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Sunrise Sunset Calculator

Estimate sunrise, sunset, and solar noon for coordinates, date, and an explicit civil UTC offset, including polar-day states.

Privacy: your files never leave your device. All processing happens locally in your browser.

How to use

  1. 1.Choose a date from 1901 through 2099 and enter latitude with north positive and longitude with east positive.
  2. 2.Enter the civil UTC offset that applies on that date, including daylight saving time when necessary.
  3. 3.Read sunrise, solar noon, and sunset or the polar state, then treat the minute values as apparent-horizon estimates.

About Sunrise Sunset Calculator

Sunrise Sunset Calculator estimates apparent sunrise, sunset, and solar noon for a calendar date and geographic coordinates. Enter latitude with north positive, longitude with east positive, and the civil UTC offset that applies on the chosen date. The page reports local clock times and identifies polar day or polar night when the Sun does not cross the modeled apparent horizon. The calculation runs locally and does not request location permission or send coordinates to a remote geocoding service.

The implementation follows the compact solar-position equations documented by NOAA's Global Monitoring Laboratory and derived from Jean Meeus's astronomical algorithms. It computes Julian time, geometric solar longitude and anomaly, orbital eccentricity, apparent longitude, corrected obliquity, solar declination, and the equation of time. Solar noon follows from longitude and equation of time. The sunrise hour angle is calculated for an apparent zenith of 90.833 degrees, then added to or subtracted from solar noon.

The 90.833-degree convention accounts approximately for atmospheric refraction near the horizon and the Sun's visible radius. It does not mean the geometric center is exactly on an unobstructed zero-degree horizon at the displayed minute. NOAA explains that refraction is modeled rather than measured. Actual weather, air density, elevation, nearby terrain, buildings, trees, and the observer's horizon can shift when the disk first appears or finally disappears.

Latitude is accepted from -89.8 through 89.8 degrees. Longitude is accepted from -180 through 180 with east positive and west negative. This sign convention matters: New York uses a negative longitude, while Sydney uses a positive longitude. The UTC offset is separate from longitude because civil time zones are political and can include daylight saving rules. Enter the offset for that specific place and date; the calculator deliberately does not guess a time-zone name or historical DST rule.

Dates are limited to the Gregorian years 1901 through 2099, matching the intended accuracy scope of this lightweight browser tool. NOAA states that its calculator is theoretically accurate to about a minute within ±72 degrees latitude, with possible errors up to ten minutes beyond that range. Results here are estimates for planning and education, not official ephemerides, legal determinations, religious rulings, navigation, or safety-critical operations.

Independent golden tests compare six ordinary locations and seasons with U.S. Naval Observatory rise/set output, allowing a three-minute difference for model and rounding choices. The tests also cover Tromsø at the June and December solstices, where the independent reference reports the Sun continuously above or below the horizon. When no crossing exists, the page reports the state instead of inventing a clock time.

Clock results are rounded to the nearest minute after the astronomical calculation. If an extreme combination of coordinates and manually selected offset moves an event across midnight, a parenthetical previous- or next-day marker appears beside the time and is included in copied text. Solar declination and equation of time are shown as diagnostic values so the result is more transparent and easier to compare with another implementation.

For normal use, obtain coordinates from a reliable map, check the date's actual UTC offset, and compare the result with your visible horizon. A city-center coordinate is adequate for broad planning but not for exact observations across a large region. For high latitudes, official schedules, field navigation, or telescope work, consult a full ephemeris that includes elevation, pressure, temperature, and the required event definition. This page provides a reproducible NOAA-style approximation with its assumptions kept visible.

Methodology & sources

Validate Gregorian date, coordinates, and UTC offset; derive NOAA/Meeus solar terms at the date's Julian noon; compute apparent sunrise hour angle at zenith 90.833°; convert solar noon ± hour angle from UTC minutes to local civil minutes; round to the nearest minute and preserve any day offset. Classify an hour-angle cosine above 1 as polar night and below -1 as polar day.

Frequently asked questions

Why must I enter the UTC offset manually?
Coordinates do not uniquely determine civil time. Time-zone borders and daylight saving rules change, so you must enter the offset that applies to the selected date.
What does apparent sunrise mean?
The model uses a 90.833° zenith to approximate atmospheric refraction and the Sun's visible radius near an unobstructed horizon.
Why can observed sunrise differ from the result?
Weather, elevation, terrain, buildings, the actual horizon, coordinate precision, and approximation error can all move the visible event.
What are polar day and polar night?
At high latitudes the Sun may remain above or below the apparent horizon for the entire local date, so no rise or set clock time exists.

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