An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 458
liquid crystal
  بلور ِ آوه   
bolur-e âvé (#)

Fr.: cristaux liquides   

A type of material that possesses less geometrical regularity or order than normal solid crystals, and whose order varies in response to alterations in temperature, electric field, and other quantities.

liquid; → crystal.

liquid helium
  هلیوم ِ آوه   
heliom-e âvé

Fr.: hélium liquide   

The state of helium (4He) below its boiling point of 4.2 K. Its normal form is called → helium I, but converts into superfluid → helium II below 2.17 K (→ lambda point). Liquid helium is colorless and transparent so that it is impossible to see the surface of the liquid with the naked eye. Helium was first liquefied in 1911 by the Dutch physicist Heike Kamerlingh Onnes (1853-1936), Physics Nobel Prize 1913.

liquid; → helium.

liquid mirror
  آینه‌ی ِ آوه   
âyene-ye âvé

Fr.: miroir liquide   

A mirror composed of liquid, taking advantage of the parabolic shape of a spinning liquid and the fact that the mirror's focal length can be adjusted by altering the velocity at which the liquid's container spins.

liquid; → mirror.

liquid water
  آب ِ آوه   
âb-e âvé

Fr.: eau liquide   

Water in a state that is neither ice nor vapor.

liquid; → water.


Fr.: liquidus   

In the → phase diagram of a → mixture (such as an → alloy) at constant pressure, the → curve that separates the all liquid phase from the liquid+solid phase. Below the liquidus the mixture will be partly or entirely → solid. See also → solidus.

From L. liquidus, → liquid.

LISA Pathfinder
  رهیاب لایزا   
rahyâb LISA

Fr.: LISA Pathfinde   

An → ESA spacecraft that was launched on December 3, 2015 to test technologies needed for the Evolved Laser Interferometer Space Antenna (eLISA), an ESA → gravitational wave observatory planned to be launched in 2034. LISA Pathfinder paves the way for future missions by testing in flight the very concept of gravitational wave detection.

LISA, short for → Laser Interferometer Space Antenna; → pathfinder.

Lissajous figure
  خم ِ لیساژو   
xam-e Lissajous (#)

Fr.: courbe de Lissajous, figure de ~   

A curve traced out by a point which is oscillating simultaneously in two mutually perpendicular directions. In general, the amplitude and frequency may be different in the two directions, and the two oscillations may have an arbitrary initial phase difference. The simplest pattern is a straight line, being obtained from two oscillations of equal frequency in phase with each other. The patterns can become very involved if the ratio of the frequencies is not a simple one.

After the French physicist Jules Antoine Lissajous (1822-1880), who first demonstrated such curves (Comptes-Rendus, 1857, 44, 727); → figure.

Xam, → curve.

Lissajous orbit
  مدار ِ لیساژو   
madâr-e Lissajous

Fr.: orbite de Lissajous   

A quasi-periodic path resembling a → Lissajous figure around the L1 or L2 → Lagrangian points of a two-body system. Lissajous orbits, resulting from a combination of planar and vertical components, are used by certain space telescopes (such as → WMAP, → Planck Satellite, and → Herschel Satellite) that are required to be in a stable position relative to the Earth and Sun while making long-term observations.

Lissajous figure; → orbit.


Fr.: litre   

A metric unit of volume, formerly defined as the volume of one kilogram of pure water under standard conditions; now equal to 1 cubic decimeter (dm3); hence 1 liter = 0.001 m3 and 1000 liter = 1 m3.

From Fr. litre, from litron, obsolete Fr. measure of capacity for grain, from M.L. litra, from Gk. litra "pound."

neveštârgân (#)

Fr.: littérature   

1) Writings in which expression and form, in connection with ideas of permanent and universal interest, are characteristic or essential features, as poetry, novels, history, biography, and essays.
2) The entire body of writings of a specific language, period, people, etc.
3) The writings dealing with a particular subject (

From L. literatura/litteratura "writing, grammar, learning," from litera/littera "letter."

