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

Separated and made visible in an → image or → spectral feature. → resolved line.

Past participle of → resolve.

A → spectral line that is not contaminated by other nearby lines.

→ resolved; → line.

A measure of an optical system's ability to produce an image which separates two points or parallel lines on the object.

Resolving verbal adj. of → resolve; → power.

A solution which can exist in equilibrium with excess of solute. The saturation concentration is a function of the temperature.

→ saturate; → solution.

The first exact solution of → Einstein's field equations that describes the → space-time geometry outside a spherical distribution of mass.

Briefly following Einstein's publication of → General Relativity, Karl Schwarzschild discovered this solution in 1916 (Sitzungsberichte der Königlich Preussischen Akademie der Wissenschaften zu Berlin, Phys.-Math. Klasse, 189); → Schwarzschild black hole.

Of partial differential equations, the solution which cannot be obtained from the general solution by particular choice of arbitrary functions. → general solution; → particular solution.

→ singular; → solution.

A term introduced by the → International Astronomical Union (August 2006) to name the → solar system bodies other than → planets and → dwarf planets. Small solar system bodies include → asteroids, → comets, and → meteoroids.

→ small; → solar; → system; → body.

The solar day on Mars, which has a mean period of 24 hours 39 minutes 35.244 seconds (based on SI units), about 2.7% longer than Earth's solar day. The Martian sidereal day, as measured with respect to the fixed stars, is 24h 37m 22.663s, as compared with 23h 56m 04.0905s for Earth.

Sol, from L. sol "sun," cognate with Pers. hur, → Sun.

Of or pertaining to the Sun.

Adjective from L. sol; → Sun.

→ solar photospheric abundance, → solar system abundance.

→ solar; → abundance.

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.

Same as the → solar cycle.

→ solar activity; → cycle.

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.

→ solar; → analogue.

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.

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.

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.

→ solar; → axial; → tilt.

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.

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.

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.

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.