Why does the astronaught see the sky color black onstead of blue?
Answers
There's no such thing as sky. What we see directly is space. You can see that at night. During the day, due to the sun there's scattering of light and blue scatters the most due to earths atmosphere hence the sky.
Blue light has the shortest wavelength and the highest frequency in the visible light spectrum. It is scattered more than red light which has the longest wavelength and the shortest frequency. So, when the Sun is high in the sky, blue light is scattered in all directions as sunlight passes through the atmosphere and we see the sky as blue.
But during sunrise or sunset it's a different case. When the Sun is close to the horizon at sunset or sunrise the practical distance between us and the sun is more. Blue light as it scatters more is lost in the atmosphere. And having a short wavelength it doesn't reach the observer. Red light on the other hand has longest wavelength in the visible spectrum. Hence, we see the scattered red sky during sunrise or sunset.
For an astronaut, there's no atmosphere in space to scatter light. Hence, he see's the black space.