הארץ גדולה מן הירח כמו ארבעים פעמים
I am curious if anyone has an idea where the Rambam got this from. The Rambam writes in Hil Kiddush haChodesh (ch 17) that the ancient Greeks figured out the math and astronomy needed to calculate our calendar. It seems that the Greeks already knew that the moon was about ¼ the size of the earth, so where did the Rambam get the figure 1/40 from? (I am not concerned with the number being off – I am just looking for a source.)
I'm tempted to suggest that there is a printer’s error here and the Rambam should read "k'mo arba" instead of "k'mo arba'im" (I haven’t checked the Frankel edition to see if there are other girsa’os).