Neveštârgân, from neveštâr, literally "written; writing," verbal noun from neveštan, nevis- "to write;" Mid.Pers. nibištan, nibes- "to write;" Av./O.Pers. nī- "down; in, into," → ni- (PIE), + paēs- "to paint; to adorn," paēsa- "adornment" (Mid.Pers. pēsīdan "to adorn"); O.Pers. pais- "to adorn, cut, engrave" (Mod.Pers. pisé "variegated"); cf. Skt. piśáti "adorns; cuts;" Gk. poikilos "multicolored;" L. pingit "embroiders, paints;" O.C.S. pisati "to write;" O.H.G. fēh "multicolored;" Lith. piēšti "to draw, adorn;" PIE base *peik- "colored, speckled," + -gân suffix of suffix forming plural entities, from Mid.Pers. -gânag.

litiom (#)

Fr.: lithium   

A metallic → chemical element; symbol Li. → Atomic number 3; → atomic weight 6.941; → melting point about 180.54°C; → boiling point about 1,342°C. Lithium is a soft, silver-white metal. It is the lightest metal and one of the alkali metals in Group 1 of the → periodic table. Lithium does not occur on Earth in its free form. It is a minor part of almost all igneous rocks and is found in many natural brines, in total 0.0007% of the Earth's crust. It has two stable → isotopes, 7Li (92.5%) and 6Li (7.5%). The element was discovered in the mineral petalite, LiAl(Si2O5)2, by the Swedish mineralogist Johan August Arfwedson in 1817. It was isolated by W.T. Brande and Sir Humphrey Davy. Many uses have been found for lithium and its compounds. Lithium has the highest → specific heat (3.6 J/gK) of any solid element and is used in heat transfer applications. It is used in rechargeable lithium ion batteries. It is also used as an alloy with → aluminum, → copper, and → manganese to make high performance aircraft parts. It is used to make special glasses and ceramics, including the Mount Palomar telescope's 5 m mirror. Lithium also has various nuclear applications, for example as a coolant in nuclear breeder reactors and a source of → tritium, which is formed by bombarding lithium with neutrons. In medicine it is used to treat bipolar disorder (manic depression), a serious mental illness that causes extreme shifts in mood, energy, and functioning.
In astrophysics, → Spite plateau.

Lithium, from L. lithos "stone" because lithium was thought to exist only in minerals.

lithium I line
  خط ِ لیتیوم I   
xatt-e litiom I

Fr.: raie de lithium I   

A → resonance line of → lithium at 6707.81 Å doublet 6707.76 and 6707.91 Å.

lithium; I for → neutral atom; → line.

lithium star
  ستاره‌ی ِ لیتیومی   
setâre-ye litiomi (#)

Fr.: étoile à lithium   

A peculiar evolved star of spectral type G or M whose spectrum displays a high abundance of lithium.

lithium; → star.

lithium test
  آزمون ِ لیتیوم   
âzmun-e litiom

Fr.: test du lithium   

The presence or not of the lithium absorption line at 6708 Å, which is considered to be a sufficient condition for → substellarity in → L dwarfs. It has been shown that any object with lithium absorption and → effective temperature less than 2670 K is a → brown dwarf. For a discussion of potential problems with the lithium test see Kirkpatrick et al. (1993, ApJ 406, 701).

lithium; → test.

sangsepehr (#)

Fr.: lithosphère   

The solid portion of the → Earth, as compared to the → atmosphere and the → hydrosphere. The lithosphere consists of semi-rigid plates that move relative to each other on the underlying → asthenosphere. The process is known as → plate tectonics and helps explain → continental drift.

From litho- a combining form of Gk. lithos "stone," + → sphere.

Sangsepehr, from sang, → igneous rock, + sepehr, → sphere.

