Yes they are. I've only ever fiddled a little bit
with telling time
by the moon, but I did build a sundial at Pole - it was easy - the
normal calculations all cancel out (think of "tangent of 90 degrees"),
and I effectively made what looks like a dartboard, divided into 24
equal-angle slices. Piece of cake (or is that pi?)
At the pole... That's cheating!
So, if you want to know what time it is during July, you have to call
someone at the other pole?
See ya, SteveRob