crepuscu-, crepusc-

(Latin: twilight, dusky, dawn; in the evening or early-morning hours; dim, indistinct)

anticrepuscular arch, antitwilight arch
A narrow band, pink or with a purple cast, that sometimes appears at twilight just above the horizon opposite the sun.
anticrepuscular ray
In rare cases, crepuscular rays extend across the entire sky and anticrepuscular rays converge at the point opposite the sun.
Twilight or the time of day just after sunset or before dawn, when the sun is below the horizon.

Twilight is also defined as the soft, diffused light from the sky when the sun is below the horizon, either from daybreak to sunrise or, more commonly, from sunset to nightfall.

crepuscular (adjective)
1. Active during the sunrise or sunset evening in the twilight hours: "The crepuscular activities of the bats flying out of the cave was a signal that a lot of bugs would be consumed very soon."
2. In zoology, active or primarily active at the time around dawn or dusk (evening); such as, rabbits, deer, bats, and other mammals, as well as various insects: "Rabbits are crepuscular animals, much like deer; so, during the day, they like to sleep in their burrows, in depressions of grass, or even in their cages."
The time of day immediately following sunset.
Pertaining to twilight; illuminated by twilight, dim, dusky or the soft faint illumination of the sky when the sun is below the horizon before sunrise and especially after sunset.
1. Flying in the twilight or evening, or before sunrise; referring to certain birds and insects.
2. Pertaining to twilight; glimmering; hence, imperfectly clear or luminous.

Creatures that feed only in the twilight; such as, bats and owls, are called crepuscular.