Science!

Optimus Prime said

This article doesn't say but now I'm curious how far out you'd have to be for it to be super dark in space

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I dont think it would ever be super dark anywhere in space. If they still have that much light intensity past the heliosphere (compared to 15 times more the amount of light earth sees on a full moon night) and Alpha Centauri only being about 4 light years away and that Rigil Kentaurus (also known as Alpha Centauri A) is 50% bigger and Brighter than our own sun, I think you would have light from neighboring star systems before you get far enough away to lose light from the sun (or your closest star)

Now, as you begin to enter voids that have mass and matter free floating, like gas clouds and nebulas, it may become completely dark, but that's not because you are so far away from the light source but because you are being surrounded by light absorbing/blocking matter.