Of or pertaining to the Sun.
Adjective from L. sol; → Sun.
Fr.: abondance solaire
→ solar photospheric abundance, → solar system abundance.
Fr.: activité solaire
The general term for all forms of short-lived phenomena on the Sun, including → solar flares, → sunspots, → prominences, etc., indicating that the Sun is an active star.
solar activity cycle
carxe-ye žirandegi-ye xoršid
Fr.: cycle d'activité solaire
Same as the → solar cycle.
→ solar activity; → cycle.
Fr.: analogue du soleil
A member of a class of unevolved or slightly evolved → Population I disk stars with an → effective temperature, degree of evolution, → metallicity, and kinematic property not very different from those of the Sun. See also → solar-like star; → solar twin.
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.
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 axial tilt
gerâ-ye âse-ye xoršid
Fr.: inclinaison de l'axe du Soleil
The angle between the Sun's → rotation axis and perpendicular to the → ecliptic plane. In other words, the inclination of the Sun's → equator with respect to the → ecliptic plane. It is 7.25 degrees.
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.
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.
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.
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.
ruz-e xoršidi (#)
Fr.: jour solaire
The length of time between two successive transits of the Sun over the same meridian.
Fr.: dépression solaire
The → angle between the → sea horizon, the → center of → Earth, and the center of the → solar disk.
→ solar; → depression.
Fr.: disque solaire
The apparent shape of the → Sun's → photosphere.
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.
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 ecliptic limit
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.
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.
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 → megatons of → T.N.T..