I define 'dark conditions' as the absence of other light sources or very few and far between. And it is entirely possible to be seen from a mile away. Just don't expect to see that distance yourself.

Here's my (flawed?) logic on the being seen from a mile away. A light source can be detected at a greater range than said source can project a beam (usually). Take a flashlight and have some one hold it while you move away from it. Have them call out when you are no longer visible to them from the beam. Keep moving away a bit before turning back. You'll see that speck of light before you enter it's beam. Similar effect from street lights- you'll notice it before you get close enough to notice any shadows that it is creating from other objects.