have you ever got the feeling that we don't see that many stars in the night sky? the reason why is that some people that live in cities with too many lights is called light pollution. they can affect the sky and we can't see the milky way with fulled stars at the night sky. the light can affect people's sleep. its best if you go to a place without light for example like national park. (i live and new york almost near new york city and i dont see any stars at the night sky but a couple. if you want me to proove it go outside and see the night sky if you have to many lights at your state/COUNTRY.