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

The temperature at which a mixture of air-saturated pure water and pure ice may exist in equilibrium at a pressure of one standard atmosphere.

→ ice; → point.

A large mass of floating or stranded ice that has broken away from a glacier; usually more than 5 m above sea level.

Iceberg, half Anglicization, half adoption of Du. ijsberg "ice mountain," from ijs, → ice, + berg "mountain" (cf. Ger. Eisberg, Sw. isberg), from P.Gmc. *bergaz; cf. M.H.G. berc, O.H.G. berg "mountain;" cognate with Pers. boland, borz, berg, as below; PIE base *bheregh- "high, elevated."

Yaxberg, from yax, → ice, + berg "mountain, hill," in Laki dialect, related to Pers. boland "high," variants bâlâ "up, above, high, elevated, height," borz "height, magnitude" (it occurs also in the name of the mountain chain Alborz), Laki dialect berg "hill, mountain;" Mid.Pers. buland "high;" O.Pers. baršan- "height;" Av. barəz- "high, mount," barezan- "height;" cf. Skt. bhrant- "high;" L. fortis "strong" (Fr. & E. force); O.E. burg, burh "castle, fortified place," from P.Gmc. *burgs "fortress;" Ger. Burg "castle," Goth. baurgs "city," E. burg, borough, Fr. bourgeois, bourgeoisie, faubourg); PIE base *bhergh- "high."

1) A minute gap between the adjacent parts of a body or objects close together.
2) In a crystal lattice, the empty space between adjacent atoms. The interstices are of two types: Tetrahedral-interstices and Octahedral-interstices. Also called → interstitial site.

From L. interstitium "space between; interval," from intersistere, from → inter- "between," + stem of stare "to stand," cognate with Pers. istâdan, → stand

Andarjâ, literally "a place between," from andar "between," → inter-, + jâ, → place.

An interplanetary mission currently in development by the → European Space Agency planned for launch in 2020. It is aimed mainly at in-depth studies of three potentially ocean-bearing satellites, → Ganymede, → Europa, and → Callisto. JUICE will complete a unique tour of the Jupiter system including several flybys of each planet-sized world, culminating with orbit insertion around Ganymede, the largest moon in the Solar System, followed by nine months of operations in its orbit. JUICE will carry the most powerful scientific payload ever flown to the outer Solar System. It consists of 10 state-of-the-art instruments plus one experiment that uses the spacecraft telecommunication system with ground-based instruments.

→ Jupiter; → icy; → explorer; → moon.

1) The quality of being just; righteousness, equitableness, or moral rightness.
2) The moral principle determining just conduct.
3) The administering of deserved punishment or reward (Dictionary.com).

M.E., from O.Fr. justice "justice, legal rights, jurisdiction," from L. iustitia "righteousness, equity," from iustus "upright, → just."

Dâd "justice, law" from Mid.Pers. dâd "law, justice, scriptures with legal content;" related to Mid.- and Mod.Pers. daheš "creation," dâdan "to give;" Av. dā- "to place upon, give;" → datum.
Dâdmandi noun from dâmand, → just.
Dâdgari "administration of justice," from dâdgar, literally "just doer," "an administrator of justice," from dâd + -gar, → -or.
Dâdgostari, from Dâdgostar, literally "justice spreader," with gostar, from gostardan "to spread, → expand."

1) A regular geometric arrangement of points in a plane or in space.
2) → Crystal lattice.
3) A structure in a nuclear reactor containing nuclear fuel and other materials arranged in a regular geometrical pattern.
4) Math.: A partially ordered set in which each two-element subset has both a greatest lower bound and a least upper bound.

From O.Fr. latiz "lattice," from late "lath, board, plank, batten" (Fr. latte); cf. O.H.G. latta "lath."

Jâré, from jarra "net; snare," Afghan jâli "reticulated garment," Tabari jarazin "grilled apparatus used in a watercourse to gather thatch and trash;" cf. Skt. jāla- "net, snare, lattice."

The energy required to separate an ion from a → crystal to an infinite distance. In other words, the energy released when one → mole of a crystal is formed from gaseous ions.

→ lattice; → energy.

A roughly 400-year period from the mid-16th through the mid-19th centuries when temperatures over much of Europe were unusually cold. Glaciers in the Alps advanced and European rivers froze much more often than during the past century. Harvests failed, livestock perished, and poor people suffered from famine and disease. The Little Ice Age coincided with two successive low → solar activity periods, the → Sporer minimum and the → Maunder minimum.

→ little; → ice; → age.

An electronic device whose output is not directly proportional to its input. For example, in a → diode the current is a nonlinear function of the voltage; its voltage-current characteristics do not obey → Ohm's law.

→ nonlinear; → device.

The point in the orbit of one component of a binary system which is closest to the center of mass of the system; opposite of → apocenter.

→ peri- + → center.

