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

1) A line segment that forms part of the perimeter of a plane geometric figure.
2) A surface of a solid geometric figure.

M.E., from O.E. side "flanks of a person, the long part of anything;" cf. O.S. sida, O.N. sitha, M.Du. side, O.H.G. sita, Ger. Seite.

Bar "side; breadth; breast," variant var; Mid.Pers. var "breast;" Av. vouru "wide, broad, extended" (vourucašāni- "looking far"), related to varah- "breast;" cf. Skt. urú- "wide, broad," úras- "breast;" Gk. eurus "wide, broad;" PIE base uer-, ueru-s "wide, broad."
Pahlu "side, flank;" Mid.Pers. pahlug "side, rib," Av. pərəsu- "rib," Ossetic fars "side, flank," cf. Skt. párśu- "rib," O.C.S. prbsi "breast," Lit. piršys (pl.) "horse breast."
Kenâr "side," variant karân "edge, limit;" Mid.Pers. karân, karânak, kenâr "edge, limit, boundary;" Av. karana- "side, boundary, end."
→ octagon, → polygon, → quadrilateral, → triangle.

1) In → radio astronomy, smaller amounts of gain found either side of the main lobe.
2) In transmitting antennae, radiation in any direction other than that required.

→ side; → lobe.

Either of the two bands of frequencies, one just above (upper side) and one just below (lower side) a carrier frequency, that result from modulation of a carrier wave.

→ side; → band.

Bând, → band; kenâr "side," variant karân "edge, limit;" Mid.Pers. karân, karânak, kenâr "edge, limit, boundary;" Av. karana- "side, boundary, end."

Of, relating to, or determined by or from stars.

From M.Fr. sidereal, from L. sidereus "starry, astral," from sidus (genitive sideris) "star, constellation."

Axtari, pertaining to axtar "star," probably a variant of setâré→ star.

The period of → Earth's rotation around its axis, the mean value of which is about 23h 56m 04.092s (23.934 470 hours). In other words, the interval between two successive passages of a star across a given → meridian. The sidereal day is 3 minutes 56 seconds shorter than the → mean solar day. The reason is that Earth moves a little less than a degree around the Sun during the time it takes for one full axial rotation. So, for the Sun to appear on the same meridian in the sky again after one full axial rotation, the Earth has to rotate one extra degree to bring the Sun into the same apparent meridian in the sky. This is also why the stars rise and set about 4 min earlier each day.

→ sidereal; → day.

The angle on the celestial sphere measured westward from the hour circle of the vernal equinox to that of the celestial body.

→ sidereal; → hour angle.

The time taken by the Moon to complete one → revolution around the Earth with respect to a background, → fixed star. The average time is 27.321 661 days (27d 7h 43m 11.5s). Same as → lunar sidereal orbital period.

→ sidereal; → month.

→ sidereal revolution period; → sidereal rotation period.

→ sidereal; → period.

The time taken by a planet or satellite to complete one revolution about its primary with respect to stars. For Earth, same as → sidereal year. Sidereal periods of the solar system planets, interms of the sidereal year, are as follows: Mercury 0.240846 (87.9691 days); Venus 0.615 (225 days); Earth 1 (365.25636 solar days); Mars 1.881; Jupiter 11.86; Satrurn 29.46; Uranus 84.01; and Neptune 164.8. That of the Moon is 0.0748 (27.32 days) and for → Sedna 12050.

→ sidereal; → revolution; → period.

The rotation period of a celestial body with respect to fixed stars. For Earth, same as → sidereal day.

→ sidereal; → rotation; → period.

The time based upon → Earth's rotation with respect to the stars, with the → sidereal day as the unit of measurement. At the moment when the → vernal equinox crosses the → meridian in → upper culmination, sidereal time is equal to zero hours for that observing position. The → hour angle of the vernal equinox is equal to sidereal time.

→ sidereal; → time.

The interval between two successive passages of the Sun, in its apparent → annual motion around the → celestial sphere, through a particular point relative to stars. It is equal to 365.256356 days for the J2000.0 epoch and is 20m 24.5s longer than the → tropical year.

→ sidereal; → year.

1) A mineral composed of iron carbonate, FeCO₃, that is a valuable ore of → iron.
2) A category of → meteorites consisting mainly of → iron and → nickel, commonly referred to as Irons. There are 13 different chemical groups of siderites. These groups are defined based on the relative abundance of nickel, gallium, germanium, and iridium. Irons are also categorized by their structural type.

→ sidero-; → -ite.

A combining form meaning "iron," used in the formation of compound words; variant sider- before a vowel.

From Gk. sideros "iron."

Âhan-, from âhan, → iron.
Sidero-, loan from Gk., as above.

The category of → meteorites commonly referred to as → stony-irons. The three classes of siderolites are → lodranites, → mesosiderites, and → pallasites.

From Gk. sidero-, from sideros "iron" + -lite a combining form used in the names of minerals.

→ siderophile element.

→ sidero-; → -phile.

In the → Goldschmidt classification, any → chemical element that has an → affinity to combine with → iron rather than some other element. These elements are concentrated in the → Earth's core. The group includes → iron (Fe), → nickle (Ni), → cobalt (Co), → platinum (Pt), → gold (Au), → tin (Zn), and → tantalum (Ta). The siderophile elements include → highly siderophile element (HSE).

→ siderophile; → element.

A mirror arrangement with clock drive that reflects light from a celestial body to a fixed position. → coelostat; → heliostat.

From L. sidero-, from sidus (genitive sideris) "star, constellation" + -stat prefix denoting something that stabilizes, keeps, fixes, from -stata, from Gk. -states "one that causes to stand," or statos "standing," from *sta- "to stand."

Axtardâštâr, from axtar, → star, + dâštâr "holder, maintainer," from dâštan "to hold, maintain; to have; to possess;" Mid.Pers. dâštan; O.Pers./Av. dar- "to hold, keep back, maintain, keep in mind;" cf. Skt. dhr-, dharma- "law;" Gk. thronos "elevated seat, throne;" L. firmus "firm, stable;" Lith. daryti "to make;" PIE base *dher- "to hold, support."

The SI unit of electrical conductance, equal to the reciprocal of the ohm and replacing the equivalent MKS unit.

Named for the German electrical engineer Werner von Siemens (1816-1892).

A classical method of finding all → prime numbers up to any given number n. The method consists of listing all positive integers from 2 up to the given number and then deleting some of them sequentially in steps. For example, if we wish to find the primes less than or equal to 50, we proceed as follows. All integers from 2 to 50 are first written. The integers that are divisible by 2, other than 2, are crossed out from the list. Since 3 is the first integer greater than 2 that is not removed, all the integers divisible by 3, other than 3, are crossed out. We do the same with 5 and then 7. Since all composite integers ≤ 50 are divisible by 2, 3, 5, or 7 (i.e. ≤ √50), all the remaining integers not deleted are prime numbers: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, and 47.

M.E. sive, O.E. sife "sieve;" cf. M.Du. seve, Du. zeef, O.H.G. sib, Ger. Sieb, of unknown origin. Related to sift.

Qarbâl (variants qarbil, qarbir, qelber, qalbur, gerbâl), probably related to the PIE base *krei- "to sieve, separate;" cf. Gk. krinein "to separate, decide, judge," krisis "decision;" L. cribrum "sieve" (Fr. crible), cernere "to sift, separate;" O.E. hriddel "sieve;" O.Ir. criathar; O.Welsh cruitr "sieve." Pers. qarbâl loaned in Ar. as gharbala "to sift," itself loaned in It. garbellare; M.Fr. garbeler "to sift;" E. garble "to sift impurities from."