why is it when you watch the sun you sneeze??

Question

when watching the sun or even a light bulb one eventually begins to get the urge to sneeze.

Answer 1

It seems you have a photic sneeze reflex, a genetically inherited condition. (see source below for more information)

Answer 2

Ah Hah ! Ven you is vatching at za Sun or a lightning bulb, you is looking at a energetic light source und not a reflected light sorcerer like da Moon or a portrait of za Napoleon Boneypants. You have your head tilted up so all them little energized photons is shining up into za schnoz und dancing all around tickling da tiny hair frolickles making you go kerchoo all over za place.
To keep the little rascals out, grow a mustache like mine.