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

If a line segment is divided into a larger subsegment (a) and a smaller subsegment (b), when the larger subsegment is related to the smaller exactly as the whole segment is related to the larger segment, i.e. a/b = (a + b)/a. The golden ratio, a/b is usually represented by the Greek letter φ. It is also known as the divine ratio, the golden mean, the → golden number, and the golden section. It was believed by Greek mathematicians that a rectangle whose sides were in this proportion was the most pleasing to the eye. Similarly, the ratio of the radius to the side of a regular → decagon has this proportion. The numerical value of the golden ratio, given by the positive solution of the equation φ² - φ - 1 = 0, is φ = (1/2)(1 + √5), approximately 1.618033989. The golden ratio is an → irrational number. It is closely related to the → Fibonacci sequence.

→ golden; → ratio.

A → geochemical classification scheme in which → chemical elements on the → periodic table are divided into groups based on their → affinity to form various types of compounds: → lithophile, → chalcophile, → siderophile, and → atmophile. The classification takes into account the positions of the elements in the periodic table, the types of electronic structures of atoms and ions, the specifics of the appearance of an affinity for a particular → anion, and the position of a particular element on the → atomic volume curve.

Developed by Victor Goldschmidt (1888-1947); → classification.

An extremely faint and broad ring (in fact two rings) of tiny particles around → Jupiter lying just outside the main ring.

Gossamer "a film of cobwebs floating in air in calm clear weather; an extremely delicate variety of gauze, used esp. for veils," from M.E. gossomer, from gos "goose" + somer "summer." Possibly first used as name for late, mild autumn, a time when goose was a favorite dish, then transferred to the cobwebs frequent at that time of year; → ring.

Halqé, → ring; tanté "cobweb, spider's web," from tanidan "to spin, twist, weave" (Mid.Pers. tanitan; Av. tan- to stretch, extend;" cf. Skt. tan- to spin, stretch;" tanoti "stretches," tantram "loom;" Gk. teinein "to stretch, pull tight;" L. tendere "to stretch;" PIE base *ten- "to stretch"), Pers. târ "string," tur "fishing net, net, snare," and tâl "thread" (Borujerdi dialect) belong to this family; variants tanta "cobweb," tanadu, tafen, kartané, kârtané, kâtené, Pashtu tanistah "cobweb;" cf. Skt. tantu- "cobweb, thread, string."

1) Talk about other people's private or personal matters often including remarks that are unkind or untrue.
2) Engage in gossip.

From M.E. gossib, godsib "a close friend or relation, a confidant," from O.E. godsibb, "godfather, godmother," literally "a person related to one in God," from god "→ God" + sibb "a relative," → sibling. In M.E. the sense was "a close friend with whom one gossips," hence "a person who gossips," later "idle talk."

Gotré, from Shirâzi gotré "idle talk, nonesence," cf. (Qatrân, Damâvand) gotâré "loquacious," related to goftan "to say, tell," → promise.

A band of hot, young stars (O and B types) and molecular clouds that stretches around the sky. It is tilted by about 20 degrees with respect to the Galactic plane, and has a diameter of about 3000 light-years.

Named after the American astronomer Benjamin A. Gould (1824-1896), who discovered it in 1879 by studying the distribution of the nearest luminous stars in space; → belt.

General: To rule over, to exercise authority.
Science: To serve as or constitute a law for, e.g. physical laws governing star formation, the Universe, and so on.
To regulate the speed of (an engine) with a governor.

From O.Fr. governer "to govern," from L. gubernare "to direct, rule, guide," originally "to steer," from Gk. kybernan "to steer or pilot a ship" (the root of cybernetics).

Faršâyidan, from Av. fraxšā(y)- "to establish authority, to deploy lordship," from fra- "forward, forth" (Av. pouruua- "first"; cf. Skt. pūrva- "first," pra- "before, formerly," Gk. pro; L. pro; O.E. fyrst "foremost," superlative of fore, from P.Gmc. *furisto; E. fore) + xšā(y)- "to rule, have power," xšayati "has power, rules," xšāyô "power;" O.Pers. xša- "to rule," pati-xša- "to have lordship over," Xšyāršan- "hero among kings" or "ruling over heroes" the proper name of the Achaemenid emperor Hellenized as Xerxes, upari.xšay- "to rule over," xšāyaθiya- "king;" Mid.Pers. šâh "king," pâdixšâ(y) "ruler; powerful; authoritative;" Mod.Pers. šâh "king," pâdšâh "protecting lord, emperor, monarch, king," šâyestan "to be worth, suit, fit;" cf. Skt. ksā- "to rule, have power," ksáyati "possesses;" Gk. ktaomai "I acquire," ktema "piece of property;" PIE base *tkeh- "to own, obtain."

The way that a city, company, etc., is controlled by the people who run it (Merriam-Webster.com).

→ govern; → -ance.

1) The act or process of governing; specifically: authoritative direction or control.
2) The organization, machinery, or agency through which a political unit exercises authority and performs functions and which is usually classified according to the distribution of power within it.
3) The complex of political institutions, laws, and customs through which the function of governing is carried out (Merriam-Webster.com).

→ govern; → -ment.

