IT ACTUALLY IS POSSIBLE TO BE ALLERGIC TO THE SUN. DAMN!

Hahahhaha. I googled sneezing in exposure to sunlight, and found a Wiki link on the Photic Sneeze Reflex. Awesome stuff.

Apparently your optic nerve and that nerve that makes you sneeze are associated. But this only happens in a small percentage of people- it's a congenital malfunction in nerve signals. So anyway, in the presence of bright sunlight (now I feel like I'm talking about the food making process in plants), the sneezy nerve is triggered and well, you sneeze.

Weird, but super cool. Now that's one more thing that'll make you sneeze apart from pepper or feathers.