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

Thermal radiation with a temperature of 2.73 K that is apparently uniformly distributed in the Universe. It is believed to be a redshifted remnant of the hot radiation that was in thermal equilibrium with matter during the first hundred thousand years after the Big Bang. Same as → cosmic microwave background (CMB) radiation.

→ microwave; → background; → radiation.

Electromagnetic radiation carried by → microwaves.

→ microwave; → radiation.

1) The process or act of migrating; a migratory movement.
2) For an astronomical body, the process or act of changing its place over considerably large distances under the effect of certain physical forces. See, for example, → orbital migration; → Type I migration; → Type II migration.
3) Chem.: A movement or change of position of atoms within a molecule (Dictionary.com).

→ migrate; → -tion. Kuc "the act of moving from a dwelling, a place to another, decamping, migration."

A thousand thousand (10⁶).

O.Fr. million, from It. millione, literally "a great thousand," augmentative of mille "thousand," from L. mille.

Milyon, Loan from Fr.

The approximation of a stellar atmosphere with a plane parallel grey atmosphere in radiative equilibrium. It is assumed that a spectral is formed in such a way that the ratio of the line absorption coefficient to the continuous absorption coefficient is constant with depth.

→ Milne Universe; Arthur Stanley Eddington (1882-1944), prominent British astrophysicist; → approximation.

Same as → angle of minimum deviation.

→ minimum; → deviation.

The minimum distance between the paths of two orbiting objects around a → primary. Such distance between an object and Earth is called Earth MOID.

→ minimum; → orbit; → intersection; → distance.

The faintest and the westernmost of the three stars which appear in a row and make up the → Orion's Belt. It is a blue star of magnitude 2.23 lying 915 light-years away. Mintaka is in fact an → eclipsing binary with a period of 5.7 days. The main star has a → spectral type of O9.5 and radiates near 90,000 times the → solar luminosity. Mintaka is remarkable as regards the discovery of the → interstellar medium. The ISM was discovered by the German astronomer Johannes Hartmann (1855-1936) through the study of δ Orionis. He remarked that the calcium line at 3934 Å did not share in the periodic displacements of the lines caused by the orbital motion of the star. This suggested that the calcium line was not from the stars but from an intervening interstellar absorbing cloud.

Mintaka, from al-Mintaqah "the belt," from al-Mintaqah al-Jauzâ' (المنطقه‌الجوزاء) "the belt of the central one (Orion)."

An operation designed to carry out the goals of a specific program, such as a a space flight or voyage.

Mission, from L. missionem (nominative missio) "act of sending," from mittere "to send," of unknown origin.

Gosilân, from gosil, variant gosi "sending away, dismission;" Mid.Pers. wisé "to despatch" (Parthian Mid.Pers. wsys- "to despatch;" Buddhist Mid.Pers. wsydy "to despatch;" Sogdian 'ns'yd- "to exhort"), from Proto-Iranian *vi-sid- "to despatch, send off," from prefix vi- "apart, away, out," + *sid- "to call" + -ân nuance suffix.

1) The act of modernizing; the state of being modernized; something modernized.
2) A pattern of social and economic change initiated in the 17th century in Western Europe and subsequently extended to many other parts of the world. Its characteristics include secularization, rationalization in political and economic life, industrialization, urbanization, and increased level of popular involvement in public affairs.

Verbal noun of → modernize; → -tion.

An act or instance of modifying; the state of being modified; partial alteration.

Verbal noun of → modify.

General: The modification of some property of a phenomenon by another distinct phenomenon.
Physics: Variation of some characteristic (amplitude, phase, or frequency) of a radio wave, called the carrier wave, in accordance with instantaneous values of another wave, called the modulating wave. → amplitude modulation; → frequency modulation.
Optics: A synonym for contrast, particularly when applied to a series of parallel lines and spaces imaged by a lens.

Verbal noun of → modulate.

A measure of the ability of an optical system to reproduce (transfer) various levels of detail from the object to the image, as shown by the degree of contrast (modulation) in the image. → optical transfer function.

→ modulation; → transfer; → function.

Of a gas included in the composition of a → gas mixture, the ratio of the number of moles of this gas to the total number of moles of all the gases in the mixture. Same as mole fraction and mole-fraction concentration.

→ molar; → concentration.

The amount of heat energy required to vaporize 1 mole of a liquid at its → boiling point, usually expressed in kJ/mol.

→ molar; → heat; → vaporization.

A mixing process in a → fluid caused by the → random relative motions due to → Brownian motion of the individual particles. See also → eddy diffusion.

→ molecular; → diffusion.

An → electromagnetic radiation emitted by → interstellar molecules through → transitions between → energy states of → molecules.

→ molecular; → emission.

In → propositional logic, a → sentence containing at least one → connectives. See also → atomic proposition.

→ atomic; → proposition.

The dynamical motion of chemically bound atoms which constantly change their position with each other. The vibration of molecules is treated within → quantum theory. Therefore, the energy of molecular vibration can only take → discrete values. To a first approximation, molecular vibrations can be approximated as → simple harmonic oscillator assigned to each mode.

→ molecular; → vibration.

Any of several theories about how the → Moon originated, among which: → fission theory, → capture theory, → co-formation theory, and → giant impact hypothesis. The model that is best supported by all the available data is the giant impact hypothesis. See also → canonical model.

→ lunar; → formation.