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

General: Any thing or place from which something comes, arises, or is obtained.
Physics: A point, line, or area in space from which the lines of force in a vector field originate.
Electricity: Any active component, battery, or generator that supplies energy.
Thermodynamics: Any body, device, or system that provides energy.

M.E., from O.Fr. sourse "a rising, beginning, fountainhead of a river or stream," from p.p. of sourdre "to rise, spring up," from L. surgere "to rise," → surge.

Xan "source," variant xân (Gilaki xoni, Tabari xoni,Laki kyani, Tâleši xâni, xoni,); Mid.Pers. xân, xânig "source, spring," Av. xâ-, xan- "source, fountain, spring," xayana- "belonging to a spring;" cf. Khotanese khâhâ- "spring, fountain;" Skt. khâ'- "spring, source."

For a radiating material, the ratio of emissivity to opacity.

→ source; → function.

The cardinal point which is opposite to north. It is also the direction of the Sun at local noon (in the northern hemisphere).

M.E. suth(e), south(e), from O.E. suth "southward, in the south;" cf. O.S., O.Fris. suth "southward, in the south," M.Du. suut), O.H.G. sund, perhaps related to base of *sunnon "sun," with sense of "the region of the sun."

Note: South is related to right since it is to the right when one faces the rising Sun. This occurs in, for example, in Av., Skt., and O.Ir., as below.

Daštar, from Mid.Pers. dašn "right hand;" Av. dašina- "right; south;" Ossetic dæsni "skillful, dexterous;" cf. Skt. dáksina- "right; southern;" Gk. dexios (<*deks-i-uo-) "right," dexiteros "located on the right side;" L. dexter "right;" Goth. taihswo "right hand;" O.Ir. dess "on the right hand, southern;" PIE base *deks- "right." The second element -tar direction suffix, as in Mid.Pers. ošastar "east" (Av. ušastara- "eastern"), dôšastar "west" (Av. daôšatara-, daôšastara- "western"), abâxtar "north" (Av. apāxtara- "northern"), Mod.Pers. bâxtar, → west.

A region of the Earth where the inner → Van Allen belt comes closest to the Earth's surface. It is due to the fact that the → geomagnetic field is offset from the center of the Earth. The region is centered near 25 degrees South 50 degrees West, close to the Atlantic coast of Brazil. The excess of trapped energetic particles in that region presents a problem for satellites in orbit around the Earth.

→ south; → Atlantic; → anomaly.

The point in the → southern hemisphere where the → rotation axis of the Earth touches the → celestial sphere. In contrast to the → north celestial pole, no bright star is visible in that direction.

→ north; → celestial; → pole.

The point on → horizon in direction of → geographic south pole.

→ south; → point.

A large area of the south polar region of → Mars which is covered with layers of → water ice and → dust. The SPLD, like the NPLD, has a maximum relief relative to the surrounding terrain of ~ 3.5 km and ~ 1,000 km across. Above the SPLD lies a very thin temporary (1-10 m) cap of → carbon dioxide ice/frost that snows out in the winter and sublimates over the spring and summer seasons. It is believed that the rhythmic nature of the deposits is related to oscillations in Mars' → orbital parameters (J. J. Plaut et al., 2007, Science 316, 92).

→ south; → polar; → layer; → deposit.

1) An → imaginary point in the → southern hemisphere representing the intersection of the → Earth's → rotation axis with the → globe with the → celestial sphere.
2) For a → magnet, the pole which points toward the geographic south.
3) In a → magnetic field, the point which receives a → line of force coming from the → north pole.

→ south; → pole.

Of or pertaining to the south.

M.E., O.E. suðerne, from suð, → south, + -erne, suffix denoting direction.

Daštari, relating to daštar, → south.

Popular name for the constellation → Crux. Its four brightest stars form a distinctive cross shape.

→ southern; → Crux.

The half of the → Earth or another → north pole between the → south pole and the → equator.

→ southern; → hemisphere.

The transit of a celestial object, especially the Sun, across the meridian due south of the observer.

Verbal noun from → south (v.).

Gozar-e daštar-su, literally "passage southward," from gozar, → passage; daštar→ south; su, → direction.

1) Physics: That part of the boundless four dimensional continuum in which matter can be physically extended.
2) Astro.: That part of the Universe which lies beyond the Earth's atmosphere and in which the density of matter is low. Also known as outer space.

M.E., from O.Fr. espace, from L. spatium "room, area, distance, stretch of time," of unknown origin.

Fazâ, loan from Ar.

Electricity: An electric charge belonging to a cloud of electrons lying between a cathode and plate within an electric tube.
Geophysics: An excess of either negatively or positively charged ions in a layer of the atmosphere, giving that layer either a negative or positive charge.

→ space; → charge.

Man-made objects in orbit around the Earth that no longer serve any useful purpose. The estimated number of debris include about 22,000 tractable objects larger than 10 cm in all orbits, of which 2,200 are dead satellites and last stages of the rocket that put them in orbit. There are also left-overs from spacecraft and mission operations, such as bolts, lens caps, clamp bands, auxiliary motors, etc. The debris presents a threat because of their high speeds, which ranges between 15 and 20 km/sec. Also called space junk, space waste, orbital debris.

→ space; → debris.

A travel outside the Earth by manned or unmanned vehicle requiring space technology.

→ space; → flight.

Set of operations (rotation about an axis, reflection across a plane, translation, or combination of these) which when carried out on a periodic arrangement of points in space brings the system of points to self-coincidence.

The word group comes from the mathematical notion of a group.

A manned or unmanned space flight outside the Earth's atmosphere.

→ space; mission, from L. missionem (nominative missio) "act of sending," from mittere "to send," of unknown origin.

Gosilân, from gosil, variant gosi "sending away, dismission;" Mid.Pers. wisé "to despatch" (Parthian Mid.Pers. wsys- "to despatch;" Buddhist Mid.Pers. wsydy "to despatch;" Sogdian 'ns'yd- "to exhort"), from Proto-Iranian *vi-sid- "to despatch, send off," from prefix vi- "apart, away, out," + *sid- "to call" + -ân nuance suffix; fazâyi adj. of fazâ, → space.

The velocity and direction of motion of a star or celestial object with respect to the Local Standard of Rest. Same as → peculiar velocity.

→ space; → motion.

A spacecraft carrying instruments intended for use in exploration of the physical properties of outer space or celestial bodies other than Earth.

→ space; → probe.