After watching the Nova on Galileo again I am struck by a question that
comes up in my classes every year for which I don't have a clear answer.
With all the pre Copernican emphasis on heavenly objects being based on
the "perfect sphere" what was the thinking at that time about the moon
which to the naked eye looks far from "perfect". How did the naked eye
appearance of the earth's moon fit with the "perfect spheres" ideas from
Ptolemy through Copernicus?