> It makes me wonder, why is it that our eye in real life sees straight lines as straight, the way this demo renders the image? Not always. Next time the Sun a

> It makes me wonder, why is it that our eye in real life sees straight lines as straight, the way this demo renders the image? Not always. Next time the Sun and the Moon happen to be in view at the same time, look at the dividing line X on the Moon between the parts illuminated and in shadow. Then draw a straight line Y from the Moon to the Sun. Common sense tells us that the two lines are perpendicular, but often this is not the case. I don't understand it completely myself, but it is something to do with us residing on a curved surface.