Re: Can I say 'she' referring to a planet?
It's a common literary device to refer to inanimate objects as "she." Some otherwise normal men speak lovingly of their cars as "she."
However, choose carefully. Most of the planets are named for male gods, so there might be some discord between "she" as a planet when "he" was a god. Venus, obviously, works in the female.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.