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

All of that changed when photography was developed in the 19th century, and then was applied to astronomy later in that century. —Big Think, 4 Feb. 2026

The astronomy community was therefore concerned about the precedent a permission to build INNA near Paranal would set. —Tereza Pultarova, Space.com, 4 Feb. 2026

Book an astronomy tour to look through professional telescopes and learn more about the celestial beauty above. —Evie Carrick, Travel + Leisure, 4 Feb. 2026

The periodical, which began in 1818 in Maine, has long covered a wide variety of topics, including long-range weather forecasts, moon phases and astronomy, gardening advice, recipes, and practical advice. —Kait Hanson, Southern Living, 31 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