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

Diverge or deviate from the straight path; produce → aberration.

Aberrate, from aberrare "go astray," from ab- "away" + errare "to wander."

Birâhidan, from birâh "a devious path; a wanderer, who deviates, errs," from bi- "without" + râh "way".

(v.tr.) To increase the velocity of a body; to cause to undergo acceleration.
(v.intr.) To increase in speed.

Verbal form of → acceleration.

The motion of an object subject to → acceleration. Opposite to → uniform motion.

Accelerated, from → accelerate; → motion.

Jonbeš, → motion; šetâbdâr "accelerated," from šetâb→ accelerate + dâr "having, possessor" (from dâštan "to have, to possess," Mid.Pers. dâštan, O.Pers./Av. root dar- "to hold, keep back, maitain, keep in mind;" cf. Skt. dhr-, dharma- "law;" Gk. thronos "elevated seat, throne;" L. firmus "firm, stable;" Lith. daryti "to make;" PIE *dher- "to hold, support").

The amount of mass → accreted during unit time. The accretion rate for the → collapse of a singular → isothermal sphere is expressed by: dM/dt = 0.975 c_s³/G, where c_s is the isothermal → sound speed (Shu 1977, ApJ 214, 488). This relation can be written as: dM/dt = 4.36 x 10^-6 (T / 20 K)^3/2 in units of solar masses per year, where T is the temperature. Observed temperatures of 10-20 K in regions of → low-mass star formation imply accretion rates of about 10^-6 to 10^-5 solar masses per year. Accretion rates for → massive stars amount to values of 10^-4 to 10^-3 solar masses per year.

→ accretion; → rate.

1) Conforming exactly to truth or to a standard; free from error.
2) Designating → accuracy.

Accurate, from L. accuratus, → accuracy.

An expression specifying the number of meaningful digits to the right of the → decimal point. For example, e = 2.71828 ... = 2.718 is said to be accurate to three decimal places and 2.72 to two decimal places.

→ accurate; → decimal; → place.

An expression specifying the number of meaningful digits used to express the value of a measured quantity. Same as accurate to n significant figures. For example, e = 2.71828 ... = 2.718 is rounded to four significant digits, and 2.72 to three significant digits. → accurate to n decimal places.

→ accurate; → significant; → digit.

1) (v.) To collect or gather into a cluster or mass.
2) (adj.) Gathered together into a cluster or mass.
3a) (n.) A mass of things clustered together.
3b) A rock composed of rounded or angular volcanic fragments (Dictionary.com).

From L. agglomeratus, p.p. of agglomerare "to wind or add onto a ball," from → ad- "to" + glomerare to "wind up in a ball," from glomus (genitive glomeris) "ball of yarn," globus "globe;" PIE *gel- "to make into a ball."

Bargolemidan, from suffix bar- "to, on, upon," + golem, from Lori, Laki golemâ, golama "curd, obtained from milk by coagulation, used to make cheese," Lori golem "stagnating water," Sangesari, Semnâni, Sorxe-yi, Lâsgardi golma, "boll, i.e. the rounded seed capsule of plants such as cotton," + -idan infinitive suffix.

Verbal form of → astration.

→ astration.

Same as → Meteor Crater.

Names after Daniel Barringer (1860-1929), American geologist, who bought the Crater in 1903, convinced that it was made by a huge → meteorite; → crater.

To adjust or determine, by comparison with a standard, the response magnitude of a measuring instrument as a function of the input signal. For example, to determine line wavelengths in the spectrum of an astronomical object, or to graduate a hygrometer.

From M.Fr. calibre, via Sp. or It., from Ar. qalib "a mold, last," perhaps from Gk. kalopodion "a shoemaker's last," from kalon "wood" + podos gen. of pous "foot."

Kabizidan, verbal form of kabiz (varianats kaviz, kaviž, kafiz) "a measure for grain, a bushel," from Mid.Pers. kabiz "a grain measure," loaned in Arm. kapic "a grain measure," and in Gk. kapithe, as attested in Xenophon.

