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sunset
The timing of sunset varies with the time of year and the latitude and longitude of the viewer's location. The precise local time of sunset also depends mainly upon the viewer's precise vicodin longitude within a given time zone. Small daily changes and noticeable semi-annual changes in timing of sunset are driven by the axial tilt of Earth, the spherical shape of the Earth, and the planet's movement in its annual orbit around the sun. Some apparent anomalies exist however, the main one caused by the Earth's axial tilt and the Earth's elliptical orbit. In the Northern Hemisphere, the earliest sunset does not fall on the winter solstice around December 21, but instead it occurs earlier in December. Likewise, the latest sunset does not fall on the summer solstice around June 21 lexapro , but instead it happens later in June or in early July, depending on one's latitude. The same phenomenon exists in the Southern Hemisphere except with the respective dates being some time before June 21 in winter and some time after December 21 in summer, possibly in January of the following year. For one or two weeks surrounding both solstices, both sunrise and sunset get slightly later or earlier each day. Even on the equator, sunrise and sunset shift several minutes back and forth through the year, along with solar noon. This effect is plotted by an analemma.
Due to Earth's axial tilt, whenever and wherever sunset occurs, sunset is always to the northwest from the March equinox to the September equinox buy propecia , and to the southwest from the September equinox to the March equinox. Sunsets occur precisely due west on the equinoxes, and the duration of day and night are approximately equal on the equinoxes for all viewers on Earth (precisely 12 hours if measured from the geometric (unrefracted) centre of the sun).
As sunrise and sunset are calculated from the leading and trailing edges of the sun, and not the centre, the duration of "day" is slightly longer than "night". Further, because the light from the sun is bent by the atmospheric =refraction, the sun is still visible after it is geometrically below the horizon. The sun also appears larger on the horizon, which is another optical illusion, similar to the moon illusion.
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