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

A device producing cross dispersion.

→ cross; → disperser.

Dispersion of a light beam by using two dispersing elements (grating, grism), one for separating spectral orders, the other for resolving spectral features within an order.

→ cross; → dispersion.

The identification of an object in a data base or catalog and matching it with the same object identified in another catalog.

→ cross; → identification.

Same as → vector product.

→ cross; → product.

Reference from one part or element of a book or data catalog to something in another for further information.

→ cross; → reference.

1) Math: The intersection of a plane with a geometric figure, usually at right angles to an axis of symmetry.
2) Physics: A quantity that expresses the effective area that a given particle presents as a target to another incident particle, giving a measure of the probability that the incident particle will induce a particular atomic or nuclear reaction. Also called collision cross section. The cross section has the dimensions of a surface. In nuclear and particle physics, the commonly used units for the cross section are the barn and cm².

In classical mechanics, the cross section for the collision of a point particle with a hard sphere is just be the surface of a section through the middle of the sphere. This explains the name "cross section." → cross; → section.

A spectrograph that utilizes cross dispersion.

→ cross; → dispersion; → spectrograph.

A system of two perpendicular fine threads of wire placed in the focus of the eyepiece of an optical instrument and used as a sighting reference.

→ cross; → hair.

Târbast, from târ + bast. The first component târ "thread, string, wire," cognate with tanidan, tan- "to spin, twist, weave," → tension; the second component bast "to bind; to arrange" (past stem of bastan, from Mid.Pers. bastan/vastan "to bind, shut," → band.

A concept used for checking the stability of a group of mass such as a → cluster of galaxies or a → star cluster. The crossing time is given by t_c = R/V, where R is the average projected radial distance of group members from the center of mass and V the Gaussian dispersion in internal velocity.

→ cross; → time.

Any of several large oscine birds of the genus Corvus, of the family Corvidae, having a long, stout bill, lustrous black plumage, and a wedge-shaped tail (Dictionary.com).

O.E. crawe, imitative of the bird's cry; cf. O.Saxon kraia; Du. kraai; O.H.G. chraja; Ger. Kräke; L. corvus "a raven," Gk. korax; cognate with Pers. kalâq, → raven.

Zâq "crow, raven," of unknown origin.

1a) A large number of persons gathered closely together; throng.
1b) Any large number of persons.
1c) Any group or set of persons with something in common.
2) To gather in large numbers; throng; swarm (Dictionary.com).
→ crowded, → crowded field, → crowding.

M.E. crowden, from O.E. crudan "to press, crush;" akin to M.Du. cruden "to press, push," M.H.G. kroten "to press, oppress," Norwegian kryda "to crowd."

Capiré (Dehxodâ), variants cabiré, capar "crowd, troop, people gathered for something." Capiré, from capir, from capar, ultimately from Proto-Ir. *ui-par-, from *par- "to fill;" cf. Av. pər- "to fill, stuff with," pouru- "full, much, many;" O.Pers. paru- "much, many;" Pers. anbâr "ricks, storehouse," por, bol "full, much, many;" PIE *pel- "to fill;" → population.

Filled so that there is little or no room for anyone or anything else. → crowded field.

Past participle of → crowd.

An area on the sky where a large number of objects, commonly stars, are seen gathered together, usually as revealed by imaging.

→ crowded; → field.

1) The state or action of filling a particular place in large numbers.
2) For a → field of view, state of containing a large number of objects.

Verbal noun of → crowd.

The process of procuring needed services by soliciting a large group of people outside the demanding company, society, or institute. Two examples of crowdsourcing in astronomy involve → variable star studies and search for → meteorites.

Combination of → crowd and → outsourcing.

An optical, alkali-lime glass which is harder than → flint glass, and has a lower → index of refraction and lower → dispersion. It is used in the production of → compound lenses.

Such named because of the crown-like shape given to the blank after the process of blowing the glass; M.E. coroune, from O.Fr. corone, from L. corona "crown," originally "wreath, garland;" cf. Gk. korone "anything curved, kind of crown;" → glass.

A curve, on the pressure versus specific volume plane, representing the locus of all the theoretically possible states that can be attained by the → detonation products of an → explosive. The Crussard curve relates to the → Hugoniot curve through a translation caused by the chemical energy liberated during the detonation. The Crussard curve consists of several portions characterizing various burning regimes: detonations (strong and weak), a forbidden region, and → deflagrations (weak and strong).

Named after the French engineer Jules Louis Crussard (1876-1959), who conducted several pioneering studies in mining techniques, in particular on shock waves (Ondes de choc et onde explosive, Bulletin de la Société de l'industrie minérale de Saint-Etienne, 4e série, tome VI, 1907); → curve.

Any more or less hard or stiff outer covering or surface. → Earth's crust.

M.E., from O.Fr. crouste from L. crusta "rind, crust, shell, bark;" cf. Skt. krud- "make hard, thicken;" Av. xruzdra- "hard;" Gk. kryos "icy cold," krystallos "ice, crystal;" Lett. kruwesis "frozen mud;" O.H.G. hrosa "ice, crust;" O.E. hruse "earth;" PIE base *kreus- "to begin to freeze, form a crust."

Pusté, → shell.

The Southern Cross. A small but brilliant → constellation in the southern hemisphere, at 12h 30m right ascension, 60° south declination. Also known as → Southern Cross. The constellation contains four bright stars so situated that they depict the extremities of a Latin cross. Abbreviation Cru; genitive Crucis.

L. crux "cross, gibbet" is a rendering of the Gk. stauros "an upright stake or pole," in the Vulgate, the Latin translation of the Bible attributed to Saint Jerome at the end of the fourth century A.D.

Calipâ, loanword from Aramean.

A branch of physics that studies the methods of producing very low temperatures (below 150 °C) and the behavior of materials and processes at those temperatures.

From cryo- "freezing" + -gen(y) "having to do with production" + -ics.
Cryo-, from Gk. kryos "icy cold," krystallos "ice, crystal," PIE base *kreus- "to begin to freeze, form a crust;" cf. L. crusta "crust, shell, bark," Skt. krud- "make hard, thicken;" Av. xruzdra- "hard," Lett. kruwesis "frozen mud;" O.H.G. hrosa "ice, crust;" O.E. hruse "earth."
-geny, from Gk. geneia, from genes "born," cf. Av. zan- "to bear, give birth to a child, be born," infinitive zazâite, zâta- "born," cf. Skt. janati "begets, bears," L. gignere "to beget," PIE base *gen- "to give birth, beget."
→ -ics.

Zamâzâyik, from zam "cold (weather)" + zâyi "generating" + -ik.
Mod.Pers. zam "cold," Mid.Pers. zam "winter," Av. zimô "winter," Skt. hima- "cold, frost," Ossetic zymæg/zumæg "winter," Gk. xeimon "winter," L. hiems "winter," Lith. ziema "winter," PIE *gheim- "snow, winter."
Zâyi, from zâ- present tense stem of zâdan "to give birth," Mid.Pers. zâtan, Av. zan- "to bear, give birth to a child, be born," infinitive zazâite, zâta- "born," cf. Skt. janati "begets, bears," L. gignere "to beget," PIE base *gen- "to give birth, beget," as above.
→ -ics.