A molecular compound made from just three → chemical elements: → carbon, → hydrogen, and → oxygen. Carbohydrates have the general molecular formula C_xH_2yO_y, and thus were once thought to represent "hydrated carbon." However, the arrangement of atoms in carbohydrates has little to do with → water molecules. Carbohydrates are a source of energy for the body. They include sugars, starches, cellulose and many other compounds found in living organisms. In their basic form, carbohydrates are simple sugars or monosaccharides.

→ carbo-; → hydrate.

A crater about 200 km in diameter on the northern coast of the Yucatan Peninsula, near the town of Chicxulub, Mexico. It is attributed to a 10 km wide → asteroid that hit the Earth about 65 million years ago (→ Chicxulub impactor). Ten years before the 1990 discovery of the Chicxulub crater, physicist Luis Alvarez and geologist Walter Alvarez proposed a theory to explain the formation of the crater. They noted increased concentrations of the element → iridium in 65-million-year-old clay. Iridium is rare on Earth, but it's more common in some objects from space, like → meteors and asteroids. According to the Alvarez theory, a massive asteroid had hit the Earth, blanketing the world in iridium. The collision caused fires, climate change and widespread extinctions, among which that of dinosaurs, who had lived for 180 million years.

Named after a twon in the Mexican state of Yucatan, which lies near the geographic center of the → crater.

1) A negative ion, ClO₃^- derived from chloric acid.
2) Any salt of chloric acid.

From chlor-, → chlorine, + → -ate.

A chemical substance in which a molecule of one compound fills a cavity within the crystal lattice of another compound. An example is clathrate hydrate, a special type of gas hydrate in which small molecules (typically gases) are trapped inside "cages" of hydrogen bonded water molecules. Large amounts of methane have been discovered both in permafrost formations and under the ocean floor. Similarly oceans contain large quantities of trapped CO₂, which dissociate when the temperature rises sufficiently.

From L. clathratus, p.p. of clathrarer "to fit with bars," from clathra "bars, lattice," from Gk. kleithron " bar," from kleiein "to close."

A parameter used in star formation models representing the ratio of the total mass in → star clusters to the corresponding age range (Bastian, 2008, MNRAS 390, 759, arxiv/0807.4687).

→ cluster; → formation; → rate.

(adj.) Of the same size, extent, or duration as another; proportionate.

L.L. commensuratus, from → com- "together, with" + mensuratus, p.p. of mensurare "to measure," from menusra "measure."

Hammasâ, from ham- "together," → com- + masâ "size, greatness," from Mid.Pers. masây, masâk "size," Av. masah- "size, greatness, length," maz-, masan-, mazant- "great, important," mazan- "greatness, majesty," mazišta- "greatest," cf. Skt. mah-, mahant-, Gk. megas, L. magnus; PIE *meg- "great."

Of two bodies orbiting around a common barycenter, when the orbital period of one is an exact fraction, for example one-half or two-thirds, of the other.

→ commensurate; → orbit.

1) To bring or draw to a common center or point of union.
2) Of a solution, to make denser, stronger, or purer, esp. by the removal or reduction of liquid.

Verb with p.p. → concentrated.

1) Gathered together closely.
2) Made denser, purer.

Past participle of → concentrate.

1) Past participle of hammarkazidan, → concentrate.
2) Dabz "dense, thick, concentrated, coarse," variants dafzak and gabz; Av. bəzuuant- "thick, dense," bazah- "thickness, denseness;" Baluchi baz "thick, coarse;" Zazaki vezdin "oily, greasy" Ossetic bæzgin "thick, dense;" cf. Skt. bamh "to thicken, become dense;" Gk. pakhos "thickness, density;" PIE base b^heng^h- "to become/make dense, thick" (see Cheung 2007).