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

A first-order improvement on the → ideal gas law that corrects for the finite volume of molecules.

After Rudolf Clausius (1822-1888), a German physicist and mathematician, → equation.

If heat flows by conduction from body A to another body B, then a transformation whose only final result is to transfer heat from B to A is impossible. Clausius's postulate is a formulation of the → second law of thermodynamics. It is also equivalent to → Kelvin's postulate.

→ Clausius equation; → postulate.

An approximation of the → Clapeyron equation for liquid-vapor equilibrium that incorporates the → ideal gas law and states that the logarithm of vapor pressure is inversely proportional to temperature.

→ Clausius equation; → Clapeyron equation.

A broad class of hydrous → silicate minerals that has the tetrahedral silicate groups linked in sheets. Clay commonly forms as a product of rock weathering. Deposits of phyllosilicates, such as chamosite and nontronite, recently identified on Mars are attributed to the action of liquid water in the past history of this planet.

O.E. clæg "stiff, sticky earth; clay," from PIE base *glei- "to stick together;" cf. Gk. gloios "sticky substance," L. glus, gluten "glue," O.Slav. glina "clay." The Pers. gel "clay, mud," Mid.Pers. gil "clay" may belong to this family.

Ros, variant rost "clay," of unknown origin.

1) Free from darkness, obscurity, or cloudiness.
2) Transparent; pellucid.
3) Without discoloration, defect, or blemish (Dictionary.com). → clear night.

M.E. clere, from O.Fr. cler, from L. clarus "clear, bright, distinct."

Runé, from Kurd. (Sorani) rûn "bright, clear," rûn kirdin "to explain," variant of rowšan, → bright.

A night sky without clouds, mist, or haze, atmospheric dust particles, and without city lights in which a sixth magnitude star is visible by naked-eye.

→ clear; → night.

An ancient device for measuring time by marking the regulated flow of water through a small opening. A water clock.

L., from Gk. klepsudra, from kleptein "to steal" + hudor "water," PIE *wed- "water."

Pangân or pang was a clepsydra in Iran. It consisted of "a copper bason with a small hole in the bottom, for water in which it is placed to flow through, used for measuring time;" etymology unknown.

A very high steep rock or ice face, especially one that runs along a coastline. → scarp.

M.E., O.E. clif (cf. O.S. clif, O.N. klif, O.H.G. klep, M.Du. klippe, Ger. Klippe "cliff, steep rock").

Tondân, from tond "swift, rapid, brisk," → scarp + -ân a suffix of nuance/relation.

The characteristic meteorological conditions (temperature, precipitation, and wind) and their extremes, of any place or region. In other words, weather patterns averaged over a given period of time to obtain a consistent pattern of the expected atmospheric conditions.

M.E. climat, from M.Fr. climat, from L. clima, climat- "region, slope of the Earth," from Gk. klima "region, zone," from base of klinein "to slope," thus "slope of the Earth from equator to pole," from PIE base *klei- "to lean," → inclination.

Kelimâ, loan from Fr., as above.
Âbohavâ, from âb, → water, + -o- "and" + havâ "weather" → air.

The scientific study of climates. More specifically, the analysis of weather condition trends over a relatively long period of time (past, present or future). Climatology is distinct from meteorology, which is associated with short-term weather system studies.

→ climate; → -logy.

A device (not carried or worn) for measuring and showing the time. See also: → hour, → gnomon, → clepsydra.

M.E. clokke "clock with bells," from O.Fr. cloque "bell" (Fr. cloche, Du. klok, Ger. Glocke), M.L. clocca "bell," of Celtic origin.

Sâat from Ar.

Successive risings and lowerings of voltage on the electrodes of a CCD in order to move the electrons from one pixel to the next.

In the same direction as the rotating hands of a clock when viewed from in front.

From → clock + wise "way, manner," O.E. wise (adj.), from wis, from P.Gmc. *wisaz (cf. Du. wijs, Ger. weise "wise"), PIE base *weid-/*wid- "to see, to know;" cf. Av vaeda "I know," Skt. veda "I know," Gk. oida "I know".

Sâ'atsu, from sâ'at, → clock, + su "direction," Mid.Pers. sôg, sôk "side, direction".

A shoe made of wood.

M.E., of unknown origin.

Katelé, from (Tabari, Gilaki) katelé "wooden shoe," from katel "tree log, tree stump."

Having little or no space between elements or parts, as in → close binary, → close approach; tight and compact.

M.E. clos, closed, from O.Fr., from L. clausus, p.p. of claudere "to close."

Kip "close, tight" in spoken Pers.

In astronomy a general term to describe the positions of two or more objects that come unusually near one to another. In particular, regarding an asteroid's position with respect to Earth, when it is within the Moon's orbit.

→ close; → approach.

A binary system in which the separation of the component stars is comparable to their diameters, so that they influence each other's evolution most commonly by the tidal forces.

→ close; → binary; → star.

A → binary system in which the distance separating the stars is comparable to their size. Most close binaries are spectroscopic binaries (→ spectroscopic binary) and/or eclipsing binaries (→ eclipsing binary). In most of them → mass transfer occurs at some stage, an event which profoundly affects the → stellar evolution of the components. The evolution of close binaries depends on the → initial masses of the two stars and their → separation. When the more massive star evolves into a → red giant first, material will spill through the inner point onto its companion, thereby affecting its companion's evolution. Mass transfer can also alter the separation and → orbital period of the binary star.

→ close; → binary; → system.

1) In a → star cluster, coming across of two stars so closely that their → orbits alter by their mutual → gravitational attractions.
2) As regards an → asteroid or → comet, a situation when it crosses the Moon's orbit and approaches the Earth with a risk of collision. See also → close approach, → encounter.

→ close; → encounter.

Having boundaries; limited. → closed curve; → closed Universe.

Closed, p.p. of close, from M.E. clos, from O.Fr., from clore "to shut," from L. clausus, p.p. of claudere "to close."

Basté p.p.of bastan, from Mid.Pers. bastan/vastan "to bind, shut," Av./O.Pers. band- "to bind, fetter," banda- "band, tie," Skt. bandh- "to bind, tie, fasten," PIE *bhendh- "to bind," cf. Ger. binden, E. bind, → band.