An Etymological Dictionary of Astronomy and Astrophysics
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An annual → meteor shower that takes place within the boundaries constellation → Capricornus near the star named Alpha. The meteor shower is visible between July 03 and August 15 with the peak occurring on July 30. Alpha Capricornids meteors are bright and often include spectacular colorful → fireballs.

→ alpha; → Capricornus.

A process by which a planet loses its atmospheric gases to space. There are three main types: 1) → thermal escape, 2) → suprathermal escape (or → nonthermal escape), and 3) → impact erosion. According to models, the two mechanisms that can most efficiently cause substantial atmospheric loss are hydrodynamic escape and impact erosion (see, e.g., Catling, D. C. and Kasting, J. F., 2017, Escape of Atmospheres to Space, pp. 129-167. Cambridge University Press).

→ atmospheric; → escape.

1) A covering for the head.
2) The top part of something (such as a hill or mountain). → polar cap.
3) A removable cover or lid.

M.E. cappe; O.E. cæppe "hood, head-covering," from L.L. cappa "a cape, hooded cloak," possibly shortened from capitulare "headdress," from L. caput "head;" cf. Pers. Lori kapu "head," kapulek "skull, middle of the head;" Kurd. Kurmanji qaf "head;" Pashto kaparay "skull;" Farâhâni kapâl "a blow on the head."

Kolâhak, diminutive of kolâh "cap;" maybe related to PIE base *kel- "conceal;" cf. L. celare "to hide, conceal," occulere "to dissimulate;" Gk. kalyptein "to cover," kalia "hut, nest;" Skt. cala "hut, house;" Goth. hilms "helmet," huljan "cover over," hulistr "covering;" E. hull "seed covering," from O.E. hulu, from O.H.G. hulla, hulsa; O.E. hol "cave;"

The ratio of the charge Q on either conductor of a → capacitor to the → potential difference, or → voltage V between the conductors. It is given by C = Q/V. Capacitance can also be described by the relation: C = ε₀A/d, where ε₀ is the → permeability of free space, A is the area of one capacitor plate, and d is the distance between the capacitor plates. Capacitance is measured in → farads or, for convenience, in microfarads.

From capacit(y), → capacity + → -ance, a suffix used to form nouns either from adjectives in -ant or from verbs.

Gonjâyi, from gonjâ "able to hold," from gonjidan→ capacity + -yi noun suffix.

A device for storing electric charge. The simplest sort of capacitors consists of two parallel, conductive plates having equal amounts of opposite charges and separated by a → dielectric material. When a capacitor is fully charged there is a → potential difference between its plates. The larger the area of the plates and/or the smaller the separation between them the greater will be the charge that the capacitor can hold and the greater will be its → capacitance. The actual charge Q on the plates of a capacitor is given by: Q = C . V, where C is the capacitance and V the → voltage.

From capacit-, from → capacity + → -or.

From gonjân transitive stem of gonjidan "to be contained; to hold exactly; to be filled," → capacity, + -gar, → -or.

The ability to receive or contain.
Electricity: → capacitance.

From M.Fr. capacité, from L. capacitatem, from capax "able to hold much," from capere "to take, grasp."

Gonjâyeš "capacity, holding, containing," from gonjdan "to be contained; to hold exactly; to be filled;" Mid.Pers. winj- "to be contained;" Proto-Iranian *uiac-/*uic-; cf. Skt. vyac- "to contain, encompass," vyás- "extent, content, extension;" L. uincire "to bind."

The sixth brightest star in the sky, Capella lies in the Northern Hemisphere → constellation  → Auriga. Also known as HD 34029 = HR 1708 = HIP 24608. Capella lies about 42 → light-years away (13.159 ± 0.015 → parsecs). Its → apparent visual magnitude is V = 0.07. A → spectroscopic binary, it consists of a pair of G8 III and G0 III → giants with an → orbital period of 104 days. The more evolved former/→ primary star has a slightly larger mass and luminosity (2.6 Msun and 79 Lsun) than that of the latter/→ secondary star (2.5 Msun and 73 Lsun). The primary is a typical late G giant presumably in the He-burning stage (→ red clump), which is lithium deficient and a slow rotator as other normal giants. In contrast, the secondary is a fast rotator (projected rotational velocity is v_e sin i ~ 35 km s-1) with high stellar activity (characterized by conspicuous chromospheric emission lines in UV) and shows a remarkably strong Li line, which indicates that the initial Li content is almost retained without being diluted (the surface Li composition for the secondary is ~100 times higher than that for the primary). That is, the secondary star belongs to the unusual group of Li-rich giants (see, e.g., Takeda et al., 2018, ApJ 862, 57 and Torres et al., 2015, ApJ 807, 26).

