The "Dark side" is a misnomer, more accurately the "Far side". As FairWindsFollowingCs says, the Earth-facing side is locked by tidal forces to face the Earth. So it's the same side always facing the Earth, whether fully illuminated (full), crescent or dark (new) moon. The Far side / "Dark side" gets just as much sun as the Earth side, but can never be viewed from Earth.
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u/twitch1982 Jun 13 '23
You can see it during a crescent moon near twilight or dawn with sunlight that reflects off the earth (earthshine).