<blockquote>
<p>What is the obstruction creating the crescent considering the moon is between the earth &amp; sun?</p>
</blockquote>
<p>The moon. The part of the moon that's dark is in the shadow of the rest of the moon. <em>Because</em> the crescent moon is nearly between the earth and sun, the side that's lit (the side that's nearer the sun) is mostly facing away from us.</p>

CC BY-SA 4.0
2022-02-27T10:00:19.060Z
This is by far the best answer. The Moon always shadows half of itself, and we're seeing only the shadowed side at new Moon, and mostly the shadowed side a few days before and after new Moon. Short and sweet.
David Hammen
CC BY-SA 4.0
2022-02-28T19:13:23.503Z
It might be worth mentioning that the "dark side" of the moon is not perpetually dark, and the "light side" is not perpetually light.
Tech Inquisitor
CC BY-SA 4.0
2022-02-28T19:30:54.137Z
@TechInquisitor You presumably mean the _far_ and _near_ sides. We could define dark and light to match their names and thus make you wrong, but then they wouldn't be constant halves, because the Moon is tidally locked to Earth, not the Sun. This is part of why people try not to use the dark/light terms with either meaning.
J.G.
CC BY-SA 4.0
2022-02-28T20:35:34.627Z
The word "dark" is a has multiple meanings, one of which means "hidden." For example, "a dark secret." When people refer to the "dark side" of the Moon, they're using this definition, not the definition meaning "lack of light."
Don Branson
CC BY-SA 4.0
2022-02-28T20:46:51.617Z
@J.G. My point is that many people call them the "dark" and "light" sides; in fact, this is probably the most common terminology among the general population. And I've encountered many people who think these are literal descriptions. (Among other amazing things, like adults who never noticed that the moon can be out during the day. Thanks, cartoons where the sun sets and a *crescent* moon pops up.) The answer would be improved by mentioning this common source of confusion.
Tech Inquisitor
CC BY-SA 4.0
2022-02-28T20:48:22.310Z
@DonBranson I know this, and you know this, but we are a tiny minority.
Tech Inquisitor
CC BY-SA 4.0
2022-02-28T21:02:46.297Z
@TechInquisitor I wrote it the way I did to try to avoid the whole issue. :)
hobbs
CC BY-SA 4.0
2022-02-28T21:04:11.987Z
@hobbs It might *be* the whole issue. To me, the question immediately suggests this misconception.
Tech Inquisitor
CC BY-SA 4.0
2022-02-28T21:17:37.500Z
@TechInquisitor we are tiny, but we are _mighty_. Soon all will know. Apparently, all will know about the dark side. That didn't come out the way I intended.
Don Branson
CC BY-SA 4.0
2022-02-28T21:31:44.727Z
Having said this, I'm not convinced people say "dark side" really thinking that the far side of the Moon is in constant darkness. It seems like most everyone who's graduated high school is going to know this.
Don Branson
CC BY-SA 4.0
2022-02-26T23:54:25.780Z
2022-02-26T23:54:25.780Z
hobbs
<p>The Moon doesn't really rise and set exactly &quot;with the sun&quot;,  it is usually somewhat north or south of it, because its orbit is somewhat tilted with respect to Earth's orbit.</p>
<p><em>In this picture</em> the bright side of the Moon points <em>very close</em> to where the Sun is. As discussed below, this doesn't work as well when the Moon is fuller, but for the purposes of understanding a crescent Moon it helps us understand what's going on.</p>
<p>This is a flat picture so we can't see depth, but the arrow point strongly <em>into the page</em> because the Sun is much further away the than the Moon.</p>
<p>See also (though they may confuse more than help)</p>
<ul>
<li><a href="https://astronomy.stackexchange.com/q/27747/7982">How does the Moon move in the &quot;night&quot; sky as seen from the poles?</a></li>
<li><a href="https://en.wikipedia.org/wiki/Orbit_of_the_Moon" rel="noreferrer">Orbit of the Moon</a></li>
</ul>
<p><a href="https://i.sstatic.net/ymqP8.jpg" rel="noreferrer"><img src="https://i.sstatic.net/ymqP8.jpg" alt="enter image description here" /></a></p>
<p>The following paper <a href="https://www.seas.upenn.edu/%7Eamyers/MoonPaperOnline.pdf" rel="noreferrer">The Moon Tilt Illusion</a> by Andrea K. Myers-Beaghton and Alan L. Myers takes us through perspective projection to show that when the Moon is much further away from the Sun this doesn't work as well, but <strong>for the purposes of this answer</strong> about a thin crescent Moon it's perfectly fine to assume the Sun is in the direction where the bright side of the Moon suggests it is.</p>
<p><a href="https://i.sstatic.net/ZKxHY.png" rel="noreferrer"><img src="https://i.sstatic.net/ZKxHY.png" alt="enter image description here" /></a></p>
<blockquote>
<p>Figure 11. Moon tilt illusion for waning phases in northern hemisphere. Sun is rising due east. Red line is observed slope and blue line is expected slope of moon-sun line. Azimuth measured CW from north.</p>
</blockquote>

