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

A particular extent of space or surface; the scope of a concept, operation, or activity.

The etymology is not clear; perhaps akin to L. arere "to be dry" → arid.

Pahné "area, field," from pahn "broad, wide" (Mid.Pers. pah(a)n, Av. pathana- "broad, wide, spacious," probably related to perethav- "broad, wide," Skt. prthav-, Gk. platus; PIE *plat- "to spread") + noun forming suffix -é.

The study of the surface features of Mars; the geography of Mars.

Areography, from Gk. Ares "Mars" + → -graphy.

Bahrâm-negâri, from Bahrâm "Mars" + -negâri→ -graphy.

The study of the origin, history, and structure of Mars; the geology of Mars.

Areology, from Gk. Ares "Mars" + → -logy.

Bahrâm-šenâsi, from Bahrâm "Mars" + -šenâsi→ -logy.

A geometrical representation of → complex numbers, which like the → Cartesian coordinates, uses two reference perpendicular axes. The horizontal axis represents the → real number part of the number and the perpendicular axis the → imaginary number part.

Named after Jean Robert Argand (1768-1822), a Swiss mathematician, who introduced this representation; → diagram.

A technique to estimate the brightness of a → variable star. It involves comparing the variable with a sequence of neighboring stars of slightly different → magnitudes.

Friedrich Wilhelm Argelander (1799-1875), German astronomer. His most important work was his compilation of the Bonner Durchmusterung; → method.

An extensive constellation, one of the 48 constellations known to Greeks, representing the ship of Argonauts. It was divided in 18th century into the constellations → Carina, → Puppis, and → Vela.

The ship in which Jason sailed in search of the Golden Fleece.

Kašti "ship," from Mid.Pers. kaštik.

A generally reddish matter that settles from a liquid, especially from wine. Same as → tartar.

M.E. argul, argoile, from M.Fr. argoil, from L. argilla "argil."

Lerd ou lert "the sediment of liquids, dregs, lees" (Dehxodâ).

A → chemical element which occurs as a colorless, odorless, and tasteless gas in the atmosphere (of which it constitutes 0.94% by volume) and in some volcanic gases; symbol Ar. → Atomic number 18; → atomic weight 39.948; → melting point -189.2°C; → boiling points -185.7°C.

Argon, from Gk. neutral of argos "inactive, idle, lazy," from negation prefix → a- + ergon "work," → energy. It was discovered in 1895 by the Scottish chemist William Ramsay and the English physicist Robert John Strutt (Lord Rayleigh) in liquified atmospheric air.

To put forth reasons for or against.

→ argument.

1) General: A discussion involving differing points of view; debate; a process of reasoning; series of reasons.
2a) Math.: The → independent variable of a → function.
2b) Math.: The → angle of a → complex number measured from the positive horizontal axis.
3) Astro.: → argument of periapsis, → argument of perigee, → argument of perihelion.
4a) Logic: A sequence of → propositions with one or more → premises and a → conclusion. Arguments are usually divided into two kinds, → deductive and → inductive.
4b) Logic: A → propositional symbol (→ variable or → constant) taken by a → predicate in an → atomic wff.

M.E., from M.Fr., from L. argmentum, from arguere "to make clear." Compare with L. argentum "silver," Gk. argos "white," arguron "silver," Av. auruša- "white" (Mid.Pers. arus "white, bright"), Av. ərəzata- "silver," Skt. arjuna- "white, shining," rajata- "silver," Mod.Pers. arziz "silvery metal tin;" PIE *arg- "to shine, be white, bright, clear."

Âruzmân, from Av. āroc- "to enlighten, make light," Av. raocah- "light, luminous; daylight;" Skt. roka- "brightness, light," cognate with Gk. leukos "white, clear;" L. lux "light" (also lumen, luna); PIE *leuk- "light, brightness" + noun forming suffix -mân.

The angular distance between the → ascending node of an object orbiting a → primary and its periapsis measured from the primary. Argument of periapsis is measured in the → orbital plane in the direction of motion. It is one of the → orbital elements. See also → argument of perigee, → argument of perihelion.

→ argument; → perigee.

The angular distance between the → ascending node of an object orbiting the Earth and its perigee, measured from the Earth. See also: → argument of perihelion, → argument of periapsis.

→ argument; → perigee.

The angular distance between the → ascending node of an object orbiting the Sun and its perihelion. Argument of perihelion is measured in the → orbital plane with respect to the Sun and in the direction of motion. It is one of the → orbital elements and usually shown with the symbol ω. See also: → argument of perigee, → argument of periapsis.

→ argument; → perihelion.

The presentation and elaboration of an argument or arguments.

Noun from → argument.

1) Fond of or given to argument and dispute.
2) Of or characterized by argument; controversial.

→ argue; → -ive

Lacking sufficient water or rainfall.

L. aridus, from arere "to be dry, i.e. burnt up"; compare with Gk. azaleos "dry," PIE *as- "to burn, glow".

Kamâb, from Mod.P. kam "little, few, deficient, scarce" + âb "water".

A measure of the degree to which a climate lacks effective moisture.

Aridity, noun from → arid.

Kamâbi, noun from amâbi, → arid.

A satellite of → Uranus discovered by Lassell in 1851. It is orbiting at a mean distance of 192,000 kilometers with a period of 2.52 days.

Ariel, a spirit in William Shakespeare's The Tempest.

The Ram. A constellation of the → Zodiac, representing a ram (R.A. = 2h 30m, Dec. = +13 deg). Its brightest star is → Hamal (α Arietis). Abbreviation: Ari; genitive form: Arietis.

L. aries "ram," perhaps akin to Gk. eriphos "a kid, a young goat," O.Ir. heirp "she-goat;" cf. Lith. erytis, O.C.S. jarici, Arm. oroj "lamb."

Barré "ram, sheep; Aries" from Mid.Pers. warrag "lamb, ram; Aries," compare with Av. varənâ- "wool," Skt. urana, urabhra "wool-beared = ram," from urna "wool," L. vervex "a wether, sheep".

Put in modern notation, if α and β are acute angles and if β <α, then sin α / sin β <α / β < tan α / tan β. Aristarchus probably used this inequality to show that the Sun is between 18 and 20 times as far from the Earth as the Moon is.

Aristarchus of Samos (c.310-c.230 BC); → inequality.