County Maps US

Tools Elevation, time and sun

Sunrise and Sunset Calculator

Pick a place and a date. Times are computed with standard astronomical algorithms and shown in the local time zone of the place, not yours.

How to use it

  1. Type a place or click the map, then pick a date (today is preset).
  2. Read sunrise, sunset, solar noon, day length, the golden hours and the three twilights, all in the place’s own time zone.
  3. Use "Previous day" and "Next day" to step, and the seven-day table for the week ahead.

How it works

The sun’s position is computed in your browser with the algorithms in Jean Meeus’s Astronomical Algorithms (chapter 25 for the sun, chapter 28 for the equation of time). Solar noon is found by iterating the hour angle to zero, then sunrise and sunset are the moments the sun’s centre is 0.833 degrees below a flat horizon, which allows for refraction and the sun’s radius; civil, nautical and astronomical twilight use 6, 12 and 18 degrees, and golden hour ends when the sun reaches 6 degrees above the horizon. The result agrees with published almanacs to within about a minute.

The place’s time zone comes from the tz-lookup library and the browser’s Intl database, so daylight saving is handled for the date chosen. Real horizons are not flat: hills, buildings and your own altitude move the visible sunrise by minutes. Inside the polar circles the page says outright when the sun does not rise or does not set.

Questions

Are the times in my time zone or the place’s?
The place’s. Searching Tokyo gives Tokyo clock times, whatever zone you are in.
What is civil twilight?
The period after sunset (or before sunrise) while the sun is less than 6 degrees below the horizon. It is bright enough to work outdoors without lights and is the usual legal definition of "dusk" and "dawn". Nautical twilight runs to 12 degrees, astronomical to 18, after which the sky is fully dark.
What is golden hour?
The stretch after sunrise and before sunset while the sun is below 6 degrees, when light is warm and shadows are long. The exact length depends on latitude and season; near the Equator it is much shorter than an hour.
How accurate are the times?
Within about a minute of the US Naval Observatory tables for a sea-level horizon. Terrain and weather account for larger differences you may notice in practice.

All map tools, free and without an account. Location data is processed in your browser and by the open geocoding services named on the sources page; nothing is stored by this site.