Difference between revisions of "1738: Moon Shapes"

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==Explanation==
 
==Explanation==
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{{incomplete|Table needs pictures.}}
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The phases of the moon are created by sunlight reflecting off the moon's surface. This means that the bright side of the moon always needs to be facing towards the sun. However, the moon often appears in works of art in ways that are very dramatic, but violate this rule. This comic lists some of the some common mistakes. In some
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{| class="wikitable"
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|+Explanation of individual items in the list
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!Image
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!Explanation
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|-
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|Full moon|| Normal
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|-
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|Gibbous moon||Normal
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|-
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| Crescent moon facing towards horizon || Normal
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|-
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|Crescent moon facing away from horizon || This can only happen when the sun is above the horizon. This isn't necessarily ''only'' during a solar eclipse, but since a crescent moon means that the Sun and Moon are relatively close in the sky, it's hard to see at other times.
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|-
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|Crescent-like moon where the black area doesn't touch the poles || The moon is a nearly-perfect sphere, so when it's lit from one side, the dark side will always cover precisely 50% of its surface, and the dark area should begin and end on the moon's axis. If the moon looks like this, the shadows are in the wrong place. This is only possible if the Earth is casting an extra shadow on the moon, as during an eclipse. Randall labels this "dubious", since the shadow during an eclipse should be much fuzzier than shown here.
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|-
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| Crescent-like moon where the horns extend well past the poles || Again, the shadow should just touch the poles. This situation is even harder to create than the previous one - the Earth's shadow is too big to cover the moon but leave an edge like this - a huge ''Independence Day'' spaceship might be the right size. It does however resemble a partial {{w|annular eclipse}} if you imagine that the black area is the moon covering up the white sun.
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|-
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|Crescent moon blocking stars|| Normal
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|Crescent moon with stars between horns || As the moon is a huge ball, it should block the stars behind it. If stars are visible, there is either a hole, or a light-source on the moon.
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==Transcript==
 
==Transcript==

Revision as of 08:13, 26 September 2016

Moon Shapes
Whenever I see a picture of the moon where the points go more than halfway around, I assume it's being eclipsed by one of those Independence Day ships and interpret the rest of the image in light of that.
Title text: Whenever I see a picture of the moon where the points go more than halfway around, I assume it's being eclipsed by one of those Independence Day ships and interpret the rest of the image in light of that.

Explanation

Ambox notice.png This explanation may be incomplete or incorrect: Table needs pictures.
If you can address this issue, please edit the page! Thanks.

The phases of the moon are created by sunlight reflecting off the moon's surface. This means that the bright side of the moon always needs to be facing towards the sun. However, the moon often appears in works of art in ways that are very dramatic, but violate this rule. This comic lists some of the some common mistakes. In some

Explanation of individual items in the list
Image Explanation
Full moon Normal
Gibbous moon Normal
Crescent moon facing towards horizon Normal
Crescent moon facing away from horizon This can only happen when the sun is above the horizon. This isn't necessarily only during a solar eclipse, but since a crescent moon means that the Sun and Moon are relatively close in the sky, it's hard to see at other times.
Crescent-like moon where the black area doesn't touch the poles The moon is a nearly-perfect sphere, so when it's lit from one side, the dark side will always cover precisely 50% of its surface, and the dark area should begin and end on the moon's axis. If the moon looks like this, the shadows are in the wrong place. This is only possible if the Earth is casting an extra shadow on the moon, as during an eclipse. Randall labels this "dubious", since the shadow during an eclipse should be much fuzzier than shown here.
Crescent-like moon where the horns extend well past the poles Again, the shadow should just touch the poles. This situation is even harder to create than the previous one - the Earth's shadow is too big to cover the moon but leave an edge like this - a huge Independence Day spaceship might be the right size. It does however resemble a partial annular eclipse if you imagine that the black area is the moon covering up the white sun.
Crescent moon blocking stars Normal
Crescent moon with stars between horns As the moon is a huge ball, it should block the stars behind it. If stars are visible, there is either a hole, or a light-source on the moon.

