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

A → ccordinate system on the surface of the Earth that defines every location by a set of numbers and letters, indicating the → latitude and → longitude.

→ geographic; → coordinate; → system.

A synonym for → geodetic latitude or → astronomical latitude.

→ geographic; → latitude.

→ north pole.

→ geographic; → north; → pole.

→ south pole.

→ geographic; → south; → pole.

The science dealing with the areal differentiation of the Earth's surface, as shown in the character, arrangement, and interrelations over the world of such elements as climate, elevation, soil, vegetation, population, land use, industries, or states, and of the unit areas formed by the complex of these individual elements (Dictionary.com).

→ geo-; → -graphy.

1) A visual representation of data that displays the relationship among variables, usually cast along X and Y axes.
2) In → graph theory, a graph G = (V, E) consists of a set of objects V called vertices and a set E which contains unordered pairs of distinct elements of V called edges.

Short for graphic (formula), from L. graphicus "of painting or drawing," from Gk. graphikos "able to draw or paint," from graph(ein) "to draw, write" + -ikos, → ic.

Negâré, from negâr "picture, figure" (verb negârdan, negâštan "to paint"), from prefix ne-, O.Pers./Av. ni- "down; into," → ni-, + gâr, from kar-, kardan "to do, to make" (Mid.Pers. kardan; O.Pers./Av. kar- "to do, make, build;" Av. kərənaoiti "he makes;" cf. Skt. kr- "to do, to make," krnoti "he makes, he does," karoti "he makes, he does," karma "act, deed;" PIE base *k^wer- "to do, to make").

The branch of → mathematics dealing with → graphs. In particular, it involves the ways in which sets of points (→ vertex) can be connected by lines or arcs (→ edge).

→ graph; → theory.

(Adj.) Pertaining to the use of diagrams, graphs, mathematical curves, or the like.
Math.: Pertaining to the determination of values, solution of problems, etc., by direct measurement on diagrams instead of by ordinary calculations.
(n.) A product of the graphic arts, as a drawing or print. A computer-generated image.

→ graph + → -ic.

A particular crystalline form of → carbon occurring as a soft, black, lustrous mineral. The carbon atoms in graphite are strongly bonded together in sheets. Because the bonds between the sheets are weak, other atoms can easily fit between them, causing graphite to be soft and slippery to the touch. Graphite conducts electricity and is used in lead pencils and electrolytic anodes, as a lubricant, and as a moderator in nuclear reactors. If graphite is subjected to high pressure, it will be transformed into → diamond.
Graphite is present in the → interstellar medium; it forms in circumstellar shells and supernova ejecta. In particular, the 2175 Å interstellar extinction feature is accounted for by small graphite grains.

From Ger. Graphit, from Gk. graph(ein) "to write, draw," so called because it was used for pencils, → graph + -it a suffix of chemical compounds, equivalent to E. -ite.

1) An instrument for photographing the Sun, consisting of a camera and a specially adapted telescope.
2) A simple device using a mirror to reflect sunlight to a distant observer. By moving the mirror, flashes of light can be used to send coded messages. The heliograph was a highly effective instrument for instantaneous optical communication over 80km or more in the 19th century.
3) Meteo.: An instrument which records the duration of sunshine and gives a quantitative measure of the amount of sunshine.

→ helio-; + → -graph.

Of, relating to, or produced using → holography; three-dimensional.

→ holo- + → -graphic.

A → diffraction grating produced from a series of constructive → interference fringes. The fringes, whose intensities vary in a sinusoidal pattern, correspond to the grooves of the grating. They are recorded on a photosensitive substrate and subsequently treated using a chemical procedure. Since the grooves are created by the interference of light, such a grating is free from the random and periodic errors present in → ruled gratings.

→ holographic; → grating.

A technique for making three-dimensional images by recording → interference patterns from a split → laser beam on a medium such as photographic film. One of the → coherent beams irradiates the object, the second beam illuminates a recording medium. The two beams produce an interference pattern, called → hologram, on the film. The hologram contains information on both → phase and → amplitude of the object. However, this information is in a coded form, and the image must be reconstructed. When the object is removed and the hologram is illuminated by the laser from the original direction, a 3-dimensional image of the object appears where the object was originally, as if it were not removed. The visible object seems so real that the observer can detect → parallax by changing the position of one's head.

From → holo- "whole" + → -graphy. By using the term holography, Dennis Gabor (1900-1979), the Hungarian-British electrical engineer and inventor, wanted to stress that the technique records complete information about a wave, both about its amplitude and its phase, in contrast to the usual photography in which only the distribution of the amplitude is recorded.

The study, measurement, and description of depths and currents in open seas, lakes, estuaries, and rivers.

→ hydro- + → -graphy.

An instrument that records the hygrometer's measure of water vapor.

→ hygro- + → -graph.

A branch of → linguistics that deals with the principle and methods of writing dictionaries.

→ lexicology; → -graphy.

The study of the ocean, embracing and integrating all knowledge pertaining to the ocean's physical boundaries, the chemistry and physics of sea water, and marine biology.

→ ocean + → -graphy.

Oqyânus→ ocean + -šenâsi→ -logy.

In astronautics, the study of satellite orbits and precise determination of orbital elements which gives the exact position of the satellite.

→ orbital + → -graphy.

The → number of → vertices.

→ order; → graph.

A picture produced by photography. → picture.

From → photo- + → -graph.

Aks, from Ar. 'aks "to inverse, reverse." Šidnegâr, nurnegâr, from šid, nur, → photo-, + negâr, → graph.