An Etymological Dictionary of Astronomy and Astrophysics
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In molecular quantum mechanics, any of → quantum states corresponding to a particular → electron configuration (i.e. an arrangement of the electron(s) in certain → orbitals). The electron configuration with the lowest energy is called the → ground state. All higher energy states are called → excited states.

→ electronic; → state.

The → transfer of an → electron from one → energy level to another.

→ electronic; → transition.

The science dealing with the development and application of → devices and → systems involving the flow of → electrons in a → vacuum, in → gaseous media, and in → semiconductors (Dictionary.com).

→ electron; → -ics.

The production of stationary electric charges on an uncharged object as a result of a charged body being brought near it without touching it. A positive charge will induce a negative charge, and vice versa.

→ electrostatic; → induction.

The unified description of two of the four fundamental interactions of nature, → electromagnetism and the → weak interaction which would merge into a single force under conditions of extreme temperature (above 10¹⁶ degrees, 10² GeV) prevalent in the early history of the → Universe.

→ electroweak; → interaction.

An equation with surprising simplicity that expresses a fundamental result relating several apparently unassociable elements. For example, → Euler's formula for the particular case of θ = π, and the → mass-energy relation.

→ elegant; → equation.

An important physical process occurring in stars, which is the relative separation of the various → chemical elements. It is caused by → gravitational settling and → thermal diffusion, on the one hand, and → radiative levitation on the other. This process, which was described by Michaud (1970) to account for the abundance anomalies observed in → chemically peculiar  → A star, is now recognized as occuring in all types of stars. Its influence on the observed → chemical abundances is extremely variable, however, due to competing macroscopic motions like → convective  → mixing or rotation-induced → turbulence. In the Sun, no observable abundance anomalies are expected from element diffusion, as the time scale of the process is longer than the solar lifetime. However the small induced → depletion of → helium and → heavy elements by about 20% is detectable through → helioseismology. Such detections are more difficult in stars, as only global → oscillation modes can be detected, in contrast to the Sun, where local oscillations of the surface can be analyzed (Théado et al., 2005, A&A 437, 553).

→ element; → diffusion.

1) The height to which something is elevated or to which it rises.
2) An elevated place, thing, or part; an eminence (Dictionary.com).

Verbal noun of → elevate; → -tion.

1) The act of eliminating; the state of being eliminated.
Math.: The process of solving a system of simultaneous → equations by using various techniques to remove the → variables successively (Dictionary.com).

Verbal noun of → eliminate; → -tion.

That part of → annual aberration proportional to the → eccentricity of the Earth's orbit.

→ elliptic; → aberration.

The → polarization of an → electromagnetic radiation in which the electric vector at any point in the path of the beam describes an ellipse in a plane perpendicular to the propagation direction. Elliptical polarization results from the combination of two perpendicular → linearly polarized waves whose → phase difference is other than 0, 90, or 180°. The form of the ellipse is determined by the amplitudes of the component waves and the phase difference. → Linear polarization and → circular polarization can be considered as limiting cases of elliptical polarization.

→ elliptical; → polarization.

To draw out to greater length; lengthen; extend.

From L.L. elongatus "lengthened out," p.p. of elongare "to make longer, to remove to a distance," from → ex- "out" + longus "long;" PIE base *dlonghos- "long;" cf. Av. darəga-, darəγa- "long," drājištəm "longest;" Mod.Pers. derâz "long," dir "late; long;" Skt. dīrghá- "long (in space and time);" Gk. dolikhos "long;" P.Gmc. *langgaz (Ger. lang; O.N. langr; M.Du. lanc; Goth. laggs "long;" E. long).

DerâzidanDerâzeš "to elongate," from derâz "long," Mid.Pers. drâz "long;" Av. darəga-, darəγa- "long," drājištəm "longest;" PIE *dlonghos- "long," as above.

Made longer; long and narrow.

Past participle of → elongate.

An → elliptical orbit with a high → eccentricity.

→ elongated; → orbit.

1) Increase in length per unit of original length.
2) The angular distance of a planet from the Sun as seen from the Earth. An elongation of 0° is called → conjunction; one of 180° is called → opposition; and an elongation of 90° is called → quadrature.

→ elongate; → -tion.

The brightest star in the constellation → Draco, with a visual magnitude of V = 2.23 and color B - V +1.52. It is a cool (4000 K) → giant star of spectral Type K5 III, lying 148 → light-years. Gamma Draconis has a luminosity 600 times that of the Sun and a diameter 50 times that of the Sun. It crosses the sky near the zenith point for England, a nd this was the reason why James Bradley (1693-1762) observed γ Draconis when he was trying to detect parallax and so calculate the distance. He found that the star undergoes a yearly shift of a form quite different from that expected from parallax. In a 1728 paper, Bradley announced his discovery and explained the effect as due to the → aberration of starlight . Variant names: Etamin, Etanin; Ettanin, other designations: HR 6705, HD 164058.

From Ar. At-Tinnin (التنین) "the great serpent," the Ar. rendition of the Greek constellation → Draco.

An act or instance of emanating; something that emanates or is emanated.

→ emanate; → -tion.

1) In several → lunisolar calendars, an → intercalary month employed to preserve a seasonal relationship between the Lunar and Solar cycles. For example, in the → Hebrew calendar the extra month, called Adar Alef, was inserted after Shvat so that the month of Nissan (month of spring) does not begin in winter.
2) In ancient Iranian → solar calendar the additional whole month of 30 days employed every 120 years to compensate for the left-over quarters of days in a calendar year of 365 days (120 years × 0.25 days = 30 days).

M.E. embolisme, from M.L. embolismus "intercalation," from Gk. emballein "to throw into, to insert," from em- "in" + ballein "to throw" (source of the medical term embolism "the obstruction (of an artery, etc.) by a clot of blood, bubble of air, etc."); → month.

Behizak, from Mid.Pers. vihezagig or vihezakik "movable," from vihezag "movement, progression," from vihez- "to move, progress;" mâh, → month.

Astro.: Same as → egress.

→ emerge.

An act or instance of emigrating; a body of emigrants; emigrants collectively.

Verbal noun of → emigrate.