the stars and moon are light sources, but are not enuff light to interrupt the dark of night. on a harvest moon, you can see fairly well in a meadow, it looks like black & white in a way, you can see leaves and shapes, but not colors.. my point is, if your light leak is merely enuff to see a bit inside the room, you'll likely b ok... but if there's enuff light you can see color of leaves/stems, you're likely screwed...