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Why do you see half of the moon when you can see both the sun and the moon from earth at the same time on some days?

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Are you sure its exactly half. I have seen thin crescents in the evening(4-5 pm) when the sun is high enough. –  udiboy Aug 24 '13 at 12:32
possible duplicate of Why does the moon face earth with the same side? –  hwlau Aug 24 '13 at 17:16
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closed as unclear what you're asking by Dilaton, Emilio Pisanty, Chris White, Waffle's Crazy Peanut, Qmechanic Aug 27 '13 at 7:13

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1 Answer

enter image description here

You see, if you're standing at the south part of the earth in this picture you can only see half the moon, also called a crescent moon, because the part that you can not see is facing the oppsite direction of the sun, therefore not receiving any sunlight.

You don't always see exactly half, sometimes you only see a thin strip of the moon, google for "crescent moon" and you'll see what I mean.

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out of scale, of course :-) –  Jan Dvorak Aug 24 '13 at 17:02
@JohnRennie The thing you said is simply not true; unless by day you mean at noon. –  Ali Aug 24 '13 at 17:16
@Ali: oops, yes, that was posted in excessive haste :-( –  John Rennie Aug 25 '13 at 10:15
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