the earth is concave. these three pictures prove it. upward curving in all three. funny, the whole piece is considered one panoramic image when its just three individual pictures side by side...why would you need to break it up that way, unless it would show a clean upward curve! can't have that now can we!
plus, if the earth were a ball globe, wouldn't the horizon be curving downward?!? yes, it should, but it doesn't. cuz its not a ball globe. nor is it flat.