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

People imagine astronomy involves memorizing the entire sky at once, knowing exactly where each star is and what it's called. — Jamie Carter, Space.com, 24 July 2026

Hoffman graduated from Scarsdale High School in 1962 and received a bachelor’s in astronomy (summa cum laude) from Amherst College in 1966. — Encyclopedia Britannica, 22 July 2026

Space exploration and space scientific work will also benefit, with for instance, more science projects and various types of astronomy, including large scale gravity wave telescopes. — Thomas Coughlin, Forbes.com, 21 July 2026

Britt Lundgren is a physics and astronomy professor at the University of North Carolina at Asheville. — David M. Klein, Washington Post, 16 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