as·​tron·​o·​my | \ ə-ˈsträ-nə-mē How to pronounce astronomy (audio) \
plural astronomies

Definition of astronomy

: the study of objects and matter outside the earth's atmosphere and of their physical and chemical properties

Keep scrolling for more

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 If this new model is correct, hunting for this type of optical signature could become a new observing strategy in the broader context of multi-messenger astronomy. Jennifer Ouellette, Ars Technica, "Astronomers think this black hole collision may have exploded with light," 25 June 2020 Large projects are kicking off, funds are materializing, and astronomy courses now include a broader perspective on humanity’s place in the universe. Nadia Drake, National Geographic, "My dad launched the quest to find alien intelligence. It changed astronomy.," 19 June 2020 In early March, an astronomy student from the University of British Columbia discovered 17 new exoplanets, including one that is roughly the same size as Earth. Fox News, "6 billion 'Earth-like' planets in the Milky Way galaxy, study suggests," 18 June 2020 Stargazers and astronomy-lovers can get their fill of gorgeous dark skies over the Arizona desert. Andrea Romano, Travel + Leisure, "Grand Canyon National Park Is Hosting a Virtual Stargazing Party All Week," 15 June 2020 Where, or even whether, true Earth-twins exist remains one of astronomy's top mysteries. Charlie Wood, Popular Science, "We’re one step closer to tracking down another Earth," 28 Aug. 2019 Astrology was important in sixteenth-century Italy, not yet separate from the discipline of astronomy, and Michelangelo’s father, as a minor aristocrat, took care to have a professional cast his newborn son’s horoscope. Ingrid D. Rowland, The New York Review of Books, "He Made Stone Speak," 17 June 2020 These presentations are live and are a great opportunity to ask the experts questions about astronomy. Andrea Romano, Travel + Leisure, "Grand Canyon National Park Is Hosting a Virtual Stargazing Party All Week," 15 June 2020 The discovery marked the culmination of 60 years of effort by physicists around the world to detect neutrinos from beyond our galaxy and heralded the arrival of the new science of neutrino astronomy. Daniel Oberhaus, Wired, "The Hunt Is On for Elusive Ghost Particles in Antarctica," 12 June 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'astronomy.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of astronomy

12th century, in the meaning defined above

History and Etymology for astronomy

Middle English astronomie, from Anglo-French, from Latin astronomia, from Greek, from astr- + -nomia -nomy

Keep scrolling for more

Learn More about astronomy

Time Traveler for astronomy

Time Traveler

The first known use of astronomy was in the 12th century

See more words from the same century

Statistics for astronomy

Last Updated

2 Jul 2020

Cite this Entry

“Astronomy.” Dictionary, Merriam-Webster, Accessed 11 Jul. 2020.

Keep scrolling for more

More Definitions for astronomy


How to pronounce astronomy (audio)

English Language Learners Definition of astronomy

: the scientific study of stars, planets, and other objects in outer space


as·​tron·​o·​my | \ ə-ˈsträ-nə-mē How to pronounce astronomy (audio) \

Kids Definition of astronomy

: a science concerned with objects and matter outside the earth's atmosphere and of their motions and makeup

Keep scrolling for more

More from Merriam-Webster on astronomy

Rhyming Dictionary: Words that rhyme with astronomy

Spanish Central: Translation of astronomy

Nglish: Translation of astronomy for Spanish Speakers

Britannica English: Translation of astronomy for Arabic Speakers Encyclopedia article about astronomy

Comments on astronomy

What made you want to look up astronomy? Please tell us where you read or heard it (including the quote, if possible).


See Definitions and Examples »

Get Word of the Day daily email!

Test Your Vocabulary

Words for Summer: A Quiz

  • a closeup of a sunflower
  • Which of the following words means “of or relating to summer”?
Spell It

Can you spell these 10 commonly misspelled words?

Add Diction

Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!