[ per-ee-as-truh n, -tron ]
/ ˌpɛr iˈæs trən, -trɒn /
noun, plural per·i·as·tra [per-ee-as-truh] /ˌpɛr iˈæs trə/. Astronomy.
the point at which the stars of a binary system are closest (opposed to apastron).
Origin of periastron
1850–55; < peri- + Greek ástron star; modeled on perihelion
Related formsper·i·as·tral, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for periastron
At least, the periastron effects; there was another angle to it.Oomphel in the Sky|Henry Beam Piper
British Dictionary definitions for periastron
/ (ˌpɛrɪˈæstrɒn) /
astronomy the point in the orbit of a body around a star when it is nearest to the star, esp applied to double-star systems
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Science definitions for periastron
[ pĕr′ē-ăs′trən, -trŏn ]
The point at which an object, such as a planet or comet, is closest to the center of mass of the star it is orbiting. Compare apastron.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.