Human vision is strongly exponential in terms of brightness sensitivity. In photography we talk about “stops” which are powers of two of light intensity. Consu

Human vision is strongly exponential in terms of brightness sensitivity. In photography we talk about “stops” which are powers of two of light intensity. Consumer digital cameras around 2005 could see maybe 9 stops for a single exposure. Now they can do maybe 10-14 (which means they’re ~30x more capable of a range of light values). Human vision can handle adapting to a much wider range because we don’t see with a single exposure. The iris adjusts, we saccade around the scene collecting data and mentally aggregating it. A good approximation is the iPhone’s panorama mode. It’s really recording video and adapting the dynamic range window as you pan, so the sun tends not to blown out the rest of the image. The main point I want to make is that outdoor sunlight on earth is indeed a million times more intense in terms of lux, lumens, candelas, or watts, than interior living (say lit by a nightlight or candle). This works out to 20 stops. - 100,000 lux outdoors on earth - 0.1 lux finding your seat in a theater So we can see already when the light is 0.0001% the power of “Earth, noon”. We could see Uranus. Sunlight on earth is extremely intense! You feel it direct on your skin like being 2 feet from a fire. It damages your cells. It evaporates the sea and propels hurricanes. I’d we hadn’t evolved to live with it, we’d find it quite intolerable.