The eyes of human beings can not keep staring straight at the sun all the time. It is because that the sun light is very very strong, the crystalline lens and vitreous body of the eyeballs are just like a condenser lens (convex lenses). When the eyes are staring straight at the sun, through crystalline lens and vitreous body, the sun light will converge as a small point of light of very high power at the retina of the eyeballs, which can easily burn the retina and do great damage to the eyes. Therefore, you had better not stare straight at the sun. Wearing a pair of sunglasses could effectively protect your eyes from the ultra-violet light when you are outside on the day of great sunlight.
If you stare at the sun for a long time, your eyes may get burning, red and dry. The uv rays in the strong sun lights will harm your eyes nerves. In addition, your eyes may feel itchy after the exposure at the strong sun lights. I suggest you not to do this. You could wear the sunglasses which will protect your eyes to some degree.
Well, it is not a good idea to have a try. Staring at the sun can cause serious vision damage. The sunlight which enter and focus on your retina will burn your retina and cause permanent vision loss. When the damage is done, it could be irreversible. The blind spot in your vision field can never be removed.