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

A narrow region of abrupt, nearly discontinuous change in the physical characteristics of a medium in which the flow of a fluid changes from subsonic to supersonic. Across a shock wave there is always an extremely rapid rise in pressure, temperature, and density of the fluid.

→ shock; → wave.

A form of quartz that has a deformed microscopic structure caused by intense pressure which alters the crystalline structure of quartz along planes inside the crystal. It was first discovered after underground nuclear bomb testing. It is found worldwide at the boundary between Cretaceous and Tertiary rocks. This is further evidence (in addition to iridium enrichment) that the transition between the two geological eras was caused by a large meteorite impact.

→ shock; → impact.

Colloquial name for → meteor.

Shooting, from shoot (v.); M.E. shoten; O.E. sceotan "to shoot" (cf. O.N. skjota, Du. schieten, Ger. schießen), from PIE base *skeud- "to shoot, to chase, to throw;" → star.

Šahâb, → meteor.

1) Having little length. Not tall or high.
2) Lasting for only a small amount of time.

M.E. schort; O.E. sceort; cf. O.N. skorta "to be short of," skort "shortness;" O.H.G. scurz "short."

Kutâh "short," related to kucak "small," kudak "child, infant;" Mid.Pers. kôtâh "low," kôtak "small, young; baby;" Av. kutaka- "little, small."

A relatively low → resistance contact, usually accidental, between two points of an → electric circuit with initially different → potential. A short circuit brings about a flow of excess → electric current that can damage the circuit and present a danger for the user.

→ short; → circuit.

Gardrâhband, literally "link, bind, bond in circuit," from gardrâh, → circuit, + band, → band.

A comet with a period less than 200 years. Same as → periodic comet.

→ short; → period; → comet.

A variable star that has a relatively short period with respect to stars of similar types.

→ short; → period; → variable.

1) A deficiency in quantity.
2) The amount of such → deficiency.

From → short + suffix -age.

Kambud, from kam "little, few, deficient, scarce" + bud, from budan, → exist.

Same as → Schottky noise; → shot noise.

Translation of Ger. Schroteffekt, from Schrot "small shot, buckshot" + Effekt; → effect.

Same as → Schottky noise and → shot effect.

→ shot effect.

→ Schottky noise.

The upper joint of each of a person's → arms and the part of the → body between this and the → neck.

M.E. schuldre, sholder, shulder, schulder, from O.E. sculdra, sculdor, akin to Du. schouder, Ger. Schulter.

Duš "shoulder;" Mid.Pers. dôš "shoulder;" Av. daoš- "shoulder;" cf. Skt. dós- "shoulder."
Soft "shoulder;" Mid.Pers. suft.

→ scapula.

→ shoulder; blade, M.E.; O.E. blæd "blade of grass;" cognate with Du. blad, Ger. Blatt.

Šâné, ketf, → scapula.

1) A brief, abrupt precipitation from a cloud, characterized by the suddenness with which it begins and ends and by the rapid changes in intensity.
2) An abundant flow; an outpouring, such as → cosmic-ray shower; → air shower; → meteor shower.

M.E. shour; O.E. scur "short fall of rain, fall of missiles or blows;" cf. O.N. skur, O.S., O.H.G. scur, Ger. Schauer.

Ragbâr "cloudburst," from rag "cloudburst; thunder," → rain + bâr "raining, rain," from bâridan, → rain.
Tondbâr, with tond "fast," → velocity.

A → meteor that is part of a group moving in the same orbit around the Sun. → meteor shower.

→ meteor; → shower.

1) A pair of rolling lids that are used to open or close the dome slit. Same as → dome shutter.
2) A mechanical device that controls the time during which light is admitted in an optical system.

Shutter, from shut (v.), from O.E. scyttan from W.Gmc. *skutjanan + → -er.

Bastâr, from bast, past tense stem of bastan + -âr. Bastan, from Mid.Pers. bastan/vastan "to bind, shut," Av./O.Pers. band- "to bind, fetter," banda- "band, tie," Skt. bandh- "to bind, tie, fasten," PIE *bhendh- "to bind," cf. Ger. binden, E. bind, → band. The suffix -âr creates agent nouns (as in xaridâr, virâstâr, foruxtâr, nemudâr, etc.).

The system of → SI units.

→ SI units.

A coherent and rationalized system of units, in common use in physics since 1969. The seven basic units are the → meter, the → kilogram, the → second, the → ampere, the → kelvin, the → mole, and the → candela. Same as international system of units.

SI, from Fr. Système Internationale d'unités; → unit.

A person's brother or sister.

M.E., from O.E. sibling "relative, kinsman," from sibb "kinship, relationship; love, friendship," cf. O.Saxon sibba, M.Du. sibbe, O.H.G. sippa, Ger. Sippe "kin, related," Icelandic sifi "related."

Barxâ, from bar- first syllable of barâdar, → brother, + xâ-, short for xâhar (x^wâhar), → sister.
Hamšir, literally "of the same milk," more specifically "sucking the same breast." However, a hamšir may not be a person's brother or sister.

1) An implement for cutting grain, grass, etc., consisting of a curved, hooklike blade mounted in a short handle.
2) → Sickle of Leo.

M.E. sikel, O.E. sicol; cf. Du. sikkel, Ger. Sichel, ultimately from L. secula "sickle," from PIE root *sek- "to cut," → section.

Das "sickle," Mid.Pers. dâs "sickle;" variant dahre, → scythe; Wakhi δətr, Parachi dêš "sickle;" ultimately from Proto-Iranian *dāθra-; cf. Skt. dātra- "sickle, scythe."

A sickle-shaped → asterism forming the back of the Lion's head. It is marked by six stars: ε Leonis, μ Leonis, ζ Leonis, γ Leonis, η Leonis, and α Leonis (→ Regulus).

→ sickle; → Leo.