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

A monarch who rules or reigns over an empire.

M.E., from O.Fr. empereor "emperor, leader, ruler," from L. imperiatorem (nominative imperiator) "commander, emperor," from p.p. stem of → imperare "to command."

Parmâtyâr, from parmât, present stem of parmâtidan, → imperare, + suffix -yâr, as in šahryâr "sovereign, king," hušyâr "sober, cautious, intelligent," kušyâr "name of a physician; industrious" kâmyâr "happy, powerful," and baxtyâr "fortunate, rich."

Special stress laid upon, or importance attached to (Dictionary.com).

From L. emphasis, from Gk. emphasis "significance, implied meaning," from emphainein "to show, indicate," from en "in" + phainein "to show." It developed a sense of "extra stress" laid on a word or words to make the significance clear, or to show their importance.

Barâvaž, present stem of barâvažidan, literally "to speak loudly," from bar- "on, upon, up," → over-, + âvaž variant of âvâz "voice, sound, noise, clamour," cf. Sariqoli awuj "voice, sound," Wakhi awôγ "voice, sound," related to vâž, → word.

To give → emphasis to; lay stress upon; stress (Dictionary.com).

→ emphasis + → -ize.

1) Uttered, or to be uttered, with emphasis; strongly expressive.
2) Using emphasis in speech or action (Dictionary.com).

From Gk. emphatikos, variant of emphantikos, from emphainein, → emphasis.

Barâvaži, from barâvaž + -i adj. suffix.

1) A political unit having an extensive territory or comprising a number of territories or nations and ruled by a single supreme authority.
2) The territory included in such a unit (TheFreeDictionary).

M.E., from O.Fr. empire "rule, authority, kingdom," from L. imperium "command, dominion, sovereignty," from → imperare "to command."

Parmâtgân, from parmât, present stem of parmâtidan, → imperare, + -gân suffix denoting relation and place appearinfg in the name of lands and localities (Šâpurgân, Gorgân, Golpâyegân, etc.).

Based on the results of → experiment and → observation only, without → theory.

From L. empiricus, from Gk. empeirikos "experienced," from empeiria "experience," from empeiros "skilled," from en- "in" + peira "experiment."

Ârvini, adj. of ârvin "experience, experiment, test," from prefixed Av. vaēn- (Mod.Pers. bin, present stem of didan "to see, look") "to see," aibī-vaēn- "to look, notice;" cf. Parthian Mid.Pers. frwyn- "to foresee," frwyng "foreseeing," frwyngyft "foresight," from Proto-Iranian *fra-uain.

1) In physics, a mathematical equation that predicts observed results, but has no known theoretical basis to explain why it works.
2) In chemistry, a simple expression of the relative number of each type of atom in a chemical compound.

→ empirical; → formula

A branch of knowledge, including → natural sciences and → social sciences, that is based on observable phenomena and must be capable of being verified by observation.

→ empirical; → science.

1) Philo.: The doctrine that all → knowledge of matters of fact derives from experience and that the mind is not furnished with a set of concepts in advance of experience.
2) The use of empirical methods (Dictionary.com).

From empiric, → empirical, + → -ism.

Containing nothing; having none of the usual or appropriate contents (Dictionary.com).

M.E., from O.E. æmettig "vacant, not occupied," from æmetta "a leisure," from æ "not" + -metta, from motan "to have."

Tohi "empty," → void.

In → graph theory, a graph with any number of → vertices which do not have → edges.

→ empty; → graph.

A set containing no → elements.

→ empty; → set.

A → cosmological model based on → Einstein's field equations in which the → Universe is devoid of → matter and → radiation. There are two types of empty Universes: the → de Sitter Universe and the → Milne Universe.

→ empty; → Universe.

