inexplainable vs unearthly

inexplainable

adj
  • That cannot be explained. 

unearthly

adj
  • Strange, enigmatic, or mysterious. 

  • Ideal beyond the mundane. 

  • Ridiculous, ludicrous, or outrageous. 

  • Preternatural or supernatural. 

  • Not of the earth; non-terrestrial. 

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