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: 647
eavesdropping
  گوشاری   
gušâri (#)

Fr.: écoute éléctronique   

The monitoring and/or examining the data that is passed over the network without sender and receiver's permission and/or knowledge. For example, a user on the Internet could eavesdrop on someone's phone conversation or e-mail.

Noun from → eavesdrop.

ebb tide
  بازکش   
bâzkeš (#)

Fr.: reflux   

A → tidal current that generally moves seaward and occurs during the part of the tide cycle when sea level is falling.

M.E. eb(be); O.E. ebba; cognate with O.Fr. ebba, Du. eb(be), Ger. Ebbe ebb, M.E. ebben, O.E. ebbian, derivative of the noun; akin to → off; PIE base *apo- "off, away;" → tide.

Bâzkeš, from bâz- a suffix denoting "reversal, repetition, opposition," → re-, + keš present stem of kešidan "to draw, drag, carry," → tide.

eccentric
  اسمرکز   
osmarkaz

Fr.: eccentrique   

1) An orbit that has a high → eccentricity, i.e. is highly elliptical.
2) In Ptolemy's geocentric model, a → deferent which is slightly off-center from the Earth.

ex-; → center; → -ic.

eccentric anomaly
  ناسانی ِ اسمرکز   
nâsâni-ye osmarkaz

Fr.: anomalie eccentrique   

Of a planetary orbit, the angle measured from the perihelion position, to the center of the circumscribing auxiliary circle, to the projected position of the planet on the circle. → anomaly; → mean anomaly; → true anomaly.

eccentric; → anomaly.

eccentricity
  اسمرکزی   
osmarkazi

Fr.: eccentricité   

The amount by which the orbit deviates from circularity: e = c/a, where c is the distance from the center to a focus and a the semi-major axis. If e = 0, the orbit is a circle. If e < 1, the orbit is an ellipse, if e > 1 it is a hyperbola, and if e = 1 it is a parabola. The eccentricity is one of the six → orbital elements that define a → Keplerian orbit.

eccentric; → -ity.

echelle grating
  توری ِ نرده‌ای   
turi-ye narde-yi (#)

Fr.: réseau à échelle   

A diffraction grating in which the groves are relatively widely spaced and serves to provide high resolution and dispersion.

Echelle, from Fr. échelle "ladder," , from O.Fr. eschele, from L. scala "ladder;" → grating.

Turi, → grating; nardé, contraction of nardebân "ladder; échelle."

echelle spectrograph
  بیناب‌نگار ِ نرده‌ای   
binâbnegâr-e narde-yi (#)

Fr.: spectrographe à échelle   

A spectrograph that uses an echelle grating to disperse the light.

echelle grating; → spectrograph.

echo
  پژواک   
pažvâk (#)

Fr.: écho   

Acoustics: Effect produced when sound is reflected or thrown back on meeting a solid obstacle.
Radio.: A wave returned to the transmitter with sufficient magnitude and delay to be distinguished from the directly transmitted wave. In radar, the portion of the energy of the transmitted pulse reflected back to the receiver.

From L. echo, from Gk. echo, personified as a mountain nymph, from ekhe "sound."

Pažvâk, literally "return sound," from paž "back, against, opposite," varaint pâd- (Mid.Pers. pât-, from O.Pers. paity "agaist, back, opposite to, toward, face to face, in front of;" Av. paiti, akin to Skt. práti "toward, against, again, back, in return, opposite;" Pali pati-; Gk. proti, pros "face to face with, toward, in addition to, near;" PIE *proti) + vâk "sound," Mid./Mod.Pers. vâng/bâng "sound, clamour;" Av. vacah- "word," from vac- "to speak, say;" cf. Mod.Pers. vâžé "word," âvâz "voice, sound, song" (Skt. vakti "speaks, says," vacas- "word;" Gk. epos "word;" L. vox "voice;" PIE base *wek- "to speak").

eclipse
  گرفت   
gereft (#)

Fr.: éclipse   

The passage of the shadow of a celestial body over the surface of another. The maximum number of solar and lunar visible eclipses occurring annually is seven; the minimum number is two, both being solar. → Solar eclipses take place when the new Moon is close to an → orbital node and on the same longitude with the Sun. At that moment either the → umbra, → antumbra, or the → penumbra touches the Earth's surface. For an observer located in the umbra the eclipse is total, while for one placed in the antumbra it is annular. → Annular eclipses occur around lunar → apogee. An observer situated in the penumbra sees only a → partial eclipse. A total or annular eclipse can be seen from a band with a width of 270 km at the most, around which, the much larger partiality zone extends. The Moon's shadow crosses the Earth from west to east at about 3,200 km/h. During → total eclipses the Sun's disk is entirely covered and the → solar corona can be seen. A solar eclipse can last up to 3 h (between the first and the → fourth contacts). Totality has a theoretical maximum duration of 7m 31s, but it is usually shorter. A → lunar eclipse can be seen from any place on Earth where the Moon is above the horizon; it occurs when the full Moon passes through the central dark shadow of the Earth. The Earth's shadow is much wider than the Moon and this is why the lunar eclipses can last up to four hours (between the first and the fourth contact) (M.S.: SDE).