CC BY-SA 4.0
2022-02-26T21:35:22.217Z
-1. The shadow of the Moon does necessarily not point toward the Sun as seen from the Earth. I'll add a reference shortly.
David Hammen
CC BY-SA 4.0
2022-02-26T21:45:52.853Z
Reference: https://www.seas.upenn.edu/~amyers/MoonPaperOnline.pdf . See figures 10 & 11.
David Hammen
CC BY-SA 4.0
2022-02-27T00:40:17.883Z
@DavidHammen you know darn well that in this situation it's very close. I've updated and added the U Penn paper, it's a *beauty!*
uhoh
CC BY-SA 4.0
2022-02-27T09:39:00.580Z
@DavidHammen Your very reference proves that, with the illuminated side of the crescent pointing to the left, the photo could only have been taken at sunset in the *southern hemisphere* (which the author denies though). Otherwise, it must have been taken at sunrise or the photo has been flipped around.
Thomas
CC BY-SA 4.0
2022-02-27T09:50:19.180Z
@Thomas The only time one can see that thin of a crescent Moon is very near sunrise or sunset. What I was disputing was the line toward the Sun. That that line doesn't always work is something flat earthers love to use as "evidence" in favor of their nonsense. It is evidence -- evidence of 3D projective geometry.
David Hammen
CC BY-SA 4.0
2022-02-27T10:17:05.813Z
@DavidHammen There is no odd projective geometry effect visibile here. The crescent points in a direction below the horizon as you would intuitively expect it. But if this is a sunset photo taken in the northern hemisphere, the crescent must point towards the right, not the left.
Thomas
CC BY-SA 4.0
2022-02-27T10:41:31.080Z
@Thomas That the crescent moon always points to the right at sunset in the Northern Hemisphere is incorrect. The Moon's orbit is inclined with respect to the ecliptic by 5 degrees.
David Hammen
CC BY-SA 4.0
2022-02-27T16:25:39.257Z
@Thomas I think David means [this effect](https://physics.stackexchange.com/a/331058/21441). The Moon's lit side only points "correctly" to the sun when lunar phase is 50%, so that it "looks" exactly to the side.
Ruslan
CC BY-SA 4.0
2022-02-28T08:31:29.173Z
@Ruslan We are not talking about pointing exactly in the direction of the sun, only pointing approximately in its direction or approximately opposite, It should do the former, but if this were a sunset it would be the latter, which is impossible,
Thomas
CC BY-SA 4.0
2022-02-26T17:29:13.223Z
2022-02-27T00:38:50.840Z
2022-02-27T00:38:50.840Z
uhoh
<p>It's not a shadow. The only time the moon is shadowed is when it's full and there's a lunar eclipse. What you saw was the moon when most of the side we see was facing away from the sun. At the time of a full moon all of the side we see is facing the sun.</p>

