Sun Calculator

Calculate sunrise, sunset, twilight times, and solar position for any date and location.

Input Parameters

Year

Month

Day

Latitude (°)

Longitude (°)

Elevation (m)

Hour (UT)

Sun Arc

Understanding Solar Motion

Sunrise & Sunset

Sunrise and sunset times are calculated using the USNO (U.S. Naval Observatory) algorithm. The Sun is considered to rise or set when its center is 50 arcminutes below the geometric horizon — accounting for 34' of atmospheric refraction and 16' for the Sun's semi-diameter.

Twilight

Civil twilight (Sun 6° below horizon): enough light for outdoor activities. Nautical twilight (12°): horizon still visible at sea. Astronomical twilight (18°): sky fully dark — ideal for deep-sky observation.

Equation of Time

The difference between apparent solar time (sundial) and mean solar time (clock). It varies through the year due to Earth's orbital eccentricity and axial tilt, ranging from about −14 to +16 minutes.

Solar Coordinates

The Sun's position is given in Right Ascension (RA) and Declination (Dec) — the celestial equivalent of longitude and latitude. The ecliptic longitude traces the Sun's apparent path through the zodiac constellations.