from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. The point of greatest separation between two stars, especially in a binary star situation.

from the GNU version of the Collaborative International Dictionary of English

  • n. That point in the orbit of a double star where the smaller star is farthest from its primary.

from The Century Dictionary and Cyclopedia

  • n. In astronomy, that part in the orbit of a double star where it is furthest from its primary.


apo- +‎ astron (Wiktionary)


  • They had already passed apastron and were downward bound.


  • The station was outward bound for the apastron of its shortened and cometary path.


  • In this region, nearing apastron, no unusual velocity change was needed to alter orbit radically.


  • Nevertheless the ship took days, terrible days to reach apastron.


  • Now, at apastron, with Vixen's atmosphere to filter its radiation, the sun might almost have been Sol: smaller, brighter, but gentle in a blue sky where tall white clouds walked.

    Agent Of The Terran Empire

  • The eccentricity of their orbit approaches in form that of Faye's comet, which travels round the Sun; consequently the stars, when at apastron, are twice their periastron distance.

    The Astronomy of Milton's 'Paradise Lost'

  • The pair travel in an orbit from fourteen to forty-two times the radius of the Earth's orbit; so that when at apastron they are three times as distant from each other as when at periastron.

    The Astronomy of Milton's 'Paradise Lost'

  • These orbs complete a revolution in 180 years, and when in apastron are seventeen times more remote from each other than when at periastron.

    The Astronomy of Milton's 'Paradise Lost'

  • Any approach to, or recession from this point, must occur simultaneously with each; they must always occupy corresponding parts of their orbits, and be in apastron and at periastron in the same period of time.

    The Astronomy of Milton's 'Paradise Lost'

  • Consequently, neither star can approach or recede from this point without the other affecting a similar motion, they must be at periastron and apastron together, and any acceleration or retardation of speed must occur simultaneously with each.

    The Astronomy of Milton's 'Paradise Lost'


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