An Etymological Dictionary of Astronomy and Astrophysics
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The use of → Newtonian mechanics to derive homogeneous and isotropic solutions of → Einstein's field equations, which represent models of expanding Universe. The Newtonian cosmology deviates from the prediction of → general relativity in the general case of anisotropic and inhomogeneous models.

→ Newtonian; → cosmology.

Any → fluid with a constant → viscosity at a given temperature regardless of the rate of → shear.

→ Newtonian; → fluid.

The focus obtained by diverting the converging light beam of a reflecting telescope to the side of the tube.

→ Newtonian; → focus.

The limit attained by → general relativity when velocities are very smaller than the → speed of light or gravitational fields are weak. This limit corresponds to the transition between general relativity and the → Newtonian mechanics. See also → Newtonian approximation.

→ Newtonian; → limit.

A system of mechanics based on → Newton's law of gravitation and its derivatives. Same as → classical mechanics.

→ Newtonian; → mechanics.

A potential in a field of force obeying the inverse-square law such as → gravitational potential.

→ Newtonian; → potential.

The Newton's equations of motion, if they hold in any → reference frame, they are valid also in any other reference frame moving with uniform velocity relative to the first.

→ Newtonian; → principle; → relativity.

The laws of physics are unchanged under → Galilean transformation. This implies that no mechanical experiment can detect any intrinsic diff between two → inertial frames. Same as → Galilean relativity.

→ Newton; → relativity.

A telescope with a concave paraboloidal objective mirror and a small plane mirror that reflects rays from the primary mirror laterally outside the tube where the image is viewed with an eyepiece.

→ Newtonian; → telescope.

For a ring inclined to the planet's equator, the points at which the ring crosses the equator (nodes) slowly move around the planet (regress) in a direction opposite to that of the ring's orbital motion. (Ellis et al., 2007, Planetary Ring Systems, Springer).

→ nodal; → regression.

The time interval between two successive passages of the Moon through its ascending node (27.212220 days, i.e., 27 days 5 hours 5 minutes 35.8 seconds). Nodical month is important for predicting eclipses. Also called → draconic month.

Nodical adj. of → node; → month.

Mâh, → month; gerehi, adj. of gereh, → node; gowzahri→ draconic month.

An act or instance of nominating, especially to office. The state of being nominated (Dictionary.com).

Verbal noun of → nominate.

A prefix meaning "not."

From O.Fr. non-, from L. non "not," from Old L. noenum "not one;" in some cases perhaps from M.E. non "not" (adj.), from O.E. nan.

Nâ- "no, not," variants na, ni, ma- (prohibitive) "not;" from Mid.Pers. nê, ma "no, not;" O.Pers. naiy, nai "not;" Av. nôit, naē "not;" cf. Skt. ná "not;" cf. L. ne-, in-, un-; Gk. ni; Lith. nè; O.C.S. ne "not;" PIE *ne-.

A → transcendental function. Examples are: exponential, logarithmic, and trigonometric functions.

→ non-; → algebraic + → function.

→ Dark matter composed of → non-baryonic particles.

→ non-; → baryonic; → dark; → matter.

Matter that, unlike the ordinary matter, is not made of baryons (including the neutrons and protons). It is proposed as a possible constituent of dark matter.

→ non-; → baryonic matter.

Radiation having waves that are out of phase in space and/or time; radiation which is not → coherent.

→ non-; → coherent; → radiation.

Describing a → proposition that is either → true in every possible circumstance or → false in every possible circumstance. A proposition that is not → contingent.

→ non-; → contingent.

A medium in which the → phase velocity is independent of frequency.

→ non-; → dispersive; → medium.

Any of several geometries which do not follow the postulates and results of Euclidean geometry. For example, in a non-Euclidean geometry through a point several lines can be drawn parallel to another line. Or, the sum of the interior angles of a triangle differs from 180 degrees. According to Einstein's general relativity theory, gravity distorts space into a non-Euclidean geometry.

→ non-; → Euclidean geometry.