The Bortle Scale
Utah is home to several "dark sky" parks, perhaps the most for a state in the US. Check that for me.
That "darkness" is a bit of a misnomer - on clear nights the sky is anything but dark. Really, what is meant is the air is clear and free of light pollution. This clarity is measured by something called the Bortle Scale. I'm pretty sure I was seeing Bortle 1 skies tonight, the clearest possible.