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: 50 Search : out
south pole
  قطب ِ دشتر   
qotb-e daštar

Fr.: pôle Sud   

1) An → imaginary point in the → southern hemisphere representing the intersection of the → Earth's → rotation axis with the → globe with the → celestial sphere.
2) For a → magnet, the pole which points toward the geographic south.
3) In a → magnetic field, the point which receives a → line of force coming from the → north pole.

south; → pole.

South Pole Star
  ستاره‌ی ِ قطب ِ دشتر   
setâre-ye qotb-e daštar

Fr.: étoile du pôle sud   

A star that would mark the south → celestial pole. Presently no bright visible star is situated along the → rotation axis of the Earth in the southern hemisphere. But, because of the Earth's → axial precession, about 7,000 years from now the star → Delta Velorum in the constellation → Vela, the Sail, will come to within 0.2 degrees of the South Celestial Pole (around the year 9250 B.C.). That is closer to marking the celestial pole than → Polaris or → Sirius ever do during their reigns as pole stars! Sirius will become the South Pole Star some 60 thousand years from now (around the year 66270 B.C.). In that time, Sirius will come to within 1.6 degrees of the South Celestial Pole.

south; → celestial; → pole.

southern
  دشتری   
daštari

Fr.: du Sud, méridional   

Of or pertaining to the south.

M.E., O.E. suðerne, from suð, → south, + -erne, suffix denoting direction.

Daštari, relating to daštar, → south.

Southern Cross
  چلیپای ِ دشتری   
calipâ-ye daštari

Fr.: Croix du Sud   

Popular name for the constellation → Crux. Its four brightest stars form a distinctive cross shape.

southern; → Crux.

southern hemisphere
  نیم‌سپهر دشتری   
nimsepehr-e daštari

Fr.: hémisphère sud   

The half of the → Earth or another → north pole between the → south pole and the → equator.

southern; → hemisphere.

southing
  گذر ِ دشتر-سو   
gozar-e daštar-su

Fr.:   

The transit of a celestial object, especially the Sun, across the meridian due south of the observer.

Verbal noun from → south (v.).

Gozar-e daštar-su, literally "passage southward," from gozar, → passage; daštarsouth; su, → direction.

Trouton's rule
  رزن ِ تروتون   
razan-e Trouton

Fr.: règle de Trouton   

The ratio of the → molar heat of vaporization of any liquid to its → boiling point is a constant, about 88 joules per mole per Kelvin. The rule is equivalent to the statement that the → entropy of vaporization is constant. It is not always followed, especially by liquids such as water in which hydrogen bonding occurs between the molecules.

Named after Frederick Thomas Trouton (1863-1922), an Irish physicist; → rule.

Trouton-Noble experiment
  آزمایش ِ تروتون-نوبل   
âzmâyeš-e Trouton-Noble

Fr.: expérience de Trouton-Noble   

An experiment first carried out in 1903 to reveal the absolute motion of the Earth with respect to the → ether. The experiment consists of detecting a torque on a charged parallel-plate → capacitor that was suspended so that its plates were vertical. Since the Earth moves around the Sun, the moving charges were expected to produce magnetic fields, and the resulting torque should tend to turn the capacitor bringing its plates parallel to its velocity. No such effect was observed, and the absence of the torque supports the theory of → special relativity.

Named after Frederick T. Trouton (1863-1922) and Henry R. Noble; → experiment.

waterspout
  تنوره‌ی ِ دریایی   
tanure-ye daryâyi (#)

Fr.: trombe marine   

A spinning column of rising humid air that occurs over a body of warm water. Waterspouts fall within the class of atmospheric phenomena known as convective vortices that includes → tornadoes, → dust devils, and → hurricanes. They can feature wind speeds over 200 kilometers per hour.

water + spout, from M.E. spouten akin to M.Du. spiten "to spout;" O.E. spiwan "to spew."

Tanure-ye daryâyi, from tanuré (kešidan) "turning and raising in the air," probably from tanidan "to turn, spin," → tension; daryâyi, → marine.

youth paradox
  پارادخش ِ جوانی   
pârâdaxš-e javâni

Fr.: paradoxe de jeunesse   

Same as → paradox of youth.

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