proper motion

noun

Definition of proper motion

: the apparent change in position of a star usually expressed in seconds of arc per year that results from the projection on the celestial sphere of its motion with respect to the solar system — see tangential motion

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properly

proper motion

proper noun

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Cite this Entry

“Proper motion.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/proper%20motion. Accessed 27 Nov. 2021.

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