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

The emission of electromagnetic radiation from an atom or molecule that does not depend on the presence of external fields.

→ spontaneous; → emission.

A physical phenomenon whereby a symmetric system becomes permanently asymmetric. A simple example is a ball lying on top of a hill in equilibrium. The hill-ball system is symmetric about the vertical axis through the top of the hill. Moreover, there is no preferred horizontal direction to the system. However, its state is unstable, since the slightest perturbing force will cause the ball to roll down the hill in some particular direction. The system becomes permanently asymmetric because the ball will not roll uphill by itself. Symmetry breaking is found in several fields of physics, for example in → magnetism (→ ferromagnetism), → thermodynamics (→ crystallization), and → particle physics, where it constitutes the basis of → electroweak interactions. In cosmology, according to the → Big Bang model, the fundamental forces of the Universe split off from one another in a form of spontaneous symmetry braking. If a single, unified force existed with a certain symmetry just after the Big Bang, if that symmetry were somehow broken so that the unified force were fractured, then the result might be several fundamental forces. See also → grand unified theory, → theory of everything, → phase transition.

→ spontaneous; → symmetry; → break.

An → atomic transition that gives rise to a → spontaneous emission.

→ spontaneous; → transition.

A meteor occurring occasionally, and not associated with any known meteor shower.

Sporadic, from M.L. sporadicus "scattered," from Gk. sporadikos "scattered," from sporas (genitive sporados) "scattered," from spora "seed, a sowing;" related to sporos "sowing," and speirein "to sow," from PIE *sper- "to strew;" → meteor.

Šahâb, → meteor; gahgâhi "from time to time," from gah, gâh "time; place" (Mid.Pers. gâh, gâs "time;" O.Pers. gāθu-; Av. gātav-, gātu- "place, throne, spot;" cf. Skt. gâtu- "going, motion; free space for moving; place of abode;" PIE *gwem- "to go, come").

A reproductive body in flowerless plants corresponding to the seeds of flowering ones.

From Modern L. spora, from Gk. spora "a seed, a sowing, seed-time," related to speirein "to sow, scatter."

Hâg, variant of xâg, → egg.

A period of low → solar activity that lasted from about A.D. 1420 to 1570. It occurred before → sunspots had been studied, and was discovered by analysis of the proportion of carbon-14 in tree rings, which is strongly correlated with solar activity.

Named for the German astronomer Gustav Spörer (1822-1895); → minimum.

A period of low → solar activity that lasted from about A.D. 1420 to 1570. It occurred before → sunspots had been studied, and was discovered by analysis of the proportion of carbon-14 in tree rings, which is strongly correlated with solar activity.

Named for the German astronomer Gustav Spörer (1822-1895); → minimum.

The empirical law that predicts the variation of → sunspot latitudes during a → solar cycle. At the start of a sunspot cycle, sunspots tend to appear around 30° to 45° latitude on the Sun's surface. As the cycle progresses, they appear at lower and lower latitudes, until 5° to 10°, at the end of the cycle. This tendency is revealed on a → butterfly diagram. Although named after Gustav Spörer, the "law" was first discovered by Richard Carrington.

→ Sporer minimum; → law.

The empirical law that predicts the variation of → sunspot latitudes during a → solar cycle. At the start of a sunspot cycle, sunspots tend to appear around 30° to 45° latitude on the Sun's surface. As the cycle progresses, they appear at lower and lower latitudes, until 5° to 10°, at the end of the cycle. This tendency is revealed on a → butterfly diagram. Although named after Gustav Spörer, the "law" was first discovered by Richard Carrington.

→ Sporer minimum; → law.

A mark on a surface differing sharply in color from its surroundings. → sunspot; → Great Red Spot.

M.E. spotte "a spot, blot, patch;" M.Du. spotte "spot, speck."

Lak(k), lak(k)é "spot, stain."

1a) To draw, stretch, or open out, especially over a flat surface, as something rolled or folded (often followed by out).
1b) To stretch out or unfurl in the air, as folded wings, a flag, etc.
2) An act or instance of spreading; expansion, extension, or diffusion (Dictionary.com).

M.E. spreden, from O.E. sprædan "to spread, extend," cf. Dan. sprede, O.Swed. spreda, M.Du. spreiden, O.H.G. and Ger. spreiten "to spread," from PIE root *sper- "to strew."

Gostardan "to spread; to diffuse, to expand," from Mid.Pers. wistardan "to extend; to spread;" Proto-Iranian *ui.star-; Av. vi- "apart, away from, out" (O.Pers. viy- "apart, away;" cf. Skt. vi- "apart, asunder, away, out;" L. vitare "to avoid, turn aside") + Av. star- "to spread," starati "spreads" (cf. Skt. star- "to spread out, extend, strew," strnati "spreads;" Gk. stornumi "I spread out," strotos "spread, laid out;" L. sternere "to spread;" Ger. Strahlung "radiation," from strahlen "to radiate," from Strahl "ray;" from M.H.G. strāle; from O.H.G. strāla "arrow," stripe; PIE base *ster- "to spread").

1) The season that starts when the Sun, during its apparent yearly motion, attains the celestial longitude 0 degree in the Northern Hemisphere and 180 degrees in the Southern Hemisphere. The current length of the spring season, around the year 2000, is about: spring 92.76 days.
2) A surface flow of groundwater which occurs any time the water table intersects the surface. Related concept → source = xan (خن).
3) An elastic device, usually a twisted piece of metal, that returns to its original shape when it is pressed or stretched, used chiefly to exert constant tension or absorb movement.

