Why does looking directly into the sun with both eyes hurt, yet if you do it with one eye, it does not?
As you no doubt already know, looking directly into the sun with both eyes hurt.
However, if you close one eye and only look directly into the sun with one eye, it is tolerable.
Why do you suppose that is?
Some sort of neural stimulus overload?
This question is in the General Section. Responses must be helpful and on-topic.