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

A particular type of radioactive waste that is produced as part of the nuclear fuel cycle. These include extraction of uranium from ore, concentration of uranium, processing into nuclear fuel, and disposal of byproducts.

→ nuclear; → waste.

A → calendar year that contains 365 days and therefore is not a → leap year.

→ ordinary; → year.

A secretion consisting mainly of calcium carbonate, CaCO₃, produced by various mollusks.

M.E. perle, from O.Fr. perle, M.L. perla of unknown origin.

Morvârid "pearl;" Mid.Pers. murwârid, murgârid; cf. Sogd. marγārit, marrγārt; Khotanese mrāhe. Gk. margarites "pearl" may be a loanword from Iranian.

The time required for a complete revolution of the Earth's pole on the celestial sphere as the result of → precession. A Platonic year is equal to 25 800 years.

Of or pertaining to Gk. philosopher Plato, from Gk. Platon "broad-shouldered," from platys "broad." → year.

The planet Earth during its → protoplanetary stage.

→ proto-; → Earth.

A nuclear reaction that takes place at high densities and relatively low temperatures. Pycnonuclear reactions are almost temperature independent and occur even at zero temperature. These reactions are extremely slow at densities typical for normal stars but intensify with increasing density. For example, carbon burns into heavier elements at densities over 10¹⁰ g cm^-3.

Pycnonuclear, from pycno- a combining form meaning "dense, thick," from Gk. pyknos "dense, solid" + → nuclear; → reaction.

Vâžireš, → reaction; cagâl-hasteyi, from cagâl, → dense, + hasteyi, → nuclear.

In plasma physics, the theory that considers the interactions between waves and particles are of first order only. It ignores all terms of second order in the fluctuating quantities.

→ quasi-; → linear; → theory.

Any of the group of metallic → chemical elements with → atomic numbers between 57 and 71 inclusive. The name is an inappropriate terminology, since they are neither rare nor earth; preferred name → lanthanide.

→ rare; → earth; → element.

In a straight line; consisting of straight lines. → curvilinear

From recti- combining form of rectus, → right, + → line + -ar, variant of the adjective-forming suffix → -al.

Râst-xatt, from râst, → right, + xatt→ line.

The motion of light in the first approximation, as evidenced from the formation of shadows and other every day experience. However, → diffraction

→ rectilinear; → propagation; → light.

An optical system that is corrected for → distortion and → spherical aberration and therefore forms the image of a straight line as a straight line.

→ rectilinear; → system.

1) (n.) A systematic inquiry or investigation into a subject in order to discover or establish or revise facts, theories, applications, etc.
2) (v.) To carry out research into a subject.

From M.Fr. recerche, from O.Fr. recercher "to seek out, search closely," from → re-, intensive prefix, + cercher "to seek for," from L. circare "to go about, wander, traverse," from circus→ circle.

Pažuheš, verbal noun of pažuhidan "to search;" Mid.Pers. wizôy- "to examine, investigate;" ultimately from Proto-Iranian *pati-iud-, from *pati- "agaist, back, opposite to, toward, face to face, in front of (cf. O.Pers. paity; Av. paiti; Skt. práti; Pali pati-; Gk. proti, pros "face to face with, toward, in addition to, near;" PIE base *proti) + *iud- "to struggle for something, to fight (Av. yūδ- "to fight, struggle;" Mod.Pers. justan, juy- "to search, seek, ask for"); cf. Mid.Pers. vijuyihitan "to search, seek."

Systematic activity combining both basic and applied research, and aimed at discovering solutions to problems or creating new goods and knowledge. (BusinessDictionary.com).

→ research; → development.

A person who has the quality of guiding, regulating, or controlling the work of other researchers.

→ research; → director.

A nuclear reactor designed for radionuclide production, materials testing, and training.

→ research; → reactor.

A scientist who devotes himself to doing research.

Agent noun, from → research + → -or.

To explore or examine in order to find something.

M.E. serchen, cerchen, from O.Fr. cerchier "to search," from L. circare "to go about, wander, traverse," from circus "circle."

Jost-o-ju interfixed jost and juy past and present stem of jostan/juyidan "to seek, strive for;" Proto-Iranian *iud- "to struggle for something, to fight" (Av. yūδ- "to fight, struggle;" Mod.Pers. justan, juy- "to search, seek, ask for"); cf. Mid.Pers. vijuyihitan "to search, seek."

The scientific attempt to detect → intelligent extraterrestrial → life by surveying the sky to find the existence of → transmissions, especially → radio waves or → light, from a → civilization on a distant → planet. The SETI Institute, that carries out the project, is a private non-profit center founded in 1984. There are many methods that SETI scientific teams use to search for extraterrestrial intelligence. Many of these search billions of radio frequencies that reach Earth from all over the → Universe, looking for an intelligent → radio signal. Other SETI teams search by looking for signals in pulses of light emanating from the stars.

→ search; → extraterrestrial; → intelligence.

1) (n.) General: A scissors of large size.
Physics: A → stress applied to a body in the plane of its faces or perpendicular to its axis. As a consequence, parallel planes in the body remain parallel, but are displaced in a direction parallel to themselves. See also → strain.
2) (v.) General: To cut hair, fleece, or foliage from the surface of something using a sharp tool.
Physics: To cause something to deform or break by applying forces acting parallel to the plane.

M.E. sheren, O.E. sceran, scieran; cf. O.H.G. scrinden "to split;", Du. scheren, Ger. scheren "to shear;" from PIE *(s)ker- "to cut, to scrape, to hack;" cf. Pers. kârd "knife;" Av. kart- "to cut;" Skt. krntáti "cuts;" Gk. keirein "to cut, shear;" Lith. skiriu "to separate."

1) Karn, from Laki caré, Farâhâni carra, Tabari carci "a scissors for cutting sheep wool," cognate with Pers. kârd "knife; " Mid.Pers. kârt "knife," karēnītan, karītan "to cut;" Av. karət- "to cut;" cf. Skt. kart- "to cut," krpāna- "sword, knife;" Gk. karpos "fruit;" L. carpere "to cut, divide, pluck;" PIE base *(s)ker- "to cut."
Karnidan infinitive from karn.

The ratio of the applied → stress to the change in shape (→ strain) produced in an → elastic body. The bigger this quantity the more rigid is the material since for the same change in strain a bigger force is needed. Also called → shear modulus.

→ shear; → modulus.