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

Check my main feed for more in-depth articles on stargazing, astronomy, eclipses and more. —Jamie Carter, Forbes.com, 19 Jan. 2026

Learn about astronomy at the Cincinnati Observatory Enroll in Planetary Defense 101 for an informal education class on asteroid deflection and mitigation. —Caroline Ritzie, Cincinnati Enquirer, 18 Jan. 2026

The problem was that astronomy was starved for data because of the realities of gaining access to telescopes. —Adam Harrington, CBS News, 18 Jan. 2026

That’s a great match with communities like Wind Crest, with a lock-n-leave lifestyle, along with pickleball courts, two choral groups, and lots of specialty clubs, including an astronomy group that is getting an observatory built in the community. —Chris Jackson, Denver Post, 16 Jan. 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