Polaris vs pole star

Polaris

name
  • A type of U.S. ballistic missile, capable of carrying a nuclear warhead and designed to be launched from a submarine. 

  • The pole star, a trinary star in the constellation Ursa Minor that currently lies close to the north celestial pole; Alpha (α) Ursae Minoris 

pole star

noun
  • 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. 

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

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