CC BY-SA 4.0
2022-02-26T15:19:33.700Z
you can add those *animations and diagrams* to make this answer look more complete
Kavin Ishwaran
CC BY-SA 4.0
2022-02-26T15:31:17.370Z
I guess one could stretch the definition and it is a shadow, but the moon is shadowing itself
GrapefruitIsAwesome
CC BY-SA 4.0
2022-02-26T13:28:03.537Z
2022-02-26T17:12:36.647Z
2022-02-26T17:12:36.647Z
stretch
<p>As you said in your question, the phases of the moon are determined by the positions of the Sun, Moon and Earth in space (it is easy to test out the principle at home using a light bulb and a ball and changing their relative positions to yourself). The dark parts are just those parts of the Moon that are on the backside as seen from the Sun. And these thin crescents appear when the Earth, Moon and Sun are close to being in one line (in that order) i.e. at a time close to New Moon. But you will never see the crescent both at sunrise and sunset on the same day. You will either see it a couple of days before New Moon shortly before sunrise or a couple of days after New Moon shortly after sunset (it is in this order as the Moon appears to move slightly slower in the sky than the Sun (the orbital motion of the Moon is opposite to the Earth's rotation)) .</p>
<p>Based on these insights, one can conclude that, if your picture was taken in the northern hemisphere, it must actually have been taken at sunrise (not sunset as it claims). This is because because the Sun and Moon are both moving from East to West, which means in the northern hemisphere from left to right. So if your photo would be a sunset photo, the crescent would be moving from the top left to the bottom right. The Sun would have already done that and would be ahead of the crescent below the horizon. So the illuminated side of the crescent should broadly point to the right. But it is in fact broadly pointing to the left, which means the crescent was <em>rising</em> from the bottom left to the top right, with the Sun about to rise behind it.</p>
<p>This is also confirmed by the figures in the <a href="https://www.seas.upenn.edu/%7Eamyers/MoonPaperOnline.pdf" rel="nofollow noreferrer">scientific publication</a> mentioned in some of the comments here. The possible phases at <strong>sunset</strong> are not consistent with the photo at all</p>
<p><a href="https://i.sstatic.net/MVZos.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/MVZos.jpg" alt="moon phases at sunset" /></a></p>
<p>whilst the possible <strong>sunrise</strong> phases contain instances that are consistent with the photo;</p>
<p><a href="https://i.sstatic.net/btPm1.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/btPm1.jpg" alt="moon phases at sunrise" /></a></p>
<p>If the photo was indeed taken at sunset, it must either have been taken in the southern hemisphere (where everything would be reversed) or flipped horizontally.</p>
<p>Here are the sunset/moonset and sunrise/moonrise views visible from Albuquerque, New Mexico around New Moon on 1 Feb. 2022 (courtesy of <a href="https://skyandtelescope.org/interactive-sky-chart/" rel="nofollow noreferrer">Sky and Telescope Skychart</a> )</p>
<p><strong>Sunset 3 Feb. 2022</strong>
<a href="https://i.sstatic.net/3s3a6.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/3s3a6.jpg" alt="Sunset 3 Feb. 2022" /></a></p>
<p><strong>Sunrise 29. Jan. 2022</strong>
<a href="https://i.sstatic.net/wqphd.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/wqphd.jpg" alt="Sunrise 29. Jan. 2022" /></a></p>
<p>And below again the photo taken by the OP (obviously showing the scenario slightly later/earlier than the charts, with the Sun below the horizon)</p>
<p><a href="https://i.sstatic.net/gIiNq.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/gIiNq.jpg" alt="photo" /></a></p>
<p>So if the photo indeed taken at around the last New Moon (which is not confirmed by the OP as yet) it could only have been taken at sunrise not sunset. The chart shows a few planets near the Moon on this occasion as well, but they may have been too close to the horizon to show on the photo given the probably shortish exposure time. If that would be a sunset photo, the illuminated side of the crescent would not only point opposite to the sun (which is impossible, and which I have never seen in 50+ years observing the sky) but it should have been considerably higher in the sky as well)</p>

