Light coming from nowhere? In Cycles I'm getting this mysterious light that doesn't have a apparent source. In Eevee it doesn't happen, but in Cycles it does. There is one, and only one, small lamp at the head of a bed. That's the ONLY light source. But even the exterior of this room is brightly lit.
Here's the ONLY light source in this scene.

But here's a shot from farther away lit only by dim starlight.

And here's what it looks like in Eevee

Now in Eevee you can't even see the light from the small lamp, and that makes sense. Eevee doesn't do light from things like a small lamp in a room without a lot of fiddling around with light probes.
But in Cycles there's no reason I can fathom for the outside of a room to be lit up like that. I even tried this with a plain black background, and that blasted mystery light is still there. That one small lamp really is the ONLY source of light. There are no other lights of any kind anywhere in the file. No hidden &quot;sun&quot; lights, nada. I checked to make sure that blue material isn't emitting light. It isn't. Emission is set to zero.  And the strength of the stars in the background can be set to zero with no effect at all on that bizarre exterior &quot;light from nowhere&quot;.
Any ideas on where the mystery light is coming from and how to get rid of it? Anyone?
The default color for the world is a light gray. Think of it like a giant sphere that surrounds the scene that is emitting light.

To make the world black, change the color, or disconnect any nodes to the surface of the world, or bring the Strength to $0$