periastron

[per-ee-as-truhn, -tron]

noun

Astronomy.

plural

periastra 

1. the point at which the stars of a binary system are closest (apastron ).

periastron

/ ˌpɛrɪˈæstrɒn /

noun

1. 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

periastron

plural

periastra 

1. 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.

2. Compare apastron

Other Word Forms

• periastral adjective

Word History and Origins

Origin of periastron¹

1850–55; < peri- + Greek ástron star; modeled on perihelion

Example Sentences

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

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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.

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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.

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All went well, there were no incidents, no vessels disturbed him; though had the two components of the binary been at periastron, it would have simplified the work with the position micrometer.

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The last periastron was ninety years ago, and we've only been here for sixty-odd; all we have is verbal accounts from memory from the natives, probably garbled and exaggerated.

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