CC BY-SA 4.0
2022-02-28T23:09:28.007Z
I'm not sure your conclusions are supported yet. The link is to a very nice looking tutorial, not a scientific publication (there's no evidence of peer review) and the Moon's orbit does precess every 18 years. I'll go off and do some Skyfield simulations but I have a hunch that just after sunset in Arizona the Moon can be either left or right of the Sun.
uhoh
CC BY-SA 4.0
2022-03-01T07:35:49.873Z
No, “altitude” is exactly “altitude”. Check for instance the sentence “For example, in Figure 10 for a waxing moon, the horizontal “boat” moon at high altitude in the west is observed near the equator but not in temperate zones” (and the figure shows the “boat” as corresponding to 75°): hence, they actually refer to a moon high in the sky and seen from a latitude near to 0° (equator).
DaG
CC BY-SA 4.0
2022-03-01T19:06:20.400Z
@DaG Yes, you are right. I removed this note from my answer.
Thomas
CC BY-SA 4.0
2022-03-01T22:14:00.953Z
@uhoh The paper was published in "Journal of the Croatian Society for Geometry and Graphics" . See also the skycharts I added to my answer, which also prove that this can not be a sunset photo in the northern hemisphere (not to mention that I have never seen such a scenario in 50+ years observing the sky)
Thomas
CC BY-SA 4.0
2022-03-01T22:19:11.680Z
@Thomas Thanks for all of that! Please don't equate "I'm not sure your conclusions are supported yet" with suggesting that anything is wrong here. It's just me, and I'm simply not yet sure.
uhoh
CC BY-SA 4.0
2022-02-27T17:26:14.693Z
2022-03-02T08:25:21.250Z
2022-03-02T08:25:21.250Z
Thomas
<pre><code>   Sorry if you've received your satisfactory answer already but this caught my eye so here's my analogy. (Dang it! sorry this got so long)
(*When* your photo was taken will be helpful as to the &quot;which side is lit&quot; question but that's in my second part. So I'd love to know that!) 
</code></pre>
<p>To address your question:</p>
<p>The Set up:
We're walking single file into the low setting sun and I am directly in front of you. You are following behind me looking right at the back of my head and the low setting sun is likely blocked from your view by my head. So you, me, then the sun all in alignment. (Our shadows would align stretching behind us)</p>
<p>You would see zero directly-lit, sun-reflecting parts of my face. (My head is the &quot;moon&quot; here)</p>
<p>The Change:
Then you quicken your pace and are behind me still but just off to the side a bit (as if to catch up to walk along side say. We're not aligned anymore) The sun would be in your view now, as you've sidestepped a little, and almost immediately, once you move out from behind me, you would catch a sliver of my face and it reflecting the sunlight. That sliver of reflecting face would grow as you caught up to me.</p>
<p>The Conclusion:
So when there is a crescent moon that means the earth (you) and the moon (me) and the sun (the sun) are very closely in alignment to get only a sliver of the moon to be lit up and in your view. When there is a crescent moon and you are pointing at it in the sky you would then need to move your finger only a little bit to redirect and point at the sun. They always appear near each other in the view of the sky.</p>
<p>Crescent Direction explained...maybe, mostly:</p>
<p>As to the direction of your crescent photo some were discussing (not sure they'll get to see this but):
Oddly enough there are times when the moon sets north of where the sun sets. So the sun would be on its left as we face it by the time the moon is all the way down. This might be why the lit part was on the bottom left. So I am not agreeing about the northern hemisphere crescent moon &quot;always&quot; being lit on the bottom right as one suggested (I mean, I believe you anyway) But for most crescent nights I believe it will be bottom right. Just a rare few that aren't (and only at the horizon).</p>
<p>Its arc in the sky changes over the course of a few days even. As you know the sun's arc crossing the sky is higher in the sky in summer and lower (more southern) in winter. (Think tilted hulahoop) This similar arc change for the moon happens much faster. I remember seeing the moon rise one night on the south side of a local mountain from my view. The very next night it rose on the north side of the mountain. So I knew it was setting similarly. I never really put together how much it moved like that before. (Helpful website down below)</p>
<p>I can't quite pinpoint the date of your photo but I'll leap at Feb 3rd 2022?
This was one of those times where the moon set after the sun, <em>and</em> was north of where the sun went down (in NM). You can see this effect on mooncalc .org -That's a link so in good practice google search it- You can change the date to around Feb 7th and see its arc set really north vs Feb 28th. Click and move the dot along the top timeline too. A similar site is called suncalc .net just for the sun instead. Also helpful is time and date .com</p>
<p>I'm more photographer but night photoing got me to dabble in astronomy too, timing for moonless nights.</p>
<p>Anyway, hope this helps!</p>

CC BY-SA 4.0
2022-03-01T13:48:05.753Z
Your conclusion about the direction of the crescent when setting is wrong. I agree the moonset was farther north than the sunset, but that does not matter. What matters are the positions at the time the photo is taken. At anytime after sunset and before moonset, the sun was farther north (and below the horizon of course) by approximately 15 to 20 degrees. Therefore, the crescent would be facing to the right. In late spring the crescent can be pointing more "straight down" toward the horizon, but it will never be facing to the left as shown in the photo. The photo is sunrise, IMHO.
JohnHoltz
CC BY-SA 4.0
2022-03-01T22:08:53.027Z
@JohnHoltz See the added skycharts in my answer, which prove as well, that this can only be a sunrise photo
Thomas
CC BY-SA 4.0
2022-03-01T09:23:45.747Z
2022-03-01T09:23:45.747Z
Brian R
<p>I need help understanding this images I personally took. If the phases of the moon are determined by the position of the earth, moon &amp; sun. Then how is the moon a crescent while it is rising in the east with the sun &amp; still a crescent while setting with the sun? What is the obstruction creating the crescent considering the moon is between the earth &amp; sun?<a href="https://i.sstatic.net/LSwal.jpg" rel="noreferrer"><img src="https://i.sstatic.net/LSwal.jpg" alt="Sunset Crescent Moon " /></a></p>

