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

A moving star cluster containing over 100 stars that are scattered over an area of sky more than 1,000 minutes of arc in diameter. The five brightest stars of the → Big Dipper as well as → Sirius belong to this → dynamical stream.

→ Ursa Major; → star; → cluster.

The Lesser Bear. A constellation situated in the northern hemisphere, at about 15h right ascension, +79° declination. Its two brightest stars, both of 2nd magnitude, are → Polaris, the present pole star, and → Kochab. Abbreviation: UMi, Genitive: Ursae Minoris.

Ursa,from L. ursus "bear," cognate with Pers. xers, as below; Minor "smaller, less," from minus related to L. minuere "make small;" cf. Gk. meion "less," minuthein "to lessen;" Skt. miyate "diminishes, declines;" O.E. minsian "to diminish;" PIE base *mei- "small."

Xers "bear," dialectal Tabari aš; Mid.Pers. xirs, Av. arša- "bear;" cf. Skt. rksa- "bear;" Gk. arktos; L. ursus; PIE base *rtko- "bear;" kucak "small;" Mid.Pers. kucak "small," related to kutâh "short, small, little," kudak "child, infant," kutulé, → dwarf; Mid.Pers. kôtâh "low," kôtak "small, young; baby;" Av. kutaka- "little, small."

A dwarf spheroidal galaxy of faint luminosity that is a member of the Local Group.

→ Ursa Minor; → system.

An annual → meteor shower whose → radiant lies in the constellation → Ursa Minor and is active between December 17 and December 24. The shower usually peaks around December 23.

→ Ursa Minor; → -ids.

An → impact cratrer on → Ceres which is the third largest crater on this → dwarf planet. Urvara is located south of → Occator and is about 160 km wide and 6 km deep. It has a prominent central peak that is about 3 km high.

Named for the ancient Indo-Iranian personification of fertility, Av. urvarā- "plant," often defied, Skt. urvárā- "land, soil, fertile field."

A person who uses or exploits something, such as a computer.

From use; M.E. usen from O.Fr. user "to use, employ," from V.L. *usare "to use," from L. uti "to use."

Kârbar "user," from bé kâr bordan "to use."

A committee whose members represent the astronomers who use the facilities of an observatory and which is intended to improve the interaction between the observatory and the users.

→ user; committee, M.E., from O.Fr. commettre "to commit," from L. committere "to bring together," from → com- + mittere "to put, send."

Komité, loan from Fr.; kârbarân plural of kârbar→ user.

1) Of, relating to, or in the interests of utility.
2) Of, characterized by, or adhering to → utilitarianism.

Coined by Jeremy Bentham (1748-1832) from → utility + -arian.

Philosophy: A doctrine according to which the virtue of a thing or an action is determined by its utility. The goal of utilitarian ethics is to promote the greatest happiness for the greatest number of people. The founders of this philosophical school were Jeremy Bentham (1748-1832) and James Mill (1773-1836).

→ utilitarian; → -ism.

1) The state or quality of being useful; usefulness.
2) Having, or made for, useful practical purposes. → utility software.

M.E. utilite, from O.Fr. utilite "usefulness," earlier utilitet, from L. utilitatem "usefulness, profit," from utilis "usable," from uti "to use."

Hudemandi, from hudemand "utile," from hudé "use" (as in bihudé "useless, vain, absurd"), from Mid.Pers. hudâg "good, useful, beneficent;" Av. hūdā- "doing good, producing wealth," from hū-, hu-, → eu-, + Av./O.pers. dā- "to give, grant, put," dadāiti "he gives;" Mid.Pers./Mod.Pers. dâdan "to give, put" (cf. Skt. dadáti "he gives;" Gk. tithenai "to place, put, set," didomi "I give;" L. dare "to give, offer;" Rus. delat' "to do;" O.H.G. tuon, Ger. tun, O.E. don "to do;" PIE base *dhe- "to put, to do") + -mand(i)

A part of the system software designed to support the operation of application software and is used to manage the computer files. Examples of utility software are disk diagnosis program, backup software, password generation software, and virus protection software. Also called utilities.

→ utility; → software.

The act or process of utilizing.

Verbal noun of → utilize.

