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

Since the 1990s, the continent has been a major center for astronomy research, hosting a wide range of sensors and telescopes. — Daniella McCahey, The Conversation, 12 Oct. 2026

The ancient light collected by the telescopes was captured with a range of ZWO astronomy cameras and filters. — Anthony Wood, Space.com, 11 Oct. 2026

More by Peter Hall Joseph Howlett is a senior reporter at Scientific American covering physics, math, astronomy, and more. — Joseph Howlett, Scientific American, 8 Oct. 2026

Gravitational waves are a relatively new area of astronomy, using detectors spread across a wide area, like on a continent or in space, to identify ripples in the fabric of space-time generated by cataclysmic events in the distant cosmos. — Stephen Clark, ArsTechnica, 7 Oct. 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