noon vs solar day

noon

noun
  • The time of day when the sun is in its zenith; twelve o'clock in the day, midday. 

  • The highest point; culmination. 

  • The letter ن in the Arabic script. 

verb
  • To relax or sleep around midday 

solar day

noun
  • one day of solar time, the time between successive noons; the time in which a planet such as Earth apparently rotates once around its axis, relative to the sun (on Earth about 24 hours as an average - the length of solar day is not constant throughout the year) 

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