People keep saying "It's darkest just before dawn." That is simply not true. Darkness is symmetric with the night. It is darkest when the sun is farthest below the horizon, which is at true solar midnight. The sky is lighter before and after that point. (There are other lighting effects, but we're keeping it simple.)

Darkness is being confused with temperature. It typically gets colder throughout the night, with the rate of cooling greatest at midnight, but the cumulative effect of the cooling continuing until dawn. As an amateur astronomer who has experienced many cold nights standing around outside, the hours before dawn are when the optics of your telescope will become covered with dew or frost. The early morning hours are also when twilight starts creeping in and the darkness of the sky deteriorates.

I know the subtitle is not the point of this essay, but let's get it right, people!