Transcript

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Discussion

It's a reflection of the nuclear war on the sun's surface. Mikemk (talk) 08:08, 26 September 2016 (UTC)

I can't find any photoshopped Moon that looks like the last image. Somebody has to make one. --162.158.92.207 13:22, 26 September 2016 (UTC)

Randall uncharacteristically missed an opportunity for pointing out additional errors that people make: It's interesting to note that you can get a decent estimate of the artist's latitude by looking at how they draw a crescent moon. In equatorial cultures, the crescent looks like a cup or a boat - and they interpret it like that. But if you look at most english language children's books, the crescent looks like a letter 'C' or a 'D' with a human face - suggesting that they were probably made in the tradition of northern Europe. When I first moved from the UK (more or less a 'C'-shaped crescent moon) to the southern USA (more like Randall's depiction of the correctly-drawn crescent with the points at a roughly 45 degree angle to the horizon) - I subconsciously felt that the moon "looked wrong" - it was only much later that I understood the reason.
Furthermore, this rotation of the moon relative to the observer also explains why "The man in the moon" is a common trope caused by the pareidolia interpretation of the cratering patterns of the moon in northern cultures. But in southern cultures, people tend to see a rabbit in those full-moon patterns - and that has become the source of many of their stories.
Now that I'm more acutely aware of this - it's interesting to note how many movies get the orientation of the moon wrong for the location that their story is supposedly set in! SteveBaker (talk) 13:41, 26 September 2016 (UTC)
In Japan, for example, the patterns are interpreted as a rabbit making mochi (a sort of dense dumpling made from rice pounded into a powder) on the moon - the Sea of Tranquillity forming the head, and the Sea of Clouds forming part of the pestle in which the rabbit is pounding the rice. 188.114.102.167 (talk) (please sign your comments with ~~~~)
Considering how many movies features the famous Mountains of Illinois, I would be more surprised when they get it right. -- Hkmaly (talk) 13:38, 27 September 2016 (UTC)
Not quite sure how to add this but Gibbon is the author of The Decline and Fall of the Roman Empire - or a type of Ape. It is not a phase of the moon. Also I think the moon depicted is Waning. 141.101.98.113 14:02, 26 September 2016 (UTC)
I think the correct expression is gibbous - "having the illuminated part greater than a semicircle and less than a circle" 141.101.98.68 (talk) (please sign your comments with ~~~~)
Yes, the one he says is correct has me thinking: "OMG, the moon is drunk and has fallen over on its ass." No self-respecting moon lies on its back like that.162.158.114.222 14:17, 26 September 2016 (UTC)
Indeed - but that's pretty much how it looks down here in sunny Texas. It's one of those things you never think about - but once the fact of it clicks in your head, you get this visceral feeling of how you're standing on a large ball rather than a flat plane! Ha! Take that flat-earthers! :-) SteveBaker (talk) 18:46, 26 September 2016 (UTC)
Living in Florida, our crescent moons are almost horizontal. 108.162.212.60
"Wax gibbon" is probably nothing more than a joke on mispronouncing "waxing gibbous". As drawn, it is the way a waning gibbous would appear in the northern hemisphere, but a waxing gibbous in the southern hemisphere. Harperska (talk) 16:18, 26 September 2016 (UTC)

Link to the DreamWorks logo image please? There seem to be multiple versions. 108.162.237.216 15:16, 26 September 2016 (UTC)

I'm surprised Randall missed the chance to include a joke about guys with fishing rods. --162.158.85.141 15:41, 26 September 2016 (UTC)
http://www.roadtovr.com/wp-content/uploads/2014/11/dreamworks-logo.jpg... Here's the link to the Dreamworks logo. You're welcome. --JayRulesXKCD (talk) 16:17, 26 September 2016 (UTC)
neither of the examples for the "stars in the moon" apply here. both randall's examples imply a spherical moon. spring and the dreamworks child are supported on a crescent moon for which only the light section actually exists. better examples, please. --141.101.98.84 12:26, 27 September 2016 (UTC)
While the dreamworks logo features a child sitting on the crescent moon as though the dark portion wasn't there, none of the versions of the logo which contain stars in the sky actually show stars 'inside' the moon's disk, so the logo probably isn't a good example of what Randall is complaining about. See https://www.youtube.com/watch?v=xPpy8mYHQps. Harperska (talk) 17:16, 27 September 2016 (UTC)

The first "wrong" image is also only possible if the bright portion is presumed to be the sun during a solar eclipse, assuming the sky is actually depicted as black. You can only have a crescent moon during a solar eclipse if the solar system suddenly acquired a second sun. Harperska (talk) 16:28, 26 September 2016 (UTC)

Here's a good counter-example: EXAMPLE. The bright dot is actually the ISS transiting the moon - but it certainly looks like an impossibility! SteveBaker (talk) 18:50, 26 September 2016 (UTC)

