astronomy

noun

as·​tron·​o·​my ə-ˈsträ-nə-mē 

plural astronomies

: the study of objects and matter outside the earth's atmosphere and of their physical and chemical properties

Did you know?

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

The moon will appear full the night before, so astronomy buffs can look up into the evening sky Aug. 8 to spot the full moon. —Jenna Prestininzi, Freep.com, 7 Aug. 2025

In addition to stupendous views of the eclipse, guests can expect to enjoy fascinating culture, history, food and wine, along with insightful programming on eclipses and cosmic wonders curated by distinguished lecturer Dr. Alex Filippenko, professor of astronomy at UC Berkeley. —Cassidy Randall, Forbes.com, 6 Aug. 2025

Under the force of high-velocity winds, these particles could become mechanically aligned, like tiny boats drifting in formation down a river, Elijah Mullens, a graduate student in the astronomy and space science department at the university who led the new study, said in the statement. —Sharmila Kuthunur, Space.com, 1 Aug. 2025

Check my main feed for more in-depth articles on stargazing, astronomy, eclipses and more. —Jamie Carter, Forbes.com, 28 July 2025

Word History

Etymology

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

Phrases Containing astronomy

• radar astronomy
• radio astronomy
• X-ray astronomy

Rhymes for astronomy

• aeronomy
• agronomy
• autonomy
• economy
• gastronomy
• metonymy
• taxonomy
• deuteronomy

Kids Definition

astronomy

noun

as·​tron·​o·​my ə-ˈsträn-ə-mē 

plural astronomies

: the science of the heavenly bodies and of their sizes, motions, and composition

astronomer

-mər

noun