@sapphire @Saber @charliebrownau @grey @Nudhul @bleedingphoenix I'm not sure how those masses would work, but I don't see any model that could cause a circular shadow/light to be projected onto the moon at night when the sun is on the other side of the pancake plane.

But also, if they're only 3k miles away, you couldn't possibly navigate using the sun because it would change apparent position drastically based on where you are. People have been navigating using the sun for forever, but especially in the age of sail to cross the oceans. You could test this simply by taking a commercial flight somewhere and measuring the sun's angles before takeoff and after landing. If their model lined up they could test it right now on almost no budget.