The article doesn't mention the "nuclear war" joke. Does it need explaining? 141.101.98.49 19:29, 26 September 2016 (UTC)

It does now. WingedCat (talk) 22:24, 27 September 2016 (UTC)
your welcome ;-) NotLock (talk) 22:30, 27 September 2016 (UTC)

I've always wanted to create a story, and have the horns of the moon connect on the other side, so you have a blackbody in front of the moon, in parody of this tendency. Also, interesting how the moon is at different rotations in different locations. I never did see the rabbit in the moon. Now I know why. 108.162.245.74 04:34, 27 September 2016 (UTC)

Some of the examples of "incorrect" moons are kinda questionable - like, how relevant is the position of the moon when there's literally a giant divine skyperson standing on it, grabbing stars and scattering of them? 172.68.35.80 23:09, 26 September 2016 (UTC)

I fixed part of the explanation by mentioning the title text. --JayRulesXKCD (talk) 14:41, 26 September 2016 (UTC)

I think that's enough detail for an explanation, so I removed the "incomplete" bar. --JayRulesXKCD (talk) 14:52, 27 September 2016 (UTC)

Should the table of explanations include the text in the comic? NotLock (talk) 22:30, 27 September 2016 (UTC)

The comic has been updated on xkcd. Randall revised the description of #4. Maybe this should be updated? 108.162.242.135 21:55, 27 September 2016 (UTC)

for trivia doesn't mass bend light so IMHO probably still possible for star light on that position 162.158.163.61 05:07, 28 September 2016 (UTC)

Nope - if a distant star's light were being gravitationally lensed by the moon, then its light would appear adjacent to the moon's disk, not on it. A star's light could only appear to originate on the moon's disk if its light were being lensed by another massive object between the earth and the moon (such as a second moon). Whoop whoop pull up (talk) 17:10, 16 October 2016 (UTC)

For the Dreamworks logo, it seems that the static versions don't sport the stars-through-the-moon problem, but I suspect the animated versions (the ones showing at the beginning of their movies) might and probably do. As it so happens, I'm watching Kung Fu Panda 2 for the first time right now, - the fishing kid is a turtle in this case, LOL! - and I note that this problem isn't present here, though there are no stars at all during the logo, so that might be the only reason why. (Of course, if a kid can sit there fishing, the rest of the moon is clearly absent, why wouldn't we see stars there, LOL!) - NiceGuy1 108.162.218.239 18:40, 28 September 2016 (UTC) I finally signed up! This comment is mine. NiceGuy1 (talk) 11:12, 9 June 2017 (UTC)


I swear to god I've seen an Upside down moon before.... both in the day and at night the cusps were pointed down or towards the horizon heres an example of one https://www.flickr.com/photos/dcysurfer/14631243979 i'm 100% sure this is not fake and that there is no reason why one would use a dslr upsidedown or rotate it in post (this is in the southern hemisphere so that may be why... i also swear that many times i've seen the cusps pointed directly to the side (northern hemisphere) heres a nasa photo http://www.nasa.gov/centers/wallops/news/InOMN.html Needforsuv (talk) 06:57, 3 October 2016 (UTC)

You haven't, at least not at night. The Flickr photo isn't evidence at all -- people often rotate pictures for best effect. 172.68.55.80 15:55, 3 October 2016 (UTC) i swear it was at night. also the nasa photo looks the same...

i'll take a photo of it one day... it could've been dusk/ last light and maybe it was just a touch rotated down without accounting for the slope the user is standing on but its not impossible -- Needforsuv (talk) (please sign your comments with ~~~~)

'If the Moon is in the night sky, the Sun must be somewhere "below" the horizon on the other side of the Earth.' Funny how people still talk as if Earth is the center of the universe. More correct would have been to say something about "Earth's rotation" and stuff. 162.158.83.144 (talk) (please sign your comments with ~~~~)

Not funny at all. There is no concept of 'down' except from the point of view of a person on the Earth.

The moon that does look like the last one is the one in the old Proctor and Gamble logo. https://goo.gl/images/4UE6n6 162.158.10.4 (talk) (please sign your comments with ~~~~)

Phil Plait reads xkcd

Has anyone else noticed the Phil Plait message in the news section (up top) ? In case it changes: "Thank you to Phil Plait for the correction on #4!" Blagae (talk) 20:16, 4 June 2017 (UTC)


UPSIDE down moon PROOF:

[1] 
I took the photos MYSELF Needforsuv (talk) 09:26, 28 March 2018 (UTC)