CC BY-SA 4.0
2022-02-26T13:25:02.373Z
unfortunately, the other images I took of sunrise are too large to post in this format. Regardless of how much I compress it.
Cody Page
CC BY-SA 4.0
2022-02-26T13:52:23.777Z
What would you expect to see if the moon is between the sun and the Earth.? Try holding a ball so it is between you and the sun.
James K
CC BY-SA 4.0
2022-02-26T17:53:02.083Z
Is this picture taken in the southern hemisphere? Otherwise there would be something wrong with it. Sunset/moonset is from left to right in the northern hemisphere, so with the sun already gone, the moon crescent should be facing to the right not the left.
Thomas
CC BY-SA 4.0
2022-02-26T21:09:38.017Z
This was in New Mexico, in the Northern hemisphere
Cody Page
CC BY-SA 4.0
2022-02-26T21:21:25.137Z
Related: https://astronomy.stackexchange.com/q/19985/16685 & https://physics.stackexchange.com/q/6969/123208 & https://physics.stackexchange.com/q/669264/123208
PM 2Ring
CC BY-SA 4.0
2022-02-27T00:28:34.787Z
The photo labeled sunset showing the crescent pointed to the left looks like sunrise.
JohnHoltz
CC BY-SA 4.0
2022-02-27T09:44:06.397Z
If the photo was taken in the northern hemisphere, it must have been at sunrise not sunset. Or you must have flipped the photo around. Otherwise it would not be possible that the illuminated side of the crescent points to the left.
Thomas
CC BY-SA 4.0
2022-02-27T11:23:07.997Z
Are you confusing the phases of the moon — due to the direction from which the spherical moon is illuminated by the sun — and a lunar eclipse — due to the shadowing of the moon by the earth?
Andrew Jaffe
CC BY-SA 4.0
2022-02-28T02:24:12.027Z
A simple trick to get around the photo size limitation is to take a screenshot of the image at roughly the zoom level you want it to show in your post, then insert that. If you use the Windows snipping tool it automatically puts the screenshot on your clipboard.
LShaver
CC BY-SA 4.0
2022-02-28T19:12:43.027Z
@Thomas In the current edit, the asker doesn't specify whether the photo was taken at sunrise or sunset.
Tech Inquisitor
CC BY-SA 4.0
2022-02-28T20:40:56.003Z
@TechInquisitor Click on the photo
Thomas
CC BY-SA 4.0
2022-02-28T21:18:34.657Z
Could it be simply that "the moon is a crescent rising in the east with the sun & still a crescent while setting with the sun" makes no sense?

Might it be that as such, no "obstruction creating the crescent considering the moon is between the earth & sun" could have a real meaning?
Robbie Goodwin
CC BY-SA 4.0
2022-03-01T15:57:29.433Z
I created an image shrinker. Info at https://www.picturepdf.com/shrink/ Email the picture to shrink@PicturePDF.com and it will email back a shrunken picture (max 1.5 Meg.) and also a temporary link for "paste image link". Pictures are only saved for 1 hour and then automatically deleted. Max. starting image 15 Meg.
manassehkatz-Moving 2 Codidact
<the-moon><moon-phases>
How is this picture of the moon possible?
Cody Page
# How is this picture of the moon possible?

(Asked by: username_0 on 2022-02-26)

I need help understanding this images I personally took. If the phases of the moon are determined by the position of the earth, moon & sun. Then how is the moon a crescent while it is rising in the east with the sun & still a crescent while setting with the sun? What is the obstruction creating the crescent considering the moon is between the earth & sun?[![Sunset Crescent Moon ](https://i.sstatic.net/LSwal.jpg)](https://i.sstatic.net/LSwal.jpg)

**Tags:** the-moon, moon-phases

> **Comments:**
> **username_0**: unfortunately, the other images I took of sunrise are too large to post in this format. Regardless of how much I compress it.  
> **username_1**: What would you expect to see if the moon is between the sun and the Earth.? Try holding a ball so it is between you and the sun.  
> **username_2**: Is this picture taken in the southern hemisphere? Otherwise there would be something wrong with it. Sunset/moonset is from left to right in the northern hemisphere, so with the sun already gone, the moon crescent should be facing to the right not the left.  
> **username_0**: This was in New Mexico, in the Northern hemisphere  
> **username_3**: Related: https://astronomy.stackexchange.com/q/19985/16685 & https://physics.stackexchange.com/q/6969/123208 & https://physics.stackexchange.com/q/669264/123208  
> **username_4**: The photo labeled sunset showing the crescent pointed to the left looks like sunrise.  
> **username_2**: If the photo was taken in the northern hemisphere, it must have been at sunrise not sunset. Or you must have flipped the photo around. Otherwise it would not be possible that the illuminated side of the crescent points to the left.  
> **username_5**: Are you confusing the phases of the moon — due to the direction from which the spherical moon is illuminated by the sun — and a lunar eclipse — due to the shadowing of the moon by the earth?  
> **username_6**: A simple trick to get around the photo size limitation is to take a screenshot of the image at roughly the zoom level you want it to show in your post, then insert that. If you use the Windows snipping tool it automatically puts the screenshot on your clipboard.  
> **username_7**: @username_2 In the current edit, the asker doesn't specify whether the photo was taken at sunrise or sunset.  
> **username_2**: @username_7 Click on the photo  
> **username_8**: Could it be simply that "the moon is a crescent rising in the east with the sun & still a crescent while setting with the sun" makes no sense?  Might it be that as such, no "obstruction creating the crescent considering the moon is between the earth & sun" could have a real meaning?  
> **username_9**: I created an image shrinker. Info at https://www.picturepdf.com/shrink/ Email the picture to shrink@PicturePDF.com and it will email back a shrunken picture (max 1.5 Meg.) and also a temporary link for "paste image link". Pictures are only saved for 1 hour and then automatically deleted. Max. starting image 15 Meg.  

