nadir vs perihelion

nadir

noun
  • The point of the celestial sphere, directly opposite the zenith; inferior pole of the horizon; point of the celestial sphere directly under the place of observation. 

  • The lowest point; time of greatest depression. 

  • The axis of a projected conical shadow; the direction of the force of gravity at a location; down. 

verb
  • To extend (a beehive) by adding an empty box at the base. 

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. 

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