An Etymological Dictionary of Astronomy and Astrophysics

7 terms — Z › ZO

Z ZA ZE ZH ZI ZO ZR ZZ

zodiac   برجگان، برج زنار   borjgân Fr.: zodiaque An imaginary belt around the heavens extending about 9° on either side of the → ecliptic. The orbits of the Moon and of the principal planets also lie entirely within the zodiac. The zodiac was created during the first half of the first millennium B.C. by Babylonian astronomers, who divided it into 12 constellations (→ sign of the zodiac) each considered to occupy 1/12, or 30°, of its great circle. They were named after living creatures, with the exception of Libra: → Aries, → Taurus, → Gemini, → Cancer, → Leo, → Virgo, → Libra, → Scorpius, → Sagittarius, → Capricornus, → Aquarius, → Pisces. However, as a result of → precession, these signs no longer correspond to the astronomical constellations in which the Sun actually appears. The constellations are irregular in size and shape, and the Sun regularly passes through 13 constellations as it moves along the ecliptic. The additional 13th constellation is → Ophiuchus, situated between → Scorpius and → Sagittarius. See also → dodekatemorion. Etymology (EN): From M.E. zodiaque, from O.Fr. zodiaque, from L. zodiacus, from Gk. zodiakos (kyklos) “zodiac (circle),” literally “circle of little animals,” from zodiaion, diminutive of zoion “animal,” literally “a living being,” from PIE base *gwei- “to live, life;” cognate with Pers. zist, → bio-. Etymology (PE): Borjgân, from borj, → sign of the zodiac, -gân suffix denoting multiplicity, order, organization.

zodiacal   برجگانی   borjgâni Fr.: zodiacal Of or relating to the → zodiac. See also: → zodiac; → -al.

zodiacal belt   کمربند ِ برجگانی، زنار ِ ~   kamarband-e borjgâni, zonâr-e ~ Fr.: ceinture zodiacale → zodiac. See also: → zodiacal; → belt.

zodiacal light   نور ِ برجگانی   nur-e borjgâni Fr.: lumière zodiacale A cone-shaped faint glow along the → ecliptic, visible to the naked eye in the west after sunset or in the east before sunrise. Zodiacal light results from sunlight reflected by interplanetary dust concentrated in the plane of the ecliptic. See also: → zodiacal; → light.

zodiacal sign   برج   borj (#) Fr.: signe zodiacal → sign of zodiac. See also: → zodiacal; → sign.

zone   زنار   zonâr (#) Fr.: zone The portion of the surface of a sphere included between two parallel planes. Etymology (EN): From L. zona “geographical belt, celestial zone,” from Gk. zone “a belt,” related to zonnynai “to gird,” from PIE base *yes- “to gird, girdle;” cognate with Pers. parhun “circle,” as below. Etymology (PE): Zonâr most probably loan from from Gk., as above; it is related to Pers. parhun “circle,” ultimately from Proto-Iranian *pari-iâhana- “girdle, belt,” from pari-, variant pirâ-, → circum-, + iâhana- “to girdle,” cf. Av. yâh- “to girdle.” The Pers. pirâhan “shirt” is a variant of parhun.

zone of avoidance   زنار ِ تسنش   zonâr-e tosneš Fr.: zone d'évitement, zone vide The region on the sky covered by the plane of the → Milky Way. It is characterized by an apparent absence of galaxies, due to the obscuring effect of → interstellar dust in the → Galactic plane. See also: → zone; → avoidance.