The darkness and the light

The sky is not as it seems. Certainly, gazing upon it on a clear night you see so much: stars, planets, the glow of hot gas here and there... but there's also darkness. Look at the Milky Way, its stream split down the middle by a rift of black. Gape at a gaudy nebula, and you'll see it pocked here and there by pools of black. But what is inky pitch to our eyes glows with a cold light to those attuned to it. Tell me, what do you see here?