Earth vs Gaia

Earth

name
  • The personification of the Earth or earth, (chiefly) as a fertile woman or (religion) goddess. 

  • The third planet of the Solar System; the world upon which humans live. 

Gaia

name
  • A Greek goddess, the personification of the earth, and one of the primordial deities from whom all the others descend. 

  • The ecosystem of the Earth regarded as a self-regulating superorganism. 

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