Latitude.
Geographic longitude will affect the "time" you see something in the sky realtive to someone *not so far away*
Geographic longitude will affect the "position" of that something in the sky by someone *not so far away*
Basically, as you travel south, the position of the celestial objects in the sky appear farther north.
Once you move far enough south (from the north) that object "crosses" the point where it can be seen directly overhead, and instead of being visible "right-side-up" (from your perspective) in the south, it appears "Upside-down" and in the north.
Think of it this way. Hold a book in front of you, so that the words are upright and readable in teh normal sencse.
Now, slowly move the book higher and higher, until it is over your head.
Keep moving it (you might need a friend to hold if for you, because this creates an awkward body position) past the point of overhead. It is now "behind" you, but still visible if you turn and face the opposite direction as you were facing at first....
But, wait, all the letter are upside down!
