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

Meyer captured the data using his Sky Watcher Esprit 120mm telescope and astronomy camera equipped with a series of red green and blue filters, before post-processing the data in PixInsight, Photoshop and Lightroom. —Anthony Wood, Space.com, 15 Jan. 2026

The planetarium, located in the Jenks High School Math and Science building, includes a 50-foot-high SciDome, classes and talks on astronomy and individual telescopes. —Isa Almeida, Oklahoman, 15 Jan. 2026

Applying private-sector disruption to astronomy The private sector turning its attention toward science is a compelling concept, from an innovation perspective. —Chris Young, Interesting Engineering, 14 Jan. 2026

Try to plan your visit during the Dark Sky Festival, held annually in the late winter or early spring, to meet up with fellow stargazing enthusiasts and hear astronomy talks by park rangers. —Elizabeth Rhodes, Travel + Leisure, 10 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