From O.Fr. éclipse, from L. eclipsis, from Gk. ekleipsis "a leaving out, forsaking, an eclipse," from ekleipein "to forsake a usual place, fail to appear, be eclipsed," from ek "out," → ex-, + leipein "to leave."

Gereft, past stem of gereftan "to obscure, close up; to take, seize, catch; to undergo an eclipse," from Mid.Pers. griftan, Av./O.Pers. grab- "to take, seize," cf. Skt. grah-, grabh- "to seize, take," graha "seizing, holding, perceiving" (see also → concept); cf. M.L.G. grabben "to grab;" E. grab "to take or grasp suddenly;" PIE base *ghrebh- "to seize".

eclipse magnitude
  برز ِ خورگرفت   
borz-e xorgereft

Fr.: grandeur de l'éclipse, magnitude ~ ~   

The fraction of the Sun's diameter occulted by the Moon. It is strictly a ratio of diameters and should not be confused with → eclipse obscuration, which is a measure of the Sun's surface area occulted by the Moon. Eclipse magnitude may be expressed as either a percentage or a decimal fraction (e.g., 50% or 0.50). By convention, its value is given at the instant of → greatest eclipse (F. Espenak, NASA).

eclipse; → magnitude.

eclipse mapping
  نقشه‌برداری ِ گرفتی   
naqše bardâri-ye gerefti

Fr.: cartographie par éclipse   

A method for imaging the continuum light distributions of the → accretion disks of → cataclysmic variable stars. It relies on geometrical information contained in eclipse light curves. An alternative method is → Doppler tomography.

eclipse; → mapping.

eclipse obscuration
  تیره‌شد ِ خورگرفت   
tirešod-e xorgereft

Fr.: obscuration de l'éclipse   

The fraction of the Sun's area occulted by the Moon. It should not be confused with → eclipse magnitude, which is the fraction of the Sun's diameter occulted by the Moon. Eclipse obscuration may be expressed as either a percentage or a decimal fraction (e.g., 50% or 0.50) (F. Espenak, NASA).

eclipse; obscuration, verbal noun from → obscure.

eclipse season
  فصل ِ گرفت   
fasl-e gereft

Fr.: saison d'éclipse   

The period during which the Sun is close enough to one of the → lunar orbit nodes so that an eclipse can take place. This time window lasts for 37 days for → solar eclipses and almost 24 days for → lunar eclipses. These seasons occur every 173.31 days. Two eclipse seasons make up an → eclipse year.

eclipse; → season.

eclipse year
  سال ِ گرفتی   
sâl-e gerefti

Fr.: année des éclipses   

The interval of time (346.620 03 days) between two successive passages of the Sun through the same node of the Moon's orbit. It takes less than a solar year to complete an eclipse year because the Moon's orbit and the lunar nodes are slowly regressing.

eclipse; → year.

eclipsing binary
  دورین ِ گرفتی   
dorin-e gerefti

Fr.: binaire à éclipses   

A binary star in which one of the two stars passes in front of the other so that the system's total light periodically fades. The most famous eclipsing binary is → Algol.

eclipse; → binary.

eclipsing variable
  ورتنده‌ی ِ گرفتی   
vartande-ye gerefti

Fr.: variable à éclipses   

Same as → eclipsing binary.

eclipse; → variable.

ecliptic
  هورپه   
hurpeh

Fr.: écliptique   

The Sun's apparent path in the sky relative to the stars in the course of a year. It is also the projection of the Earth's orbital plane onto the → celestial sphere. Because of the inclination of the → Earth's rotation axis, the ecliptic is tilted by about 23.4° with respect to the → celestial equator, an angle known as the → obliquity of the ecliptic. The ecliptic crosses the celestial equator at the → equinoxes.

From L. ecliptica linea "path of eclipses," so called because eclipses happen only when the Moon is near this path, from eclipsis, → eclipse.

Hurpeh "sun path," from hur "sun," variant xor, cognate with Gk. helios, → Sun, + peh "path, way," from O.Pers. paθi- "path, way;" Av. paθ-, variants paθi-, paθā-, pantay-; Mid/Mod.Pers. pand "path, advice, councel;" Khotanese pande "road, path;" Ossetic fœndœg "path, road;" cf. Skt. pánthā- "road, path, course;" Gk. patos "path, way;" L. pons "bridge, path;" E. find; PIE base *pent- "to go, to tread."

ecliptic latitude
  ورونای ِ هورپهی   
varunâ-ye hurpehi

Fr.: latitude écliptique   

One of the two coordinates in the → ecliptic system; the angle measured from the ecliptic, positive toward the north.

ecliptic; → latitude.

ecliptic longitude
  درژنای ِ هورپهی   
derežnâ-ye hurpehi

Fr.: longitude écliptique   

One of the two coordinates in the → ecliptic system; the angle measured eastwards along the ecliptic from 0° to 360°, with the origin at the → vernal equinox.

ecliptic; → longitude.

ecliptic plane
  هامن هورپهی   
hâmon-e hurpehi

Fr.: plan de l'écliptique   

The plane of Earth's orbit around the Sun.

ecliptic, → plane.

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