An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 1295
solar antapex
  پادچکاد خورشیدی   
pâdcakâd-e xoršidi

Fr.: antiapex solaire   

The apparent direction (in the constellation → Columbia) away from which the Sun is moving in its orbit around the center of the Galaxy. → solar apex.

solar; → antapex.

solar apex
  چکاد ِ خورشیدی   
cakâd-e xoršidi

Fr.: apex solaire   

The point on the celestial sphere toward which the Sun is apparently moving relative to the → local standard of rest. Its position, in the constellation → Hercules, is approximately R.A. 18h, Dec. +30°, close to the star → Vega. The velocity of this motion is estimated to be about 19.4 km/sec (about 4. AU/year). As a result of this motion, stars seem to be converging toward a point in the opposite direction, the → solar antapex.

solar; → apex.

solar calendar
  گاهشمار ِ خورشیدی   
gâhšomâr-e xoršidi (#)

Fr.: calendrier solaire   

A calendar based on the apparent yearly motion of the Sun on the → celestial sphere. The year is usually reckoned with respect to the → vernal equinox, approximately for example in the case of the → Gregorian calendar and accurately in the case of the → Iranian calendar.

solar; → calendar.

solar constant
  پایای ِ خورشیدی   
pâypa-ye xoršidi (#)

Fr.: constante solaire   

The amount of solar radiation in all wavelengths received per unit of time per unit of area on a theoretical surface perpendicular to the Sun's rays and at Earth's mean distance from the Sun. Its mean value is 1367.7 W m-2 or 1.37 × 106 erg sec-1 cm-2. In other words, the solar constant is the mean → solar irradiance on the outer atmosphere when the Sun and Earth are spaced at 1 → astronomical unit. See also: → solar luminosity.

solar; → constant.

solar corona
  هورتاج، تاج ِ خورشیدی   
hurtâj, tâj-e xoršid (#)

Fr.: couronne solaire   

The outermost atmosphere of the Sun immediately above the → chromosphere, which can be seen during a total solar eclipse. It consists of hot (1-2 × 106 K), extremely tenuous gas (about 10-16 g cm-3) extending for millions of kilometer from the Sun's surface.

solar; → corona.

solar cycle
  چرخه‌ی ِ خورشیدی   
carxe-ye xoršidi (#)

Fr.: cycle solaire   

The periodic variation in frequency or number of solar active events (→ sunspots, → prominences, → flares, and other solar activity) occurring with an interval of about 11 years. The solar cycle was discovered in 1843 by Samuel Heinrich Schwabe (1789-1875), a German apothecary and amateur astronomer, who after 17 years of observations noticed a periodic variation in the average number of sunspots seen from year to year on the solar disk. Solar cycle numbering goes back to the 18-th century, when the Cycle 1 peak occurred in 1760. Cycle 23 peaked in 2000, and the following Cycle 24 will reach its maximum in 2013.

solar; → cycle.

solar day
  روز ِ خورشیدی   
ruz-e xoršidi (#)

Fr.: jour solaire   

The length of time between two successive transits of the Sun over the same meridian.

solar; → day.

solar depression
  نشیب ِ خورشید   
nešib-e xoršid

Fr.: dépression solaire   

The → angle between the → sea horizon, the → center of → Earth, and the center of the → solar disk.

solar; → depression.

solar disk
  گرده‌ی ِ خورشید   
gerde-ye xoršid

Fr.: disque solaire   

The apparent shape of the → Sun's → photosphere.

solar; → disk.

solar dynamo
  توانزای ِ خورشیدی   
tavânzâ-ye xoršidi (#)

Fr.: dynamo solaire   

A model for explaining the generation of the → solar magnetic field and the related observational features (mainly → solar cycle, → Sporer's law, → Hale's law, → Joy's law, → polarity reversal). The global frame of this model is the interaction between a → turbulent plasma in the → convective zone (reciprocal generation of magnetic and electric fields) and the solar differential rotation (mutual transformation of meridional magnetic field into azimuthal magnetic field). The idea that a dynamo is responsible for generating the solar magnetic field was first proposed by Larmor (1919) and further developed by Cowling (1933), Parker (1955) and others.

solar; → dynamo.

solar eclipse
  خورگرفت، گرفت ِ خورشیدی   
xor gereft, gereft-e xoršidi (#)

Fr.: éclipse de soleil   

An eclipse in which the Earth passes through the shadow cast by the Moon. Solar eclipses only happen when the Moon is new and when the Moon lies close to the node of its orbit.

solar; → eclipse.

solar ecliptic limit
  حد ِ هورپهی ِ خورشید   
hadd-e hurpehi-ye xoršid

Fr.: limite écliptique du Soleil   

The greatest angular distance from a → lunar orbit node within which a → solar eclipse may occur when the Sun and Moon are in conjunction there. The solar ecliptic limit extends about 17° on each side of the node.

solar; → ecliptic; → limit.

solar equation
  هموگش ِ خورشیدی   
hamugeš-e xoršidi

Fr.: équation solaire   

In ancient astronomy, the difference between the Sun's mean and actual position. The ancients observed that, although the motion of the Sun in the ecliptic is almost uniform, it is subject to a small annual variation.

solar; → equation.

solar flare
  آلاو ِ خورشیدی   
âlâv-e xoršidi (#)

Fr.: éruption solaire   

A bright eruption form the Sun's → chromosphere in the vicinity of a → sunspot. Solar flares are caused by tremendous explosions on the surface of the Sun. In a matter of just a few minutes they heat the material to many millions of degrees and release as much energy as a billion → megatones of → T.N.T..

solar; → flare.

solar instrument
  سازال ِ خورشیدی   
sâzâl-e xoršidi

Fr.: instrument solaire   

An instrument especially designed for solar observations.

solar; → instrument.

solar irradiance
  تابشداری ِ خورشیدی   
tâbešdâri-ye xoršidi

Fr.: irradiation solaire   

The radiative power per unit area in all wavelengths from the Sun received by the Earth at its average distance from the Sun. Its mean value is called the → solar constant. The solar irradiance changes over a year by about 6.6% due to the variation in the Earth/Sun distance. Moreover, solar activity variations cause irradiance changes of up to 1%.

solar; → irradiance.

solar limb
  لبه‌ی ِ خورشید   
labe-ye xoršid

Fr.: bord solaire   

The edge of the → disk of the → Sun.

solar; → limb.

solar longitude
  درژنای ِ خورشیدی   
derežnâ-ye xoršidi

Fr.: longitude du Soleil   

The ecliptic longitude of the Sun. It varies from 0° (at the vernal equinox) to 360° during the year. By Kepler's Second Law, the rate of change of the solar longitude is such that the Earth sweeps out equal areas on the ecliptic plane in equal times.

solar; → longitude.

solar luminosity
  تابندگی ِ خورشید   
tâbandegi-ye xoršid (#)

Fr.: luminosité solaire   

The total → radiant energy, in all wavelengths, emitted by the Sun in all directions. It is 3.828 × 1026 W or 3.828 × 1033 erg sec-1 (International Astronomical Union, Resolution B3, 14 August 2015, Honolulu, USA). This is the luminosity unit conventionally used to give the luminosities of stars. See also: → solar constant.

solar; → luminosity.

solar magnetic cycle
  چرخه‌ی ِ مغناتیسی ِ خورشید   
carxe-ye meqnâtisi-ye xoršid

Fr.: cycle magnétique solaire   

The period of time, about 22 years, after which the magnetic → polarity of the Sun returns to its earlier state. It consists of two consecutive → solar cycles.

solar; → magnetic; → cycle.

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