Nightfall

Sunset

Sunset is the disappearance of the Sun at the end of the Sun path, below the horizon of the Earth due to its rotation. As viewed from everywhere on Earth, it is a phenomenon that happens approximately once every 24 hours, except in areas close to the poles. The equinox Sun sets due west at the moment of both the spring and autumn equinoxes. As viewed from the Northern Hemisphere, the Sun sets to the northwest in the spring and summer, and to the southwest in the autumn and winter; these seasons are reversed for the Southern Hemisphere.

Twilight

Twilight is daylight illumination produced by diffuse sky radiation when the Sun is below the horizon as sunlight from the upper atmosphere is scattered in a way that illuminates both the Earth's lower atmosphere and also the Earth's surface. Twilight also may be any period when this illumination occurs, including dawn and dusk.

Nightfall (missile)

The Nightfall is a short-range ballistic missile under development by the United Kingdom. In August 2025 the UK Ministry of Defence published a request for information (RFI) for the missile. While initial requirements specified a 300 kg (660 lb) payload and 600 km (370 mi) range, with some basic maneuverability, they were later reduced to 200 kg (440 lb) and 500 km (310 mi). A ground vehicle must have the ability to deliver multiple missiles.

Nightfall (Asimov novelette and novel)

"Nightfall" is a 1941 science fiction short story by the American writer Isaac Asimov about the coming of darkness to the people of a planet ordinarily illuminated by sunlight at all times. It was adapted into a novel with Robert Silverberg in 1990. The short story has appeared in many anthologies and six collections of Asimov stories. In 1968, the Science Fiction Writers of America voted "Nightfall" the best science fiction short story written prior to the 1965 establishment of the Nebula Awards and included it in The Science Fiction Hall of Fame, Volume One, 1929–1964.

nightfall

Noun

1. The close of the day; the coming of night.
2. Nocturnal emission.