Or be switching them be correct, since the original assignment was a historical convention? Or do neither suffix convey enough meaning; we can create 'bionomy' if 'biology' was already taken?

  • By now they're proper and proprietary names. Astrology is what astrologers do, and astronomy is what astronomers do. Both have to do with stars, but in completely different ways and using completely different concepts of star -- just as different as the Hollywood concept of star. Astronomers don't like to be called astrologers, and vice versa. Commented May 24, 2014 at 19:01
  • Clear as crystal. Commented May 24, 2014 at 19:05
  • All words are conventional. The history of words is often interesting, but utterly unreliable in determining the current meaning. You are welcome to use words in unconventional ways (e.g. swapping two established words), but you risk being misunderstood if you do so.
    – Colin Fine
    Commented May 24, 2014 at 22:01
  • @Colin Prof Pullum wouldn't welcome you. Commented May 24, 2014 at 22:26
  • Another, arguably better, word for astrology is astromancy. "divination by stars".
    – Neil W
    Commented May 24, 2014 at 22:31

3 Answers 3


I've often wondered the same thing. I expect astronomy was coined to differentiate the scientific study of heavenly bodies from the pseudoscience of predicting fortunes from them. Had astrology never existed as a term, it seems like a likely candidate as the term for what we know as astronomy.

These kind of etymologies are never going to be quite right, of course—physicists and physicians have little to do with each other, but the words come from the same root.

Another question about the etymology of astronomy. Given that the suffix -nomy refers to systems and rules, it seems like the term should really refer to the rules that govern the heavenly bodies (compare to economy and taxonomy), rather than the study of those rules and the bodies. Why isn't the field of study called astronomics (like economics)?


Astronomy is a science which involves studying everything outside our planet earth, looking through telescopes, studies and research etc. On the other hand Astrology deals with the positioning of planets and stars and their effect on humans and events (astrology is not a science but a belief that stars and planets effect human lives). Hope this helps. Ciao:)

  • Astonomy is indeed a science. Astrology, like numerology, is for the intellectually-challenged >;-) Commented May 24, 2014 at 20:41

According to the etymology of the terms, it appears that astrology was used since the beginning with a scientific meaning, while astrology which developed later, was used to refer to both astronomy (natural astrology) and astrology ( judicial astrology). The later and current meanings of these two terms appear to reflect their original definition and evolution trough the centuries.

astronomy (n.)

c.1200, from Old French astrenomie, from Latin astronomia, from Greek astronomia, literally "star arrangement," from astron "star" (see astro-) + nomos "arranging, regulating," related to nemein "to deal out" (see numismatic). Used earlier than astrology and originally including it. Þer wes moni god clarc to lokien in þan leofte, to lokien i þan steorren nehʒe and feorren. þe craft is ihate Astronomie. [Layamon, "The Brut," c.1200]

astrology (n.)

late 14c., from Latin astrologia "astronomy, the science of the heavenly bodies," from Greek astrologia "telling of the stars," from astron "star" (see astro-) + -logia "treating of" (see -logy).

Originally identical with astronomy, it had also a special sense of "practical astronomy, astronomy applied to prediction of events." This was divided into natural astrology "the calculation and foretelling of natural phenomenon" (tides, eclipses, etc.), and judicial astrology "the art of judging occult influences of stars on human affairs" (also known as astromancy, 1650s). Differentiation between astrology and astronomy began late 1400s and by 17c. this word was limited to "reading influences of the stars and their effects on human destiny."

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