Little Dipper
  هفت خواهران، چمچه‌ی ِ کوچک   
haft xâharân (#), camce-ye kucak (#)


An asterism in the constellation → Ursa Minor. This group of stars ends at → Polaris, the pole star of the Northern Hemisphere.

Little, from M.E., O.E. lytel, from W.Gmc. *lutila- (cf. Du. luttel, O.H.G. luzzil, Ger. lützel, Goth. leitils), from PIE *leud- "small;" dipper, from dip, O.E. dyppan "immerse," from P.Gmc. *dupjanan.

Haft xâharân "the seven sisters," from haft "seven" (Mid.Pers. haft; Av. hapta; cf. Skt. sapta; Gk. hepta; L. septem; P.Gmc. *sebun; Du. zeven; O.H.G. sibun; Ger. sieben; E. seven; PIE *septm) + xâharân plural of xâhar "sister;" Mid.Pers. xwâhar "sister;" Av. xvanhar- "sister;" cf. Skt. svásar- "sister;" Sogdian xwār; Gk. eor; L. soror (Fr. soeur); Arm. k'oyr; O.C.S., Rus. sestra; Lith. sesuo; O.Ir. siur; Welsh chwaer; M.Du. suster; Du. zuster; O.H.G. swester; Goth. swistar; Ger. Schwester; Swed. sister; Dan. søster; O.E. sweostor, swuster; E. sister.
Camcé "a spoon, ladle; a wooden bowl or cup;" 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").

Little Ice Age
  عصر ِ یخ ِ کوچک   
asr-e yax-e kucek

Fr.: petit âge glaciaire   

A roughly 400-year period from the mid-16th through the mid-19th centuries when temperatures over much of Europe were unusually cold. Glaciers in the Alps advanced and European rivers froze much more often than during the past century. Harvests failed, livestock perished, and poor people suffered from famine and disease. The Little Ice Age coincided with two successive low → solar activity periods, the → Sporer minimum and the → Maunder minimum.

little; → ice; → age.

Littrow prism
  منشور ِ لیترو   
manšur-e Littrow

Fr.: prisme de Littrow   

A prism having angles of 30, 60, and 90°, which uses the same face for input and dispersed radiation. The beam is reflected at the face opposite to the 60° angle because it is coated to be highly reflecting. A beam entering at the → Brewster angle undergoes minimum deviation and hence maximum dispersion. Littrow prisms are used in laser cavities to fine tune lasers by selection of wavelength.

Joseph Johann Littrow (1781-1840), Austrian astronomer; → prism.

Lloyd's mirror
  آینه‌ی ِ لوید   
âyene-ye Lloyd (#)

Fr.: miroir de Lloyd   

An optical arrangement in which light from a source is allowed to fall on a plane mirror at → grazing incidence. The light directly coming from the source interferes with the light reflected from the mirror forming an → interference pattern. See also → Fresnel's biprism, → Fresnel's mirrors.

After the Irish physicist Humphry Lloyd (1800-1881); → mirror.

  ۱) بار؛ ۲) بار کردن   
1) bâr; 2) bâr kardan (#)

Fr.: 1) charge; 2) charger   

1) Something that is borne or carried.
2) Computers: To bring (a program or data) into main storage from external or auxiliary storage.
To place (an input/output medium) into an appropriate device, as by inserting a disk into a disk drive. See also: → download, → upload, → overload.

From M.E. lode, originally the same word as lode, from O.E. lāad "way, course, carrying;" cf. O.N. leith "way, route," O.H.G. leita "procession."

Bâr kardan "to load," composite verb from bâr "load, charhe, burden," (Mid.Pers. bâr, from O.Pers./Av. base bar- "to bear, carry;" Mod.Pers. bordan "to carry;" L. brutus "heavy, dull, stupid, brutish;" Skt. bhara- "burden, load," bharati "he carries;" Gk. baros "weight;" Mod.Pers. gerân "heavy;" Skt. guru; L. gravis; PIE *gwere- "heavy," *bher- "carry, give birth") + 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 kwer- "to do, to make").

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