An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 998
parabola
  سهمی   
sahmi (#)

Fr.: parabole   

A plain curve obtained by slicing a cone with a plane parallel to one side of the cone. A parabola can be considered an ellipse with an infinite major axis. It is one of the types of conic sections.

N.L., from Gk. parabole "comparison, application," literally "a throwing beside," from → para- + bole "throwing," related to ballein "to throw."

Sahmi, of unknown origin.

parabolic
  سهمی   
sahmi

Fr.: parabolique   

Having the form of a parabola.

of or pertaining to → parabola.

parabolic antenna
  آنتن ِ سهمی   
ânten-e sahmi (#)

Fr.: antenne parabolique   

An antenna comprising a parabolic reflector with a receiving and/or transmitting element positioned at or near its focal point.

parabolic; → antenna.

parabolic mirror
  آینه‌ی ِ سهمی   
âyene-ye sahmi (#)

Fr.: miroir parabolique   

A concave mirror that has the form of a paraboloid of revolution.

parabolic; → mirror.

parabolic orbit
  مدار ِ سهمی   
madâr-e sahmi

Fr.: orbite parabolique   

An orbit whose overall shape is like a parabola; it is the limiting case between an elliptical orbit (eccentricity less than 1) and a hyperbolic orbit (eccentricity larger than 1). The speed necessary to form a parabolic orbit is known as the escape velocity.

parabolic; → orbit.

parabolic velocity
  تندای ِ سهمی   
tondâ-ye sahmi

Fr.: vitesse parabolique   

The speed necessary to form a parabolic orbit around a gravitational center. It is also the minimum speed necessary to escape from the gravitational pull of a body.

parabolic; → velocity.

paraboloid
  سهمی‌وار   
sahmivâr (#)

Fr.: paraboloïde   

A solid formed by the revolution of a parabola about its axis.

From parabol(a), → parabola, + → -oid.

paradigm
  پرادیش، پارادیش   
parâdiš, pârâdiš

Fr.: paradigme   

1) General: A typical example of something.
2) Grammar: A set of word forms giving all of the possible inflections (declensions, conjugations) of a word.
3) Philosophy of science: A framework of concepts, results, and procedures within which subsequent work is carried out, as defined by the influential Thomas Kuhn (1922-1996) in his classic The Structure of Scientific Revolutions (1962). "Normal science" proceeds within such a framework or paradigm. When a paradigm has to be changed (→ paradigm shift), there comes about a crisis and then scientific revolution. For example, Newton's mechanical paradigm was replaced by the paradigm of Einstein's relativistic universe. Each paradigm is an interpretation of the world, rather than an objective explanation. For criticism of Kuhn's views, see, e.g., Stanford Encyclopedia of Philosophy.
4) Term now occurring frequently in every kind of discourse, usually to mean something like "way of thinking" or "approach to a problem."

L.L. paradigma "pattern, example," especially in grammar, from Gk. paradeigma "pattern, model," from paradeiknynai "to exhibit, show side by side," from → para- "beside" + deiknynai "to show," related to dokein "to appear, seem, think," cognate with Av. daēs- "to show" (Mod.Pers. andišé, andiš "thought, think," see below); Skt. diś- "to show, point out," diśati "he shows;" L. dicere "to utter;" PIE base *deik- "to show, to pronounce."

Parâdiš, pârâdiš, from parâ-, pârâ, → para- + diš "to show," as in andiš, andišidan "to → think" (related to dis, disé, → form); Sogd. andiš "to seem," andêš "to show," andêšik "appearing;" ultimately from Av. daēs- "to show," s-aorist forms dāiš-, dôiš-, diš-, akin to Gk. deiknynai "to show," as above, dike "manner, custom;" Skt. diś- "to show, point out;" L. dicere "to utter, say;" O.H.G. zeigon, Ger. zeigen "to show;" O.E. teon "to accuse," tæcan "to teach."

paradigm shift
  کیب ِ پرادیش، دگرگونی ِ ~   
kib-e parâdiš, degarguni-ye ~

Fr.: changement de paradigme   

1) Philosophy of science: A process of revolutionary change in scientific → paradigms, whereby established scientific ideas are replaced by new ones. For instance, Copernicus' evidence that the Earth revolved around the Sun caused a paradigm shift in astronomy.
2) The idea of paradigm shift has been transferred from the sciences to other areas of society and culture, referring to a fundamental reorganization of how people think about an entire topic.

paradigm; → shift; → change.

paradox
  پارادخش   
pârâdaxš (#)

Fr.: paradoxe   

A statement, proposition, or situation that seems self-contradictory or absurd but in reality is or may be true. → Fermi paradox; → faint early Sun paradox; → twins paradox; → paradox of youth.

From L. paradoxum "contrary to expectation," from Gk. paradoxon, from neuter of adj. paradoxos "contrary to common opinion, unbelievable," from → para- "contrary to" + dox(a) "opinion, belief" + -os adj. suffix. The main component dox, from dokein "to appear, seem, think," is cognate with Av. daēs- "to show;" Skt. diś- "to show, point out," diśati "he shows;" L. dicere "to utter;" PIE base *deik- "to show, pronounce solemnly."

Pârâdaxš (on the model of Gk. paradoxos), from pârâ-, → para-, + daxš, from Av. daxš- "to reveal, instruct, point out," fradaxštar- "teacher," *daxšārə "revelations;" Mod.Pers. daxš "task, effort;" cf. Skt. daks- "to be able," dáksa- "able, expert."

paradox of youth
  پارادخش ِ جوانی   
pârâdaxš-e javâni

Fr.: paradoxe de jeunesse   

The observed presence of young stars in the immediate vicinity of the → supermassive black hole (SMBH), → Sgr A*, residing in the center of our Galaxy. The stellar population within 1 pc of the SMBH contains a variety of young and → massive stars orbiting the SMBH. Some of them are only about 20 Myr old and get as close as a few light-days to the SMBH, while from 0.1 to 0.4 pc even younger stars are found with ages of 3-7 Myr. The presence of these stars so near to the SMBH is a paradox. Their → in situ formation should be almost impossible, since the environment is too hostile for these stars to form. Indeed the strong → tidal influence of the SMBH should hamper their formation. On the other hand, the scenario considering their → migration from other places does not seem to be adequate. The time required for the migration from > 1 pc by dynamical friction would exceed their inferred ages unless the migration rate were somehow accelerated. This apparent contradiction was termed "paradox of youth" by Ghez et al. (2003, ApJ 586, L127). See also Genzel et al. (2010, Rev.Mod.Phys. 82, 3121, also at astro-ph/1006.0064).

Youth, the condition of being → young; → paradox.

parahydrogen
  پارا-هیدروژن   
pârâ-hidrožen

Fr.: parahydrogène   

Molecular hydrogen in which the nuclei (protons) of the two hydrogen atoms contained in the molecule have spins in opposite directions. → orthohydrogen

para-; + → hydrogen.

parallactic
  دیدگشتی   
didgašti

Fr.: parallactique   

Of or pertaining to a parallax.

Adj. form of → parallax.

parallactic angle
  زاویه‌ی ِ دیدگشتی   
zâviye-ye didgašti

Fr.: angle parallactique   

Of an object in the sky, the angle between the → celestial pole, the object, and the → zenith. Since parallactic angle describes the orientation on the sky of the object for a particular observer, it can be an important quantity in some observations.

parallactic; → angle.

parallactic ellipse
  بیضی ِ دیدگشت   
beyzi-ye didgašt

Fr.: ellipse de parallaxe   

The path on the sky of the apparent position of a star as seen from the Earth, due to the Earth's annual motion around the Sun.

parallactic; → ellipse.

parallactic inequality
  ناهموگی ِ دیدگشتی   
nâhamugi-ye didgašti

Fr.: inégalité parallactique   

An irregularity in the Moon's motion caused by the Sun's gravitational attraction, which sets the Moon ahead or behind its normal orbital position. The Moon is about 2 arcminutes ahead of its expected position at first quarter, and a similar amount behind at last quarter.

parallactic; → inequality.

parallactic motion
  جنبش ِ دیدگشتی   
jonbeš-e didgašti

Fr.: mouvement parallactique   

The proper motion of a star due to the effect of the Sun's motion relative to the → local standard of rest.

parallactic; → motion.

parallax
  دیدگشت   
didgašt (#)

Fr.: parallaxe   

The apparent → shift of a nearby object's → position in relation to more distant ones when the nearby object is observed from different → viewing angles. See also → stellar parallax.

From M.Fr. parallaxe, from Gk. parallaxis "change, alteration," from parallassein "to alter, make things alternate," from → para- "beside" + allassein "to change," from allos "other;" → alias.

Didgašt, literally "view change," from did "sight, view; eye," from didan "to see" (Mid.Pers. ditan "to see, regard, catch sight of, contemplate, experience;" O.Pers. dī- "to see;" Av. dā(y)- "to see," didāti "sees;" cf. Skt. dhī- "to perceive, think, ponder; thought, reflection, meditation," dādhye; Gk. dedorka "have seen") + gašt "change, alteration," past stem of gaštan, gardidan "to turn, to change" (Mid.Pers. vartitan; Av. varət- "to turn, revolve;" Skt. vrt- "to turn, roll," vartate "it turns round, rolls;" L. vertere "to turn;" O.H.G. werden "to become;" PIE base *wer- "to turn, bend").

parallax angle
  زاویه‌ی ِ دیدگشت   
zâviye-ye didgašt

Fr.: angle de parallaxe   

The angular displacement associated with → parallax.

parallax; → angle.

parallel
  پراسو   
parâsu

Fr.: parallèle   

1) Said of two or more things, such as lines or planes, that are equally distant from one another at all points.
2) Electricity: An arrangement of the components in an electric circuit so that the same voltage is applied to each component. Compare → series.

From M.Fr. parallèle, from L. parallelus, from Gk. parallelos "parallel," from para allelois "beside one another," from → para- "beside" + allelois "each other," from allos "other," → alias.

Parâsu, from parâ-, → para-, + su "direction, side," from Mid.Pers. sôk "direction, side."

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