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

A body that revolves around a more massive body under the → gravitational attraction of the latter is called the → primary body.
The less massive component in a → binary system.

→ secondary; → body.

An indicator of extragalactic distances that relies on → primary calibrators in our Galaxy. Secondary calibrators of the distance scale depend on statistical measures of the properties of a class of objects, such as the brightness of H II regions, globular clusters, red and blue stars, or the neutral hydrogen 21-cm line width or velocity dispersion (of spiral galaxies), etc. Same as secondary distance indicator.

→ secondary; → calibrator.

An electric cell that can be charged by passing a current through it in reverse direction to its discharge. Same as → accumulator. See also → primary cell.

→ secondary; → cell.

A burst of secondary charged and neutral particles arising when → primary cosmic rays collide with the atmospheric oxygen or nitrogen nuclei in the upper atmosphere. The collision produces mostly → pions (π), along with some → kaons (K), → antiprotons, and → antineutrons. Neutral pions very quickly decay, usually into two → gamma rays. Charged pions also decay but after a longer time. Therefore, some of the pions may collide with yet another nucleus of the air before decaying, which would be into a → muon and a → neutrino. The fragments of the incoming nucleus also interact again, also producing new particles.

→ secondary; → cosmic; → ray.

A crater formed by the relatively low-velocity impact of fragments ejected from a large primary crater. Secondary craters tend to cluster in a ring around the primary crater.

→ secondary; → crater.

Of a transiting → exoplanet, the event and the interval of time during which the planet passes behind its host star. → primary eclipse.

→ secondary; → eclipse.

Electrons ejected from the atoms of a material when bombarded with high energy electrons. Secondary electrons are produced when an incident electron excites an electron in the material and loses some of its energy in the process. The excited electron moves toward the surface of the sample undergoing elastic and inelastic collisions until it reaches the surface, where it can escape if it still has sufficient energy. The secondary electron yield depends on many factors, and is generally higher for high atomic number targets, and at higher angles of incidence.

→ secondary; → electron.

The emission of → secondary electrons from the surface of a material when an incident particle (often, charged particle such as electron or ion) impacts the material with sufficient energy.

→ secondary; → emission.

The second reflecting surface in a → reflecting telescope. It directs the light either out a side opening of the tube (→ Newtonian telescope) or back toward a → focal point behind and through the → primary mirror (→ Cassegrain telescope). The secondary is usually suspended in the beam and therefore obstructs part of the primary.

→ secondary; → mirror.

A fainter rainbow appearing about 10° above the → primary rainbow, as viewed by the observer. The secondary rainbow is about twice as wide, and has its colors reversed.

→ secondary; → rainbow.

In a → binary system, the star that revolves around the more massive → primary component.

→ secondary; → star.

1) Something that is or is kept secret, hidden, or concealed; a → mystery.
2) Done, made, or conducted without the knowledge of others (Dictionary.com).

From L. secretus "set apart, withdrawn; hidden, concealed," p.p. of secernere "to set apart, part, divide; exclude," from se- "without, apart," properly "on one's own" + cernere "to separate," → crisis.

Râz, from Mid.Pers. râz "secret, mystery;" cognate with Mod.Pers. rastan/rah- "to escape, be liberated;" O.Pers. (+*aua-) avarad- "to leave, abandon;" cf. Skt. rah- "to be lost, be lonely," rahas- "loneliness, privacy; a secret, mystery" (Cheung 2007).

The officials or office entrusted with administrative duties, maintaining records, and overseeing or performing secretarial duties, especially for an international organization (Dictionary.com).

From Fr. secrétariat, from M.L. secretariatus, from secretarius, → secretary.

Dabirxâné, literally "house of secretaries," from dabir, → secretary, + xâné, → house.

A person, usually an official, who is in charge of the records, correspondence, minutes of meetings, and related affairs of an organization, company, association, etc. (Dictionary.com).

M.E. secretarie "one trusted with private or secret matters; confidant," from M.L. secretarius "confidential officer, confidant, clerk, notary," from L. secretum "a secret, a hidden thing."

Dabir, from Mid.Pers. dipîr, contraction of dipîvar (Mid.Pers. dip, dīp "document;" dīb "letter"); from O.Pers., from Proto-Ir. *dipī-uara- "he who preserves the documents;" cf. O.Pers. dipī- "inscription" + *Huar- "to cover;" cf. Av. vār- "to cover, hide, protect."

