# Whats with the moon? **URL:** \ **Category:** Factual Questions\ **Created:** [October 25, 2008, 11:45am UTC](https://boards.straightdope.com/t/whats-with-the-moon/469498 "2008-10-25T11:45:49Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![panache45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/panache45/32/64_2.png) [@panache45](https://boards.straightdope.com/u/panache45)\ **Post date:** [October 25, 2008, 8:47pm UTC](https://boards.straightdope.com/t/whats-with-the-moon/469498/21 "2008-10-25T20:47:30Z")
> [@Usram](#): > > That reminds of a trip to California when we were driving through the Sierra Nevada one night, quite high up I guess, and noticed this long cloud running the whole length of the sky, like a plane’s con trail but wider and stretching from horizon to horizon. What the hell was it? We got out of the car and realised that it was the Milky Way. I had never seen it so clearly before, it was just stunning. Seen from England, it’s much fainter. I saw it from the top of Haleakala and Mauna Kea in Hawaii, about as clear a sky as you can find. Yes, it looked like a cloud transversing the sky. The funniest thing was the people photographing it with their flashes on. ---
**Author:** ![whiterabbit](https://avatars.discourse-cdn.com/v4/letter/w/cab0a1/32.png) [@whiterabbit](https://boards.straightdope.com/u/whiterabbit)\ **Post date:** [October 25, 2008, 9:22pm UTC](https://boards.straightdope.com/t/whats-with-the-moon/469498/22 "2008-10-25T21:22:40Z")
I’ve seen the Milky Way from right here at my house – it’s faint, and it took me about three nights of seeing it to realize that’s what it was! But I don’t remember ever seeing it before. It gets _dark_ here. Really dark. One of my favorite things about working into the evenings is that when I get off work when it’s dark, I get home, and just look up for a few minutes. The sky is spectacular. I also had no idea how much light a full moon sends our way. It’s _bright_! ---
**Author:** ![Hirka\_T\_Bawa](https://avatars.discourse-cdn.com/v4/letter/h/db5fbb/32.png) [@Hirka\_T\_Bawa](https://boards.straightdope.com/u/Hirka_T_Bawa)\ **Post date:** [October 25, 2008, 11:34pm UTC](https://boards.straightdope.com/t/whats-with-the-moon/469498/23 "2008-10-25T23:34:36Z")
> [@RickJay](#): > > Lots of people also think the phases of the moon are caused by the Earth’s shadow. I always thought the phases of the Moon were caused by the Earth’s shadow. So, if that is not the case, what causes the Moon’s phases? ---
**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:** [October 25, 2008, 11:43pm UTC](https://boards.straightdope.com/t/whats-with-the-moon/469498/24 "2008-10-25T23:43:02Z")
> [@](#): > > I always thought the phases of the Moon were caused by the Earth’s shadow. So, if that is not the case, what causes the Moon’s phases? In short, the Moon’s shadow. Get a flashlight and a baseball, and go into a dark room. The flashlight represents the Sun, and the baseball represents the Moon. Shine the light on the baseball: Half of the ball will be lit up by the light, and half of it will be dark. If you look at it from the side that’s lit, you’ll see a full circle of glowing baseball. Look at it from the opposite side, you’ll see all of it unlit, or maybe a thin sliver of light along one edge. Look at it from the side, and you’ll see a half-circle lit and a half-circle dark. ---
**Author:** ![jmcvann](https://avatars.discourse-cdn.com/v4/letter/j/8491ac/32.png) [@jmcvann](https://boards.straightdope.com/u/jmcvann)\ **Post date:** [October 25, 2008, 11:47pm UTC](https://boards.straightdope.com/t/whats-with-the-moon/469498/25 "2008-10-25T23:47:00Z")
> [@CutterJohn](#): > > I just got off work, and on my way to the car I looked up and saw the moon, which was behaving oddly. > > Its a crescent right now, and you can certainly see the side of the moon brightly lit by the sun, but, unless my eyes are playing tricks, I am seeing the rest of the moon as well, albeit much