Question

why is space dark?........even there are many bright stars and sun too.

Answer 1

The color black usually signals the absence of light. But inside the solar system, space is filled with light. Light usually travels straight ahead in a line unless it reflects off of something or is bent by a lens,” explains Geza Gyuk, Director of Astronomy 

Answer 2

Answer: At night when that part of Earth is facing away from the Sun, space looks black because there is no nearby bright source of light, like the Sun to be scattered. If you were on the Moon which has no atmosphere.