Answer:
Against the sun I protect your eyes and am often worn on the face of spies
I am essential to life on earth! I am split into thirds. Two thirds are the same. One of the thirds is 8. The other two are 1 each.
I am not alive but I can die. What am I?
I am black when you buy me, red when you use me. When I turn white, you know it's time to throw me away. What am I?
I open to close but I close to open. I'm surrounded by water but I'm never soaking. What am I?
I am rarely touched but often held. If you are smart you'll use me well. What am I?