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

Different from the best cameras for astrophotography (mirrorless and DSLR models), these cameras are dedicated solely to astronomy and are used in combination with one of the best telescopes to image the night sky. —Damian Peach, Space.com, 28 May 2025

Urban sky-gazers take a contemporary spin on this Neolithic astronomy concept by pinpointing days when the sun seems to rise or set between a canyon of skyscrapers. —Stephanie Vermillion, Outside Online, 27 May 2025

Kristen Pope is a freelance writer covering travel, wildlife, outdoor adventure, astronomy, and how people connect with the natural world. —Kristen Pope, AFAR Media, 22 May 2025

From capturing the earliest glimpses of galaxy formation to measuring the expansion rate of the universe, Hubble has been at the heart of modern astronomy for decades. —Discover Magazine, 20 May 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