mean sun

noun

Definition of mean sun

: a fictitious sun used for timekeeping that moves uniformly along the celestial equator and maintains a constant rate of apparent motion equal to the average rate of apparent motion of the real sun

First Known Use of mean sun

1765, in the meaning defined above

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The first known use of mean sun was in 1765

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Cite this Entry

“Mean sun.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/mean%20sun. Accessed 27 Jan. 2021.

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