I don't think it's worthwhile to debate flat-earthers. And I didn't initiate this debate. But one thing leads to another, so I will say a bit more. There are folks more qualified than I to discuss this. Since, however, I doubt there are any scientifically qualified flat-earthers, my only disadvantage is that if you spend all your leisure time defending a conspiracy theory, you have prepared answers to stock objections. Likewise, you can cite factoids that ordinary folks haven't investigated.
1. I Googled some modern flat-earth maps. One thing I notice is that there doesn't seem to be any standardization in flat-earth circles regarding the distribution of oceans and contingents. Flat-earth maps vary.
That, itself, is problematic for zetetic astronomy. If you can't show us, in detail, what the flat earth looks like, what's your empirical evidence that the earth is, indeed, flat?
2. That said, the maps had something in common. They resemble a projection map of the globe. Reducing a global image to a flat map.
The difference is that flat-earth maps take a topdown approach whereas conventional maps take a sideways view. The flat-earth maps I saw have the north pole at the center, surrounded by the continents. Continents in the northern hemisphere are closer to the center, while continents in the southern hemisphere are closer to the circumference. Flat-earth maps vary somewhat on where to put the oceans.
3. However, this immediately poses problems for flat-earthers:
i) Since, on their view, the sun shines directly on what would be the northern hemisphere, how does that square with climate zones?
ii) Likewise, how does that square with time zones? Suppose a flat-earther views the sun like a spotlight that moves incrementally across the terrestrial disk. Even if that would explain longitudinal alternations in day and night, how would that synchronize with latitudinal alternations? Everything above and below the spotlight would be dark.
iii) Even more problematic, once the sun completes its progression from left to right, it would have to travel under the flat earth to resume the cycle. But that would plunge the entire earth into darkness for however long it takes the sun to pass under the flat earth.
4. It's demonstrably the case that a pilot can, by flying continuously in a straight line, return to his point of departure. How is that possible on a flat earth?
Sure, if you fly in a circle on a disk, you can return to your point of departure. But I'm talking about a flight path in a straight line.
It is, of course, possible for a trajectory to be both straight and circular. But that only works on a sphere where you have an extra coordinate.
5. I should have been more explicit about what I mean regarding satellite photography.
i) I'm not primarily alluding to the fact that the earth appears to be spherical according to satellite photography. Rather, this is what I mean. Consider a class room globe. You can only see whatever part of the earth is facing the viewer. To see the whole earth, you must either walk around the globe or remain in place and spin the globe.
ii) We have an equivalent situation with spy satellites and earth observation satellites. They can't photograph the earth all at once. They only display a portion of the earth facing the satellite.
But as the earth rotates under the satellite, in the course of an orbital period the satellite can photograph the entire earth. That makes perfect sense if the earth is spherical and spinning on its axis.
iii) If, by contrast, the earth is flat, why can't we see the whole earth from space, all at once, just like we can see a flat map of the earth at a glance?
iv) And even if a flat-earther postulates that a satellite is too close for a wide shot, there's still another problem. Suppose a satellite begins to photograph the earth at the meridian. After an orbital period, the meridian is once again facing the satellite. Continuous photography tracks the continuous counterclockwise rotation of the earth.
If, however, the earth is flat, and the satellite is photographing the earth from left to right or right to left, then it must reverse direction to return to the starting-point. Yet, when photographing the earth from space, there is no break. You see the same portions of the earth coming into view in the same direction. Admittedly, I'm no expert on satellite photography, but do flat-earthers have any hard evidence to the contrary?
6. In addition, zetetic astronomy must rewrite the laws of physics. That's extremely complicated. Has any flat-earther produced detailed alternative physics to make it work? Is there anything comparable to the level of detail and empirical confirmation in standard astrophysics?
7. Finally, flat-earthers have to prop up their theory by invoking conspiracy theories to discount empirical evidence that runs counter to zetetic astronomy. Now, I don't deny the existence of conspiracies. However, a conspiracy theory loses credibility when the scale of the conspiracy involves too many independent players, sometimes with rival motivations. As well as too many people who must somehow be kept in the dark.