The head or chief administrative officer of a secretariat.

→ secretary; → general.

A part that is cut off or separated.
A distinct part or subdivision of anything. → cross section; → intersection

From M.Fr. section, from L. sectionem "a cutting, division," from secare "to cut;" PIE base *sek- "cut" (cf. O.C.S. seko, sesti "to cut," Lith. isekti "to engrave, carve;" O.S. segasna, O.E. sigðe "scythe;" O.E. secg "sword," seax "knife, short sword").

Sekanj "a scraping, shaving, cutting," cognate with Pers. šekast-, šekastan "to break;" Av. skand- "to break," Skt. khand- "to break," khanda- "piece;" Pers. dialect Tabari šag "a special razor used to make incisions in the walls of unripe opium poppies in order to extract the milky sap," may be related to PIE *sek- "cut," as above.

1a) General: Going on from age to age; continuing through long ages.
1b) Astro.: Gradual or taking place over a long period. → secular acceleration; → secular change.
2a) (adj.) Worldly or material rather than spiritual.
2b) (adj.) Not overtly or specifically relating to religion or to a religious body.
2c) (adj. & n.) Relating to or advocating secularism; a layperson.

Secular from O.Fr. seculer, from L.L. sæcularis "of an age, occurring once in an age," from sæculum "age, span of time, generation, the spirit of the age."

1) Diryâz "long lasting, from dir "slowly, tardily; late" (Mid.Pers. dêr, variants dagr, drâz "long;" (Mod.Pers. derâz "long," variant Laki, Kurdi derež); O.Pers. darga- "long;" Av. darəga-, darəγa- "long," drājištəm "longest;" cf. Skt. dirghá- "long (in space and time);" L. longus "long;" Gk. dolikhos "elongated;" O.H.G., Ger. lang; Goth. laggs "long;" PIE base *dlonghos- "long") + yâz present stem of yâzidan "to stretch out the arms; grow up" (Parthian Mid.Pers. y'd "to reach a goal, come to, stretch out;" Av. yat- to reach, take one's place," yaiiata "places," frā-iiatāt "has reached;" cf. Skt. yat- "to be in place, put in place, line up;" PIE base *iet- "to be in place").
2) Giyâné, giyâni from giyân, variant of Mod.Pers. jahân, keyhân, geyhân "world," giti "world, material world, time," Mid.Pers. gêhân "world," gêtig "the material world; wordly," Manichean Mid.Pers. gyh "world," gyh'n "worlds;" Av. gaē&thetaā- "being, world, matter, mankind," gaya- "life, manner of living", root gay- "to live" (present tense jiva-), O.Pers. gaiθā- "live-stock," cognate with Skt. jīv- "to live," jīva- "alive, living;" Gk. bios "life," L. vivus "living, alive," vita "life;" PIE base *g^wei- "to live" (cf. O.E. cwic "alive;" O.C.S. zivo "to live;" Lith. gyvas "living, alive;" O.Ir. bethu "life," bith "age, life, world;" Welsh byd "world"). The Pers. words zistan "to live," zendé "alive," zendegi "life," and jân "vital spirit, soul; mind" belong to this family.

The smallest component of the aberration of starlight which is caused by the motion of the solar system through space. → annual aberration; → diurnal aberration.

→ secular; → aberration.

The apparent gradual increase in the → Moon's motion in its orbit, as measured relative to → mean solar time. Secular acceleration corresponds to an extremely gradual reduction in the speed of the → Earth's rotation. The slow-down of the Earth's spin comes mainly from → tidal frictions from the Moon. Historically, Edmond Halley (1656-1742) was the first to suggest that the Moon's mean rate of motion relative to the stars was gradually increasing. In 1693, Halley compared eclipses of recent, medieval, and classical Babylonian time, and discovered that the Moon's mean motion had been gradually increasing. Using Lunar Laser Ranging measurement, based on laser reflectors left by the Apollo astronauts on the Moon's surface (1969 to 1972), the secular acceleration is derived to be -25".4 ± 0".1 century ² (Xu Huaguan et al., 1996, in Earth, Moon and Planets 73, 101). This corresponds to a linear increase of about 3.5 cm yr^-1 in the mean Earth-Moon distance.

→ secular; → acceleration.

A continuous, non-periodic change in one of the attributes of the states of a system. Often, a change in an orbit due to dissipation of energy. See also → canonical change.

→ secular; → change.