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

Dissipation of energy which occurs, due to magnetic hysteresis, when the magnetic material is subject to changes of magnetization.

→ hysteresis; → loss.

The seventeenth of Saturn's known satellites and the third largest. It is 1436 km across and revolves around Saturn at a mean distance of 3.5 million km with a period of 79 days. The most unique and perhaps most remarkable feature on Iapetus is a topographic ridge 13 km higher than the surrounding terrain, as discovered in the images obtained with Cassini spacecraft. The ridge extends at least 1300 km almost exactly parallel with Iapetus's equator.

Iapetus was one of the Titan gods, sons of Ouranos (Heaven) and Gaia (Earth). Discovered 25 October 1671 by Jean-Dominique Cassini.

A small → dwarf irregular galaxy belonging to the → Local Group, which is located in the constellation → Cassiopeia. IC 10 is about 2.3 million light-years distant and about 5,000 light-years across. With an absolute B magnitude of -16.5, IC 10 has an integrated luminosity that is comparable to that of the → Small Magellanic Cloud, although it is considerably smaller. Its → metallicity is roughly a factor of 2 higher than that of the SMC and in the same proportion smaller than → LMC's. Compared to other Local Group galaxies, IC 10 has a large population of newly formed stars that are massive and intrinsically very bright, especially → Wolf-Rayet stars. Its W-R star density is larger than those of the LMC and SMC. Moreover, the relative number of known → WC to → WN type Wolf-Rayet stars is unusually high, which is unexpected for IC 10's metallicity. IC 10 is also known to be unusual in having → H I gas that extends about 7 times the optical dimensions of the galaxy. IC 10 is the nearest example of a → starburst galaxy. IC 10 was discovered by the American astronomer Lewis A. Swift (1820-1913) in 1887.

Number 10 in the → Index Catalogue.

A → dwarf irregular galaxy (also called Caldwell 51) located in the constellation → Cetus. IC 1613 is a member of the → Local Group of galaxies and has a → morphological classification of IBm (Irregular Barred, → Magellanic type galaxy). IC 1613 has a very → low surface brightness and a very low → dust content. It lies just over 2.38 ± 0.07 million → light-years away from us. IC 1613's distance is known to a remarkably high precision, partly due to the unusually low levels of dust lying both within the galaxy and along the line of sight from the → Milky Way. Moreover, the galaxy hosts a number of → Cepheid variables and → RR Lyrae variables which can be used to precisely determine distances. It was discovered by Max Wolf in 1906.

IC, short for → Index Catalogue.

A bright → emission nebula running north to south near → Alnitak, the eastern star of → Orion's Belt. It is the bright background nebula against which the famous dark region called the → Horsehead Nebula stands out.

IC, → Index Catalogue.

1) The solid form of water; it is found in the atmosphere as snow crystals, hail, ice pellets, etc., and on the Earth's surface in forms such as frost, rime, glaze, glacier ice, etc.
2) The solid, frozen form of gases in cold astronomical objects.

Ice, from O.E. is "ice," from P.Gmc. *isa-; cf. O.N. iss, O.Fris. is, Du. ijs, Ger. Eis. Cognate with Pers. yax, as below.

Yax, from Av. aexa- "ice, frost," isav-, isu- "icy, chilly;" cf. Sarikoli (Pamir dialect) īš "cold;" P.Gmc. *isa-, as above.

Meteo.: The process by which a layer of ice builds up on solid objects that are exposed to freezing precipitation or to supercooled fog or cloud droplets.

→ ice; → accretion.

A major interval of geologic time during which extensive ice sheets (continental → glaciers) formed over many parts of the world. There have been at least five significant ice ages in Earth's history, with approximately a dozen epochs of glacial expansion occurring in the past 1 million years. The last one ran from about 75,000 to 15,000 years ago.

→ ice; → age.

A tiny particle of ice within which → water molecules are all lined up in a precise → crystalline structure. Ice crystals come in various shapes including needles, → dendrites, hexagonal columns, and → platelet. If the temperature decreases the water molecules can crystallize, arranging themselves around the suspended impurities such as dust particles. See also → snow crystal.

→ ice; → crystal.

A member of the lesser mass group of → gas giants. Ice giants contain a higher quantity of materials that form ices at low temperatures, such as → water, → methane, and → ammonia. There are two ice giants in the Solar System, → Uranus and → Neptune.

→ ice; → giant.

A building for storing ice throughout the year, mainly used prior to the invention of the refrigerator.

→ ice; → house.

Yaxcâl, literally "a pit of ice," but "any place or vessel in which ice is kept," from yax, → ice, + câl "pit, → hole."

The temperature at which a mixture of air-saturated pure water and pure ice may exist in equilibrium at a pressure of one standard atmosphere.

→ ice; → point.

A large mass of floating or stranded ice that has broken away from a glacier; usually more than 5 m above sea level.

Iceberg, half Anglicization, half adoption of Du. ijsberg "ice mountain," from ijs, → ice, + berg "mountain" (cf. Ger. Eisberg, Sw. isberg), from P.Gmc. *bergaz; cf. M.H.G. berc, O.H.G. berg "mountain;" cognate with Pers. boland, borz, berg, as below; PIE base *bheregh- "high, elevated."

