equation of time
noun phraseDefinition of equation of time
: the difference between apparent time and mean time usually expressed as a correction which is to be added to apparent time to give local mean time
The Equation of Time is the difference between your local apparent solar time, when the Sun crosses your meridian, and local mean solar time, which is the average rate of solar time used in clocks. Because the Earth travels at varying speeds as it traverses its elliptical orbit, the difference can be as much as 16 minutes.— Kathleen Hill Zeller
Keep scrolling for more
Comments on equation of time
What made you want to look up equation of time? Please tell us where you read or heard it (including the quote, if possible).
Test Your Vocabulary
Slippery Words Quiz—Changing with the Times
- What is an earlier meaning of nice?
Can you spell these 10 commonly misspelled words?
TAKE THE QUIZ
A daily challenge for crossword fanatics.
TAKE THE QUIZLove words? Need even more definitions?
Merriam-Webster unabridgedWords at Play
Ask the Editors
Word Games
- Slippery Words Quiz—Changing with the Times
Do you know these earlier meanings of words?
Take the quiz - Words of Snow and Ice Quiz
A selection of words from the chillier parts of t...
Take the quiz - Spell It
Can you spell these 10 commonly misspelled words?
Take the quiz - Word Winder's CrossWinder Play the game
Share equation of time
Time Traveler for equation of time
The first known use of equation of time was in 1645
See more words from the same year