planetoid vs space satellite

planetoid

noun
  • A dwarf planet 

  • An asteroid of any size 

  • An asteroid-like body in an orbit beyond the asteroid belt, such as a centaur or Kuiper belt object 

  • A larger, planetary, body in orbit around the Sun, such as Vesta or (candidate) dwarf planets such Eris or Sedna 

space satellite

noun
  • A crewed or robotic spacecraft designed to orbit the Earth 

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