Building a Universe populated by stars identical to our Sun and taking into consideration the wave-particle duality of light, the biological limits of the human eye, the finite size of stars and the finiteness of our Universe, we conclude that the sky could very well be dark at night. Besides the human eye, the dominant parameter is the finite dimension of the Universe: point-like stars in an infinite Universe lead to a night sky infinitely bright while an infinite Universe with finite-sized stars leads to a night sky with finite luminosity, but only 1000 times weaker than our Sun. In order to get a dark sky at night, one must use the finiteness of the Universe. (Contains 1 table and 2 footnotes.)