusion. If you use a non-idiom (or something that your audience thinks is not an idiom) idiomatically, you’ll cause a lot more confusion. A lot of people hear statements like “the dark side of the Moon never faces the Earth”, and conclude that only the side which faces the Earth is ever illuminated, which causes all sorts of confusion. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [August 8, 2017, 2:06pm UTC](https://boards.straightdope.com/t/moon-question/792982/40 "2017-08-08T14:06:01Z")
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