May one draw a sun, moon or stars?
It is forbidden to make a sculpture of a sun, moon or stars. It is likewise forbidden to engrave them in any way, whether intruding or protruding. It is also forbidden to draw them in any way, whether with a pen or pencil. This however only applies when making an engraving or drawing for non-learning purposes; it is however permitted to draw them, or engrave them in even a protruding manner, if it is for learning purposes. Likewise it is only forbidden to draw them in their full structure, such as a whole sun or a whole shape of a moon, it is however permitted to draw an incomplete picture of them.
 Michaber 141/4
 Implication of Michaber ibid that drawing is forbidden, as it makes no difference if it is protruding or not; Kitzur SHU”A 168/1; Sheilas Yaavetz 1/101; Yad Efraim
 Michaber ibid
 This prohibition includes even a non-full moon, such as the shape of the moon in the beginning of the month. [Darkei Teshuvah 141/37]
Other opinions: Some Poskim rule that only a hole moon is forbidden. [Mahram Alshich 77, brought in Darkei Teshuvah 141/38]
 Shach 141/25