astronomy

IPA/əˈstrɒnəmi/
KK[əstrˈɑnəmi]IPA/əˈstrɑːnəmi/

astronomy — noun

1. the science that looks at what lies beyond Earth — including stars, planets, moo

1.nounB2
Definition

the science that looks at what lies beyond Earth — including stars, planets, moons, galaxies, and the way the universe formed and changes over time.

Example

Hadiya studied astronomy at university and now works at a planetarium in Tokyo.

study astronomy at + [institution]

Modern astronomy uses huge telescopes to see stars billions of miles from Earth.

modern astronomy + tools/instruments

Common collocations
  • study astronomy
  • amateur astronomy
  • modern astronomy
  • astronomy club
Synonyms
  • astrophysics

    narrower; focuses on the physics and chemistry of space objects

  • cosmology

    narrower; specifically the origin and structure of the whole universe

  • stargazing

    informal; the hobby of looking at stars rather than the academic field

Antonyms
  • astrology

    often confused with astronomy but is a belief system, not a science

Usage Note

Uncountable noun: never 'an astronomy' or 'astronomies'. Distinguish from astrology, which is the non-scientific belief that stars influence human affairs.

Common Mistakes

My sister reads my astronomy every morning in the newspaper.
My sister reads my horoscope every morning; that is astrology, not astronomy.
astronomy is science; astrology is belief about star signs.
He studies an astronomy at college.
He studies astronomy at college.
uncountable, no article.

Word family

Synonym discussion

Sense: noun/1

Astronomy is the broad scientific field that observes and describes everything beyond Earth's atmosphere, from planets and comets to distant galaxies. Astrophysics is a sub-branch that asks how these objects work, applying the laws of physics and chemistry to questions like how stars produce light or how black holes form. Cosmology is even narrower, focused on the universe as a single system — its origin, large-scale shape, and ultimate fate. Astrology, despite the similar spelling, is not a science at all; it is the traditional belief that the positions of stars and planets at one's birth shape personality and events. So you 'study astronomy' at university, 'do research in astrophysics' in a lab, 'discuss cosmology' at a conference, but 'read your astrology' in a magazine.

astronomy ↗astrophysics ↗cosmology ↗astrology ↗

Common collocations

Nouns

  • astronomy class
  • astronomy textbook
  • astronomy professor
  • astronomy department

Phrases

  • a degree in astronomy
  • the field of astronomy
  • amateur astronomy
  • professor of astronomy

Prepositions

  • in astronomy
  • of astronomy

Etymology

GreekLatinOld FrenchEnglish

Astronomy entered English in the 1200s from Old French 'astronomie', which came from Latin 'astronomia'. The Latin word was borrowed from Greek 'astronomia', literally 'star-arranging' — from 'astron' (star) plus 'nomos' (law, arrangement). For centuries the word was used interchangeably with 'astrology'; the two meanings only split clearly during the scientific revolution of the 1600s, when astronomy became the empirical study of the heavens and astrology was left as the older fortune-telling tradition.