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

A small starlike symbol (*), used in printing or writing as a reference mark, as an indication of the omission of letters or words, to denote a hypothetical linguistic form, or for various arbitrary meanings.

M.E. astarisc, from L.L. asteriscus, from Gk. asteriskos "small star," from aster-, → astro- + -ikos "diminutive suffix."

Axtarak, from axtar "star" → astro- + -ak "diminutive suffix."

A group of stars in the sky which are traditionally imagined to present a pattern within a → constellation. Examples include the → Big Dipper, the → Northern Cross, the → Square of Pegasus, and → Orion's Belt.

Gk. asterismos "a marking with stars, constellation," from aster, → astro- + → -ism.

Axtargân, from axtar "star" → astro- + -gân suffix denoting collective nature.

1) A small rocky object orbiting the Sun. There are millions of asteroids moving in orbits in the main → asteroid belt, between → Mars and → Jupiter and in the → Kuiper belt. The largest and the first discovered, → Ceres, about 1,000 km in size, is now classified as → dwarf planet (2006 IAU General Assembly). The largest asteroid in the solar system (Ceres apart), is → Pallas, with a size of 582 × 556 × 500 km. On the other hand, the smallest asteroid ever studied is the 2 meters space rock 2015 TC25, which was observed when it made a close flyby of Earth in October 2015. See also → near-Earth asteroid; → binary asteroid.
2) Math.: A → hypocycloid with four → cusps in which the → radius of the rolling → circle is a → quarter of the radius of the fixed circle. It has the → parametric equations x = a cos³θ, y = a sin³θ, where a is the radius of the fixed circle.

Gk. asteroeides "star-like," from aster, → astro- + → -oid "like, resembling."

Sayyârak "small planet," from sayyâré, → planet, + -ak "diminutive suffix."
Axtarvâr, from axtar, → astro-, + -vâr, → -oid.

The region of the → solar system located between → Mars and → Jupiter where over a million objects bigger than 1 km across orbit the Sun. Another region populated by minor bodies lies beyond the orbit of → Neptune, the → Kuiper belt.

→ asteroid; → belt.

1) For an asteroid whose orbit is precisely known, a number and optionally a proper name, e.g. (7) Iris, (24101) Cassini, (99942) Apophis.
2) For an asteroid whose orbit is not known, a provisional designation composed of four elements: number.letter.letter.(optionally)number. The first number indicates the year of discovery. The first letter denotes the half-month of the discovery (A: first half of January, Y: second half of December; the letter "I" is excluded). The second letter and the following number indicate the order of discovery within the half-month. For example, the first asteroid discovered in the first half of May 1960 is: 1960 JA. Since more than 25 objects (without "I") might be detected within a half-month, the number following the second letter indicates the number of 25 discoveries. Hence, 2001 SD3 was discovered in the second half of September 2001 and was the (D =) 4 + (25 x 3) or the 79th object found during that period.

→ asteroid; → designation.

A group of asteroids that share the same or similar proper orbital elements (semi-major axis, eccentricity, inclination). In 1918, the Japanese astronomer K. Hirayama first recognized some non random concentrations of asteroid elements. He noticed that certain "groups" of asteroids had similar orbital elements, and hence he first introduced the concept of "asteroid families," and identified three of them: Koronos, Eos, and Themis. The names of these groups were chosen by the parent (brightest) asteroid that the smaller group asteroids follow. Some of the more common asteroid families include the Trojans, which are actually not an asteroid family, but a group of asteroids caught in the Sun-Jupiter gravitational equilibrium points known as L3 and L4 → Lagrangian points.

→ asteroid; → family.

Systematic observation of the sky in particular searching for → asteroids that may have a close approach to the Earth. → near-Earth object.

→ asteroid; → survey.

Bardid, → survey; sayyârakhâ plural of sayyârak, → asteroid.

Of or relating to → asteroseismology.

→ spectropolarimetry; → -ic.

The study of the → internal structure of stars through the interpretation of their pulsation periods (→ stellar pulsation). The radial pulsations are the result of → sound waves resonating in the stars interior. Different → pulsation modes penetrate to different depths inside a star. If a large number of pulsation modes occurs, then the stellar interior, which is not directly observable, can be probed from oscillation studies because the modes penetrate to various depths inside the star. Using a complex mathematical analysis, very detailed investigations of the structure of the star's interior can be carried out. Applied to the Sun, it is called → helioseismology.

From → astero- "star," from aster-, → astro-, + → seismology.

Axtarlarzešenâsi, from axtar "star," → astro-, + larzešenâsi, → seismology.

A layer of soft, partly molten, rock in the → Earth's mantle, located at a depth of 100 to 250 km, over which the more rigid plates of the → lithosphere are in motion.

Asthenosphere, from Gk. asthenes "weak" + → sphere.

Sostsepehr, from sost "weak, tender" + sepehr, → sphere.

The optical system which is affected by → astigmatism.

