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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 1022
piston
  پیستون   
piston (#)

Fr.: piston   

A disk or cylindrical part tightly fitting and moving within a cylinder, either to compress or move a fluid collected in the cylinder, as air or water, or to transform energy imparted by a fluid entering or expanding inside the cylinder, as compressed air, explosive gases, or steam, into a rectilinear motion usually transformed into rotary motion by means of a connecting rod (Dictionary.com).

From Fr. piston, from M.Fr. piston "large pestle," from O.It. pistone "a piston," from pestare "to pound," from L.L. pistare, from pistare "to pound."

pitch
  دنگ   
dong

Fr.: hauteur   

The sensation of a sound frequency; the relative highness or lowness that we hear in a sound. A high pitch sound corresponds to a high frequency sound wave and a low pitch sound corresponds to a low frequency sound wave. In music, a sound that has a definite pitch is called a → tone. Sounds may be generally characterized by pitch, → loudness, and → quality.

M.E. picchen "to thrust, pierce, set;" maybe akin to pick.

Dong "voice, sound," variants bâng, vâng, vang, zang, Tabari šong "cry;" related to vâž, → word.

pitchbelende
  پیچبلند   
pitchbelende (#)

Fr.: pitchbelende   

A natural ore consisting mainly of → uranium oxide, U3O8, with small amounts of → radium, of which is the principal source. It usually contains some → lead and variable amounts of → thorium and → rare-earth elements.

From Ger. Pechblende, from Pech "pitch" (from its black color) + Blende "a mineral."

Pitot tube
  لوله‌ی ِ پیتو   
lule-ye Pitot

Fr.: tube de Pitot   

A → device used to → measure the → velocity of a flowing → fluid. The Pitot tube is used on → aircrafts to determine their → speed. It is also used to meaure water speed of a boat as well as liquid, air, and gas velocities in industrial applications. It is a small tube that has two holes on it. The front hole is placed in the airstream to measure the → stagnation pressure. The side hole measures the → static pressure. The difference between these pressures gives the → dynamic pressure, which can be used to calculate airspeed. See also the → Bernoulli equation.

Named after the French inventor Henri Pitot (1695-1771), a hyraulic engineer; → tube.

pixel
  پیکسل   
piksel (#)

Fr.: pixel   

The smallest useful element of image information.

From pix, plural of pic, short for → picture + el, from → element.

place
  جا   
jâ (#)

Fr.: place, lieu   

An area, position, or portion of space. → mean place

O.E. from O.Fr. place, from M.L. placea "place, spot," from L. platea "courtyard, open space, broad street," from Gk. plateia (hodos) "broad (way)," feminine of platus "broad;" cognate with Av. pərəθu- "broad;" Skt. prthú- "broad, wide;" Lith. platus "broad;" Ger. Fladen "flat cake;" O.Ir. lethan "broad;" PIE base *plat- "to spread."

"place" (from Mid.Pers. giyag "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").

place-value notation
  نمادگان ِ جا-ارزشی   
nemâdgân-e jâ-arezeši

Fr.: notation positionnelle   

A mathematical notation system in which the → numerals get different values depending on their position relative to the other numerals. Same as → positional notation and → positional number system.

place; → value; → notation.

plage
  پلاژ   
plâž (#)

Fr.: plage   

A bright cloud-like feature that appears in the vicinity of a sunspot. Plages represent regions of higher temperature and density within the chromosphere. They are particularly visible when photographed through filters passing the spectral light of hydrogen or calcium.

From Fr., from It. piaggia, from L.L. plagia "shore;" noun use of the feminine of plagius "horizontal;" frpm Gk. plagios "slanting, sideways" from plag(os) "side" + -ios adj. suffix.

Plâž, loan from Fr., as above.

plain
  دشت   
dašt (#)

Fr.: plaine   

An extent of flat land not noticeably diversified with mountains, hills, or valleys.

M.E. from O.Fr. plain, from L. planum "level ground, plain."

Dašt, from Mid.Pers. dašt "plain, open ground."

plan-
  تخت-   
taxt- (#)

Fr.: plan-   

Variant of → plano-.

plano-.

Planck
  پلانک   
Planck

Fr.: Planck   

Short for Max Planck (1858-1947), German physicist, great authority on thermodynamics and creator of the quantum theory.

Planck curve
  خم ِ پلانک   
xam-e Planck

Fr.: courbe de Planck   

Same as → blackbody curve.

Planck; → curve.

Planck density
  چگالی ِ پلانک   
cagâli-ye Planck

Fr.: densité de Planck   

The density corresponding to a → Planck mass in a cubic region of edge length given by the → Planck length: ρP = c5/(ħG2) ≅ 5.16 x 1093 g cm-3, where c is the → speed of light, ħ is the → reduced Planck's constant, and G is the → gravitational constant.

Planck; → density.

Planck distribution
  واباژش ِ پلانک   
vâbâžeš-e Planck

Fr.: distribution de Planck   

The distribution of radiation with wavelength for a blackbody, given by → Planck's radiation law.

Planck; → distribution.

Planck energy
  کاروژ ِ پلانک   
kâruž-e Planck

Fr.: énergie de Planck   

The unit of energy in the system of Planck units. EP = √ (ħ c5/G) ≅ 1.22 x 1019 GeV. It can also be defined as EP = ħ / tP, where tP is the Planck time. This is an extraordinarily large amount of energy on the subatomic scale and particle accelerators have yet to produce a particle with this magnitude of energy. Understanding the properties of a subatomic particle that contains the Planck Energy is helpful in developing a Unified Field Theory which encompasses the realms of Quantum Theory and Relativity, although this too has evaded complete scientific understanding.

Planck; → energy.

Planck era
  دوران ِ پلانک   
dowrân-e Planck

Fr.: ère de Planck   

The first 10-43 seconds of the Universe's existence, when the size of the Universe was roughly the Planck length and during which quantum effects of gravity were significant. Also called Planck epoch. Our understanding of the Planck era is poor because theory which encompasses both quantum mechanics and general relativity is needed to be developed.

Planck; → era.

Planck function
  کریای ِ پلانک   
karyâ-ye Planck

Fr.: fonction de Planck   

Same as → Planck's blackbody formula.

Planck; → function.

Planck length
  درازای ِ پلانک   
derâzâ-ye Planck (#)

Fr.: longueur de Planck   

The size limit, lP = √ (ħ G/ c3), about 10-33 cm, at which Einstein's notions of space-time are supposed to break down, and space is predicted to become "foam like."

Planck; → length.

Planck mass
  جرم ِ پلانک   
jerm-e Planck

Fr.: masse de Planck   

The unit of mass in Planck's system of physical units, mP = √ (ħ c/ G) = 2.176 x 10-8 kg. It is also the mass of a black hole whose Compton wavelength is comparable to its Schwarzschild radius.

Planck; → mass.

Planck postulate
  فراوَس ِ پلانک   
farâvas-e Planck

Fr.: postulat de Planck   

The postulate that the energy of oscillators in a blackbody is quantized by E = nhν, where n = 1, 2, 3, ..., h is Planck's constant, and ν the frequency.

Planck; → postulate.

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