as·​tron·​o·​my ə-ˈsträ-nə-mē How to pronounce astronomy (audio)
plural astronomies
: the study of objects and matter outside the earth's atmosphere and of their physical and chemical properties

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The Difference Between Astronomy and Astrology

Some may find it easy to confuse astronomy and astrology. At one time, these two words actually were synonymous (that is, astronomy once meant what astrology means today), but they have since moved apart from each other. In current use, astronomy is concerned with “the study of objects and matter outside the earth's atmosphere,” while astrology is the purported divination of how stars and planets influence our lives. Put bluntly, astronomy is a science, and astrology is not.

Examples of astronomy in a Sentence

Recent Examples on the Web In Southern California, this should occur around 5 or 6 a.m., according to Paul Robertson, an associate professor of physics and astronomy at UC Irvine. Summer Lin, Los Angeles Times, 22 May 2024 Western astrology is based on Greek astronomy and aligns with the Gregorian calendar, while Vedic astrology draws heavily from the Vedas. Skyler Caruso, Peoplemag, 15 May 2024 See all Example Sentences for astronomy 

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'astronomy.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Middle English astronomie "study of celestial bodies, including their possible influence on human affairs," borrowed from Anglo-French & Latin; Anglo-French astronomie, borrowed from Latin astronomia, borrowed from Greek astronomía "study of the stars, especially their movements," from astro- astro- + -nomia -nomy

First Known Use

12th century, in the meaning defined above

Time Traveler
The first known use of astronomy was in the 12th century

Dictionary Entries Near astronomy

Cite this Entry

“Astronomy.” Dictionary, Merriam-Webster, Accessed 28 May. 2024.

Kids Definition


as·​tron·​o·​my ə-ˈsträn-ə-mē How to pronounce astronomy (audio)
plural astronomies
: the science of the heavenly bodies and of their sizes, motions, and composition

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