Stars put out quite a bit of light in remote areas, cloud cover may block ~75% of this, but it's still far from 'pitch black'. One of the stranger things about caving is it just keeps getting darker as you go deeper.
PS: As a kid I used to spend a lot of time walking around in starlight. I only ever really used a flashlight inside. I moved much closer to a city and light pollution is terrible to the point where there is little need to turn lights on in my apartment unless I want to read something.
PS: As a kid I used to spend a lot of time walking around in starlight. I only ever really used a flashlight inside. I moved much closer to a city and light pollution is terrible to the point where there is little need to turn lights on in my apartment unless I want to read something.