Fr.: assistant de nuit
A specialized technician in an observatory who is in charge of functioning a telescope and helping visiting astronomers during their observation run.
From → night + assistant; M.E. assistent, from L. assistent-, stem of assistens, pr.p. of assistere "assist, stand by," from → ad- "to" + sistere "take a stand, cause to stand," cognate with Pers. istâdan "to stand," → histogram.
Dastyâr "assistant," from dast "hand" (Mid.Pers. dast; O.Pers. dasta-; Av. zasta-; cf. Skt. hásta-; Gk. kheir; L. praesto "at hand;" Arm. jern "hand;" Lith. pa-žastis "arm-pit;" PIE *ghes-to-) + yâr "helper; companion" (Mid.Pers. hayyâr "helper," hayyârêh "help, aid, assistance," Proto-Iranian *adyāva-bara-, cf. Av. aidū- "helpful, useful").
Fr.: luminescence nocturne
Same as → airglow.
Nihal (β Leporis)
A yellow star of visual magnitude 2.84, the second brightest in the constellation → Lepus. It is a giant of → spectral type G5, lying some 159 light-years away. Nihal is double, with a companion, 2.5 seconds of arc apart.
From Ar. an-nihal (
M.E., from O.E. nigen, nigan, nigon, akin to M.Du. neghen, Du. negen, O.H.G. niun, Ger. neun, Goth. niun "nine," Pers. noh, as below; from PIE *newn "nine."
Noh, from Mid.Pers. nô; Av. nava; cognate with Skt. nava-; Gk. ennea; L. novem.
Gaseous chemical element; symbol N. Nitrogen is the most abundant constituent of dry air. It comprises 78.09% (by volume). → Atomic number 7; → atomic weight 14.0067; → melting point -209.86°C; → boiling point -195.8°C. Nitrogen is a colorless, odorless, tasteless diatomic gas. It was discovered by the Scottish physician and chemist Daniel Rutherford in 1772.
From Fr. nitrogène, coined 1790 by Fr. chemist Jean Antoine Chaptal (1756-1832), from combining form of Gk. nitron "sodium carbonate" + Fr. gène "producing."
Azot, loan from Fr. azote, from Gk. azotos "lifeless," from negation prefix → a- + zotos "vital."
Science of → snow.
The second satellite of → Pluto discovered in 2005 by astronomers using the → Hubble Space Telescope images. It has an estimated diameter of between 46 and 137 km and an orbital period of 24.9 days. Also called Pluto II (P2).
Nix, from Nyx in Gk. mythology the goddess of darkness and night. The conversion of "i" into "y" was to avoid conflict with the asteroid 3908 Nyx.
no boundary hypothesis
engâre-ye giti bi karân-e âqâzin
Fr.: l'hypothèse de l'Univers sans limite initiale
The proposal whereby the → Universe would not have begun with a → singularity. Instead, the → Big Bang would be an ordinary point of → space-time. The proposal, advanced by James Hartle and Stephen Hawking (1983) results from an attempt to combine aspects of → general relativity and → quantum mechanics. Based on an imaginary time assumption, it predicts a closed Universe that would start at a single point, that can be compared to the North Pole of the Earth on a two-dimensional space. Before the → Planck era there was space, but the real time began with the Big Bang event. → Hartle-Hawking initial state.
no hair theorem
farbin-e bimu-yi, ~ kacali
Fr.: théorème de calvitie
There are only three parameters that can be applied by an outside observer relating to a → black hole: → mass, → electric charge, and → angular momentum. The collapse of a star into a black hole wipes out all other details of its structure, and the observer can never discover any other properties of the star which formed the black hole. In other words, none of its characteristics leave any trace outside the black hole, and that is what is meant by "hair."
Farbin, → theorem;
bimuyi, noun from bimu "without hair," from bi- "without"
(→ in-) + mu, → hair.
Fr.: ère noachienne
>Noachian era =
Fr.: Noachis Terra
An extensive southern terrain of the planet Mars. One of the oldest terrains on Mars, it lies roughly between the latitudes -20° and -80° and longitudes 30° west and 30° east.
L. Noachis Terra "Land of Noah."
Zamin "land," → earth; Nuhiyâné adj. of Nuhi
"related to Nuh," from Nuh (
Fr.: gaz rare
A gaseous chemical element that does not readily enter into chemical combination with other elements. Examples are helium, argon, krypton, xenon, and radon. Same as → inert gas.
Noble, from O.Fr. noble, from L. nobilis "well-known, famous, of superior birth," earlier gnobilis, literally "knowable," from gnoscere "to come to know" (Fr. connaître; Sp. conocer); cognate with Pers. šenâxtan "to know, discern, distinguish, be acquainted with;" Mid.Pers. šnâxtan, šnâs- "to know, recognize," dânistan "to know;" O.Pers./Av. xšnā- "to know, learn, come to know, recognize;" cf. Skt. jñā- "to recognize, know," jānāti "he knows;" Gk. gignoskein "to know, think, judge;" P.Gmc. *knoeanan; O.E. cnawan; E. know; Rus. znat "to know;" PIE base *gno- "to know;" → gas.
Gâz, → gas; huped "noble," from Mid.Pers. hupid "noble," from hu- "good, well" (Mid.Pers. hu-; O.Pers. hu- "good, well" (ukāra- "having good people"); Av. hu-, hū- "well, good, beautiful" (hu-kərp- "well-shapen," hūxta- "well spoken," hu-manah- "good-minded"); cf. Skt. su- "good" (svasti "well-being, good luck," sumánas- "good-minded," sūktá- "well spoken"); L. from Gk. eu "well," combining form of eus "good" (hu-gies "healthy"); Gallic su-; O.S. su-; Welsh hy-; PIE base *su-) + pid "father," variant of pidar; Mod.Pers. pedar "father" (O.Pers. pitā- "father;" Av. patar-; Skt. pitár-; Gk. pater; L. pater, O.H.G. fater).
Fr.: entaille, encoche
The end part of an → arrow having a notch for holding the bowstring.
M.E. nok(ke); of uncertain origin; cf. Swedish nock "notch;" also M.L.G. nokk, Dutch nok "tip of a sail."
Sufâr "the notch in the arrow which receives the string," also "the eye of needle," related to softan, sombidan "to pierce;" Mid.Pers. sôftan "to pierce, bore;" cf. Pashtu suray, Wakhi sərv "hole, cavity," Munji surv "hole," Yidgha surv, Kurd. sontin; Proto-Ir. sup, sub, sump, sumb "to pierce."
Fr.: nuage nocturne lumineux
The highest clouds in the Earth's atmosphere, at altitudes between 75 and 90 km. They resemble thin cirrus clouds with a bluish or silverish color, and are visible only during twilight.
Relating to or of the nature of a node.
Fr.: ligne des noeuds
The line connecting the ascending and descending nodes of an orbit.
Fr.: point nodal
Any of the two points on the → axis of a → lens system, such that if the → incident ray passes through one, travelling in a given direction, the → emergent ray passes the other in a parallel direction.
Fr.: regression nodale
For a ring inclined to the planet's equator, the points at which the ring crosses the equator (nodes) slowly move around the planet (regress) in a direction opposite to that of the ring's orbital motion. (Ellis et al., 2007, Planetary Ring Systems, Springer).
1) A point of zero → amplitude in a system of
→ stationary waves. See also
From L. nodus "knot."
Gereh "knot," from Mid.Pers. grih "knot;" Sogdian γr'nš "knot, bond, joining;" Khotanese grantha- "knot;" cf. Skt. granthi- "knot."