Brain Teaser Diagram!

Hi there! I'm sorry this is my first post, but I never knew this site existed, and I'm looking forward to contributing to the forums on here.

I am updating the switches and receptacles in my house and came across this mess. Left switch is for a hallway light, middle switch is for the receptacle below this box, and the rotary switch on the right is for the front porch light on the other side of this wall. I can see that the hot (black) on the rotary switch jumps from wire nut to the left. The red and blue wires on the rotary switch go to the red and black coming out of the armored cable at the top of the box. My question is, why are there three wires going to that light out there? I don't believe it has a timer or motion sensor (but I will take the light down when I get home from work to see how many wires are coming out of it). If not for the light, is it possible the third wire goes somewhere else, like a no-longer-existing light fixture that was at the end of the walkway or something?

Thanks in advance!
Mike

 

Is there another switch somewhere which also controls that light?

 

I suspect it is wired to bypass a photocell, timer, or motion detector at the light (or a second light). You need to confirm if the switching sequence is: black-to blue and black-to-red. If the sequence is black-to-red, red-to-blue, blue-to-black (a selector switch) then some other scheme is in play.

 

Either bypass a photo cell timer or maybe two bulbs in the fixture?