Count Definition and 152 Threads

I was looking at some maps of the known universe (http://www.anzwers.org/free/universe/) and a question occurred to me - how can astronomers say how many stars are in a certain galaxy? What method is being used to count them? Is it direct observation or is it some kind of formula?

What is the official count of one second? What I mean by this is: how would one go about measuring one second exactly? Basically, at the creation of a second, how was it measured? Also, if a day is 23 hours and 56 minutes, wouldn't our clocks be off 4 minutes after each day? I understand the...