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

That component of general precession caused by the combined effect of the Moon, the Sun and the planets on the equatorial protuberance of the Earth, producing a westward motion of the equinoxes along the ecliptic about 50'' per year. According to an IAU resolution adopted in August 2006, the present terminology replaces lunisolar precession.

→ precession; → equator.

The slow motion of the equinoxes along the ecliptic, resulting from the combined motion of the equator (→ precession of the equator) and the ecliptic (→ precession of the ecliptic), or in other words the precession of the Earth's axis of rotation. Also know as → general precession. The First Point of Aries moves westward along the ecliptic at 50.38 arcseconds per year (1 degree every 71.6 years), causing the equinoxes to occur about twenty minutes earlier each sidereal year. See also → nutation.

→ precession; → equinox.

The gradual change in he orbital planes of a binary system.

→ precession; → node.

The interval with which a rotating body precesses. The precession period of the Earth is 25,770 years. For a → spinning top it is given by: T_p = (4π²I)/(mgrT_s), where I is the → moment of inertia, m the mass of the top, g gravity, r the distance between the center of mass and the contact point, and T_s is the spinning period of the top.

→ precession; → period.

A time interval over which an orbit precesses by 2π radians in its plane.

→ precession; → time.

Of or pertaing to → precession.

→ precession; → -al.

The path of either → celestial poles around the → ecliptic pole due to the → precession of equinox. It takes about 26,000 years for the celestial pole to complete path.

→ precessional; → circle.

1) Meteo.: Any form of water, such as rain, snow, sleet, or hail, that falls to the Earth's surface. The quantity of such water falling in a specific area within a specific period.
2) Chemistry: The process of separating a solid substance from a solution.

From M.Fr. précipitation, from L. præcipitationem "act or fact of falling headlong, haste," from præcipitare "fall, be hasty," from præceps "steep, headlong, headfirst," from præ- "forth" + caput, → head.

1) Bâreš, verbal noun of bâridan "to rain," bârân "rain;" Mid.Pers. vâritan, vârân; Av. vār- "rain; to rain;" cf. Skt. vār- "rain, water; to rain;" PIE base *uer- "water, rain, river."
Rizeš, verbal noun of rixtan "to flow, to pour," → overflow.
2) Tahnešast "to settle down, precipitate," from tah "→ bottom, end;" + nešast past stem of nešastan "to sit down; to settle down; to sink," → sit.

1) The state or quality of being → precise.
2) The degree to which repeated measurements of a quantity give the same results under unchanged conditions. Not the same as → accuracy, but often confused as such. See → accuracy for the difference between precision and accuracy.

Verbal noun from → precise.

1) Act of plundering or robbing; predatory behavior.
2) The preying of one animal on others.

Verbal noun, → prey.

1) Zoology Psychology: The action of grasping or seizing.
2) Philosophy: An interaction of a subject with an event or entity which involves perception but not necessarily cognition (Oxford Dictionary, lexico.com).

Verbal noun of → prehend.

A word used with a noun or pronoun to mark its relation with another word.

From L. praepositionem "a putting before," from praepositus, p.p. of praeponere "put before," from prae "before," → pre-, + ponere "put, set, place," → position.

Pišhel, from piš-, "before," → pre-, + hel-, helidan, heštan "to place, put," → leap.

1) An act of prescribing.
2) A direction, usually written, by the physician to the pharmacist for the preparation and use of a medicine or remedy. The medicine prescribed (Dictionary.com).

Verbal noun of → prescribe; → -tion.

The present number of stars on the → main sequence per unit logarithmic mass interval per square parsec. The PDMF is the basis for deriving the → initial mass function (IMF). This mass function is not corrected for stellar evolution nor losses through stellar deaths.

→ present; → day; → mass; → function.

A physical state of dense matter in which the electrostatic field of one atom should influence a neighboring atom and hence disturb atomic levels. In extreme case, such as white dwarfs, electron clouds practically rub and electrons are ionized off the parent atoms.

→ pressure; → ionization.

In cosmological models, the phenomenon that is supposed to seed the → cosmic microwave background anisotropies and the structure formation of the Universe.

→ primordial; → curvature; → perturbation.

Newton's third law of motion, which states that for every action there must be an equal and opposite reaction.

→ principle; → action; → reaction.

The principle that, for a system whose total mechanical energy is conserved, the path to be taken for the system from one configuration to another is the one whose action has the least value relative to all other possible paths and from the same configurations. Also called Maupertuis' principle, least-action principle.

→ principle; → least; → action.

The third principle of → formal logic introduced in Aristotle's theory of the → syllogism: No statement can be both → true and → false at the same time. Also called → law of non-contradiction.

→ principle; → non-; → contradiction.

The transfer from public to private ownership.

→ private; → -tion.