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

A solar eclipse that has both annular and total phases. Same as → hybrid eclipse.

→ annular; → total; → eclipse.

The maximum phase of an → annular eclipse during which the Moon's entire disk is seen silhouetted against the Sun. Annularity is the period between second and → third contact during an annular eclipse. It can last from a fraction of a second to a maximum of 12 minutes 29 seconds (F. Espenak, NASA).

→ annular; → -ity.

An → electrode from which a stream of → electrons leaves, as in an electron tube or electrolytic cell. → cathode.

From Gk. anodos "way up," from → ana- "up" + hodos "way."

Ânod, loanword from anode as above.

The time interval of 27.554 551 days (27d 13h 18m 33.2s), on average, between two successive passages of the Moon through the → perigee of its orbit.

Anomalistic from → anomaly.

Pirâzamini from pirâzamin, → perigee.

Anomalistic from → anomaly.

Pirâhuri from pirâhur, → perihelion.

Deviating from the normal or common order, form, or rule. → anomaly.

From Gk. anomalos "uneven, irregular," from → an- "not" + homalos "even," from homos "same".

Nâsân, from Pers. nâ- "not" + sân "rule, custom, law, fashion," literally "out of rule".

The phenomenon whereby the → refractive index of light in a medium changes rapidly with wavelength in the vicinity of an → absorption band. Hence the → dispersion curve of the substance shows marked deviations from → Cauchy's equation, in contrast with the behavior of → normal dispersion. On the shorter λ side of the absorption band the refractive index falls off more rapidly than required by Cauchy's equation representing values of n for visible light. On the long λ side of the absorption band the index is very high, decreasing at first rapidly and then more slowly as one goes beyond the absorption band.

→ anomalous; → dispersion.

Discrepant luminosity classes derived for the same → Am star when different criteria are used. Lore specifically, a luminosity criterion may indicate a → giant star, wheras another criterion indicates a → supergiant.

→ anomalous; → luminosity; → effect.

The high redshift of a quasar which is seemingly physically associated with a galaxy of low redshift.

→ anomalous; → redshift.

A member of a small class of → X-ray pulsars with long rotation periods (6-12 seconds), short → spin-down times (~ 10³-10⁵ years), and → soft X-ray spectrum. AXPs show no evidence of being → X-ray binary systems. Their magnetic fields, as deduced from their spin-down rate, are the highest known, reaching 10¹³-10¹⁵ → gauss. AXPs are generally believed to be → magnetars.

→ anomalous; → X-ray; → pulsar.

The splitting of a spectral line into several components in the → Zeeman effect when the magnetic field is weak. The splitting is much more complex than in the normal effect. The number of components of the lines often considerably exceeds their number in the normal effect. Contrarily to the normal Zeeman effect, the anomalous effect cannot be explained by classical theory. The historically "anomalous" effect is accounted for by the inclusion of electron spin in the total angular moment. In fact the idea of electron spin was put forward (Uhlenbeck and Goudsmit, 1926) to explain the anomalous Zeeman effect.

→ anomalous; → Zeeman effect.

In general, a deviation from the norm.
An angle that gives the position of an object in an elliptical orbit at any given time with respect to its primary. The true anomaly is the angle between the periapsis of an orbit and the object's current orbital position, measured from the body being orbited and in the direction of orbital motion. The mean anomaly is what the true anomaly would be if the object orbited in a perfect circle at constant speed.

Anomaly from → anomalous

Nâsâni, from nâ- negation suffix + sân "rule, law, custom" + -i noun maker suffix.

Having an unknown or unacknowledged name. → anonymous object.

L. annymus, from Gk. annumos "nameless," from → an- "without" + onoma, onuma "name". Compare with L. nomen, Skt. nama, Av. nama, Mod. Pers. nâm, PIE *nomen "name".

Anâm, from Persian → a-, an- "without" + nâm "name," as above. Binâm, from bi- "without" + nâm.

An → astronomical object which has not been catalogued.

→ anonymous; → object.

Plural form: ansae.
1) The "handles," or extremities, of → Saturn's rings as viewed from Earth.
2) The extremities of a → lenticular galaxy.

L. ansa "handle."

Dastak "handle," from dast "hand" (Mid.Pers. dast; O.Pers. dasta-; Av. zasta-; cf. Skt. hásta-; Gk. kheir; L. praesto "at hand;" Arm. jern "hand;" Lith. pa-žastis "arm-pit;" PIE *ghes-to-) + -ak suffix denoting relation, affinity, similarity.

In physics and mathematics an a priori assumption that is used to establish the form of an equation or a system of equations. The ansatz, which is verified later by the result, is meant to facilitate the solution. → Bethe ansatz.

From Ger. Ansatz "attempt, approach, beginning."

The direction in the sky (in → Columba) away from which the Sun seems to be moving (at a speed of 19.4 km/s) relative to general field stars in the Galaxy.

Antapex from L. ant-, → anti- "against, opposite," + L. → apex "summit, peak, tip."

Pâdcakâd from pâd-, → anti- + cakâd "summit of a mountain; top, crown of the head, top of the forehead," from Mid.Pers. cakât "summit," → apex.

The south polar area, south of latitude 66° 33' 8'' S.

Antarctic, from O.Fr. antartique, from M.L. antarcticus, from Gk. antarktikos "opposite the north," from → anti- "opposite" + arktikos, → arctic.

Daštargân, from daštar, → south, + -gân suffix indicating the direction.
Jonubgân, from jonub "south," from Ar. janub "south," + -gân, as above.

A → red supergiant star (→ spectral type M1 Ib) in the constellation → Scorpius, lying about 500 → light-years (170 (+35/-25) → parsecs) from Earth. It has a dwarf massive companion (B3 V), which is a → radio source.

Antares, in Gk. "rival of Mars," from Gk. → anti + Ares "the Gk. god of War, called Mars by the Romans." The comparison with the planet Mars is because they are both red in color and have the same brightness.

Každom-del "the heart of the Scorpion," from každom "scorpion" + del, → heart. Qalb-ol-'Aqrab "the heart of the Scorpion," from Ar. Qalb "heart" + 'aqrab "scorpion".

Logic: In a → conditional proposition, the → clause which follows if.

M.E., from from L. antecedentem, from antecedere "go before, precede," from ante- "before" + cedere "to yield, to go," → process.

Pišây, from piš "before," → pre-, + ây present stem of âmadan "to come," → process.