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

The largest → asteroid and the second to be discovered, by Heinrich Olbers in 1802. Before the reclassification of → Ceres, Pallas was the second largest asteroid. Pallas is slightly irregular in shape with dimensions 570 x 525 x 482 km. It appears to have the same composition as → meteorites classed as low-grade → carbonaceous chondrites. Its → rotation period is 9 to 12 hours, and its → semi-major axis 2.773 → astronomical unints.

In Gk. mythology, Pallas was one of the Titans. The winged husband of Styx, he is the father of Nike and maybe Eos. Some legends claim that he is the father of Athena, possibly because of her nickname Pallas-Athena.

The whole quantity or amount.

M.E. al, plural alle; O.E. eall "all, every, entire;" cf. O.Fris., O.H.G. al, O.N. allr, Goth. alls.

Hamé- "all," variant hami "all the time, always;" Mid.Pers. hamâg "all," hamê "all the time, always;" Av. hama- "any;" cf. Skt. sama-"any, every, whichever;" Gk. amo-then "whichever;" Goth. sums "any;" O.N. sumr "any;" O.E. sum "some;" E. some.

A → survey that collects data on the whole sky. For example the infrared → Two Micron All Sky Survey (2MASS) and the X-ray → ROSAT All-Sky Survey.

→ all; → sky; → survey.

A "Large Number of Small Dishes" (LNSD) array designed to be sensitive for → commensal surveys of conventional → radio astronomy projects and → SETI targets at centimeter wavelengths. The ATA will consist of 350 6m-diameter → dishes when completed, which will provide an outstanding survey speed and sensitivity. In addition, the many → antennas and → baseline pairs provide a rich → sampling of the → interferometer  → uv plane, so that a single pointing snapshot of the array of 350 antennas yields an image in a single field with about 15,000 independent → pixels. Other important features of the ATA include continuous frequency coverage over 0.5 GHz to 10 GHz and four simultaneously available 600-MHz bands at the → back-end which can be tuned to different frequencies in the overall band. The ATA is a joint project of the Radio Astronomy Laboratory of the University of California, Berkeley, and the SETI Institute in Mountain View, CA. The ATA is now complete to 42 antennas. Highlights of the system are the frequency agility, the low background and → side lobes of the antennas, the wideband feed and input receiver, the analog fiber optical system, the large spatial dynamic range, the back-end processing systems and the overall low cost (see, e.g., Backer et al., 2009, arXiv:0908.1175.pdf).

Named after Paul G. Allen (1953-2018), an American business magnate, computer programmer, researcher, investor, and philanthropist. A donation of $11.5 million by his foundation in 2004 contributed to the development of the project.

1) The act of allying or state of being allied; the result of this action.
2) A union to advance the common interests of the members.

M.E., from O.Fr. aliance, from al(ier) "to ally," → alloy, + → -ance.

Hamdasti, literally "joining hand," from ham-, → com-, + dast, → hand, + -i noun suffix.

1) General: To assign or allot for a particular purpose.
2) Computers: To assign an amount of resource (disk, memory, CPU time, etc.) to a defined user.

From M.L. allocate imperative plural of allocare "allocate," from → ad- "to" + locare "to place," from locus "a place."

Teskidan, from tesk "portion, share, part, lot; a tax upon lands, tribute extracted," variants tešk, toxs (kardan) "distribute, divide;" loaned in Ar. tisq, tasq; tasu "a weight of four barley corns; the twenty-forth part of a weight;" Mid.Pers. tasû "the fourth part," loaned in Ar. tassûj, in Syriac tassûgâ "the fourth part; a measure;" ultimately Proto-Ir. *caçû-ka-; cf. Av. caθwarô, catur-, → four.

The act of allocating; the state of being allocated.

Verbal noun of → allocate.

One of two or more forms in which a → chemical element occurs, each differing in physical properties; e.g. → diamond and → graphite are allotropes of → carbon.

From allo-, combining form of Gk. allos "other, different;" cf. L. alius "else;" → alias + trope, from Gk. -tropos "a turn, way, manner," from tropein "to turn;" PIE base *trep- "to turn" (cf. L. trepit "he turns").

Degarvâr, from degar "other, another" (Mid.Pers. dit, ditikar "the other, the second;" O.Pers. duvitiya- "second;" Av. daibitya-, bitya- "second;" Skt. dvitiya- "second;" PIE *duitiio- "second") + -vâr denoting "resembling, like;" Mid.Pers. -wâr; Av. -vara, -var; cf. Skt. -vara.

A property of certain → chemical elements, as → carbon, → sulfur, and → phosphorus of existing in two or more distinct forms, known as → allotropes.

→ allotrope.

In solid-state physics, the range of energies which electrons can attain in a material.

P.p. of v. allow, from O.Fr. alouer "approve," from L. allaudare , compound of → ad- "to" + laudare "to praise."

Bând, → band; parzâmidé, p.p. of parzâmidan "to send through, permit, allow," from parzâm "permission," from par- "through" + zâm stem of zâmidan, Mid.Pers. zâmenidan "to send, lead;" → permit

A material composed of two or more → metals, or of a metal or metals with a non-metal, exhibiting characteristic metallic properties. Some examples: → bronze is an alloy of → copper and → tin, brass is an alloy of → zinc and copper, and → steel is an alloy of → iron and → carbon. Alloys have properties which differ from those of their components. Moreover, different component proportions yield alloys with different properties.

From M.F. aloi, from O.Fr. alei, from aleier "to mix, combine," from L. alligare "to bind up," from → ad- "to" + → ligare "to bind."

Âlyâž, loanword from Fr.

The difference in position of a star as seen from the → Earth and → Sun, i.e. the angle subtended at a star by the mean → radius of the Earth's orbit around the Sun. Same as → heliocentric parallax. Because the Earth revolves around the Sun, we observe the sky from a constantly moving position in space. Therefore, we should expect to see an annual effect, in which the positions of nearby objects appear to oscillate back and forth in response to our motion around the Sun. This does in fact happen, but the distances to even the nearest stars are so great that we need to make careful observations with a telescope to detect it. The annual parallax of the nearest star, → Proxima Centauri, is 0.762 arcsec, which is too small for our → acuity of vision.

→ annual; → parallax.

A → pair of → vectors whose directions are parallel but having the opposite sense.

→ anti-; → parallel.

A spherical or approximately spherical body, either solid or hollow.

From M.E. bal, balle, from O.Fr.; cf. O.H.G. ballo, Ger. Ball; PIE root *bhel- "to blow, swell."

Tup "ball," initially "clmup, aggregation, parcel, group" (tup tup "many"); Tabari tupa "compressed, assembled," tuppi "round;" Kurd. top "ball," topâl "round;" guy, → globe.

A rare form of lightning occurring as a bright red globe observed floating or moving through the atmosphere close to the ground. It usually is seen shortly before or after, or during, a → thunderstorm. Its duration varies from a few seconds to a few minutes. See also → Saint Elmo's fire.

→ ball; → lightning.

Of or relating to → ballistics.

A missile that after being launched and guided in the early part of its flight, travels unpowered in a ballistic trajectory.

→ ballistic; → missile.

Transfer of microbes and biochemical compounds from a planet to another due to meteoric impacts. Debris being knocked off a planet like Mars can reach escape velocity and enter the atmosphere of another planet with passenger micro-organisms intact.

→ ballistic; → panspermia.

A curved path followed by an unpowered object that is being acted upon only by gravitational forces and the friction of the medium through which it moves.

→ ballistic; → trajectory.

Audible disturbance or wave caused by the compression of air ahead of a projectile in flight.

→ ballistic; → wave.