> 9) The other planets are also flat and only appear round because they are tidally locked with respect to the earth. Much harder to argue for this these days

> 9) The other planets are also flat and only appear round because they are tidally locked with respect to the earth. Much harder to argue for this these days now that amateur telescopes/decent camera optics have become reasonably cheap and cameras too. Jupiter has a rotation period of only ten hours, so one can easily see it rotate within one night. The sun takes a bit longer since it has a rotation period of 25-38d (depends on the latitude which is quite interesting) and if there are no sun spots it's kind of hard to tell.