dimmer. > > Whats the dope on this dim part? Is the dark side of the moon being lit up by sunlight that reflects off of earth? Or is it some sort of optical illusion that makes me want to complete a circle? > > I kinda think its earthlight, but if it is, this planet is a LOT brighter to the naked eye than I previously thought. There is no actual “dark side of the moon.” All the moon gets sunlight at some point. But because the moon is in synchronous rotation, it keeps nearly the same face turned toward the Earth at all times. The part that seemed dimmer to you was just the part not getting direct sunlight at that moment. That, by the way answers the other question about the phases of the moon. The half of the moon that is getting sunlight seems to rotate around the moon, from our perspective. (That probably wasn’t worded as well as it could have been.) ---
**Author:** ![Pasta](https://avatars.discourse-cdn.com/v4/letter/p/ecccb3/32.png) [@Pasta](https://boards.straightdope.com/u/Pasta)\ **Post date:** [October 25, 2008, 11:52pm UTC](https://boards.straightdope.com/t/whats-with-the-moon/469498/26 "2008-10-25T23:52:39Z")
> [@](#): > > I always thought the phases of the Moon were caused by the Earth’s shadow. So, if that is not the case, what causes the Moon’s phases? Wikipedia has a decent diagram. [Lunar phase diagram](http://upload.wikimedia.org/wikipedia/en/7/72/Lunar-Phase-Diagram.png). In looking at that diagram, you might think that the full moon phase, when viewed at midnight, would not work right because the earth is “in the way” of the sun’s light. This does happen, but only rarely. The moon’s orbit around the earth is tilted relative to the earth’s orbit around the sun, so in the full-moon-at-midnight configuration, the moon is typically above or below the earth’s shadow. When it _does_ pass through the shadow (a few times each year), you get a lunar eclipse. ---
**Author:** ![jmcvann](https://avatars.discourse-cdn.com/v4/letter/j/8491ac/32.png) [@jmcvann](https://boards.straightdope.com/u/jmcvann)\ **Post date:** [October 25, 2008, 11:52pm UTC](https://boards.straightdope.com/t/whats-with-the-moon/469498/27 "2008-10-25T23:52:43Z")
> [@Derleth](#): > > Well, _they_ likely can’t. They may or may not know whether people who live in other regions can, but the survey didn’t ask that, did it? You seem to be implying that there ARE places you cannot see the moon during the day. Unless you are unable to look up, you can see the moon during the day anywhere. ---
**Author:** ![phouka](https://avatars.discourse-cdn.com/v4/letter/p/c5a1d2/32.png) [@phouka](https://boards.straightdope.com/u/phouka)\ **Post date:** [October 25, 2008, 11:57pm UTC](https://boards.straightdope.com/t/whats-with-the-moon/469498/28 "2008-10-25T23:57:09Z")
The Moon’s phases are caused by the rotation on its axis and its revolution around the Earth. Basically, through the course of its rotation, one half of it is lit by the sun. We only ever see one side of the Moon, because it’s in tidal lock with us. So, we see that side as it slips between sunshine and shadow. You can read more about it at [Wikipedia](http://en.wikipedia.org/wiki/Moon_phases). ---
**Author:** ![Pasta](https://avatars.discourse-cdn.com/v4/letter/p/ecccb3/32.png) [@Pasta](https://boards.straightdope.com/u/Pasta)\ **Post date:** [October 26, 2008, 12:00am UTC](https://boards.straightdope.com/t/whats-with-the-moon/469498/29 "2008-10-26T00:00:32Z")
> [@phouka](#): > > The Moon’s phases are caused by the rotation on its axis and its revolution around the Earth. The moon’s rotation on its axis plays no role in generating phases. It could rotate faster or slower or not at all, and we’d see the same phases (assuming its rotation around Earth stayed the same.) ---
