Disclaimer: I'm an astronomy noob
You sometimes see in (B?) movies, that they infer dates from sky patterns. I was asking myself if you can encode a place and date in a mostly meaningful pattern? How would you do it? Would it be possible?
I was looking at 1 and maybe the relation between the visible planets? (Moon, Mars, Saturn)
Why: I want to make something special for my girlfriend (who likes "stars"), the date is special to us.