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

A set containing at least → one → element.

→ nonempty; → set.

A set that obeys the rules of → classical logic, a → crisp set, as contrasted with a → fuzzy set.

→ nonfuzzy; → set.

A star that is always seen above the horizon from a given position. These stars are located between the celestial pole and a diurnal circle with an angular distance smaller than the altitude of the pole. Same as → circumpolar star.

Nonsetting, from → non- + setting adj. of → set; → star.

Setâré, → star; hamiše peydâ literally "always visible," coined by Biruni (A.D. 973-1050) in his at-Tafhim, from hamišé "always," → perpetual, + peydâ, → visible.

1) A shift in the pointing position of a telescope with respect to a reference position.
2) Another term for the → bias in → CCD detectors.
3) Surveying: A short distance measured perpendicularly from a main survey line.

→ off- + → set.

Ap-, → off-; + neh present stem of nehâdan "to place, put; to set" Mid.Pers. nihâtan; Av. ni- "down; below; into," → ni-, + dā- "to put; to establish; to give," dadāiti "he gives;" cf. Skt. dadāti "he gives;" Gk. didomi "I give;" L. do "I give;" PIE base *do- "to give."

Guiding an astronomical exposure on a star, when the object of interest is nearby, but invisible.

→ offset; → guiding.

A → set consisting of points having → neighborhoods wholly contained in the set, as the set of points within a circle.

→ open; → set.

A set P is called perfect if P = P', where P' is the derived set of P.

→ perfect; → set.

Of two sets A and B, the set A if it is contained in B (A ⊂ B) but is not equal to B (A ≠ B).

→ proper; → subset.

A spacecraft launched in March 2004 by the → European Space Agency to be the first man-made object to orbit a → comet's → nucleus. Rosetta will also be the first spacecraft to fly alongside a comet as it heads toward → perihelion in the inner → solar system. After a ten-year voyage across the solar system, it will reach a → periodic comet known as Comet 67P/ → Churyumov-Gerasimenko. Rosetta will remain in close proximity to the icy nucleus as it plunges toward the warmer inner reaches of the Sun's realm. Rosetta orbiter's scientific payload includes 11 different instruments, in addition to a robotic lander and 10 solar panels spanning 32 m tip to tip. In November 2014, Rosetta will launch the 100 kg lander, named Philae, onto the comet. Philae will touch down and then fire a harpoon to anchor itself and prevent it from escaping the comet's weak gravity. The lander carries 10 instruments, including a drill to take samples of subsurface material. More than a year will pass before the remarkable mission comes to an end in December 2015. By then, both the spacecraft and the comet will have circled the Sun and will be on their way out of the inner solar system. Rosetta's prime objective is to help understand the origin and evolution of the solar system. The comet's composition reflects the composition of the pre-solar nebula out of which the Sun and the planets of the solar system formed, more than 4.6 billion years ago. Therefore, an in-depth analysis of comet 67P/Churyumov-Gerasimenko by Rosetta and its lander will provide essential information to understand how the solar system formed. Before arriving at 67P/Churyumov-Gerasimenk, Rosetta flew by the → asteroids 2867 → Steins and 21 → Lutetia in 2008 and 2010, respectively, and gathered data on them.

Named for the Rosetta Stone, a black stele that was inscribed with a royal decree (196 BC) in two languages using three scripts: Egyptian hieroglyphics, Egyptian Demotic, and Greek. The Rosetta Stone was found in a small village in the Nile Delta called Rashid (Rosetta) in 1799. The spacecraft's robotic lander is called Philae, after a similarly inscribed obelisk found on an island in the Nile River. Both the stone and the obelisk were key to deciphering ancient Egyptian hieroglyphs, carried out by Jean-François Champollion (1790-1832) in 1822. Astronomers hope the Rosetta mission will provide a key to many questions about the origins of the solar system.

A giant H II region of about 1° in diameter, lying about 5000 light-years away in the Milky Way, the constellation → Monoceros. It is ionized by the cluster NGC 2244, a group of hot young stars at the center of the nebula. Also called M16, the brighter portions of the nebula have been assigned different NGC numbers: 2237, 2238, 2239, and 2246.

Rosette "a rose-shaped ornament," from Fr. rosette, from O.Fr. rosette, diminutive of rose "rose;" L. rosa, probably from Gk. wrodon (Aeolic), then rhodon, a loan from Iranian, as below; → nebula.

Miq, → nebula; golsân "resembling rose, flower," from gol "flower, rose," variants vard (sohre-vard "red rose"), Semnâni dialect vela "rose;" Mid.Pers. *vard, gul, loaned in Arm. vard and Ar. ward; Av. varəδa- "rose;" loaned in Gk. wrodon (Aeolic), then rhodon; + -sân "manner, semblance" (variant sun, Mid.Pers. sân "manner, kind," Sogdian šôné "career").

The scientific attempt to detect → intelligent extraterrestrial → life by surveying the sky to find the existence of → transmissions, especially → radio waves or → light, from a → civilization on a distant → planet. The SETI Institute, that carries out the project, is a private non-profit center founded in 1984. There are many methods that SETI scientific teams use to search for extraterrestrial intelligence. Many of these search billions of radio frequencies that reach Earth from all over the → Universe, looking for an intelligent → radio signal. Other SETI teams search by looking for signals in pulses of light emanating from the stars.

→ search; → extraterrestrial; → intelligence.

