[derekp7]

I always just assumed that flat earth theory is some elaborate inside joke, that the practitioners all "get", and are collectively trolling everyone else. Somewhat like the illuminati theorists, etc. If you think about it, it takes quite a bit of effort to form a valid sounding debate on a topic that you don't believe in. And it is also fun coming up with defenses on either "side".

So here's a good one I came up with for the "round earth" side. The sun is always about the size of a dime held at arm's length, at sunrise, noon, or sunset. If there earth were flat, then the sun would appear larger at sunrise, smaller at sunset, when in New York, and it would be just the opposite (smaller at sunrise, larger at sunset) when in San Francisco.