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

Also on property is a sauna, cold plunge, and programming for stargazing and astronomy using Celestron Telescopes. — Ramsey Qubein, Forbes.com, 1 Aug. 2026

Better quantum simulations Mingjian Zhu, a graduate student in physics and astronomy at Rice, revealed the system enables independent control over a thermal environment’s temperature and dissipation rate. — Georgina Jedikovska, Interesting Engineering, 31 July 2026

While artificial intelligence played a key role in finding the candidates, the discoveries highlight the scientific potential hidden within the massive datasets produced by modern astronomy. — Samantha Mathewson, Space.com, 31 July 2026

Last year, the commission began moving to exclude satellite activities from the National Environmental Protection Act, sparking pushback from environmental and astronomy groups. — Michael Kan, PC Magazine, 29 July 2026

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