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

Same as → Gibbs free energy.

Named after Josiah Willard Gibbs (1839-1903), an American physicist who played an important part in the foundation of analytical thermodynamics; → function.

A prefix that is used to represent 10⁹ in the SI system.

From Gk. gigas, → giant.

A unit of → frequency, equal to 10⁶ Hz.

→ giga-; → hertz.

1) A support component of a gyroscope, which allows the axis to move freely.
2) A mechanical mounting frame having two mutually perpendicular axes of rotation.

Gimbal, alteration of gemel "twin," from M.E., gemelles, from O.Fr. gemeles (Fr. jumeau, jumelle), from L. gemellus, diminutive of geminus "twin;" cf. Pers. Kermâni dialect jomoli "twin;" → Gemini.

Doqâb, from do "two" (Mid.Pers. do; Av. dva-; cf. Skt. dvi-; Gk. duo; L. duo; O.E. twa; Ger. zwei) + qâb "frame," from Turkish.

The prototype of → T dwarfs discovered by Nakajima et al. (1995, Nature 378, 463). This → brown dwarf lies 21.8 → light-years away and orbits a primary star of type M1 V every about 40 years. It has a temperature of less than 1,200 K, and a mass approximately 20-50 times that of Jupiter. Its luminosity is about 2 x 10 ^-6 that of the Sun.

Gl, referring to the → Gliese catalogue.

An extended mass of ice formed from snow falling and accumulating over the years and moving very slowly, either descending from high mountains, as in valley glaciers, or moving outward from centers of accumulation, as in continental glaciers (Dictionary.com).

From Fr. glacier, from O.Fr. glace "ice," from V.L. glacia, from L. glacies "ice," probably from PIE root *gel-, → cold.

Yaxzâr, from yax, → ice, + -zâr suffix denoting profusion and abundance, as in šurezâr "infertile, salty ground; nitrous earth," xoškzâr "arid land," kârzâr "a field of battle; combat," marqzâr "a place abounding with the grass," and so forth.

The breaking off of chunks of ice at the terminus, or end, of a glacier. Ice breaks because the forward motion of a glacier makes the terminus unstable. Ice or glacier calving is the formal name for the birth of an → iceberg.

→ glacier; → calve.

1) A very harsh, bright, dazzling light.
2) A type of → light pollution which is a blinding light within the field of vision. It compromises security and safety.

M.E. glaren; cognate with M.Du., M.L.G. glaren; akin to glass.

Xirtâv, literally "dazzling light," from xir, from xiré konandé, "dazzling," from xiré "much, many; obstinate; perverse; unwilling;" + tâv, variant tâb, tâbidan "to shine," → luminous.

A noncrystalline, inorganic mixture of various metallic oxides fused by heating with glassifiers such as silica, or boric or phosphoric oxides.

From O.E. glæs, from W.Gmc. *glasam (M.Du. glas, Ger. Glas), from PIE base *gel-/*ghel- "to shine, glitter."

Šišé "glass;" Mid.Pers. šišag.

A mass of glass ready to be shaped into a telescope mirror. Same as → glass disk.

→ glass; blank, from O.Fr. blanc "white, shining," from Frank. *blank "white, gleaming," of W.Gmc. origin (cf. O.E. blanca "white horse"), from P.Gmc. *blangkaz, from PIE *bhleg- "to shine."

Gerdé, → disk; šišé→ glass.

Same as glass blank.

→ glass; → disk.

A filter used in → broad-band photometry. The → bandwidth ranges usually between 30 and 100 nm.

→ glass; → filter.

A coating of ice, generally clear and smooth, formed on exposed objects by the freezing of a film of supercooled water deposited by rain, drizzle, fog, or possibly condensed from supercooled water vapor. Also called glaze ice, verglas, and (especially British) glazed frost.

Glaze, from → glass.

Hasar "ice," probably related to Av. isu- "icy, chilly," aexa- "ice, frost," Mod.Pers. yax "ice;" cf. O.E. is "ice," from P.Gmc. *isa-; Du. ijs, Ger. Eis, E. ice.

A compilation of all known stars within the solar neighborhood with accurately known distances. The first version, Catalogue of Nearby Stars, published in 1957, contained nearly 1000 stars located within 20 pc of Earth, listing their known properties. Gliese published an updated version in 1969, extending the range out to 22 pc. He published the second edition of the catalog in 1979 in collaboration with Hartmut Jahreiss. The combined catalog is now commonly referred to as the Gliese-Jahreiss catalog.

Wilhelm Gliese (1915-1993), a German astronomer who worked at the Heidelberg observatory; → catalog.

A defect or malfunction in a machine or plan.
A brief or sudden interruption or surge in voltage in an electric circuit.
A sudden change in the rotation period of a pulsar.

Glitch, from Yiddish glitsh "slippery area;" cf. glitshn, Ger. glitschen "to slip, slide."

Geles, from Lori gelese "to fall down, to slide."

Pertaining to the whole → world; worldwide; → universal.

→ globe; → -al.

→ universal.

A coordinate positioning tool, using a combination of satellites that can rapidly and accurately determine the → latitude, → longitude, and the → altitude of a point on or above the Earth's surface. The GPS is based on a constellation of 24 Earth-orbiting satellites at an altitude of about 26,000 km. The system is a direct application of the thories of → special relativity and → general relativity.

→ global; → positioning; → system.

An increase in the average → temperature of the Earth's → atmosphere that brings about climatic changes.

→ global; → warming.

A spherical body; sphere.
The planet Earth (usually preceded by the). A sphere on which is depicted a map of the Earth (terrestrial globe) or of the heavens (celestial globe).

M.E. globe, from M.Fr. globe, from L. globus "round body, ball, sphere," cognate with Pers. guy, see below.

Guy "ball, sphere," variants golulé, gullé, goruk, gulu, gudé; cf. Skt. guda- "ball, mouthful, lump, tumour," Pali gula- "ball," Gk. gloutos "rump," L. glomus "ball," globus "globe," Ger. Kugel, E. clot; PIE *gel- "to make into a ball."

A spherical aggregate of stars made up of thousands to a few million stars which is an orbiting satellite of a galaxy. There are over 150 globular clusters orbiting our galaxy. Globular clusters are gravitationally → bound systems, highly concentrated to the center (up to a few 10³ stars per cubic → light-years), with a volume ranging from a few dozen up to more than 300 light-years in diameter. They are generally old and → metal-poor and are among the first objects to be formed in a galaxy. There is also strong evidence that they form in major galaxy interactions and → mergers. The stars in a globular cluster are thought to have a common origin and thus a single age and → chemical abundance; with some exceptions such as → Omega Centauri and NGC 2808, which exhibit multiple populations. The presence of various sub-populations within a globular cluster is interpreted as indicating distinct epochs of mass → accretion and/or major → star formation. The Milky Way hosts about 200 globular clusters. They are spherically distributed about the → Galactic Center up to a radius of 350 light-years, with a maximum concentration toward the Galactic center. All but the smallest → dwarf galaxies possess globular clusters. Some galaxies, e.g. M87, contain several thousands of them. There are, however, important differences. While all the globular clusters in our Galaxy and in → M31 are old (ages of about 10 billion years, at least), there are galaxies, such as the two → Magellanic Clouds and → M33, that host much younger globular clusters (ages of a few billion years, or less).

Globular, from → globule + -ar, variant of → -al; → cluster.

Xušé, → cluster; guysân "shaped like a globe," from guy, → globe + -sân "manner, semblance" (variant sun, Mid.Pers. sân "manner, kind," Sogdian šôné "career").