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Sunrise, sunset, or sun position for any location – U.S. only; Sunrise, sunset and day length for any location – Worldwide; Rise/Set/Transit/Twilight Data – U.S. only; Astronomical Information Center; Converting Between Julian Dates and Gregorian Calendar Dates; Approximate Solar Coordinates; Algorithms for Computing Astronomical Phenomena
Twilight Calculator Compute twilight times. Twilight time calculator Archived 2011-10-14 at the Wayback Machine; Formulae to calculate twilight duration (archived) by Herbert Glarner. The colors of twilight and sunset; HM Nautical Almanac Office Websurf Compute twilight times. Geoscience Australia "Sunrise and sunset times" Compute twilight times.
Astronomically, sunrise occurs for only an instant, namely the moment at which the upper limb of the Sun appears tangent to the horizon. [1] However, the term sunrise commonly refers to periods of time both before and after this point: Twilight, the period in the morning during which the sky is brightening, but the Sun
Calculate the sunset time, which is the solar noon time plus the sunset hour angle in degree divided by 15; Use the sunset time as input to the solar geometry routine to get the solar azimuth angle at sunset. An interesting feature in the figure on the right is apparent hemispheric symmetry in regions where daily sunrise and sunset actually occur.
A terminator or twilight zone is a moving line that divides the daylit side and the dark night side of a planetary body. The terminator is defined as the locus of points on a planet or moon where the line through the center of its parent star is tangent .
At the poles, the path of the Sun is indeed a circle, which is roughly equidistant above the horizon for the entire duration of the daytime period on any given day. The circle gradually sinks below the horizon as winter approaches, and gradually rises above it as summer approaches. At the poles, apparent sunrise and sunset may last for several ...
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Twilight patterns are produced during the time period between the beginning of astronomical twilight (when the Sun is 18° below the horizon) and sunrise, or sunset and the end of astronomical twilight. The duration of astronomical twilight depends on the length of the path taken by the Sun below the horizon.