ephemeris: meaning, definition, pronunciation and examples
C2Technical/Specialist
Quick answer
What does “ephemeris” mean?
A table or data set giving the calculated positions of a celestial body, such as a planet or satellite, at specific times.
Audio
Pronunciation
Definition
Meaning and Definition
A table or data set giving the calculated positions of a celestial body, such as a planet or satellite, at specific times.
In computing and spaceflight, a set of parameters used by a Global Navigation Satellite System (GNSS) receiver to compute the precise position of a satellite. By extension, any tabular record of periodically changing data.
Dialectal Variation
British vs American Usage
Differences
No significant difference in meaning or spelling. Both follow the same technical application.
Connotations
Neutral and technical in both varieties.
Frequency
Used with equal rarity in both British and American English, confined almost exclusively to astronomy, space science, and GNSS contexts.
Grammar
How to Use “ephemeris” in a Sentence
The [noun] published the [year]'s ephemeris.The receiver downloaded the satellite's ephemeris.The [calculation/position] is based on the latest ephemeris.Vocabulary
Collocations
Examples
Examples of “ephemeris” in a Sentence
verb
British English
- [No standard verb form. The technical verb is 'to ephemeridise', which is exceedingly rare.]
American English
- [No standard verb form.]
adverb
British English
- [No adverb form.]
American English
- [No adverb form.]
adjective
British English
- The ephemeris data must be updated frequently.
American English
- The ephemeris parameters are broadcast by the satellite.
Usage
Meaning in Context
Business
Virtually never used.
Academic
Used in astronomy, astrophysics, aerospace engineering, and geomatics courses and papers.
Everyday
Extremely rare outside of specific hobbies like amateur astronomy or high-level GPS device discussion.
Technical
Core term in satellite navigation (GPS, Galileo, etc.) and precise celestial mechanics.
Watch out
Common Mistakes When Using “ephemeris”
- Using it as a plural (the plural is 'ephemerides').
- Confusing it with the adjective 'ephemeral'.
- Mispronouncing it as /ˈɛfɪmərɪs/ (correct stress is on the second syllable).
FAQ
Frequently Asked Questions
Yes, both derive from the Greek 'ephēmeros' meaning 'lasting a day'. An ephemeris was originally a diary or a table of daily positions.
The plural is 'ephemerides' (pronounced /ˌɛfɪˈmɛrɪdiːz/).
Astronomers, astrophysicists, satellite engineers, surveyors, and some navigators and amateur astronomers.
It would be highly unusual and likely misunderstood. It is a specialised technical term.
A table or data set giving the calculated positions of a celestial body, such as a planet or satellite, at specific times.
Ephemeris is usually technical/specialist in register.
Ephemeris: in British English it is pronounced /ɪˈfɛmərɪs/, and in American English it is pronounced /ɪˈfɛmərɪs/. Tap the audio buttons above to hear it.
Phrases
Idioms & Phrases
- “[No common idioms for this technical term]”
Learning
Memory Aids
Mnemonic
Think: "EPHEMERal Information System" – a system giving short-term (ephemeral) data on where something is in space.
Conceptual Metaphor
A TIMETABLE FOR THE STARS.
Practice
Quiz
What is the primary function of an 'ephemeris'?