Considering larger objects, a skyscraper has two tall antennae separated by 3 meters. Each antenna has one blue and one red light. You can resolve the two blue lights but not the red ones.
Assume that your pupils have a diameter = 2 mm at night, and that blue light's wavelength is 475 nm, while red light's wavelength is 650 nm.
Approximately how far are you from the skyscraper? (Also assume that you have 'perfect vision' limited only by diffraction.)
The Attempt at a Solution
I know the answer is 10km, but I don't know how to get that. I was trying to find a way to determine the resolution requirement, or something like that.