From L. capella "little she-goat," diminutive of caper "goat."

Bozbân "goat keeper" (Biruni, A.D. 973-1048, in his Tafhim), from boz, → goat, + -bân prefix denoting "keeper."
Ayyuq, loan from Ar.

Same as → capillary action.

→ capillary; → -ity.

1) Resembling a strand of hair; hairlike.
2) Pertaining to or occurring in or as if in a tube of fine bore.
3) Physics: Pertaining to → capillarity.
4) Anatomy: One of the minute blood vessels between the terminations of the arteries and the beginnings of the veins (Dictionary.com).

From L. capillaris "pertaining to hair," from capillus "hair."

Muyin, muyiné, from mu(y), → hair.

The ability of a → liquid to → flow in a → narrow space, such as a thin → tube, without the assistance of, and in opposition to, external forces like → gravity. Also called → capillarity. It occurs because of intermolecular → attractive forces between the liquid and solid surrounding surfaces. If the diameter of the tube is sufficiently small, then the combination of → surface tension (which is caused by → cohesion within the liquid) and → adhesion (between the liquid and the → container) acts to lift the liquid. The capillarity of the liquid is high when adhesion is greater than cohesion. For example, water in a thin glass tube has strong → adhesive forces due to the hydrogen bonds that form between the water molecules and the oxygen atoms in the glass wall (made of → silica, SiO₂). In contrast, mercury is characterized by stronger cohesion, and hence its capillarity is much lower.

→ capillary; → action.

→ Tropic of Capricorn.

→ Capricornus.

The Sea Goat. The smallest → constellation of the → Zodiac, lying in the Southern Hemisphere at approximately R.A. 21h, Dec. -20°. Abbreviation Cap; genitive form Capricorni.

L. Capricornus "horned like a goat," from caper "goat" + cornu "horn" (Gk. karnon, Skt. srnga-, Av. sru-, srvâ-, Mid.Pers. sruw, Mod.Pers. soru, P.Gmc. *khurnaz, Ger. Horn, E. horn, PIE *ker- "head, horn, top, summit"), a translation of Gk. Aigokheros, the name of the constellation.

Vahig, Mid.Pers. "goat," the name of the Capricorn sign in Mid.Pers. texts, Mod.Pers. bahi, as mentioned by Biruni in his Athar al-Baqia written around A.D. 1000.

1) A title or explanation for a picture or illustration, especially in a magazine.
2) A heading or title, as of a chapter, article, or page (Dictionary.com).

M.E. capcio(u)n "taking, seizure," from capcion "arrest, capture, imprisonment," or directly from L. caption-, from capt(us) "taken," → capture.

Kapéš "taking, capture," verbal noun from kapidan "to seize, take, capture," related to qâpidan, qâp zadan "to rob, to seize," Malâyeri qapâl "robbing, seizure, robbing," probably related to L. capere, → capture.

The process in which an atomic, nuclear, or astronomical system acquires an additional particle or body.

From M.Fr. capture "a taking," from L. captura "a taking," from captus p.p. of capere "to take, hold, seize;" PIE base *kap- "to grasp" (cf. Skt. kapati "measure equal to the capacity of the hollows of the two hands joined;" Gk. kaptein "to swallow;" O.Ir. cacht "servant-girl," literally "captive;" Goth. haban "have, hold;" O.E. habban, E. have "to have, hold;" probably Mod.Pers. qâp-, qâpidan, kapidan "to seize, rob").

