The exhaust temp of a rotary is hot.  I get that.  But should the exhaust be glowing orange?!!

I had my older son do a tuning run-up, while I checked out what I could from the outside.  Dusk was setting in hard, so it wasn't that bright outside.  But, I didn't expect the exhaust to be glowing so brightly.  The entire exhaust from the collector back was past cherry red.

Is this normal?  I'm beginning to expect that my AFR gauge is lying to me.