the point in the orbit of a body around a star when it is nearest to the star, esp applied to double-star systems
periastron in American English
(ˌperiˈæstrən, -trɑn)
nounWord forms: plural-tra (-trə)
Astronomy
the point at which the stars of a binary system are closest (opposed to apastron)
Derived forms
periastral
adjective
Word origin
[1850–55; ‹ peri- + Gk ástron star; modeled on perihelion]This word is first recorded in the period 1850–55. Other words that entered Englishat around the same time include: boneyard, ethos, ethylene, overprint, runoffperi- is a prefix meaning “about” or “around” (perimeter, periscope), “enclosing” or “surrounding” (pericardium), and “near” (perigee, perihelion), appearing in loanwords from Greek (peripeteia). On this model, peri- is used in the formation of compound words (perimorph)
Examples of 'periastron' in a sentence
periastron
However, they passed through periastron when they were closest, in 2005.