---

## 5 answers

### Answer by username_10 on 2022-02-26. Score: 42

> What is the obstruction creating the crescent considering the moon is between the earth & sun?

The moon. The part of the moon that's dark is in the shadow of the rest of the moon. *Because* the crescent moon is nearly between the earth and sun, the side that's lit (the side that's nearer the sun) is mostly facing away from us.

> **Comments:**
> **username_11**: This is by far the best answer. The Moon always shadows half of itself, and we're seeing only the shadowed side at new Moon, and mostly the shadowed side a few days before and after new Moon. Short and sweet.  
> **username_7**: It might be worth mentioning that the "dark side" of the moon is not perpetually dark, and the "light side" is not perpetually light.  
> **username_12**: @username_7 You presumably mean the _far_ and _near_ sides. We could define dark and light to match their names and thus make you wrong, but then they wouldn't be constant halves, because the Moon is tidally locked to Earth, not the Sun. This is part of why people try not to use the dark/light terms with either meaning.  
> **username_13**: The word "dark" is a has multiple meanings, one of which means "hidden." For example, "a dark secret." When people refer to the "dark side" of the Moon, they're using this definition, not the definition meaning "lack of light."  
> **username_7**: @J.G. My point is that many people call them the "dark" and "light" sides; in fact, this is probably the most common terminology among the general population. And I've encountered many people who think these are literal descriptions. (Among other amazing things, like adults who never noticed that the moon can be out during the day. Thanks, cartoons where the sun sets and a *crescent* moon pops up.) The answer would be improved by mentioning this common source of confusion.  
> **username_7**: @username_13 I know this, and you know this, but we are a tiny minority.  
> **username_10**: @username_7 I wrote it the way I did to try to avoid the whole issue. :)  
> **username_7**: @username_10 It might *be* the whole issue. To me, the question immediately suggests this misconception.  
> **username_13**: @username_7 we are tiny, but we are _mighty_. Soon all will know. Apparently, all will know about the dark side. That didn't come out the way I intended.  
> **username_13**: Having said this, I'm not convinced people say "dark side" really thinking that the far side of the Moon is in constant darkness. It seems like most everyone who's graduated high school is going to know this.  

---

### Answer by username_14 on 2022-02-26. Score: 15

The Moon doesn't really rise and set exactly "with the sun", it is usually somewhat north or south of it, because its orbit is somewhat tilted with respect to Earth's orbit.

*In this picture* the bright side of the Moon points *very close* to where the Sun is. As discussed below, this doesn't work as well when the Moon is fuller, but for the purposes of understanding a crescent Moon it helps us understand what's going on.

This is a flat picture so we can't see depth, but the arrow point strongly *into the page* because the Sun is much further away the than the Moon.

See also (though they may confuse more than help)

* [How does the Moon move in the "night" sky as seen from the poles?](https://astronomy.stackexchange.com/q/27747/7982)
* [Orbit of the Moon](https://en.wikipedia.org/wiki/Orbit_of_the_Moon)

[![enter image description here](https://i.sstatic.net/ymqP8.jpg)](https://i.sstatic.net/ymqP8.jpg)

The following paper [The Moon Tilt Illusion](https://www.seas.upenn.edu/%7Eamyers/MoonPaperOnline.pdf) by Andrea K. Myers-Beaghton and Alan L. Myers takes us through perspective projection to show that when the Moon is much further away from the Sun this doesn't work as well, but **for the purposes of this answer** about a thin crescent Moon it's perfectly fine to assume the Sun is in the direction where the bright side of the Moon suggests it is.

[![enter image description here](https://i.sstatic.net/ZKxHY.png)](https://i.sstatic.net/ZKxHY.png)

> Figure 11. Moon tilt illusion for waning phases in northern hemisphere. Sun is rising due east. Red line is observed slope and blue line is expected slope of moon-sun line. Azimuth measured CW from north.

