It is a biggest question asking why so many person, why is there so much light on earth, but also non once you leave our planet? 

On the earth, we can see day and night vision because the earth spins on its axis, and the sun illuminates either hemisphere. It is very interesting to say that our star shines on the Moon too, but the sky about it is always black. Thanks to our God, we can see light on the earth because the unique atmosphere surrounding our Earth. The atmosphere is full of dust, dirt, gases and water drops, together all these things, which all act like tiny mirror and reflect the sunlight. When sunlight bumps into the small particle, it diffuses and creates different colours. Therefore we see a blue sky and all those spectacular shade during sunrise and sunset. 

That is way, there is no atmosphere there is no light. All of the above know that moon has no atmosphere the sky will be black. You will be able to see the stars even when the sun is blazing on the surface during the lunar day. 

Same condition with space, the space filled lost of different gases but it has no atmosphere. Without atmosphere, without molecules, the sun's rays can not diffuse in many colours, again we see the black sky in space. In other words we can say that space is empty. That's why even when the sun is shining space looks like a black void. Unfortunately, one day the earth's atmosphere disappeared, it'd be just as dark as it is in the space or on the moon. 

Recently research shows that the sun is not only one star ( source of light)  in the universe. If the other biggest stars, almost very big even our sun, why the outer space is always black? 

In 16 century, a scientist revealed that the universal had no end, and the stars in could not be counted. Why we cannot see other shining Star in the night sky? It is the biggest question of our scientist they are working on this theory may be answered in future.