as·tron·o·my | \ ə-ˈsträ-nə-mē \
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

Tom Solomon is professor of physics and astronomy at Bucknell University. Tom Solomon, Washington Post, "GPAs don’t really show what students learned. Here’s why.," 15 June 2018 But still, the Board of Longitude wasn’t ready to call him a winner and ordered another test run — this time to Barbados, against two teams using methods that relied on astronomy rather than timepieces. Rachel Becker, The Verge, "John Harrison’s super-accurate clock helped solve the longitude puzzle," 3 Apr. 2018 Jim was an avid reader especially on the topics of religion, history, science and astronomy., "James P. Ficocelli," 30 May 2018 Night skies here are free of light pollution, a perfect spot for astronomy buffs. Jill K. Robinson, San Francisco Chronicle, "Top 10 California parks: Little known wonders," 9 May 2018 The detection also triggered a powerful example of another new trend, multimessenger astronomy, in which telescopes and other instruments studied the flaring blazar in all parts of the electromagnetic spectrum, from gamma rays to radio waves. Daniel Clery, Science | AAAS, "Ghostly particle caught in polar ice ushers in new way to look at the universe," 12 July 2018 The discovery heralds the next step in what scientists call multi-messenger astronomy, which probes the cosmos with telescopes working across different wavelengths and now with detectors of gravitational waves as well. Robert Lee Hotz, WSJ, "Scientists Track Neutrinos Through Ice to Their Source in the Cosmos," 12 July 2018 Among these activities are lessons in astronomy, philosophy, art, dance, physiology, aesthetics. Tom Keogh, The Seattle Times, "Seattle Piano Institute draws students from around the world for piano and life lessons," 3 July 2018 Every week, hosts Seth Shostak and Molly Bentley use storytelling to bring scientific discovery to your ears, with the help of experts in fields such as robotics, astronomy, neurology, entomology and more. Erin Blakemore, Washington Post, "Selling science, and debunking pseudoscience, through great stories," 23 June 2018

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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Statistics for astronomy

Last Updated

17 Sep 2018

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Time Traveler for astronomy

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

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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 \

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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Comments on astronomy

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