**Author:** ![phouka](https://avatars.discourse-cdn.com/v4/letter/p/c5a1d2/32.png) [@phouka](https://boards.straightdope.com/u/phouka)\ **Post date:** [October 26, 2008, 12:02am UTC](https://boards.straightdope.com/t/whats-with-the-moon/469498/30 "2008-10-26T00:02:10Z")
> [@jmcvann](#): > > You seem to be implying that there ARE places you cannot see the moon during the day. Unless you are unable to look up, you can see the moon during the day anywhere. Well, it’s not quite _that_ simple. There are times during the lunar cycle when you can’t see the Moon during the day. When the Moon is full, it’s on the other side of the planet from the Sun, so the side that can see it is experiencing night. During the winter, with its longer nights, it’s probably a given that the Moon rises after sunset and sets before sunrise. During the summer, I suppose there might be a little crossover. Anyone know for sure? ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [October 26, 2008, 12:02am UTC](https://boards.straightdope.com/t/whats-with-the-moon/469498/31 "2008-10-26T00:02:48Z")
I don’t think this thread is complete without the spongemonkeys video [We Like The Moon](http://www.youtube.com/watch?v=wY6insZjCfU). ---
**Author:** ![phouka](https://avatars.discourse-cdn.com/v4/letter/p/c5a1d2/32.png) [@phouka](https://boards.straightdope.com/u/phouka)\ **Post date:** [October 26, 2008, 12:10am UTC](https://boards.straightdope.com/t/whats-with-the-moon/469498/32 "2008-10-26T00:10:10Z")
> [@Pasta](#): > > The moon’s rotation on its axis plays no role in generating phases. It could rotate faster or slower or not at all, and we’d see the same phases (assuming its rotation around Earth stayed the same.) Uh . . . . /tries to visualize rotation versus revolution. Brain smokes, careens into a brick wall, catches fire. I’ll take your word for it. ---
**Author:** ![jmcvann](https://avatars.discourse-cdn.com/v4/letter/j/8491ac/32.png) [@jmcvann](https://boards.straightdope.com/u/jmcvann)\ **Post date:** [October 26, 2008, 12:15am UTC](https://boards.straightdope.com/t/whats-with-the-moon/469498/33 "2008-10-26T00:15:49Z")
> [@phouka](#): > > Well, it’s not quite _that_ simple. There are times during the lunar cycle when you can’t see the Moon during the day. When the Moon is full, it’s on the other side of the planet from the Sun, so the side that can see it is experiencing night. During the winter, with its longer nights, it’s probably a given that the Moon rises after sunset and sets before sunrise. During the summer, I suppose there might be a little crossover. > > Anyone know for sure? True. I should have been more specific. I meant to say just what you said! Additionally, before I hit the POST button I considered if it were possible that maybe at the poles the angles would not allow seeing the moon during the day. Without checking, I assumed the answer to be “no.” To quote you: “Anyone know for sure?” ---
**Author:** ![Bytegeist](https://avatars.discourse-cdn.com/v4/letter/b/9dc877/32.png) [@Bytegeist](https://boards.straightdope.com/u/Bytegeist)\ **Post date:** [October 26, 2008, 1:36am UTC](https://boards.straightdope.com/t/whats-with-the-moon/469498/34 "2008-10-26T01:36:12Z")
> [@Pasta](#): > > The moon’s rotation on its axis plays no role in generating phases. It could rotate faster or slower or not at all, and we’d see the same phases (assuming its rotation around Earth stayed the same.) > [@phouka](#): > > Uh . . . . /tries to visualize rotation versus revolution. Brain smokes, careens into a brick wall, catches fire. > > I’ll take your word for it. Imagine it’s a clear night, and the moon is out. We’re pondering it up there, in the sky. Now normally the moon spins around its own axis at a rate of about once every 27 days. Pretty slow, that — kind of boring really. Tonight, let’s juice that bastard up to a screaming 800 RPM, but without changing its orbital speed at all. The visible part of the moon will now be just a white blur, but the moon’s phase will stay the same. If it was half-full before, it’s still half-full now. If it was a thin crescent before, it’s a thin crescent now. Hope that helps? ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [October 26, 2008, 1:39am UTC](https://boards.straightdope.com/t/whats-with-the-moon/469498/35 "2008-10-26T01:39:35Z")