A regulating device for maintaining uniform speed regardless of changes of load, as by controlling the supply of gas, steam, fuel, etc.

Agent noun from → govern; → -or.

A block of the Earth's crust, bounded by two normal faults, that has dropped downward in relation to adjacent portions.

Graben, from Ger. Graben "ditch, trench;" O.H.G. graban "ditch," grab "grave, tomb;" Goth. graban "ditch;" P.Gmc. *graban; cf. O.E. græf "grave, ditch;" E. a grave; PIE base *ghrebh-/*ghrobh- "to dig, to scratch, to scrape."

Foruzamin, from foru- + zamin. The first component foru- "down, downward; below; beneath;" Mid.Pers. frôt "down, downward;" O.Pers. fravata "forward, downward;" cf. Skt. pravát- "a sloping path, the slope of a mountain." The second component zamin, variant zami "earth, ground," from Mid.Pers. zamig "earth;" Av. zam- "the earth;" cf. Skt. ksam; Gk. khthôn, khamai "on the ground;" L. homo "earthly being" and humus "the earth" (as in homo sapiens or homicide, humble, humus, exhume); PIE root *dh(e)ghom "earth."

1) A degree or step in a scale, as of rank, advancement, quality, value, or intensity.
2) To arrange in a series of grades; class; sort (Dictionary.com).

From Fr. grade "grade, degree," from L. gradus "step, pace, gait, walk;" figuratively "a step, stage, degree," related to gradi "to walk, step, go," and second element in congress, progress, etc.; from PIE *ghredh-; cf. Lith. gridiju "to go, wander," O.C.S. gredo "to come," O.Ir. in-greinn "he pursues."

Padâk, from Baluci padâk "step, stair, ladder" (ultimately from Proto-Ir. *padaka-), older form of Pers. pâyé "step, base," from Mid.Pers. pâd, pây; Av. pad-, cf. Skt. pat: Gk. pos, genitive podos; L. pes; PIE *pod-/*ped-.

1) General: Degree of slope.
2) Physics: Change in the value of a quantity (as temperature, pressure) with change in a given variable.
3) Math.: A differential → operator (symbol → nabla, ∇) that, operating upon a function (f) of several variables, creates a → vector whose coordinates are the → partial derivatives of the function: ∇f = (∂f/∂x)i + (∂f/∂y)j + (∂f/∂z)k. The gradient of a → scalar function is a vector function.

From L. gradient-, gradiens, pr.p. of gradi "to walk, go," from grad- "walk" + -i- thematic vowel + -ent suffix of conjugation.

Ziné "ladder, steps, stair," may be related to ciné, from cidan "to place (something) above/upon (another similar thing);" cf. Lori râ-zina, Yazdi râ-cina "stairs," Nâyini orcen "stairs, ladder;" the phoneme change -c- into -z-, as in gozidan, gozin-/cidan, cin- both deriving from Proto-Ir. *cai- "to heap up, gather, collect."

Proceeding, taking place, changing by small degrees.

From M.L. gradualis, from L. gradus "step."

Padâkvâr, from padâk "grade," + -vâr a suffix which denotes "suiting, befitting, resembling, in the manner of, possession."
Pâypâyé "step by step," from pây, pâ "foot, step," → foot.

A burst that happens gradually, in contrast to a sudden burst.

→ gradual; → burst.

1) To divide into or mark with degrees or other divisions, as the scale of a thermometer.
2) To receive a degree or diploma on completing a course of study (often followed by from).
3) To confer a degree upon, or to grant a diploma to, at the close of a course of study, as in a university, college, or school.
4) A person who has received a degree or diploma on completing a course of study, as in a university, college, or school (Dictionary.com).

M.E., from M.L. graduatus, p.pa. of graduari "to take a degree," from L. gradus "step, → grade."

1, 3) Padâk dâdan, compound infinitive, padâkidan simple infinitive, both from padâk, → grade, + dâdan "to give, grant," → datum, and -idan, → -fy.
2) Padâk gereftan, from padâk + gereftan "→ take, hold."
4) Padâkmand, from padâk + -mand suffix of possession and ability, → -al; padâkidé, p.p. of padâkidan, as above.

1) Marking the scale of an instrument, e.g. the stem of a thermometer is graduated in degrees.
2) An act of graduating; the state of being graduated.

Verbal noun of → graduate.

1) A small, hard seed of plants, especially the seed of cereals.
2) A tiny portion or particle of something such as sand or salt; → dust grain.

M.E. grain, grein, from O.Fr. grein, from L. granum "seed;" akin to corn.

Dâné "grain, seed;" Mid.Pers. dân, dânag "seed, corn;" Av. dānô- in dānô.karš- "carrying grains; an ant;" cf. Skt. dhânâ- "corn, grain;" Tokharian B tāno "grain;" Lith. duona "corn, bread."

Sticking together of micron- to centimetre-sized grains occurring in the interstellar and protoplanetary environments to form larger grain agglomerates.

→ grain; → coagulation.

Conversion of dust grains into smaller grains due to high environmental temperatures.

→ grain; → evaporation.

The process by which dust grains are assembled or produced.

→ grain; → formation.