Can someone please explain how/why we see the different phases of the moon (ie. Quarter, half, full, new, etc.). Where is the sun in relation to the moon and earth to produce the different moon phases? Thank you eli5! Bonus points for poorly drawn pictures.
In: Physics
In a room with one light source, hold up a round object of some sort in front of you. Turn around. Note that half of the object is lit. But
* when you’re facing the light source, you don’t see that half;
* when you’re facing away, you see all the lit side;
* when you’re in between, you see part of the lit and part of the dark.
Who needs poorly drawn pictures? Wikipedia has good-quality pictures!
https://upload.wikimedia.org/wikipedia/commons/4/46/Moon_phases_en.jpg
The sun always lights up half the moon. Whatever fraction of the moon that we can see lit up, that’s because of the angle between us and the lit-up side. So if you see only a small crescent of lit-up moon, it’s because the moon is mostly between us and the sun, and we can only see a small fraction of the lit-up side. But a full moon is when the moon is behind us relative to the sun, so we can see the entire lit-up side.
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