> [@Bytegeist](#): > > Hope that helps? Yeah, until that rapidly-rotating chunk of rock explodes from the centrifugal force tearing it apart and rains down destruction upon us all. ---
**Author:** ![GusNSpot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gusnspot/32/436_2.png) [@GusNSpot](https://boards.straightdope.com/u/GusNSpot)\ **Post date:** [October 26, 2008, 4:01am UTC](https://boards.straightdope.com/t/whats-with-the-moon/469498/36 "2008-10-26T04:01:39Z")
> [@Q.E.D](#): > > Yeah, until that rapidly-rotating chunk of rock explodes from the centrifugal force tearing it apart and rains down destruction upon us all. Sitting aloft in my space ship from ‘Undomogongerali’ I have to ask, This is bad how? 🆒 ---
**Author:** ![panamajack](https://avatars.discourse-cdn.com/v4/letter/p/47e85d/32.png) [@panamajack](https://boards.straightdope.com/u/panamajack)\ **Post date:** [October 26, 2008, 4:24am UTC](https://boards.straightdope.com/t/whats-with-the-moon/469498/37 "2008-10-26T04:24:17Z")
> [@Bytegeist](#): > > Imagine it’s a clear night, and the moon is out. We’re pondering it up there, in the sky. I have to say, I definitely was not pondering what you were pondering. I think an awful lot of people who spend their day inside a building in a city can’t see the moon during the day, so maybe they could be answering honestly (Though it’s probably the survey stupidity effect.) ---
**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:** [October 26, 2008, 5:22am UTC](https://boards.straightdope.com/t/whats-with-the-moon/469498/38 "2008-10-26T05:22:56Z")
> [@](#): > > You seem to be implying that there ARE places you cannot see the moon during the day. Unless you are unable to look up, you can see the moon during the day anywhere. Well, to be fair, you usually can’t see the Moon during the day from Cleveland. Then again, though, you usually can’t see the Sun during the day from Cleveland, either. ---
**Author:** ![WotNot](https://avatars.discourse-cdn.com/v4/letter/w/e19b73/32.png) [@WotNot](https://boards.straightdope.com/u/WotNot)\ **Post date:** [October 26, 2008, 9:24am UTC](https://boards.straightdope.com/t/whats-with-the-moon/469498/39 "2008-10-26T09:24:17Z")
> [@Mycroft\_H](#): > > Although I’m sure lack of observation plays a large role, this could also be a result of pollution. When I was in high school (equivalent) in industrial northeast England, a friend of mine lived close to the blast furnaces of British Steel. Once he was visiting me out in the countryside, looked up during the daytime and saw the moon. He asked “What’s that doing there?” with honest surprise. Now this was someone very science oriented and extremely to have noticed anything astronomical. He just had never seen the daytime moon due to the levels of pollution where he spent most of his daytime hours. Interestingly, I had an almost identical experience when _I_ was at High School in North East England (actually, I suppose Cramlington would only be semi-rural, strictly speaking, but presumably there’s very little difference in terms of the Moon’s daytime visiblity). Except that my friend lived there too, so I still think I was justified in considering him clueless. ---
**Author:** ![Paul\_in\_Qatar](https://avatars.discourse-cdn.com/v4/letter/p/ccd318/32.png) [@Paul\_in\_Qatar](https://boards.straightdope.com/u/Paul_in_Qatar)\ **Post date:** [October 26, 2008, 10:28am UTC](https://boards.straightdope.com/t/whats-with-the-moon/469498/40 "2008-10-26T10:28:42Z")
Jeepers did you see the moon this morning? A most wonderfully thin crescent with perfect cusps. (I like the word “cusp,” it sounds dirty.) After yesterday’s rain, a cold clear winter morning with all the stars in their places. Beautiful. [Previous page](https://boards.straightdope.com/t/whats-with-the-moon/469498.md?page=1) [Next page](https://boards.straightdope.com/t/whats-with-the-moon/469498.md?page=3)