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

→ annual motion.

→ annual; → apparent; → motion.

An irregularity in the Moon's orbit, which can amount to 11 degrees in a period of one year. It results from the Sun's disturbing effect on the motion of the Moon due to varying distance between them.

→ annual; → equation.

The annual apparent motion of the → Sun in the sky with respect to → fixed stars along the path called → ecliptic. The apparent annual motion is due to the → Earth's → revolution about the Sun. In the course of this motion, the Sun appears to shifts about 1° eastward per day.

→ annual; → motion.

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.

Generally, the variation of a quantity over a year. In particular the yearly change in the right ascension or declination of a star, produced by the combined effects of the precession of the equinoxes and the proper motion of the star.

→ annual; → variation.

(Especially of laws or other established rules, usages, etc.) to make void or null; abolish; cancel; invalidate (Dictionary.com).

M.E., from O.Fr. anuller, from L.L. annullare "to make to nothing," from L. → ad- "to" + nullum, neuter of nullus "nothing," → null.

Ânulidan, from prefix â- + nul, → null, + -idan infinitive suffix.

Having the form of a → ring.

From Fr. annulaire or directly from L. annularis "pertaining to a ring," from annulus, diminutive of anus "ring."

Halge-yi, halqevâr, adj. from halqé, → ring.

A solar eclipse in which the Moon is close the → apogee and is, therefore, too small to cover the whole disk of the Sun, leaving a visible edge or ring of sunlight. An annular eclipse can last for 12m 30s at the most. See also → total eclipse.

→ annular; → eclipse.

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.