Gir-oft, composite verb from gir + oft. Gir "take, seize, hold," from gereftan, from O.Pers./Av. grab- "to take, seize," cf. Skt. grah-, grabh- "to seize, take," graha- "seizing, holding, perceiving," M.L.G. grabben "to grab," from P.Gmc. *grab, E. grab "to take or grasp suddenly;" PIE *ghrebh- "to seize." Oft, from oftâtan "to fall; to befal, happen," Mid.Pers. opastan, Av. pat- " to fly, fall, rush," Skt. patati "he flies, falls," L. petere "to fall, rush out," Gk. piptein "to fall," PIE base *pet- "to fly, to rush." Gir-andâzi, from gir + andâzi, verbal noun from gir-andâxtan "to throw, cast; to do, make."

One of the first scientific hypotheses about the formation of the Moon, according to which the Moon formed elsewhere in the solar system and was pulled into a stable orbit by Earth's gravity. Observational facts do not confirm this hypothesis. For example, analysis of rocks from the Apollo landings confirm the Moon is made of similar material and rock as the Earth from about the same time and have almost identical oxygen isotopes in them. Moreover, a captured moon, like Mars' → Phobos and → Deimos do not have a spherical shape. See also → giant impact hypothesis, → fission theory, → co-formation theory.

→ capture; → theory.

A hollow tube that extends out in front of the objective lens (refractors) or corrector lens (Schmidt-Cassegrains). It shields the exposed optics from wide exposure to the cool ambient air, slowing heat loss and preventing dew formation. Reflector telescopes do not need dew caps because the main mirror rests at the bottom of the tube, which acts as a dew shield.

→ dew + cap, from O.E. cæppe "hood, head-covering," from L.L. cappa "a cape, hooded cloak."

Kolâhak, from kolâh "cap," see below, + similarity suffix -ak. Kolâh "cap," cf. L. celare "to hide, conceal," occulere "to dissimulate," Gk. kalyptein "to cover," kalia "hut, nest," Skt. cala "hut, house," Goth. hilms "helmet," huljan "cover over," hulistr "covering," E. hull "seed covering," from O.E. hulu, from O.H.G. hulla, hulsa, O.E. hol "cave;" PIE base *kel- "conceal." Šabnam→ dew.

A process whereby an → unstable atom becomes stable. In this process, an → electron in an atom's inner shell is drawn into the → nucleus where it combines with a → proton, forming a → neutron and a → neutrino. The neutrino escapes from the atom's nucleus. The result is an element change, because the atom loses a proton. For example, an atom of → carbon (with 6 protons) becomes an atom of → boron (with 5 protons). Electron capture is also called K-capture since the captured electron usually comes from the atom's K-shell. See also → neutronization.

→ electron; → capture.

1) To get away; to get free of.
2) An act or instance of escaping.

From M.E. escapen; O.Fr. eschaper, from V.L. *excappare, literally "to get out of one's cape, leave a pursuer with just one's cape," from L. → ex- "out" + L.L. cappa "mantle."

Gorixtan, goriz- "to escape; to flee, run away;" Mid.Pers. virextan; Proto-Iranian *vi-raik, from vi- "apart, asunder" + *raik; Av. raek- "to leave, set free, let off;" Mid./Mod.Pers. reg/rig (in mordé-rig "inheritance"); Skt. ric- "to leave," rinakti "gives up, evacuates;" Gk. leipein "to leave;" L. linquere "to leave;" from PIE *linkw-, from *leikw- "to leave behind" (cf. Goth. leihvan; O.E. lænan "to lend;" O.H.G. lihan "to borrow;" O.N. lan "loan").

The speed an object must attain in order to free itself from the gravitational influence of an astronomical body. It is the minimum velocity for the object to enter a parabolic trajectory. The escape velocity is given by: V_e = (2GM/r)^1/2, where G is the → gravitational constant, M is the mass of the astronomical body, and r is its radius. The escape velocity of the Earth is about 11.2 km s^-1 that of the Moon is 2.4 km s^-1. The escape velocity from the Sun is about 618 km s^-1, and the solar escape velocity from Earth's orbit is about 42.1 km s^-1.

→ escape; → velocity.

The ratio of an amount of heat, dQ, transferred to a body in some process to the corresponding change in the temperature of the body: C = dQ/dT. The heat capacity depends upon the mass of the body, its chemical composition, thermodynamic state, and the kind of process employed to transfer the heat. The word "capacity" may be misleading because it suggests the essentially meaningless statement "the amount of heat a body can hold," whereas what is meant is the heat added per unit temperature rise. → specific heat.

→ heat; → capacity.