Subject: Up or down? North or South?

When the Earth is represented in texts, films, science programs, etc., the 
view
shown is always "north" at the top - "south" at the bottom.  The same is 
true
of representations of other planets.  They are always shown with the same 
end
up.  Since everything is floating in a much more vast Cosmos which can be
viewed from any angle, how do we know what is up and what is down?  Who 
decided
that one?  Surely, aliens would not have our perspective.

Re: Up or down? North or South?