Perhaps you should try some spelling variations:
practical astronomy » nautical astronomy, positional astronomy
optical astronomy » nautical astronomy, spherical astronomy, positional astronomy
patrick moocs » patrick moore, patrick mons, patrick moyes

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "the patrick moocs ((practical astronomy) OR (optical astronomy)) surveys".
• Adding a wildcard symbol may retrieve word variants: the patrick moocs ((practical astronomy) OR (optical astronomy)) surveys*.