Perhaps you should try some spelling variations:
practical astronomy » optical astronomy, positional astronomy
astronomy surveys » astronomy survey, astronomy surveying, astronomy survives
astronomy sergey » astronomy survey, astronomy seven, astronomy large
moocs practical » books practical, mics practical, colts practical
moocs nautical » hoc nautical, logs nautical, nos nautical
patrick moocs » patrick moore, patrick mons, patrick moyes

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (( the patrick moocs practical astronomy sergey ) OR ( the patrick moocs nautical astronomy surveys )).
• Adding a wildcard symbol may retrieve word variants: (( the patrick moocs practical astronomy sergey ) or ( the patrick moocs nautical astronomy surveys ))*.