Common Moon Mistakes

0:00 [Music] Warning, there are ideas in this video

0:02 that you may not be able to unsee.

0:04 There are many ways to draw the moon incorrectly,

0:07 but this video isn't just about

0:08 pedantically correcting children's books and animated movies,

0:10 though it at least partially is.

0:12 Here's the thing.

0:13 The moon is up there for any of us to look at, basically as much as we want.

0:16 And yet, the proliferation of incorrect illustrations of the moon

0:19 suggests that very few of us actually do.

0:21 I shouldn't need to make this video, but I guess here it is.

0:25 Mistake number one is showing the outside of the crescent

0:28 moon as anything other than half of a circle.

0:30 This isn't a realistic moon.

0:31 I kind of get this one.

0:33 When I think of a crescent moon, I kind of just imagine taking an arbitrary arc

0:36 and drawing another arc either outside or inside of it.

0:39 But the moon is a sphere and half of it is illuminated by the sun.

0:42 And when you look at a half illuminated sphere from different angles,

0:45 the opposite points of the crescent are always on opposite points of the sphere.

0:48 And the same thing applies for gibbous moons where you

0:50 can instead think of the dark part as the crescent.

0:53 Okay, technically speaking, the points are only exactly opposite if

0:55 you're infinitely far away from the sphere.

0:57 And if you're somewhat closer, then the crescent won't quite reach the poles.

1:01 And non- halfcircle moon related shapes can form, but only during an eclipse.

1:05 A shortened crescent moon can appear during a lunar eclipse

1:08 when the dark part is the Earth's shadow covering the moon.

1:10 And an elongated crescent sun can appear during

1:12 a solar eclipse where the moon is the dark part.

1:15 The ultimate point is in any realistic moon illustration,

1:18 the outer unobstructed portion of the moon will always be half

1:21 a circle so that the points of the crescent are opposite each other.

1:24 Mistake number two is the big one.

1:26 Showing stars inside the crescent of the moon.

1:28 The moon is a solid rocky sphere

1:30 and the crescent is the illuminated part of the sphere.

1:32 Just because the dark part isn't lit up doesn't mean you can see through it.

1:35 I get the artistic desire to put something there.

1:37 It's a nice negative space beautifully framed by the thin crescent.

1:40 But stars are farther away than the moon, so they'll be blocked by it.

1:43 If you want to put something inside the crescent,

1:45 use something that wouldn't be blocked from sight by the moon,

1:48 like a cloud, or firefly, or the International Space Station.

1:50 Or how about the rest of the moon illuminated from Earth shine,

1:53 but no stars inside the moon's disc,

1:55 unless you're illustrating a sci-fi future where we've

1:58 colonized the moon and the twinkles aren't stars,

2:00 but are actually lights from cities.

2:01 That is acceptable.

2:02 Mistake number three is about the moon's orientation and placement.

2:05 The sun lights up the moon.

2:07 So, the bright part of the moon,

2:08 whether crescent or gibbous, should always point towards the sun.

2:11 And we see a fuller moon when the moon is on the opposite side of the sun

2:14 from Earth and a thinner crescent when

2:15 the moon is between the Earth and the Sun.

2:17 So in an illustration, the fuller the moon,

2:19 the farther away from the sun it should be.

2:21 And the thinner the crescent, the closer to the sun.

2:23 In fact, the thinnest new moon crescent rise

2:25 and set almost in tandem with the sun.

2:27 Which brings us to number four,

2:29 the mistake of having the moon only come out at night.

2:31 It's true that a full moon is full because it's opposite the sun in the sky.

2:35 So a full moon always comes out at sunset,

2:37 stays up all night, and goes away at sunrise.

2:39 But a crescent moon is a crescent because it's

2:41 in the same part of the sky as the sun.

2:43 So it moves along with the sun, rising near dawn,

2:46 staying up during the day, and setting near sunset.

2:48 In this case, moonrise is sunrise, and moonset is sunset.

2:51 And a half moon will be 90° away from the sun,

2:55 spending part of its time out at night and part of it during the day.

2:58 Mistake number five is having the moon

3:00 in the wrong orientation for the location on Earth.

3:02 Because the moon's orbit is approximately aligned with the Earth's equator,

3:06 an approximately horizontally pointing crescent only happens when you're

3:09 standing on top of the Earth near the poles,

3:11 while a cup-like crescent happens near the equator,

3:13 where you've rotated yourself 90° relative to the Earth's axis.

3:16 It also works the other way around.

3:18 This photo of the Earth was taken

3:20 as the Apollo spacecraft traveled along the moon's equator.

3:22 And here, the Earth's crescent points vertically, not horizontally.

3:25 Anyway, intermediate latitudes get intermediate angles,

3:27 and the angles also vary a bit by the seasons.

3:30 The Lion King has a great example of mistakes 1, four, and five all combined.

3:35 The crescent moon above Pride Rock is one,

3:37 way too elongated and looks more like the shape of a solar eclipse.

3:40 Four, it shows a thin horizontal pointing crescent moon out in the middle

3:43 of the night rather than moving in tandem with the sun and setting near sunset.

3:46 And we can tell this scene is well past sunset because of how

3:49 many stars are visible and the lack of a colored after sunset glow.

3:52 The illuminated portion of the moon implies the sun should

3:54 be on this line here about 40 to 50° away,

3:57 which puts the sun so close to the horizon that we should still be in twilight.

4:00 And five, the crescent moon is pointed horizontally,

4:02 much like the way the crescent moon would look in, say,

4:04 North America, where the film was made.

4:06 But the movie is set in equatorial Africa,

4:08 where a crescent moon is oriented more like a cup.

4:10 Plus, when oriented vertically like this, the sun would be down here,

4:13 far enough below the horizon to be past twilight and into proper nighttime,

4:16 justifying the dark sky and the stars.

4:18 Here's what the moon should probably look like in that scene

4:20 in case they ever decide to do another remake.

4:23 If you're a Disney animator or just any human being,

4:25 here's a trick to always know what the moon looks like right now.

4:28 Take a ball outside on a sunny day,

4:30 hold it out in the same direction the moon is from you,

4:32 and the way it's lit from your perspective will show you

4:34 what phase the moon is in and what that phase looks like.

4:37 It's that simple.

4:38 And even if you can't see the moon,

4:39 you can use an augmented reality astronomy app to tell you where it should be,

4:43 and you'll still get the right moon phase.

4:45 P.S.

4:46 Jupiter's stripes are also only horizontal when

4:47 viewed from near the poles on Earth.

4:49 If you're near the equator, they'll look vertical,

4:51 just like how the moon turns into a cup.

4:53 Just something to keep in mind the next time you're

4:55 illustrating Jupiter in the sky of a tropical animated film.

4:58 Thanks to Minute Physics Patreon supporters for making my work possible.

5:02 Head to patreon.com/minutysics to become a supporter and see

5:05 a special behind-the-scenes look at the making of this [Music]