as·​tron·​o·​my | \ ə-ˈsträ-nə-mē How to pronounce astronomy (audio) \
plural astronomies

Definition of astronomy

: 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 This proliferation is bad for astronomy: the probability of a Starlink satellite crossing a telescope's field of view and ruining an observation will be quite high near sunrise and sunset, when the objects are most brightly illuminated. Ronald Drimmel, Scientific American, "Satellites Endanger Pristine Views of the Night Sky," 20 May 2020 Walkowicz has a bachelor's degree in physics and a PhD. in astronomy and has worked on space exploration projects, studied and spoken publicly and extensively about Mars and the star Vega. Bruce Vielmetti, Milwaukee Journal Sentinel, "American Girl accused of stealing astronomer's identity for its Girl of the Year doll Luciana Vega," 10 May 2020 WASP-12b’s impending demise marks a first for exoplanet astronomy and presents a rare opportunity to peer inside a star by studying its tides. Charlie Wood, Popular Science, "This pitch-black exoplanet is spiraling toward its doom," 2 Jan. 2020 The planetarium is starting to diversify its shows, not limiting them to astronomy as of old. Grant Segall, cleveland, "CMNH dung beetle expert wins nearly $1 million federal grant," 30 Jan. 2020 SpaceX has a fix in play to make its bright Starlink satellites less disruptive to astronomy, according to a SpaceNews report. Elizabeth Howell, Scientific American, "SpaceX to Make Starlink Satellites Dimmer to Lessen Impact on Astronomy," 13 Dec. 2019 The 11,258 scientists who signed the warning represent 153 countries and a wide range of scientific disciplines, from marine biology to biomedical science to astronomy. Sophie Lewis, CBS News, "More than 11,000 scientists officially declare a "climate emergency"," 5 Nov. 2019 The most popular of these programs have been in the fields of ecology, conservation and astronomy with millions of citizens contributing billions of data points every year by exploring gut microbiomes, counting birds, and searching for new planets. Smithsonian Magazine, Smithsonian Magazine, "Fifty Things We’ve Learned About the Earth Since the First Earth Day," 22 Apr. 2020 Robert Smith, who retired in 2001 shortly after running for 1,521 yards at age 28, had planned to go to medical school before settling into a career as a college football analyst and a life of, among other things, amateur astronomy. Michael Rosenberg,, "Andrew Luck and the Path to Walk Away," 6 Sep. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'astronomy.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of astronomy

12th century, in the meaning defined above

History and Etymology for astronomy

Middle English astronomie, from Anglo-French, from Latin astronomia, from Greek, from astr- + -nomia -nomy

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Time Traveler for astronomy

Time Traveler

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

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Statistics for astronomy

Last Updated

27 May 2020

Cite this Entry

“Astronomy.” Dictionary, Merriam-Webster, Accessed 4 Jun. 2020.

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More Definitions for astronomy


How to pronounce astronomy (audio)

English Language Learners Definition of astronomy

: the scientific study of stars, planets, and other objects in outer space


as·​tron·​o·​my | \ ə-ˈsträ-nə-mē How to pronounce astronomy (audio) \

Kids Definition of astronomy

: a science concerned with objects and matter outside the earth's atmosphere and of their motions and makeup

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More from Merriam-Webster on astronomy

Rhyming Dictionary: Words that rhyme with astronomy

Spanish Central: Translation of astronomy

Nglish: Translation of astronomy for Spanish Speakers

Britannica English: Translation of astronomy for Arabic Speakers Encyclopedia article about astronomy

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