> **Comments:**
> **username_11**: -1. The shadow of the Moon does necessarily not point toward the Sun as seen from the Earth. I'll add a reference shortly.  
> **username_11**: Reference: https://www.seas.upenn.edu/~amyers/MoonPaperOnline.pdf . See figures 10 & 11.  
> **username_14**: @username_11 you know darn well that in this situation it's very close. I've updated and added the U Penn paper, it's a *beauty!*  
> **username_2**: @username_11 Your very reference proves that, with the illuminated side of the crescent pointing to the left, the photo could only have been taken at sunset in the *southern hemisphere* (which the author denies though). Otherwise, it must have been taken at sunrise or the photo has been flipped around.  
> **username_11**: @username_2 The only time one can see that thin of a crescent Moon is very near sunrise or sunset. What I was disputing was the line toward the Sun. That that line doesn't always work is something flat earthers love to use as "evidence" in favor of their nonsense. It is evidence -- evidence of 3D projective geometry.  
> **username_2**: @username_11 There is no odd projective geometry effect visibile here. The crescent points in a direction below the horizon as you would intuitively expect it. But if this is a sunset photo taken in the northern hemisphere, the crescent must point towards the right, not the left.  
> **username_11**: @username_2 That the crescent moon always points to the right at sunset in the Northern Hemisphere is incorrect. The Moon's orbit is inclined with respect to the ecliptic by 5 degrees.  
> **username_15**: @username_2 I think username_11 means [this effect](https://physics.stackexchange.com/a/331058/21441). The Moon's lit side only points "correctly" to the sun when lunar phase is 50%, so that it "looks" exactly to the side.  
> **username_2**: @username_15 We are not talking about pointing exactly in the direction of the sun, only pointing approximately in its direction or approximately opposite, It should do the former, but if this were a sunset it would be the latter, which is impossible,  

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### Answer by username_16 on 2022-02-26. Score: 13

It's not a shadow. The only time the moon is shadowed is when it's full and there's a lunar eclipse. What you saw was the moon when most of the side we see was facing away from the sun. At the time of a full moon all of the side we see is facing the sun.

> **Comments:**
> **username_17**: you can add those *animations and diagrams* to make this answer look more complete  
> **username_18**: I guess one could username_16 the definition and it is a shadow, but the moon is shadowing itself  

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### Answer by username_2 on 2022-02-27. Score: 9

As you said in your question, the phases of the moon are determined by the positions of the Sun, Moon and Earth in space (it is easy to test out the principle at home using a light bulb and a ball and changing their relative positions to yourself). The dark parts are just those parts of the Moon that are on the backside as seen from the Sun. And these thin crescents appear when the Earth, Moon and Sun are close to being in one line (in that order) i.e. at a time close to New Moon. But you will never see the crescent both at sunrise and sunset on the same day. You will either see it a couple of days before New Moon shortly before sunrise or a couple of days after New Moon shortly after sunset (it is in this order as the Moon appears to move slightly slower in the sky than the Sun (the orbital motion of the Moon is opposite to the Earth's rotation)) .

Based on these insights, one can conclude that, if your picture was taken in the northern hemisphere, it must actually have been taken at sunrise (not sunset as it claims). This is because because the Sun and Moon are both moving from East to West, which means in the northern hemisphere from left to right. So if your photo would be a sunset photo, the crescent would be moving from the top left to the bottom right. The Sun would have already done that and would be ahead of the crescent below the horizon. So the illuminated side of the crescent should broadly point to the right. But it is in fact broadly pointing to the left, which means the crescent was *rising* from the bottom left to the top right, with the Sun about to rise behind it.

This is also confirmed by the figures in the [scientific publication](https://www.seas.upenn.edu/%7Eamyers/MoonPaperOnline.pdf) mentioned in some of the comments here. The possible phases at **sunset** are not consistent with the photo at all

[![moon phases at sunset](https://i.sstatic.net/MVZos.jpg)](https://i.sstatic.net/MVZos.jpg)

whilst the possible **sunrise** phases contain instances that are consistent with the photo;

[![moon phases at sunrise](https://i.sstatic.net/btPm1.jpg)](https://i.sstatic.net/btPm1.jpg)

If the photo was indeed taken at sunset, it must either have been taken in the southern hemisphere (where everything would be reversed) or flipped horizontally.

Here are the sunset/moonset and sunrise/moonrise views visible from Albuquerque, New Mexico around New Moon on 1 Feb. 2022 (courtesy of [Sky and Telescope Skychart](https://skyandtelescope.org/interactive-sky-chart/) )

**Sunset 3 Feb. 2022**
[![Sunset 3 Feb. 2022](https://i.sstatic.net/3s3a6.jpg)](https://i.sstatic.net/3s3a6.jpg)

**Sunrise 29. Jan. 2022**
[![Sunrise 29. Jan. 2022](https://i.sstatic.net/wqphd.jpg)](https://i.sstatic.net/wqphd.jpg)

And below again the photo taken by the OP (obviously showing the scenario slightly later/earlier than the charts, with the Sun below the horizon)

[![photo](https://i.sstatic.net/gIiNq.jpg)](https://i.sstatic.net/gIiNq.jpg)

So if the photo indeed taken at around the last New Moon (which is not confirmed by the OP as yet) it could only have been taken at sunrise not sunset. The chart shows a few planets near the Moon on this occasion as well, but they may have been too close to the horizon to show on the photo given the probably shortish exposure time. If that would be a sunset photo, the illuminated side of the crescent would not only point opposite to the sun (which is impossible, and which I have never seen in 50+ years observing the sky) but it should have been considerably higher in the sky as well)