Yaxberg, from yax, → ice, + berg "mountain, hill," in Laki dialect, related to Pers. boland "high," variants bâlâ "up, above, high, elevated, height," borz "height, magnitude" (it occurs also in the name of the mountain chain Alborz), Laki dialect berg "hill, mountain;" Mid.Pers. buland "high;" O.Pers. baršan- "height;" Av. barəz- "high, mount," barezan- "height;" cf. Skt. bhrant- "high;" L. fortis "strong" (Fr. & E. force); O.E. burg, burh "castle, fortified place," from P.Gmc. *burgs "fortress;" Ger. Burg "castle," Goth. baurgs "city," E. burg, borough, Fr. bourgeois, bourgeoisie, faubourg); PIE base *bhergh- "high."

1) An image; a representation.
2) A representation or picture of a sacred or sanctified Christian personage, traditionally used and venerated in the Eastern Church.
3) A person or thing regarded as a symbol of a belief, nation, community, or cultural movement.
4) Computers: A pictorial representation of a facility available on a computer system, that enables the facility to be activated by means of a screen cursor rather than by a textual instruction (TheFreeDictionary.com).

From Gk. eikon "likeness, image, portrait; a semblance;" in philosophy, "an image in the mind," related to eikenai "be like, look like," from PIE *weik- "to be like."

Zodiš, variant of Mid.Pers. uzdês "icon; image; idol," from uz-, → ex-, + dês, Av. daēs- "to show;" cognate with Gk. deiknumai "to show;" L. dicere "to utter, say, proclaim;" N.H.G. zeigen "to say;" O.E. têon "to annoince;" PIE *deik- "to show, point out; announce."

Made of, covered with, or containing → ice.

→ ice + an English suffix of adjectives denoting "characterized by or inclined to."

A thought, conception, or notion existing in the mind as a result of mental understanding, awareness, or activity. See also → thought, → concept.

Idea, from L. idea "idea," pre-Platonic Gk. idea "form, semblance, nature, fashion," in Plato "a timeless, universal archetype of existents; ideal prototype," literally "look, form," from idein "to see," from PIE *wid-es-ya-, suffixed form of base *weid- "to know, to see;" cf. Pers. bin- "to see" (present stem of didan); Mid.Pers. wyn-; O.Pers. vain- "to see;" Av. vaēn- "to see;" Skt. veda "I know."

Miné "idea," related to Pers. maneš "disposition, temperament, greatness of soul," minu "heaven, paradise," also equivalent to Ger. Geist in recent philosophical translations, došman "enemy," pašimân "penitent, regretful," pežmân "sad, mournful," šâdmân "joyful, cheerful, pleased," ârmân "desire; → ideal;" dialectal (Šuštar) mana "(he) thinks, imagines," (Tarq-e Natanz) môna "to imagine, suppose;" Mid.Pers. mênidan "to think, consider," mên "thought, idea," mênišn "thought, thinking, mind, disposition," mênitâr "thinker," mênôg "spiritual, immaterial, heavenly," from Av. man- "to think," mainyeite "he thinks," manah- "mind, thinking, thought; purpose, intention," mainyu- "mind, mentality, mental force, inspiration," traditionally translated as "spirit," Angra Mainyu "hostile mentality" (Mod.Pers. Ahriman); O.Pers. maniyaiy "I think," Ardumaniš- (proper noun) "upright-minded," Haxāmaniš- (proper noun, Hellenized Achaemenes, founder of the Achaemenian dynasty) "having the mind of a friend;" cf. Sogdian mân "mind;" Skt. man- "to think," mánye "I think," manyate "he thinks," mánas- "intelligence, understanding, conscience;" Gk. mainomai "to be angry," mania "madness," mantis "one who divines, prophet;" L. mens "mind, understanding, reason," memini "I remember," mentio "remembrance;" Lith. mintis "thought, idea;" Goth. muns "thought," munan "to think;" Ger. Minne "love," originally "loving memory;" O.E. gemynd "memory, thinking, intention;" PIE base *men- "to think, mind; spiritual activity."

1) (n.) A standard of perfection, beauty, or excellence.
Math.: A subset of a ring that is closed under addition and multiplication by any element of the ring.
2) (adj.) Existing only in the imagination; not real or actual.
Conforming exactly to an ideal, law, or standard; perfect. → ideal gas.

M.E. ydeall, from L.L. idealis "existing in idea," from L. → idea.

Ârmân "ideal" in Mod.Pers., traditionally "desire; hope; grief," variants armân, urmân, prefixed from mân, "thought, mind," → idea. The first element may be related to Av. armaē- "in peace, still; quietly;" PIE base *er[ə]- "to be still" (cf. Skt. īrmā (adv.) "quiet, still, being in the same place;" Gk. erôé "calm, peace;" O.H.G. rouwa "rest"), as in Av. armaē.šad- "sitting quietly," armaē.štā- "standing still, stagnant." Therefore, Pers. ârmân may be related to Av. *armaē.manah- (PIE *ermen-) "thought in peace, quiet mind."
Mineyi, minevâr, adj. from miné, → idea.

An fluid which has no internal friction or → viscosity, and no → resistivity as well if the fluid is a plasma.

→ ideal; → fluid.

Theoretical gas assumed to consist of perfectly elastic molecules of negligible volume and mutual attraction force. Also called → perfect gas.

→ ideal; → gas.

An → equation of state that relates pressure (P), temperature (T), and volume (V) of an ideal or → perfect gas: PV = nRT, where n is the number of → moles of gas present and R is the → universal gas constant. Equivalently: PV = NkT, where N is the number of atoms of gas present and k is → Boltzmann's constant.

→ ideal; → gas; → law.