The eighth of → Saturn's known → satellites, discovered by Herschel in 1789. It is about 500 km in diameter and orbits Saturn at a mean distance of 238,000 km with a period of 1.37 days. Enceladus has the highest → albedo (> 0.9) of any body in the → Solar System. Its surface is dominated by clean ice. Geophysical data from the → Cassini-Huygens spacecraft imply the presence of a global → ocean below an ice shell with an average thickness of 20-25 km, thinning to just 1-5 km over the south polar region. There, → jets of → water vapor and icy grains are launched through fissures in the → ice. The composition of the ejected material measured by Cassini includes salts and silica dust. In order to explain these observations, an abnormally high heat power is required, about 100 times more than is expected to be generated by the natural → decay of → radioactive elements in rocks in its core, as well as a means of focusing activity at the south pole. According to simulations, the core is made of unconsolidated, easily deformable, porous rock that water can easily permeate. The → tidal friction from Saturn is thought to be at the origin of the eruptions deforming the icy shell by push-pull motions as the moon follows an elliptical path around the giant planet. But the energy produced by tidal friction in the ice, by itself, would be too weak to counterbalance the heat loss seen from the ocean; the globe would freeze within 30 million years. More than 10 GW of heat can be generated by tidal friction inside the rocky core. Water transport in the tidally heated permeable core results in hot narrow upwellings with temperatures exceeding 90 °C, characterized by powerful (1-5 GW) hotspots at the seafloor, particularly at the south pole. The release of heat in narrow regions favors intense interaction between water and rock, and the transport of hydrothermal products from the core to the plume sources (Choblet et al., 2017, Nature Astronomy, doi:10.1038/s41550-017-0289-8)

In Gk. mythology Enceladus was a Titan who battled Athene in their war against the gods. When he fled the battlefield, Athene crushed him beneath the Sicilian Mount Etna.

Enkelâdos, from the original Gk. pronunciation of the name.

A region of decreased brightness within the A ring of Saturn.

In honor of Johann Franz Encke, → Encke's comet. Gap, from O.N. gap "chasm," related to gapa "to gape."

Gâf, variant kâf "split, slit," stem of kâftan, kâvidan "to split; to dig," Mid./Mod.Pers. škâf- škâftan "to split, burst," Proto-Iranian *kap-, *kaf- "to split;" cf. Gk. skaptein "to dig;" L. scabere "to scratch, scrape," P.Gmc. *skabanan (Goth. skaban; Ger. schaben; E. shave). PIE base *(s)kep- "to cut, to scrape, to hack."

A faint comet with the shortest known period (about 3.30 years). Its semimajor axis is 2.21 AU and aphelion 4.1 AU. it is the parent body of the Taurids meteor shower. The comet was first observed in 1786 by the French astronomer Pierre Méchain.

Named after the German astronomer Johann Franz Encke (1791-1865), who in 1819 computed its orbit and proved that sightings of apparently different comets in 1786, 1795, 1805, and 1818 were in fact appearances of the same comet. → comet.

To convert (data, information) into another format by → encoding. See also → decode and → encrypt.

From en- "in; into" + → code.

Ramzândan, infinitive from ramz, → code. Ramz gozâštan, from ramz + gozâštan "to place, put," → nomenclature.

An electronic device or software program used to convert (a message, information, data) into a specialized digital format for efficient transmission or transfer.

→ encode; → -er.

A process used for transforming data into another format by means of a scheme that is publicly available so that it can easily be reversed. See also → decoding and → encryption.

→ encode; → -ing.

General: A meeting, especially one that is unplanned, unexpected, or brief. An often violent meeting; a clash.
Coming across of two bodies (as two stars in a cluster) which results in the deviation from original directions of motion. → close encounter; → strong encounter; → weak encounter.

From O.Fr. encountrer "confront," from encontre "against, counter to," from L.L. incontra "in front of," from L. in- "in" + contra "against."

Ruyâruyi "being face to face," from ru, ruy "face, countenance," variant rox (Mid.Pers. rôy, rôdh "face," Av. raoδa- "growth," in plural "appearance," from raod- "to grow, sprout, shoot," cf. Skt. róha- "rising, height") + euphonic interfix -â- + ruy + noun suffix -i.