When a jet engine has its afterburner engaged, a bunch of fuel is dumped into the back of the engine for additional thrust. This burning fuel causes the exhaust and inside the engine to glow brightly, which is quite visible even to the casual observer. However, when the afterburner is not engaged, there is no visible light at all that I've seen coming from the engine's exhaust. I would think that the fuel burning process of a normal jet would be visible out the back as well, just not as noticeable as afterburner exhaust, but that doesn't seem to be the case.
Is there visible light from the exhaust of a non-afterburner jet and I'm just not seeing it, or is the burning fuel inside the engine so much that it just doesn't get out.