What’s Up With the Funny-Looking Moons in ‘Onward’? - WIRED

Let me just say, the Pixar movie Onward was fun.

It just so happens we have a real moon in our sky.

Ask them what causes the varying phases of the moon, and here are some of the common (wrong) answers you will hear:.

Here’s the real answer: The phases of the moon are indeed caused by a shadow, but it’s essentially the shadow of the moon on itself.

When light from the sun hits the moon, it illuminates only half of the moon’s surface, such that one side is bright and one side is dark.

Here is a view of the Earth and moon along with the light from the sun (not drawn to scale).

If you were the red dot on the Earth, your view of the moon could be represented by the dashed line.

From that angle, you would mostly see the dark side of the moon with just a little sliver of the illuminated part—in other words, a crescent moon.

So, as the moon orbits the Earth, the angle that you view it at also changes.

When things do line up, we call that Earth shadow a lunar eclipse.

Now go back to the diagram and imagine how our view from that red dot will change as the moon orbits the Earth: When the moon is on the sun side of the Earth, we see only a sliver of light, or no light at all on a “new moon.” When the moon is on the far side of Earth, we look back and see more of the bright side.

The Onward moon looks like a circle with a smaller dark circle on top of it—suspiciously like a projected shadow from Earth.

You can't make this shape with a sphere that has one dark half and one light half.

The funny thing is, this faulty depiction of a crescent moon is pretty common.