An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 8 Search : primary
primary
  نخستان   
naxostân

Fr.: primaire, principal   

1) First or highest in rank or importance; chief; principal.
2) Abbreviation for → primary body, → primary star, or → primary mirror.

M.E., from L. primarius "of the first rank, principal," from primus "first."

Naxostân, from naxost, from Mid.Pers. naxust "the first," Parthian Mid.Pers. nxwšt, from naxu, Manichean Parthian nwx "beginning" + -ist superlative suffix, Av. -išta-, cf. Skt. -istha-, Gk. -istos, O.H.G. -isto, -osto, O.E. -st, -est, -ost.

primary body
  جسم ِ نخستان   
jesm-e naxostân

Fr.: corps principal   

The body that is being orbited; such as the → Sun in the → solar system. As regards → multiple star systems, the most massive, or → primary star. See also: → secondary body.

primary; → body.

primary cell
  پیل ِ نخستان   
pil-e noxostân

Fr.:   

A → cell in which the electrochemical action producing the current is not normally reversible. Such a cell cannot be recharged by an electric current. → secondary cell.

primary; → cell.

primary cosmic rays
  پرتوهای ِ کیهانی ِ نخستان   
partowhâ-ye keyhâni-ye noxostân

Fr.: rayons cosmiques primaires   

High energy charged particles that arrive at Earth's upper atmosphere from outer space. Primary cosmic rays generally do not make it through the atmosphere to reach at the Earth's surface, in contrast to → secondary cosmic rays.

primary; → cosmic; → ray.

primary eclipse
  گرفت ِ نخستان   
gereft-e noxostân

Fr.: éclipse primaire   

Of a transiting → exoplanet, the event and the interval of time during which the planet passes in front of its host star. The planet occults a portion of the stellar disk, and a fraction of light from the star is seen after traversal through the atmosphere around the planet's limb. → secondary eclipse.

primary; → eclipse.

primary mirror
  آینه‌ی ِ نخستان   
âyene-ye noxostân

Fr.: miroir primaire   

In a → reflecting telescope, the first mirror that collects the light and focuses it to the → focal plane.

primary; → mirror.

primary rainbow
  رنگین‌کمان ِ نخستان   
rangin-kamân-e naxostân

Fr.: arc-en-ciel primaire   

The main rainbow that forms between about 40° and 42° from the → antisolar point (or about 50° from the → antisolar point), as viewed by the observer. The light path involves → refraction and a → single  → reflection inside the water → droplet. If the drops are large, 1 millimeter or more in diameter, red, green, and violet are bright but there is little blue.

As the droplets get smaller, red weakens.

Rainbows are not seen in midday since the whole 42° circle is below the horizon at most latitudes. So rainbows tend to be seen most in the later afternoon when a thundershower has passed and the Sun is illuminating from the west.

primary; → rainbow.

primary star
  ستاره‌ی ِ نخستان   
setâre-ye naxostân

Fr.: étoile principale   

In a → multiple star system, the most massive → component. In other words, the star nearest to the system's → center of garvity.

primary; → star .