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

The act or an instance of considering.

→ consider; → -tion.

The maximum amount of the apparent yearly displacement of a star, resulting from the → aberration of starlight. The value of the constant of aberration, κ, at J2000.0 is 20".49552. κ = (v/c) csc 1", where v is the average speed of the Earth about the Sun and c is the → speed of light in vacuum. The Earth's speed is given by: v = 2πa / [P(1 - e²)^1/2], where a is the → semi-major axis of the Earth's orbit, e is the → eccentricity of the Earth's orbit, and P is the → sidereal period of the Earth. Same as → constant of annual aberration. See also → constant of diurnal aberration.

→ constant; → aberration.

Same as → constant of aberration.

→ constant; → annual; → aberration.

The quantity 0''.3200 ρ cos φ', where ρ is the geocentric distance of the observer measured in units of → equatorial radius the Earth and φ' is the observer's → geocentric latitude. The numerical part is equal to 2πa csc1'' / (cP), where a is the equatorial radius of the Earth, P is its → sidereal period of rotation, and c is the → speed of light in vacuum.

→ constant; → diurnal; → aberration.

→ gravitational constant.

1) Classical mechanics: A variable X whose total rate of change dX/dt along the path of a → dynamical system is zero. In other words, a function of an object's position, velocity, or both that does not change even as the object moves. For example, the total energy of a → simple harmonic oscillator is a constant of the motion.
2) Quantum mechanics: An → observable that remains constant in time. As an example, the energy is a constant of the motion of all systems whose → Hamiltonian does not depend explicitly upon time.

→ constant; → motion.

A grouping of conspicuous stars that, when seen from Earth, form an apparent pattern. The sky is divided into 88 constellations. → asterism.

From O.Fr. constellation, from L.L. constellationem (nom. constellatus) "set with stars," from L. → com- "with" + p.p. of stellare "to shine," from stella, → star.

Hamaxtarân, from ham- "with, together" + axtar→ star + -ân suffix denoting group.

1) The act or process of composing, setting up, or establishing.
2) The system of fundamental laws and principles that prescribes the nature, functions, and limits of a government or another institution (TheFreeDictionary.com).

Verbal noun of → constitution.

1) Of or relating to a constitution.
2) Consistent with, sanctioned by, or permissible according to a constitution (TheFreeDictionary.com).

→ constitution; → -al.

The act or procedure of consulting.

Verbal noun from → consult.

1) The act of consuming.
2) The amount consumed.

Verbal noun of → consume.

The act of contemplating; thoughtful observation.

Verbal noun of → contemplate.

The act or state of continuing; the state of being continued.

Verbal noun of → continue + → -tion.

In mathematics, a fraction whose numerator is an integer and whose denominator is an integer plus a fraction whose numerator is an integer and whose denominator is an integer plus a fraction and so on.

→ continued; → fraction.

The function y = f(x) is called continuous at the point x = x₀ if it is defined in some neighborhood of the point x₀ and if lim Δy = 0 when Δx → 0.

→ continuous; → function.

A continuous radiation produced by three processes: radiative recombination due to transition between electron free-free states, two-photon decays of metastable levels, and thermal bremsstrahlung.

→ continuum; → emission.

An act or instance of contracting; the quality or state of being contracted.
→ gravitational contraction, → Kelvin-Helmholtz contraction, → length contraction, → Lorentz contraction.

Verbal noun of → contract.

1) The act of contradicting; assertion of the contrary or opposite.
2) Logic: A statement that is false under all circumstances.

M.E., from O.Fr. contradiction or directly from L. contradictionem "objection, counterargument," from contradicere, from contra dicere "to speak against," from → contra- "against" + dicere "to speak," akin to Pers. dis, → form.

Pâdguyi, literally "speaking against," from pâd, → counter-, + guyi, from goftan, → logic.

1) The act of contributing.
2) Something contributed.

Verbal noun of → contribute.

In general, mass motions within a → fluid resulting in transport and mixing of the properties of that fluid when the temperature gradient exceeds some critical value. Convection, along with → conduction and → radiation, is a principal means of → energy transfer. → Schwarzschild's criterion.

From L. convectionem "the act of carrying," from p.p. stem of convehere "to carry together," from → com- "together" + vehere "to carry," cf. Skt. vah- "to carry, lead," vahitra "vehicle," Av. vazaiti "to lead," Mid.Pers. waz-, wazidan "to carry away," Gk. oxos "chariot;" PIE base *wegh- "to go, carry, drive"

Hambaz, from ham- "together" + baz "to carry, move," → evection.
Hambord, from ham- "together," → com- + bord, from bordan "to carry," Mid.Pers. burdan, O.Pers./Av. bar- "to bear, carry," barəθre "to bear (infinitive)," Skt. bharati "he carries," Gk. pherein, L. fero "to carry," PIE base *bher- "to carry."