1) From the verb M.E. springen; O.E. springan "to leap, burst forth, fly up;" the notion is of the "spring of the year," when plants "spring up" cf. Du., Ger. springen.
2) Similarly from the verb, as above, M.E. spring(e); O.E. spring, spryng; cf. O.H.G., Dan., Sw. spring.
3) From the verb spring, as above.

1) Bahâr, from Mid.Pers. wahâr "spring;" O.Pers. vāhara- "spring time," θūra-vāhara- "name of a spring month;" Av. vaηhar "spring;" cf. Skt. vasara- "relating or appearing in the morning;" Gk. ear "spring;" L. uēr "spring," vernus "of spring;" O.N. vār "spring;" Lith. vasara "summer;" O.C.S. vesna "spring."
2) Cešmé "spring, source," from Mid.Pers. cašmag "spring, source," supposed to be related to cašm, cešm→ eye.
3) Fanar, from Turk fanâr.

A characteristic of a spring which is defined as the ratio of the force affecting the spring to the displacement caused by the force. In other words, the spring constant is the force applied if the displacement in the spring is unity. It is expressed by the equation k = -F/x (from → Hooke's law), where F = force applied, x = displacement by the spring. The spring constant is usually expressed in Newton per meter (N/m).

→ spring; → force.

→ vernal equinox.

→ spring; → equinox.

Tide that occurs when the → Earth, the → Sun, and the → Moon are in a line. This happens approximately twice a month, around → new moon and → full moon. In such a condition, known as → syzygy, the tidal force due to the Sun reinforces that due to the Moon. Spring tides have nothing to do with the season spring. The name derives from the meaning "a leap, jump, bound, rise."

Spring "a leap, jump, or bound;" M.E. springen, from spring O.E. springan "to leap, fly up; spread, grow;" cognates: O.N., O.Fris. springa, M.Du. springhen, O.H.G. springan, Ger. springen, from PIE *sprengh-, form *spergh- "to move, hasten, spring" (Skt. sprhayati "desires eagerly," Gk. sperkhesthai "to hurry."

Mehkešandak "high tide," from meh-, → high, + kešand, → tide.

1) To scatter (a liquid, powder, etc.) in drops or particles.
2) The act or an instance of sprinkling.

M.E. sprenklen (v.); cognate with Du. sprenkelen, Ger. sprenkeln; O.E. sprengan "to sprinkle, make (something) spring, scatter."

Peškidan, from (Malâyeri, Hamedâni) peška "sprinkle, water drop," variant of (Dehxodâ) pašang "sprinkle," pešanjidan "to sprinkle, spray;" (dialects of Khorâsân, Bandar Abbâs, Kermân, Dari Kermân, Lâ) pešang "spraying;" ultimately from Proto-Ir. *pati-haic- from *haic- "to pour (out), moisten);" cf. Av. patihaēc- "to sprinkle all over, pour on;" Mid.Pers. pšnc-/paššinj- "to sprinkle;" related to Pers. xēs, xis, hēs "wet;" O.H.G. sīhan "to sift;" O.E. sēon "to flow away, to sift;" PIE root *seik^w- "to pour" (Cheung 2007).

A very brief, predominantly red, luminous glow, that occurs in the → mesosphere. Sprites occur high above large → thunderstorms and last only a few milliseconds. They have a lump of light on top and numerous tendrils descending downward. Sprites can shoot about 90 to 95 km up into the atmosphere, reaching the → ionosphere, and extend 160 km across. They are very difficult to see, and for that reason were not reliably recorded until 1989. See also → elve; → blue jet.

Sprite "elf, fairy, eerie, ghost-like quality," so named by D. Sentman et al. (1995, Geophys. Res. Let, 22, 1205) because of the fleeting nature of sprites; M.E., from O.Fr. esprit "spirit," from L. spiritus "soul, vigor, breath," related to spirare "to breathe."

Farfadé, from Fr. farfadet, of dialectal origin, derived from fado "fairy."

1) A pointed device on the heel of a rider's boot used to urge on the horse.
2) A sharp horny part on the leg of some birds.
3) Geology: A lateral lower mountain ridge descending from the mountain or the main ridge crest.
4) Mining: A small vein branching from a main one.
5) → Orion Spur.

M.E. spur, from O.E. spura, spora "metal implement worn on the heel to goad a horse," akin to M.Du. spore, Du. spoor, O.H.G. sporo, Ger. Sporn "spur."

Šaxâk, from šax "hard ground, especially on the summit or at the skirt of a mountain; anything hard; a mountain," + noun/nuance suffix -âk.
Mehmiz "a spur, a goad," loan from Ar.

To emit particles, sparks, etc., forcibly or explosively, especially accompanied by sputtering sounds.

Originally "to spit with explosive sounds," cognate with Du. sputteren, W.Fris. sputterje.

Osparândan, literally "to throw out," from os- "out," → ex-, + parândan "to eject," transitive verb of paridan "to fly" (from Mid./Mod.Pers. par(r) "feather, wing," Av. parəna- "feather, wing;" cp. Skt. parna "feather," E. fern; PIE *porno- "feather").

The ejection of charged particles or atoms by a solid or liquid surface which undergoes collision with high-energy ions.

Verbal noun of → sputter.