Why isn't it any other color? Can it be explained?
Black is the absence of color.
The sky is blue because the air molecules scatter light so that you see not only light coming directly from the sun and stars but also all of the scattered light that eventually gets to your eye.
In space there is (almost) nothing to scatter light so if you are looking directly at a start you will see light from it- but no light beteen stars. No light means no color and, as Russ Watters said, no color means black.
Also see Olbers' Paradox: http://en.wikipedia.org/wiki/Olbers_paradox
More specifically, if you're seeing black, it means no visible light is scattering towards you from the region you're seeing black.
Olber's paradox, not enough galaxies and stars to fill in the gaps. Olber deduced our universe cannot be both spatially and temporally infinite.
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