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

Inside the American Museum of Natural History's glass cube, the Frederick Phineas and Sandra Priest Rose Center for Earth and Space has some of the city's best astronomy programming. —Iona Brannon, Travel + Leisure, 8 Nov. 2025

Weber bars were named for Joseph Weber, a physicist with an electrical engineering background, who specifically studied microwave radiation, and had a strong interest in astronomy and astrophysics. —Big Think, 7 Nov. 2025

The Farmers' Almanac is known for its weather predictions, astronomy, and full moon and gardening calendars. —Julia Gomez, USA Today, 7 Nov. 2025

Chanda Prescod-Weinstein is an associate professor of physics and astronomy at the University of New Hampshire. —Peter D'abrosca, FOXNews.com, 7 Nov. 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