Teaching · For Teachers · Earth and space science

Where the sun comes up,
and when.

Type a date and a place. The calculator gives sunrise and sunset, the bearing on the horizon where each happens, the noon sun’s angle and the day length, then shows how all of it swings through the year.

Find the sunriseWhat you get

The sunrise and sunset calculator

The worked example is Denver on the June solstice. Nothing you type leaves this browser.

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What you get

Teaching · For TeachersFree

What you finish with
Sunrise and sunset clock times, the rise and set bearings, solar noon and the noon angle, the day length, and a month-by-month table. It prints as a summary and downloads as a spreadsheet.
Who it is for
Earth and space science teachers and their students, and anyone planning around daylight: photographers, gardeners, hikers.
Format
Browser calculator for a phone, tablet or computer, by touch or keyboard. Prints a summary; downloads a spreadsheet (.csv); export and import a file.
Access
Free. No account, no sign-in and nothing to install. Everything you type stays in this browser; nothing is sent to Caveat.
Where it lives
The For Teachers space in Caveat Teaching.
Support
Questions, a correction or a request: team@caveatacademic.com.

How to use it

  1. Find the place’s latitude and longitude on a map.
  2. Type the UTC offset in force on that date, including daylight saving time.
  3. Choose the date.
  4. Read the times, the bearings and the noon angle.
  5. Use the table to see the bearings swing between the solstices.

Find the sunrise

How sunrise, sunset and the angles are found

The sun’s place for the date, then the geometry of your latitude.

The worked example: Denver on the June solsticeDate to the sun23.4° Ndeclination on Jun 21Hour angle112.4°sun’s centre at −0.833°Clock times5:32 AMto 8:31 PM (UTC −6)Bearings58.0°rise; set 302.0°The worked example: Denver on the June solsticeDate to the sun23.4° Ndeclination on Jun 21Hour angle112.4°sun’s centre at −0.833°Clock times5:32 AMto 8:31 PM (UTC −6)Bearings58.0°rise; set 302.0°
The sun’s declination for the date sets how far north or south it rises; latitude sets how long it stays up.

What counts as sunrise

Sunrise is the moment the top edge of the sun clears a level horizon. The air bends sunlight by about 34 arcminutes near the horizon and the sun’s disc is about 32 arcminutes across, so the official moment comes when the sun’s centre is still 0.833° below the horizon. That is why day length on the equinox is a few minutes longer than 12 hours.

Why the bearing moves

On the equinoxes the sun rises due east and sets due west everywhere. In the northern summer it rises north of east, and the higher the latitude the wider the swing: in Denver the June sunrise is about 32° north of east. The noon angle follows the same pattern: 90° minus the latitude, plus the sun’s declination for the date.

Sources

  1. NOAA Global Monitoring Laboratory. Solar Calculator and its calculation details (gml.noaa.gov/grad/solcalc).
  2. Meeus, J. (1998). Astronomical Algorithms (2nd ed.). Willmann-Bell. Chapters on solar coordinates and rising and setting.
  3. U.S. Naval Observatory, Astronomical Applications Department. Rise, set and twilight definitions (aa.usno.navy.mil).
  4. NASA Science. Seasons and the tilt of Earth’s axis (science.nasa.gov).

The worked example uses Denver’s published coordinates. Times are for a level horizon at sea level. Your entries stay in this browser. Support: team@caveatacademic.com.