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

Europe had famously fallen behind in science advancements by the Middle Ages, and the Spanish ruler’s court purposefully sought out and translated Islamic math, astronomy, and medical knowledge. —Andrew Paul, Popular Science, 19 Mar. 2026

One of our clients is passionate about astronomy. —Condé Nast, Condé Nast Traveler, 17 Mar. 2026

Still, despite all these data, researchers say the field of gravitational-wave astronomy is at a point where the flood of discovery is providing more new possibilities rather than ruling out old ones. —K. R. Callaway, Scientific American, 17 Mar. 2026

In addition, much of the feedback seems to urge the FCC to deny the plan over other impacts, including interference to astronomy and light pollution concerns. —Michael Kan, PC Magazine, 17 Mar. 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