Mother Earth vs Terra

Mother Earth

name

  • The goddess of the earth in various cultures. 

  • The personification of the Earth, (chiefly) conceived as a fertile, nurturing, and loving mother. 

Terra

name

  • The Roman earth goddess, equivalent in the interpretatio graeca to Gaea. 

  • The planet Earth. 

  • A female given name. 

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