cynosure vs pole star

cynosure

noun
  • Something that is the center of attention; an object that serves as a focal point of attraction and admiration. 

  • Ursa Minor or Polaris, the North Star, used as a guide by navigators. 

  • That which serves to guide or direct; a guiding star. 

pole star

noun
  • A person, principle, or thing which acts as a guide; a guiding light; also, something which attracts much attention; a centre of attention. 

  • The star visible to the naked eye which was in the past, is now, or will be in the future nearest a celestial pole of a planet. 

How often have the words cynosure and pole star occurred in a corpus of books? (source: Google Ngram Viewer )