sunposition

Sun position, or the sun’s position, is the apparent location of the Sun in the sky as seen from a given place at a specific time. It is commonly described in horizontal coordinates—azimuth (direction along the horizon) and elevation or altitude (angle above the horizon)—or in celestial coordinates such as right ascension and declination. The observed sun position changes daily due to the tilt of the Earth's axis and its orbit, and it also depends on the observer’s latitude and longitude.

Key quantities used in calculating sun position include the solar declination δ, the local latitude φ, and the solar hour angle H, which relates to time of day. The Sun’s elevation a is given by sin a = sin φ sin δ + cos φ cos δ cos H. Azimuth is computed from similar trigonometric relations, with the quadrant fixed by H. The Sun reaches local solar noon when H = 0. The solar declination varies seasonally from about −23.44 to +23.44 degrees. The equation of time describes the difference between apparent solar time and clock time, producing daily shifts in solar noon.

Practical calculations use solar position algorithms or ephemerides, accounting for atmospheric refraction and observer altitude. NOAA and other agencies publish reference formulas and calculators. Applications include solar energy system orientation, building design, sundials, and navigation. The Sun’s position is also a key input for astronomical observations and for studies of solar exposure and climate.