I mean, on earth, I assume that as sun shine on the day time part of earth, light are dispersed by the sky making our day time sky blue? But how does light gets distributed outside of our atmosphere?
Astronauts in the ISS experience 15 sunsets and sunrises every day because the ISS completes 1 full orbit of the Earth ever 90 minutes. That’s not really important though because they use the same 24 hour clock that we use.
>But how does light gets distributed outside of our atmosphere?
It doesn’t. That’s why space is black. You are correct in your assumption that the sky is blue because the atmosphere scatters blue light. The ISS is in space and (mostly) out of the atmosphere, so there’s nothing to scatter the light. That’s why photos of space are always black. Astronauts will always see space as black when they look out the window regardless of whether the sun is visible or not. [Here is a picture from the ISS during daytime](https://static.independent.co.uk/s3fs-public/thumbnails/image/2014/08/21/11/RTR2OVXV-v3.jpg?quality=75&width=990&auto=webp&crop=982:726,smart). You can see that the sun is visible and extremely bright and the Earth is well lit, but space is still black.
The ISS sort of experiences a day and night cycle every 90 minutes. This is the time it takes for the space station to orbit the Earth, and every orbit the Earth eclipses the Sun making it dark. You are right that even during the day the sky is dark black on the space station because there is no atmosphere to scatter the light. However it is still very bright as the sun is shining and reflecting off every surface. So there is still daytime as such and all cameras needs to be set to daytime mode in order to not be overexposed, similarly the stars and planets is not visible because the sun is so much brighter.
Not really. There’s no atmosphere in space, so the outside of the ISS will always look dark except for the stars, and the light reflecting off planets/moons/other objects.
The ISS’s “night” is when the Earth eclipses the sun, and their “day” is when the sun is shining. This happens several times in a 24 hour period, it’s quite a rapid cycle.
Presumably they still try to sleep in a single ~8 hour block though.