To make practical or worthwhile use of.

From Fr. utiliser, from It. utilizzare, from utile "usable," from L. utilis "usable," from uti "to use."

Hudidan, from hudé, hudag "use," → utility, + -idan.

A → plain in the northern hemisphere of Mars that was chosen as the landing site of the Viking II space probe on September 3, 1976.

Mod.L. Utopia, literally "nowhere," coined by Thomas More (1516), from Gk. ou "not" + topos "place;" planitia, from planus, → plain.

Dašt, → plain; nâkojâ "nowhere," from nâ-, → un-, + kojâ "where?; a place;" Mid.Pers. kugiyâg, from kū "where; that; than" + giyâk "place" (O.Pers. ā-vahana- "place, village;" Av. vah- "to dwell, stay," vanhaiti "he dwells, stays;" Skt. vásati "he dwells;" Gk. aesa (nukta) "to pass (the night);" Ossetic wat "room; bed; place;" Tokharian B wäs- "to stay, wait;" PIE base ues- "to stay, live, spend the night"); nâkojâ âbâd literally "city of nowhere, habitation of nowhere," from nâkojâ, as explained, + âbâd "city; habitation; cultivated" (Mid.Pers. âpât, âpâtân "cultivated, inhabitated;" Proto-Iranian *ā-pāta- "protected," from prefix ā + pā- "to protect, guard" (Mod.Pers. pâyidan), → observe.

1) To give audible expression to; speak or pronounce.
2) Phonetics: To produce (speech sounds, speech-like sounds, syllables, words, etc.) audibly, with or without reference to formal language (Dictionary).

M.E. outren from M.Du. uteren or M.L.G. utern "to turn out, show, speak," from uter "outer," comparative adj. from ut, → out.

Vâpidan, from Proto-Ir. *uab-/*uaf- "to utter (sing, speak), to call;" cf. Av. uf- "to sing;" Sogd. w'β, w'b "to say, speak;" Baluci gwâpt/gwâp- "to summon, call together;" Mod.Pers. gap, gab "word, chit-chat," zand-bâf "nightingale," buf "owl."

1) An act of uttering; a spoken word, statement, or vocal sound.
2) Something uttered; a word or words uttered; a cry, animal's call, or the like.
3) Linguistics: Any speech sequence consisting of one or more words and preceded and followed by silence: it may be coextensive with a sentence (Dictionary.com).

→ utter; → -ance.

A geometric plane defined for the analysis/processing of → interferometer observations, for which the axes are conventionally termed u and v. The plane is at right angles to a direction from which radiation is being received from the sky. Unlike a typical telescope, a → radio interferometer cannot produce an image of the sky directly. Instead it measures the → Fourier transform of the sky brightness distribution in the uv plane. The Fourier transform relates the → interference pattern to the intensity on the sky. A measurement on a particular → baseline corresponds to a point on this plane with coordinates u and v, at a distance from the origin equal to the projected length of the baseline measured in wavelengths. Two telescopes form one baseline which represents one point in uv plane; three telescopes create three baselines and are therefore represented by three points in uv plane. Good uv coverage requires many simultaneous baselines amongst many antennas, or many sequential observations from a few antennas. Good coverage of points is essential for high-quality → aperture synthesis mapping.

u and v conventional symbols; → plane.

A four-color stellar → photometric system devised by B. Strömgren. It is based on measurements in the ultraviolet (3500 Å), violet (4100 Å), blue (4670 Å), and yellow (5470 Å) regions of the spectrum. The filters bandwidths are 340, 200, 160, and 240 Å respectively. Also known as Strömgren four-color photometry.

u, v, b, and y referring to ultraviolet, violet, blue, and yellow respectively; → system.

A star that shows large irregular brightness variations and belongs to the Herbig Ae/Be family, i.e. pre-main sequence stars of intermediate mass. Typically a decrease of 2-3 magnitudes in the visible occurs for a few days to a couple of weeks. Current theories explain this behavior as being an obscuration of the central star by orbiting dust clouds, as well as contribution to the total luminosity by unsteady accretion onto the central star. Also called UXOr.

U and X letters of alphabet, Ori, → Orion; → star.