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

A night sky without clouds, mist, or haze, atmospheric dust particles, and without city lights in which a sixth magnitude star is visible by naked-eye.

→ clear; → night.

Generally, the middle of the night as indicated by twelve o'clock at night.
True midnight: The time when the Sun is closest to nadir and the night is equi-distant from dusk and dawn. The opposite of noon.

From mid- an E. combining form related to → middle; → night.

Nimšab, from nim "mid-, half" (Mid.Pers. nêm, nêmag "half;" Av. naēma- "half;" cf. Skt. néma- "half") + šab, → night

The phenomenon occurring when the Sun is visible above the horizon at midnight. This phenomenon can be seen at positions north of the Arctic Circle and south of the Antarctic Circle when the Sun is circumpolar (around the summer solstice in the northern hemisphere and the winter solstice in the southern hemisphere respectively).

→ midnight, → sun.

The period between → sunrise and → sunset, especially the hours of darkness.

M.E., from O.E. niht (O.H.G. naht, Du., Ger. Nacht, O.N. natt, Goth. nahts), from PIE *nok(w)t- "night;" cf. Gk. nuks; L. nox (Fr. nuit; Sp. noche); Skt. nákt-; Av. *naxtar- "night," upa.naxtar- "adjoining the night" (Kurd. Soriani nûtak (?) "sheer darkness"); Lith. naktis; Russ. noch'.

Šab, from Mid.Pers. šab, šap "night;" O.Pers. xšap- "night;" Av. xšapan-, xšafn-, xšap- "night;" cf. Skt. ksáp- "night;" PIE base *k(w)sep- "night."

A specialized technician in an observatory who is in charge of functioning a telescope and helping visiting astronomers during their observation run.

From → night + assistant; M.E. assistent, from L. assistent-, stem of assistens, pr.p. of assistere "assist, stand by," from → ad- "to" + sistere "take a stand, cause to stand," cognate with Pers. istâdan "to stand," → histogram.

Dastyâr "assistant," 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-) + yâr "helper; companion" (Mid.Pers. hayyâr "helper," hayyârêh "help, aid, assistance," Proto-Iranian *adyāva-bara-, cf. Av. aidū- "helpful, useful").

An eye disease which is the difficulty in seeing at night or in dim light. Opposite of → hemeralopia. Also called → nyctalopia.

→ night; → blindness.

Same as → airglow.

→ night; → glow.

In polar regions, the portion of the year when the Sun does not rise above the horizon. Its length changes from twenty hours at the Arctic/Antarctic Circle (latitude 66°33' N or S) to 179 days at the North/South Pole.

→ polar; → day.

The circumstance pertaining to polar latitudes in which when the Sun sets its center does not go beyond 6° below the horizon and the → twilight lasts all the night.

→ white; → night.