asterism vs constellation

asterism

noun
  • An unofficial constellation (small group of stars that forms a visible pattern). 

  • A rarely used typographical symbol (⁂, three asterisks arranged in a triangle), used to call attention to a passage or to separate subchapters in a book. 

  • A star-shaped figure exhibited by some crystals by reflected light (as in a star sapphire) or by transmitted light (as in some mica). 

constellation

noun
  • An image associated with a group of stars. 

  • A configuration or grouping. 

  • Any of the 88 regions of the sky officially recognized by the IAU, including all stars and celestial bodies in the region. 

  • A fleet of satellites of the same purpose (such as the set of GPS satellites, or Iridium satcom fleet). 

  • An asterism, an arbitrary formation of stars perceived as a figure or pattern, or a division of the sky including it, especially one officially recognised by astronomers. 

  • A wide, seemingly unlimited assortment. 

  • A network of connections that exists between people who are in polyamorous relationships, for example between one person, their partner, and that person's partner. 

  • The configuration of planets at a given time (notably of birth), as used for determining a horoscope. 

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