planetary

planetary — adjective

1. connected with planets, or showing the kind of look or movement a planet has in

1.adjectiveC1
Definition

connected with planets, or showing the kind of look or movement a planet has in space.

Example

The museum opened a planetary gallery with rocks from Mars and the Moon.

planetary + noun in science contexts

Dr. Kumar studies planetary motion with students on the school roof.

collocation: planetary motion

Common collocations
  • planetary motion
  • planetary science
  • planetary surface
  • planetary system
  • planetary mission
Synonyms
  • astronomical

    broader; it can describe stars, galaxies, and space study in general

  • orbital

    narrower; it mainly focuses on paths or movement around another body

  • cosmic

    broader and often less technical or more dramatic in tone

  • interplanetary

    specifically about travel or space between planets

Antonyms
  • terrestrial

    relating to Earth or land rather than planets in space

Grammar Patterns

planetary + noun

planetary motion / science / system

Usage Note

Usually comes before nouns such as 'science', 'motion', 'surface', 'mission', and 'system'. In technical writing, it can also describe movement that follows the pattern of a planet's path around a star.

Common Mistakes

We learned about planet science today.
We learned about planetary science today.
use the adjective before a science noun, not the noun 'planet' alone.
The probe sent back planet images.
The probe sent back planetary images.
before nouns like 'images' or 'surface', English usually uses the adjective 'planetary'.

Word family

  • planet
    nounA2
  • planetarium
    nounC1
  • interplanetary
    adjectiveC2

Synonym discussion

Sense: adjective/1

These words all connect to space, but they point to different things. 'Planetary' stays close to planets themselves, their surfaces, systems, and the way they move. 'Astronomical' is broader and can include stars, galaxies, and the study of space in general. 'Orbital' is narrower and mostly describes a path or movement around another body. 'Interplanetary' means traveling or existing between planets. 'Cosmic' is the broadest and often sounds less technical or more dramatic. You study planetary science, calculate orbital speed, discuss astronomical data, and plan an interplanetary mission. A film soundtrack may sound cosmic, but a map of Mars is planetary.

planetary ↗astronomical ↗orbitalinterplanetarycosmic ↗

Common collocations

Nouns

  • planetary motion
  • planetary science
  • planetary system
  • planetary surface

Phrases

  • planetary mission
  • planetary images

Etymology

GreekLatinOld FrenchEnglish

Built in English from 'planet' and the adjective ending '-ary'. The noun 'planet' came through Old French and Latin from Greek 'planetes', meaning 'wanderer'. Ancient people used that word because planets seemed to move across the sky instead of staying fixed like most stars.