Question

Why are there so many astronomical observatories in southern Arizona?

Answer 1

It has warm and dry weather. In order to observe space you need an un-obstructed view. Southern Arizona does not have much moisture, this means there are not as many clouds to obstruct the view.

Also the population is very sparse. Meaning less man-made lights to get in the way

Answer 2

The state's open and high spaces are great for observation!

I hope this helps!