The lapse between the set and the rise of the Sun; It is opposed to day as lapse between sunrise and sunset. The duration of the night varies with the latitude of the place of observation and, in the same place, with the declination of the Sun (that is, with the season); at the equator lasts exactly 12 hours in every period of the year; at the equinoxes (March 21 and September 23) lasts anywhere 12 hours; at 75° latitude the longest night lasts 103 days; at 85°, 161 days; at 90°, at the poles, 6 months.
The conception of the night comes in many civilizations religious aspects: on one side is quiet and peaceful, enlightened and entertained by the stars, on the other is dark and mysterious, mother of sleep and populated by evil figures. The contrast can be understood in the light of the archaic experience of reality, for which it never occurs a phenomenon that is unique. Almost universal feature of human archaic position in front of the night is the fear about the possibility that it beyond its limits, establishing a regime of perpetual darkness, rather than acts according with the alternation day-night.

Day for night:
In cinematography is a taking technique also called American night: with the use of filters or by using other devices in the exposure or in the development of the film, it allows to film in full light, giving the impression that the scene is carried out at night.
In homing is a error recorded in surveys in direction devices, especially at the rising and setting of the sun, because of the ionospheric reflection of electromagnetic waves.

Twilight:
Brightness of the eastern sky before sunrise and after sunset on the west. The morning twilight takes the proper name of sunrise or dawn. Changes of color in the sky are joined to the brightness, of varying extent and shape, produced by diffusion and by the diffraction of sun rays, which pass through the lower atmosphere, where water vapor and dust particles are more abundant. Generally we distinguish: a civil twilight (that begins or ends when the Sun is about 6 degrees below the horizon), during which the visibility is good; an astronomical twilight (that begins or ends when the Sun is about 18 degrees below the horizon), when the first or last lights of the day appear or disappear.

From Treccani.it