I remember flying at night in New Zealand, in the vicinity of Auckland. Toward the ountryside the terrain was invisible - pitch black - and a little worrying seeing as I was flying between high ground on either side! All I could see, apart from an occaisional farmhouse, was stars above me. Over the city of Auckland it was another matter. Without a wartime blackout, there was a huge scattering of orange lights. Nonetheless I could pick out individual lights even from two or three thousand feet.
The instructor, being something of a hard task master, asked me to fly a steep turn (and then told me he'd recover from the resulting dive). There was little or no external visual reference. You just have this mental image of where you are and what attitude your aircraft is in, and your instruments are your only confirmation.
When we landed at Ardmore, the lights were activated by radio blips. I did however forget to switch on the aircrafts landing light, and for that matter so did the instructor. So we landed while another aircraft was crossing the runway. No actual risk of collision, but a little alarming for all concerned.