Data Sources: Geographic coordinates provided by OpenStreetMap (© OpenStreetMap contributors). Sun times calculated using SunCalc library. All times are in local time zone based on the date provided.
Early civilizations relied on observing the sun's position to track time. Ancient Egyptians erected obelisks as early as 3500 BC; the moving shadows these monuments cast allowed the day to be divided into broad periods, making them among the earliest shadow clocks. The oldest confirmed sundial discovered so far is a limestone device dating to around 1500 BC, found in the Valley of the Kings in 2013. Babylonian astronomers developed the sexagesimal system (base 60) that gives us 60 minutes in an hour and 360 degrees in a circle. [Wikipedia, History of Timekeeping Devices] [Wikipedia, Timekeeping in Egypt]
Stonehenge in England was constructed in several phases beginning around 3100 BC, with the famous sarsen stone circle erected between roughly 2600 and 2400 BC. The completed monument aligns toward the sunrise on the summer solstice and the sunset on the winter solstice, demonstrating a sophisticated early understanding of solar patterns. The ancient Greek philosopher Anaximander (c. 610–546 BC) is credited with introducing the gnomon to Greece, a vertical rod whose shadow could indicate both the time of day and the time of year. [Wikipedia, Stonehenge] [Wikipedia, Gnomon]
Claudius Ptolemy completed the Almagest around 150 AD, a comprehensive mathematical model of planetary motion that provided methods for calculating solar positions, including sunrise and sunset. According to Britannica, his work served as the basic guide for Islamic and European astronomers until about the beginning of the 17th century, a span of roughly 1,400 years. Islamic astronomers refined these calculations during the Golden Age, building observatories and creating accurate tables for prayer times based on solar position. [Wikipedia, Ptolemy] [Britannica, Almagest]
Nicolaus Copernicus proposed a heliocentric model in 1543, placing the sun at the center rather than Earth. This shift greatly simplified the mathematics of solar position calculations. Tycho Brahe's precise observational data and Johannes Kepler's laws of planetary motion, published between 1609 and 1621, provided the foundation for modern astronomical algorithms. [Wikipedia, Kepler's Laws]
The development of electronic computers enabled precise astronomical calculations for any location on Earth. Jean Meeus published Astronomical Algorithms in 1991, providing the mathematical formulas widely used in modern software libraries for solar and lunar calculations. The United States Naval Observatory and HM Nautical Almanac Office continue publishing accurate solar and lunar position tables used worldwide. [Wikipedia, Jean Meeus] [US Naval Observatory, Rise, Set, and Twilight Definitions]
Today, open source libraries like SunCalc implement these algorithms for web applications, bringing accurate sunrise and sunset calculations to millions of users instantly. Global positioning systems and online geocoding services eliminate the need for manual coordinate lookup, making solar time information accessible to anyone with an internet connection.
Sunrise and sunset times depend on three factors: the observer's geographic latitude and longitude, the date (which determines the sun's declination), and the atmospheric refraction near the horizon. The calculation begins with finding the sun's position in the sky relative to the Earth's equatorial plane. [Wikipedia, Sunrise Equation]
The hour angle formula determines when the sun reaches the horizon. For a given latitude and solar declination, the hour angle H satisfies cos(H) equals negative tangent of latitude times tangent of declination. Solving this equation gives the time of sunrise and sunset relative to solar noon. [Wikipedia, Sunrise Equation]
Earth's atmosphere bends sunlight as it passes through, making the sun appear above the horizon when it is geometrically below it. At sunrise and sunset, atmospheric refraction raises the apparent position of the sun by an average of 34 arcminutes. Because sunrise is defined as the moment the sun's upper limb (top edge) crosses the horizon rather than its center, an additional 16 arcminutes is added for the sun's apparent radius, giving a total standard correction of 50 arcminutes. This optical effect causes the sun to rise earlier and set later than geometric calculations would predict. [Wikipedia, Atmospheric Refraction] [US Naval Observatory, Rise, Set, and Twilight Definitions]
Twilight periods occur when the sun is below the horizon but its light still illuminates the sky. Civil twilight begins when the sun is 6 degrees below the horizon, providing enough light for outdoor activities without artificial lighting. Nautical twilight occurs between 6 and 12 degrees below the horizon, when the horizon remains visible for navigation. Astronomical twilight extends from 12 to 18 degrees below the horizon, after which the sky becomes completely dark for astronomical observations. This calculator provides civil dawn and dusk times. [Wikipedia, Twilight] [TimeAndDate, Types of Twilight]
The golden hour refers to the period shortly after sunrise and before sunset when sunlight appears warmer and softer. This occurs because sunlight travels through more atmosphere at low angles, scattering shorter blue wavelengths more effectively and leaving warm orange and red tones. Photographers value this time for portrait and landscape photography due to the flattering quality of light and long shadows. The golden hour most commonly refers to the period when the sun is between approximately 6 degrees above the horizon and the horizon itself (0 degrees), where it overlaps with civil twilight. The SunCalc library exposes the start and end of this window as part of its sun position data. [TimeAndDate, Golden Hour]
Earth's axis tilts at approximately 23.5 degrees relative to its orbital plane around the sun. This tilt causes the seasons and drives the changing sunrise and sunset times throughout the year. During June in the Northern Hemisphere, the North Pole tilts toward the sun, creating longer days and earlier sunrises. Six months later in December, the Northern Hemisphere tilts away from the sun, producing shorter days and later sunrises. The equator experiences nearly equal day and night year round because axial tilt has minimal effect there. [Wikipedia, Axial Tilt]
Solar declination is the latitude on Earth where the sun appears directly overhead at solar noon. It varies between +23.5 degrees at the June solstice and -23.5 degrees at the December solstice. At the equinoxes (March and September), solar declination equals 0 degrees, meaning the sun is directly above the equator and day length approximately equals night length worldwide. The precise declination for any given date can be calculated using trigonometric functions based on Earth's orbital position, and this value is fundamental to the sunrise equation. [Wikipedia, Declination] [Wikipedia, Sunrise Equation]
The equation of time accounts for the difference between apparent solar time (measured by a sundial) and mean solar time (measured by clocks). This variation arises from Earth's elliptical orbit and axial tilt, causing solar noon to occur up to 16 minutes earlier or later than clock noon depending on the date. The cumulative effect means sunrise and sunset times do not change uniformly throughout the year. The equation of time follows a predictable pattern with two peaks and two troughs annually, and was already recognized by Ptolemy in the Almagest. [Wikipedia, Equation of Time]
Latitude dramatically affects sunrise and sunset patterns. Near the equator, day length remains approximately 12 hours throughout the year with rapid sunrises and sunsets. At mid latitudes like New York (40 degrees north), day length varies from about 9 hours in winter to 15 hours in summer. Above the Arctic Circle (66.5 degrees north), the midnight sun occurs in summer with 24 hours of daylight, while polar night brings 24 hours of darkness in winter. The Antarctic Circle experiences opposite patterns. This calculator works for all latitudes and will correctly handle extreme cases like polar day and night, returning appropriate values. [Wikipedia, Axial Tilt] [Wikipedia, Midnight Sun]