1) Math.: A finite or infinite collection of objects in which order has no significance. Members of a set are often referred to as elements and the notation a ∈ A is used to denote that a is an element of a set A. The study of sets and their properties is the object of set theory.
2) To pass below the horizon. → moonset; → sunset.
3a) (tr.v.) To put (something or someone) in a particular place.
3b) To adjust a device to a desired position.

1) M.E. sette, from O.Fr. sette "sequence," variant of secte, from M.L. secta "religious group, sect," from L. secta "manner, following, school of thought," literally "something to follow, pathway, course of conduct, school of thought," from sectari "to pursue, accompany," "a way, road," from sequi "to follow," → sequence.
2) M.E. setten, O.E. settan "cause to sit, put in some place, fix firmly;" cf. O.N. setja, O.Fris. setta, Du. zetten, Ger. setzen.

1) Hangard, from Mid.Pers. hangart "whole, complete," hangartik "complete," hangartênitan "to collect, assemble," from *hamkard- literally "created, cut together," from han- variant of ham- "together," cognate with L.L. insimul "at the same time," from in- intensive prefix + simul "together, at the same time" (cf. Gk. homos "same," Mod./Mid.Pers. ham- "together, with," O.Pers./Av. ham-, Skt. sam-; also O.Pers./Av. hama- "one and the same," Skt. sama-; originally identical with PIE numeral *sam- "one," from *som-). (→ com-), + gard, variant of kard "created, cut," Mid.Pers. kirrēnītan, kirrēn- "to cut, create," cf. fragard "section, chapter," Av. karət- "to cut," kərəntaiti "cuts, breaks," with fraca- "to create, bring forth," karəta- "knife, dagger" (Mid.Pers. kârt "knife;" Mod.Pers. kârd "knife"), Skt. kart- "to cut, split, break," krti- "sword, knife;" PIE base *(s)kert- "to cut;" Hitt. kartae- "to cut;" Arm. kherthem "to skin;" L. cortex "bark of a tree," corium "skin, leather;" O.H.G. scrinden "to split;" Lith. kertu "to fell, cut down."
2) Forušodan, literally "to descend, go down," from foru- "down, downward; below; beneath" (Mid.Pers. frôt "down, downward;" O.Pers. fravata "forward, downward;" cf. Skt. pravát- "a sloping path, the slope of a mountain") + šodan "to go, to pass; to become, to be, to be doing" (Mid.Pers. šudan, šaw- "to go;" Av. š(ii)auu-, šiyav- "to move, go," šiyavati "goes," šyaoθna- "activity; action; doing, working;" O.Pers. šiyav- "to go forth, set," ašiyavam "I set forth;" cf. Skt. cyu- "to move to and fro, shake about; to stir," cyávate "stirs himself, goes;" Gk. kinein "to move;" Goth. haitan "call, be called;" O.E. hatan "command, call;" PIE base *kei- "to move to and fro").
3) Beštidan, from bešt past stem of Tabari/Mâzandarâni beštan "to place, put, set," from intensive prefix be- + eštan, from heštan "to place, put," → intercalate.

A collection of → nonempty subsets of a set A such that every element of A is in exactly one of the subsets. In other words, A is the → disjoint  → union of these subsets.

→ partition; → set.

The branch of mathematics that studies sets. Set theory is closely associated with the branch of mathematics known as logic. It was initiated by the German mathematician Georg Cantor (1845-1918).

→ set; → theory.

To install and configure hardware and software on a computer.

Verb of → setup.

1) The act of setting; the appearance of a → celestial body below the → horizon. Opposite of → rising.
2) A change in a software program or hardware device that adjusts it to the user's preference. For example, date and time setting, language setting, display setting, font setting, etc.

→ set; → -ing.

Two graduated disks attached to the right ascension and declination axis of an equatorial mount used in amateur astronomy that help an observer find astronomical objects in the sky by their equatorial coordinates.

M.E.; O.E. settan "cause to sit, put in some place, fix firmly" (cf. O.N. setja, O.Fris. setta, Du. zetten, Ger. setzen); → circle.

Dâyeré, → circle; âmâj-giri "taking aim," from âmâj "aim, target," → point + giri "taking" (vebal noun of gereftan "to take, seize, hold;" Mid.Pers. griftan, gir- "to take, hold, restrain;" O.Pers./Av. grab- "to take, seize," cf. Skt. grah-, grabh- "to seize, take," graha- "seizing, holding, perceiving," M.L.G. grabben "to grab," from P.Gmc. *grab, E. grab "to take or grasp suddenly;" PIE *ghrebh- "to seize").

1) (tr.) To put in order; arrange in a desired state or condition.
2) (intr.) To come to rest or a halt. To become fixed in a particular place, direction, etc. (Dictionary.com).

M.E. set(t)len, O.E. setlan "to place," derivative of setl "a seat; stall; position, abode;" related to sittan "to sit," from Proto-Germanic *setla- (cognates: Middle Low German, Middle Dutch setel, Dutch zetel, German Sessel, Gothic sitls), from PIE *sedla- (cognates: L. sella "seat, chair," O.C.S. sedlo "saddle," O.E. sadol "saddle"), from root *sed-.

Niyâšidan, from Yidghda niâst- , Munji niôst- "to sit down;" Nâini âš-/âšis- "to become seated;" Baluci ništ, related to nešastan "to sit down," → sit (see also → reside); ultimately from Proto-Ir. *had- "to sit, be setaed."

A → galactic disk that has undergone → disk settling.

→ settle; → disk.

The act of a person or thing that settles. → disk settling, → dust settling.

→ settle; → -ing.