1a) To do habitually or regularly.
1b) To exercise or follow as a profession.
2a) Performance; the doing of something (contrasted with → theory). See also → praxis.
2b) Way of doing something that is common or habitual.
2c) Frequent or systematic repetition in doing something.

M.E. practisen, practizen; O.Fr. practiser "to practice," from M.L. practicare "to do, perform," from L.L. practicus "practical," from Gk. praktikos "practical."

1) Varzidan "to practice, perform; to accustom oneself to; to labor; to sow a field;" Mid.Pers. warz- "to work, do, practice;" Av. varəz- "to work, do, perform, exercise;" cf. Gk. ergon "work;" Arm. gorc "work;" Lith. verziu "tie, fasten, squeeze," vargas "need, distress;" Goth. waurkjan; O.E. wyrcan "work," wrecan "to drive, hunt, pursue;" E. work; PIE base *werg- "to work."
2) varzé, noun from present stem varz- + suffix -é.

1) A helpful act by somebody for somebody else as a job, duty, or favor.
2) A system or organization supplying some public demand, e.g. transportation, telephone, health.
3) A facility providing maintenance and repair.

M.E., from O.Fr. servise, from L. servitium "slavery, servitude," from servus "slave," servire "to serve," originally "be a slave;" cognate with Av. har- "to guard, watch," → server.

Zâvari "service" (Dehxodâ) → server.

Observation approved by the selection committee of an observatory which is carried out by the staff astronomers of the observatory.

→ service; → observation.

Two → square matrices A and B that are related by B = X^-1AX, where X is a square → nonsingular matrix.

→ similar; → matrix.

1) A thin, broad piece cut from something.
2) To cut into slices; divide into parts (Dictionary.com).

O.Fr. escliz "splinter, fragment" (Fr. éclisse), a back-formation from esclicier "to splinter, shatter, smash;" cf. O.H.G. slihhan.

Qâc, contraction of qârc, from karj "slice, a slice of melon; a piece cut out of the collar of a garment;" ultimately from Proto-Ir. *kartaka-, from *kart- "to cut," cf. Av. karət- "to cut;" Skt. kart- "to cut," karəta- "knife;" Mid.Pers. kârt, → knife.

Either of the two points on the → ecliptic at which the apparent → longitude of the → Sun is 90° or 270°. Also the time at which the Sun is at either point. Solstices occur when the Earth's axis is oriented directly toward or away from the Sun, causing the Sun to reach its northernmost and southernmost extremes. → summer solstice, → winter solstice.

M.E., from O.Fr. solstice, from L. solstitium "point at which the sun seems to stand still," from sol, → sun, cognate with Pers. xor, xoršid, hur, as below, + p.p. stem of sistere "to come to a stop, make stand still," akin to Pers. istâdan "to stand," as below.

Xoristân, is composed of two components. The first one xor "sun," variant hur; Mid.Pers. xwar "sun;" Av. hū-, hvar- "sun;" cf. Skt. surya-, Gk. helios, L. sol, cognate with E. sun, as above; PIE base *sawel- "sun." The second component istân "standing," from istâdan "to stand;" Mid.Pers. êstâtan; O.Pers./Av. sta- "to stand, stand still; set;" Av. hištaiti; cf. Skt. sthā- "to stand;" Gk. histemi "put, place, weigh," stasis "a standing still;" L. stare "to stand;" Lith. statau "place;" Goth. standan; PIE base *sta- "to stand."

The moment in the northern hemisphere when the → Sun attains its highest → declination of 23°26' (or 23°.44) with respect the → equator plane. It happens when the Earth's axis is orientated directly toward the Sun, on 21 or 22 June. During the northern solstice the Sun appears to be directly overhead at noon for places situated at → latitude 23.44 degrees north, known as the → tropic of Cancer. The summer solstice can occur at any moment during the day. Two successive summer solstices are shifted in time by about 6 h. The summer solstice in the northern hemisphere is the → winter solstice in the southern hemisphere.

→ summer; → solstice.

In fluid dynamics, a theorem that relates the speed of fluid flowing out of an opening to the height of fluid above the opening: v = (2gh)^1/2, where v is the exit velocity of the water, h is the height of the water column, and g is the acceleration due to gravity (9.81 m/s²). It was later shown to be a particular case of → Bernoulli's theorem.

After the Italian scientist Evangelista Torricelli (1608-1647), who found this relationship in 1643.

Two times, as in succession; on two occasions.

M.E. twies, from O.E. twiga, twigea "two times," from twi-, → two; cf. L. bis, Gk. dis, Skt. dvis, Av. biš.

Dobâr, from do, → two, + bâr "time, fold," from Mid.Pers. bâr; Proto-Ir. *uara-; cf. Av. var- "to choose; to convince;" Skt. vāra- "time, turn."

Plural of → vertex.

→ vertex.