The word sky comes from the Old Norse sky, meaning 'cloud, abode of God'. The Norse term is also the source of the Old English scēo, which shares the same Indo-European base as the classical Latin obscūrus, meaning

The brightness and color of the sky vary greatly over the course of a day, and the primary cause of these properties differs as well. When the Sun is well above the horizon, direct scattering of sunlight (Rayleigh scattering) is the overwhelmingly dominant source of light.

The term night sky refers to the sky as seen at night. The term is usually associated with skygazing and astronomy, with reference to views of celestial bodies such as stars, the Moon,

Flight is the process by which an object moves through or beyond the sky (as in the case of spaceflight), whether by generating aerodynamic lift, propulsive thrust, aerostatically using buoyancy, or by ballistic movement, without any direct mechanical support from

Except for direct sunlight, most of the light in the daytime sky is caused by scattering, which is dominated by a small-particle limit called

Along with pressure tendency, the condition of the sky is one of the more important parameters used to forecast weather in mountainous areas. Thickening of cloud cover or the

Many mythologies have deities especially associated with the sky. In Egyptian religion, the sky was deified as the goddess Nut and as the god Horus. Dyeus is reconstructed as the god of the sky, or the sky personified, in Proto-Indo-European religion,