What's a dark and "still" site?

   The Earth is shrouded in a thin bubble that we call an "atmosphere". The bubble is comprised of a soupy mix of air, moisture and pollutants, which is constantly bombarded and illuminated by the photons of our own artificial light. The bubble is not still or smooth, but is full of tides and ripples that are always in motion. As the ripples pass our field of view, celestial objects are alternately hidden and revealed in a strobing rapid cadence that we call turbulence. This is why stars appear to twinkle, and why it's so difficult to see objects in deep space with ground-based telescopes. The best observing sites are where the bubble is very dark, and very "still".

Left: NASA photo

    There are a few indicators you can use to tell how dark and still your location is. First, the more "still" the air is, the less stars will appear to twinkle. Second, the darker the site is, the blacker the sky will appear (especially in the eyepiece!). And third, the darker the site is, the more you can see. For instance, at a fairly dark site, you can count 5 stars in the little dipper with the naked eye. You may even see a little of the Milky Way overhead. At a very dark site, you can make out 7 stars in the little dipper, and you should see "structure" in the Milky Way (i.e: - two shades of gray, and a hint of the carpet of light associated with all those billions of stars).If you live in an urban neighborhood, the background sky in your telescope's eyepiece will appear anywhere from dark gray to pink. Sky backgrounds that are pitch-black are extremely rare, reserved for those "dark sites" that most of us only read about -- the desert Southwest, the Florida Keys, a mountain observatory...