→ astigmatism.

1) An imperfection in an optical system whereby light from a point source is formed into an image as a straight line, ellipse, or circle. The rays of light in two perpendicular planes appear as two lines at right angles.
2) A common eye defect in which the unequal curvature of one or more refractive surfaces of the eye, usually the cornea, prevents light rays from focusing clearly at one point on the retina, resulting in blurred vision.

From astigmatic, from Gk. → a- "without" + stigmatos, from stigma "a mark, spot, puncture."

1) Nâgerâvari, from nâ- "without, un" + gerâ, stem of gerâyidan "to converge," + -var, agent forming suffix, + -i, noun forming suffix.
2) The same as above with -bini "seeing, discerning".

Verbal form of → astration.

→ astration.

The cyclic process in which interstellar matter is incorporated into newly formed stars, where it undergoes nuclear processing, is thus enriched with heavier elements, and then returns into the interstellar medium through supernova explosion or stellar winds to be used in the formation of a newer generation of stars.

Astration, from astrate, from astr-, → astro-, + noun-forming suffix -ation.

Setâreš, from setâridan (from setâré "star" + verb-making suffix -idan) + noun-builder -eš.

A combining form with the meaning "pertaining to stars or celestial bodies" used in the formation of compound words. Variants aster-, and astr- before a vowel. → star.

Gk. astron "star," akin to L. stella (Fr. étoile, from O.Fr. esteile, from V.L. *stela), Skt. str-, tara-, Av. star-, Mid.Pers. star, stârag, Mod.Pers. setâré, axtar, see below; cf. O.E. steorra, E. star, Du. ster, O.H.G. sterro, Ger. Stern, PIE *ster- "star."

Mod.Pers. axtar, → star, from Mid.Pers. axtar. The variants star-, estâr, estâré, setâré are obvious. Note also the following dialectal forms: (Lori, Laki) âsâra, (Tabari) essâra, (Laki) hasâra, (Shughni) xiterj, xtarag. The form axtar is less straightforward, leading some philologists to suggest different origins for setâré and axtar. According to W. Eilers (Iranica), axtar is a back-fomation from Mid.Pers. apâxtar "planet; north" produced by artificial dropping of the first component. Apart from phonological difficulties inherent in this suggestion, one must also explain how axtar meaning "planet" became a general designation for star, as for example in Mid.Pers. axtarmâr "astronomer," despite the relatively infinitesimal number of planets known in ancient times. W. Eilers' suggestion is pure theoretical construction; no factual evidence support it. On the other hand, in Pahlavi texts, e.g. Bundahishn, axtar is extensively used for "star, planet, and the signs of zodiac."

We suggest that both words star and axtar are etymologically related. This idea is based on the fact that "s" and "x" phonemes interchange in Persian and other IE languages. For example, the PIE *swesor "sister" has evolved into Av. xvanhar-, Mid.Pers./Mod.Pers. xâhar (Skt. svasar-, L. soror, Fr. soeur, Gk. eor "daughter, cousin, relative," Arm. k'oyr, O.H.G. swester, Ger. Schwester, Du. zuster, E. sister). Similarly, *saewel- "sun" has become Av. hvar- "sun," Mid.Pers. xavr, Mod.Pers. xor, while keeping its Av. h in Mod.Pers. hur "sun" (cf. Skt. svar-, surya-, Gk. helios, L. sol, Goth. sauil, Lith. saule). Finally, *su- "hog, pig, swine" also has changed its "s" into both "h" and "x" in Av. and Mod.Pers. hu- and xuk respectively (Skt. sukara- "boar, hog, pig," Gk. hys, L. sus, Welsh hucc, Ger. Schwein, E. swine).

Same as → archaeoastronomy, megalithic astronomy.

The study of life throughout the Universe, also known as exobiology.

Astrobiology, from Gk. → astro- "star" + bio "life" + -logy "science, study."

Axtarzistšenâsi, from axtar, → star, → astro- + zistšenâsi, → biology.

A geological structure on the Earth's surface from an ancient meteorite impact.

Astrobleme, from → astro- + Gk. blema "scar, wound, missile," from ballein "to throw;" PIE *gwele- "to throw".

Axtarxasts, from axtar "star," → astro- + xast "wounded; scratched," from xastan "to wound, wound by scratching," Mid.Pers. xst, xs "to injure," Av. vixad- "to crush," Proto-Iranian *xad- "to wound, hurt," Skt. khad- "to hurt."

The study of the chemical interactions between the gas and dust of the interstellar medium.

Astrochemistry, from → astro- "star" + → chemistry.

Axtaršimi, from axtar, → astro-, + šimi, → chemistry.

The science dealing with the motion of satellites, rockets, and spacecrafts. It uses the principles of celestial mechanics.

Astrodynamics, from → astro- "star" + → dynamics.

Axtartavânik, from axtar, → astro-, + tavânik, → dynamics.