Board Thread:General Mod Discussion/@comment-108.35.168.58-20170531205843/@comment-25101089-20170601221139

Fun fact (and this is one of my favourite fun facts) - towards the later years of his life, one of the things Tolkien attempted to do was rewrite his mythology to bring it more into line with known science. This included revising the history of the Elder Days such that Arda had always been a round planet, the stars and Sun and Moon had existed since the creation of the world, the Two Lamps never existed and were a fabrication of Númenórean mythology (gasp!) - in fact, the entire Silmarillion was recast as a flawed interpretation of Men rather than a true history of the world by Elves.

But he never finished it, so the version we have is much more consistent and complete.

Round World Version of the Silmarillion