Gallienus Antoninianus

cool coin and neato reverse....luna lucifera? so is she/he to the moon as sol is for sun? A quick Internet search didn't help much.

Luna Lucifera or the Lightgiver was often associated with women rather than the emperor himself. On this coin of Julia Domna the legend refers to Diana but the figure of a woman with crescent on her shoulders and bearing a torch is similar. Diana was paired with her brother Apollo as gods of sun and moon just as Sol and Luna were paired to show that light was under control both day and night. I'm not fully clear on when and how the two sets became separate but the cult of the sun (Sol) was very popular in the later 3rd century and we see more Sol coins than Apollo but earlier types with the radiate crown are more likely to be called Apollo. That brings question on whether the rayed crowned heads from the Greeks like those of Rhodes were considered Helios (=Sol) or Apollo.

Trivia: Of the major gods and goddesses, what one is distinct by having the same name in Greek and Latin? Apollo. I'd say 'unique' but we don't like to abuse that term when there might be questions as to who is major and whether Hercules and Herakles are different.