Please answer all questions

1			Why does food taste differently when you have a stuffed nose?
2			At night, what color of light is used in the area of a submarine where the periscope is located?
3			If you are looking at a faint star at night, is it best to look directly at it or a little to the side of its expected position?
4			Most stars are colorful: red, green, blue, or violet. Why can't we see any of these lovely colors here on earth unaided?