Question

Why does the sky appear dark instead of blue to an astronaut ?

Answer 1

When sunlight strikes molecules in our atmosphere, the light is redirected in many directions. The blue light is scattered more than red light causing the sky to be blue. In the space, there is no atmosphere. So, light will not scatter in space, hence it will look dark to an astronaut instead of blue.
Hope this helped

Answer 2

Explanation:

The sky appears dark instead of blue to an astronaut because there is no atmosphere in the outer space that can scatter the sunlight. As the sunlight is not scattered, no scattered light reach the eyes of the astronauts and the sky appears black to them.