> **Comments:**
> **username_14**: I'm not sure your conclusions are supported yet. The link is to a very nice looking tutorial, not a scientific publication (there's no evidence of peer review) and the Moon's orbit does precess every 18 years. I'll go off and do some Skyfield simulations but I have a hunch that just after sunset in Arizona the Moon can be either left or right of the Sun.  
> **username_19**: No, “altitude” is exactly “altitude”. Check for instance the sentence “For example, in Figure 10 for a waxing moon, the horizontal “boat” moon at high altitude in the west is observed near the equator but not in temperate zones” (and the figure shows the “boat” as corresponding to 75°): hence, they actually refer to a moon high in the sky and seen from a latitude near to 0° (equator).  
> **username_2**: @username_19 Yes, you are right. I removed this note from my answer.  
> **username_2**: @username_14 The paper was published in "Journal of the Croatian Society for Geometry and Graphics" . See also the skycharts I added to my answer, which also prove that this can not be a sunset photo in the northern hemisphere (not to mention that I have never seen such a scenario in 50+ years observing the sky)  
> **username_14**: @username_2 Thanks for all of that! Please don't equate "I'm not sure your conclusions are supported yet" with suggesting that anything is wrong here. It's just me, and I'm simply not yet sure.  

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### Answer by username_20 on 2022-03-01. Score: -3

```
   Sorry if you've received your satisfactory answer already but this caught my eye so here's my analogy. (Dang it! sorry this got so long)
(*When* your photo was taken will be helpful as to the "which side is lit" question but that's in my second part. So I'd love to know that!) 

```

To address your question:

The Set up:
We're walking single file into the low setting sun and I am directly in front of you. You are following behind me looking right at the back of my head and the low setting sun is likely blocked from your view by my head. So you, me, then the sun all in alignment. (Our shadows would align stretching behind us)

You would see zero directly-lit, sun-reflecting parts of my face. (My head is the "moon" here)

The Change:
Then you quicken your pace and are behind me still but just off to the side a bit (as if to catch up to walk along side say. We're not aligned anymore) The sun would be in your view now, as you've sidestepped a little, and almost immediately, once you move out from behind me, you would catch a sliver of my face and it reflecting the sunlight. That sliver of reflecting face would grow as you caught up to me.

The Conclusion:
So when there is a crescent moon that means the earth (you) and the moon (me) and the sun (the sun) are very closely in alignment to get only a sliver of the moon to be lit up and in your view. When there is a crescent moon and you are pointing at it in the sky you would then need to move your finger only a little bit to redirect and point at the sun. They always appear near each other in the view of the sky.

Crescent Direction explained...maybe, mostly:

As to the direction of your crescent photo some were discussing (not sure they'll get to see this but):
Oddly enough there are times when the moon sets north of where the sun sets. So the sun would be on its left as we face it by the time the moon is all the way down. This might be why the lit part was on the bottom left. So I am not agreeing about the northern hemisphere crescent moon "always" being lit on the bottom right as one suggested (I mean, I believe you anyway) But for most crescent nights I believe it will be bottom right. Just a rare few that aren't (and only at the horizon).

Its arc in the sky changes over the course of a few days even. As you know the sun's arc crossing the sky is higher in the sky in summer and lower (more southern) in winter. (Think tilted hulahoop) This similar arc change for the moon happens much faster. I remember seeing the moon rise one night on the south side of a local mountain from my view. The very next night it rose on the north side of the mountain. So I knew it was setting similarly. I never really put together how much it moved like that before. (Helpful website down below)

I can't quite pinpoint the date of your photo but I'll leap at Feb 3rd 2022?
This was one of those times where the moon set after the sun, *and* was north of where the sun went down (in NM). You can see this effect on mooncalc .org -That's a link so in good practice google search it- You can change the date to around Feb 7th and see its arc set really north vs Feb 28th. Click and move the dot along the top timeline too. A similar site is called suncalc .net just for the sun instead. Also helpful is time and date .com

I'm more photographer but night photoing got me to dabble in astronomy too, timing for moonless nights.

Anyway, hope this helps!

> **Comments:**
> **username_4**: Your conclusion about the direction of the crescent when setting is wrong. I agree the moonset was farther north than the sunset, but that does not matter. What matters are the positions at the time the photo is taken. At anytime after sunset and before moonset, the sun was farther north (and below the horizon of course) by approximately 15 to 20 degrees. Therefore, the crescent would be facing to the right. In late spring the crescent can be pointing more "straight down" toward the horizon, but it will never be facing to the left as shown in the photo. The photo is sunrise, IMHO.  
> **username_2**: @username_4 See the added skycharts in my answer, which prove as well, that this can only be a sunrise photo  

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