From: Rabbi Moshe Sofer
To: Rabbi Hersh
A synagogue window featuring a circular sun image with radiating rays and the Tetragrammaton inscribed inside violates two distinct prohibitions: making an image of a celestial body transgresses a biblical negative commandment, and retaining it is rabbinically prohibited due to suspicion of idolatry. Additionally, the design imitates Christian iconographic conventions depicting divine glory, which is especially objectionable on the eastern wall facing worshippers. The ruling requires removal of the window.
Source: Shu"t Chasam Sofer YD §129