Sunrise Sunset Calculator

Sunrise and sunset depend mainly on latitude and the Sun's seasonal declination. Earth is tilted relative to its orbit, so the length of daylight changes through the year. Near the equator, day and night remain close to twelve hours. At middle and high latitudes, summer days become longer and winter days shorter. Within the polar circles, some dates can have continuous daylight or continuous darkness, meaning there is no ordinary sunrise-and-sunset pair. This calculator uses a standard declination approximation based on day of year. It solves the sunrise hour angle for a geometric Sun at the horizon and reports times relative to local solar noon. Solar noon is fixed at 12:00 in this result, with sunrise and sunset placed symmetrically around it. Daylight duration is twice the sunrise hour angle converted at fifteen degrees per hour. The model is useful for understanding seasonal geometry and producing quick planning estimates. Local solar time differs from civil clock time. A clock follows the legal time zone, while the Sun crosses each longitude at a different moment. Daylight saving time, longitude east or west of the time-zone meridian, and the equation of time all shift clock readings. To convert these estimates to local clock time, apply those corrections for the intended place and date. This calculator intentionally does not infer a time zone from latitude alone because many different longitudes share the same latitude. Official published sunrise and sunset commonly use an apparent solar altitude below zero to account for atmospheric refraction and the visible radius of the Sun. Elevation, terrain, buildings, weather, and local horizon shape can also alter when sunlight is actually seen. Consequently, these geometric times should not replace an astronomical almanac for navigation, religious observance, aviation, or any legal definition. They are appropriate for education, rough solar-energy studies, gardening, photography planning, and comparisons of daylight length. For leap years after February, the day number and declination approximation introduce a small additional difference, so precision work should use the full calendar date and a validated ephemeris.