What is it? Where is it?

[TomK]

how about guessing or telling us what the glow above the horizon in the attached image is caused by?

If everyone else cries uncle I'll spill the beans.. but really this isn't rocket science.. i.e., there's only one plausible answer.

So you want everyone to "cry uncle" before answering? That's weird. Why not just answer, given there's only one that makes sense? Or do you just need some posters to support you first?