I just noticed you both wear glasses.   You honestly cannot see the curve?   Hold a ruler up to it!
Were you thinking the earth was smaller for some reason, that a curve would be more than apparent?    It is, but not the size of the Astrodome!   :doh:    (did someone already mention this to you? It'd be like taking a picture of Mt. Everest barely hovering over it (not even an inch) with a camera the size of a grain of sand.      Remember the basketball curvature that some swore they could see but others agreed was flat?    
 Er, what you said  :noway: