An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 732
right angle
  زاویه‌ی ِ راست   
zâviye-ye râst

Fr.: angle droit   

An angle of 90°.

right; → angle.

right ascension
râst afrâz (#)

Fr.: ascension droite   

A coordinate in the → equatorial system measured from the → vernal equinox eastward to the point where the object → hour circle intersects the → celestial equator. Right ascension (symbol α) is expressed in hours, minutes, and seconds. See also: → declination.

right; ascension, M.E. ascencioun, from O.Fr., from L. ascendere "to climb up," from → ad- "to" + scandere "to climb."

Râst, → right; afrâz present stem of afrâzidan, afrâštan "to raise, exalt, extole," from Mid.Pers. abrâstan, abrâz- "to lift, raise," from ab-, from O.Pers./Av. abiy-/aiwi- "to, upon, against;" cf. Skt. abhi-, Gk. amphi- + râst "straight, direct, true;" from O.Pers. rāsta- "straight, true," rās- "to be right, straight, true;" Av. rāz- "to direct, put in line, set," razan- "order;" cf. Skt. raj- "to direct, stretch," rjuyant- "walking straight;" Gk. orektos "stretched out;" L. regere "to lead straight, guide, rule," p.p. rectus "right, straight;" Ger. recht; E. right; PIE base *reg- "move in a straight line," hence, "to direct, rule."

right triangle
  سه‌بر ِ راست   
sebar-e râst (#)

Fr.: triangle droit   

A triangle one of whose angles is a → right angle.

right; → triangle.

right-hand rule
  رزن ِ دست ِ راست   
razan-e dast-e râst

Fr.: règle de la main droite   

See → Fleming's rules.

right; → hand; → rule.

right-hand screw rule
  رزن ِ پیچ ِ راست‌گرد   
razan-e pic-e rast-gard

Fr.: règle de la vis droite   

A rule that gives the direction of the resultant vector in a → vector product: A x B = C. It is the direction of advance of a right-hand screw whose axis, held perpendicular to the plane of A and B, is rotated in the same sense that rotates the first-named vector (A) into the second-named vector B through the smaller angle.

right; → hand; → screw; → rule.

  راستال، راستدست   
râstâl, râstdast (#)

Fr.: droitier   

Using the right hand with greater skill or ease than the left.

right; → hand + -ed.

Râstâl, from râst, → right, + -al-al. Râstdast, with dast, → hand.

saxtpây (#)

Fr.: rigide   

1) General: Stiff or unyielding; inflexible, strict, severe.
2) Physics: → rigid body; → rigidity.

From L. rigidus "hard, stiff, rough," from rigere "to be stiff;" related to L. frigus "cold," Gk. rhigos "frost, cold."

Saxtpây, from saxt, → hard, + pây present stem of pâyidan "to stand firm, to be constant, steady, fixed;" Mid.Pers. pâyitan, pâtan, pây- "to protect; wait, stand," Sogdian p'y "to protect, watch over;" O.Pers./Av. pâ(y)- "to protect, keep" pâtar- "protector, watcher," cf. Skt. pâ- "to protect, keep," pâti "protects;" Gk. poimen "shepherd," poma "lid, cover;" L. pastor "shepherd," panis "bread;" PIE base *pa- "to protect, guard, pasture, feed."

rigid body
  جسم ِ سخت‌پای   
jesm-e saxtpây

Fr.: corps rigide   

Mechanics: A system of many particles whose positions relative to one another remain fixed.

rigid; → body.


Fr.: rigidité   

1) The quality or state of being → rigid. See also → modulus of rigidity.
2) → magnetic rigidity.

rigid + → -ity.

Rigil Kentaurus (α Centauri)
  پای ِ کنتاؤروس   
pâ-ye Kentâwros

Fr.: Alpha du Centaure   

Another name of → Alpha Centauri.

Rigel, from Ar. rijl (رجل) "foot;" Kentaurus, → Centaurus.

"foot, step" (from Mid.Pers. pâd, pây; Av. pad- "foot;" cf. Skt. pat; Gk. pos, genitive podos; L. pes, genitive pedis; P.Gmc. *fot; E. foot; Ger. Fuss; Fr. pied; PIE *pod-/*ped-); KentâwrosCentaurus.

farsaxt (#)

Fr.: rigoureux   

1) Severely exact or accurate; precise.
2) Logic, Math.: Logically valid. See also: → accurate, → exact, → precise.

M.E., from M.L. rigorosus, from rigor "stiffness, rigor," from rigere "to be stiff."

Farsaxt, from far- intensive prefix "much, abundant; elegantly" (Mid.Pers. fra- "forward, before; much; around;" O.Pers. fra- "forward, forth;" Av. frā, fərā-, fra- "forward, forth; excessive;" cf. Skt. prá- "before; forward, in fron;" Gk. pro "before, in front of;" L. pro "on behalf of, in place of, before, for;" PIE *pro-) + saxt "hard, strong, firm, secure, solid, vehement, intense" (Mid.Pers. saxt "hard, strong, severe;" Av. sak- "to understand or know a thing, to mark;" cf. Skt. śakta- "able, strong," śaknoti "he is strong," śiksati "he learns").

rigorous selection rule
  رزن ِ گزینش ِ فرسخت   
razan-e gozineš-e farsaxt

Fr.: règle de sélection rigoureuse   

A → selection rule obeyed by → discrete transitions. Among them are: rigorous selection rules for → electric dipole transitions (→ permitted) requiring: 1) ΔJ must be 0 or ± 1 with J = 0 ↔ 0 forbidden. 2) ΔMJ = 0, ± 1. 3) → Parity change, i.e. even ↔ odd.

rigorous; → selection; → rule.



A long, narrow, straight or sinuous trench or valley with steep walls and roughly parallel sides on the surface of the Moon.

From Ger. Rille "a small rivulet or brook."

Borrowed from E., as above.

labé (#)

Fr.: bord   

The outer edge, border, margin, or brink of something, especially of a circular object.

M.E., from O.E. -rima (in compounds, as in særima "seashore"); cognate with O.Norse rimi "raised strip of land, ridge"

Labé "limb, edge," from lab "lip;" Mid.Pers. lap; cognate with L. labium, E. lip; Ger. Lefze.


Fr.: rima   

A long fissure on the surface of a planet or Moon; plural form rimae.

From L. rima "fissure, slit."

Loan from E., as above.

Rindler coordinates
  هماراهای ِ ریندلر   
hamârâhâ-ye Rindler

Fr.: coordonnées de Rindler   

The coordinates that describe the → Minkowski space-time in a → hyperbolic version of → polar coordinates. If the coordinates in an → inertial frame is denoted by (t,x), the Rindler coordinates (η,ξ) are defined by: t = (1/α) eαξ sinh (αη) and x = (1/α) eαξ cosh (αη), where α is some positive constant.

Named after Wolfgang Rindler (1924-), Austrian physicist; → coordinates.

Rindler wedge
  گوه‌ی ِ ریندلر   
gove-ye Rindler

Fr.: coin de Rindler   

A portion of the → space-time described by → Rindler coordinates.

Rindler coordinates; → wedge.

  ۱) حلقه؛ ۲) زنگ   
1) halqé (#); 2) zang (#)

Fr.: 1) anneau; 2) sonnerie   

1) A circular band of something. → gossamer ring.
2) A resonant sound like that of a bell or bells.

O.E. hring "circular band" (cf. O.N. hringr, Ger. Ring), literally "something curved," from PIE base *(s)ker- "to turn, bend."

1) Halqé, loan from Ar. Halqat "ring, hoop, circle."
2) Zang "bell."

ring galaxy
  کهکشان ِ حلقه‌ای   
kahkešân-e halqeyi

Fr.: galaxie en anneau   

A galaxy with a ring-like appearance around the central luminous center. The ring consists of massive, relatively young bright stars. It is believed that ring galaxies result from the head-on collision of two different galaxies.

ring; → galaxy.

ring longitude
  درژنای ِ حلقه   
derežnâ-ye halqé

Fr.: longitude de l'anneau   

Of → Saturn, the angle measured with respect to the sub-observer point (a line connecting the observer to Saturn) in the direction of the orbital motion.

ring; → longitude.

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