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 Her notable subjects included the star of Bethlehem, the flat-Earth theory and women in astronomy., 22 May 2021 Her notable subjects included the star of Bethlehem, the flat earth theory and women in astronomy. New York Times, 21 May 2021 These are questions that may seem basic and yet have proved some of the most baffling even to modern astronomy. Jamie Carter, Forbes, 18 May 2021 After all, Barbie has kept up with the times, graduating from vacations in Malibu to the medical profession, astronomy and even president of the United States. Erich Schwartzel, WSJ, 6 May 2021 Thousands of experiments in everything from astronomy and physics to botany and medical science have been conducted in orbit. National Geographic, 7 Oct. 2020 Geoff Mathews, a professor of astronomy at Foothill College in Los Altos Hills, agreed that the satellites Saturday appeared to be from the L27 launch in the early morning hours of May 9. Kellie Hwang, San Francisco Chronicle, 23 May 2021 And its powerful instruments, designed to observe the atmospheres of planets around other stars, could usher in a new era of astronomy. NBC News, 12 May 2021 Hubble is also a precious gem in astronomy due to its ability to observe objects again and again in its decades of spaceflight. Elizabeth Howell, Forbes, 26 Apr. 2021

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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Learn More about astronomy

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

9 Jun 2021

Cite this Entry

“Astronomy.” Dictionary, Merriam-Webster, Accessed 15 Jun. 2021.

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More Definitions for astronomy



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 that deals with objects and matter outside the earth's atmosphere and their properties

More from Merriam-Webster on astronomy

Nglish: Translation of astronomy for Spanish Speakers

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


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