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periastron

noun
peri·​as·​tron | \ ¦perē¦astrən, -ˌsträn\
plural periastra\ -​strə \

Definition of periastron

: the point in the orbit of a star or other celestial body where it is nearest to the primary star with reference to which it is revolving the periastron of a comet — compare apastron

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History and Etymology for periastron

New Latin, from peri- + Greek astron star

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