Top: new moon [さく] (= 1. day of lunar month) 朔 (disobedient or reverse 屰 [chinese only], var. of reverse/opposite 逆 [out 丷 to the 一 mountain 山 and downwards ノ movements are reversed] & moon 月, bottom: earth 土
Mnemonic
For forming a counterpart of the moon you can use earth/clay and modelize it
The radical tsuki stands for moon or month when used at the right side of a character. However the radical niku肉 that stands for body or body-part is in many cases simplified to 月 and thus looks equal as "moon".
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