Sunset is the disappearance of the Sun 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.
Actual sunset: Two minutes before the Sun disappears below the horizon.
Sunset over the Delaware Bay at Sunset Beach, New Jersey, U.S., seen through cirrus clouds
Evening twilight in Joshua Tree, California, displaying the separation of yellow colors in the direction from the Sun below the horizon to the observer, and the blue components scattered from the surrounding sky
Sunset on Mars
Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth, sunlight is scattered and filtered through Earth's atmosphere as daylight when the Sun is above the horizon. When direct solar radiation is not blocked by clouds, it is experienced as sunshine, a combination of bright light and radiant heat (Atmospheric). When blocked by clouds or reflected off other objects, sunlight is diffused. Sources estimate a global average of between 164 watts to 340 watts per square meter over a 24-hour day; this figure is estimated by NASA to be about a quarter of Earth's average total solar irradiance.
The Sun, as seen from low Earth orbit overlooking the International Space Station. This sunlight is not filtered by the lower atmosphere, which blocks much of the solar spectrum.
Sunlight shining upon two different sides of the U.S. state of New Jersey. Sunrise on the Jersey Shore at Spring Lake, Monmouth County (above), and sunset on the Shore at Sunset Beach, Cape May County (below). Both are filtered through high stratus clouds.
Sunrise over the Gulf of Mexico and Florida. Taken on 20 October 1968 from Apollo 7.
Sunlight shining through clouds, giving rise to crepuscular rays