perihelion vs solar apex

perihelion

noun
  • The point in the elliptical orbit of a comet, planet, etc., where it is nearest to the Sun. 

  • The highest point or state; the peak, zenith. 

solar apex

noun
  • The point to which the Sun appears to be moving with respect to the local stars 

How often have the words perihelion and solar apex occurred in a corpus of books? (source: Google Ngram Viewer )