Did you know that you have a blind spot? Try it out yourself. Here's what you do:
1. Cover your left eye
2. Look at the cross
3. Move your head forward and back until the dot disappears. For most people, that point is about a foot away from the screen, but everyone's eyes are different.
The reason why we have a blind spot is because that is where the optic nerve connects to the retina. Pretty awesome, huh? We don't really notice it because the blind spot is in the opposite location on the other eye.