Shading represents the Sun’s position
The bright region is the side where the Sun is above the horizon at the selected instant; the dark region is the night side. The glowing point is not a city: it is the subsolar point, where the Sun is overhead.
The boundary is near sunrise and sunset
The gold boundary shows the approximate transition between day and night. Actual sunrise and sunset vary with latitude, terrain, atmospheric refraction, and the observation convention, so use the map as a visual planning aid.
Compare it with the city cards
Cities with different longitudes and time zones show different local clock readings at the same instant. Select a city and compare its local time, date, and time zone with the map shading to keep clock time and solar position distinct.
Match each map indicator to the question it answers
At the same local clock time, daylight varies with season and latitude. Read civil clock time and the map’s approximate solar position as separate information.
| Indicator | What it tells you | What it does not tell you |
|---|---|---|
| City time and date | The civil time in that zone | Actual sky brightness |
| Shading and gold boundary | Day and night from solar position | Cloud or mountain obstruction |
| Subsolar point | Where the Sun is overhead | The selected city |
Save Seoul and London and compare one reference instant. Their clocks and dates may differ, but the Sun has one position. Advancing one hour updates all city clocks and the shading together. A city near the boundary is around sunrise or sunset, but this view alone cannot determine the exact sunrise time at a photography location.
Try it on the map
- Use “Now” to return to the present or enter a date. Before comparing the map with the sky outside, check that you have not left it on a past reference time.
- Select a city and inspect its local date, UTC offset and day/night state together. Panning or zooming changes the view, not the reference instant.
- Compare the same clock time in summer and winter to see how daylight changes at high latitudes. A city clock reading 12:00 does not necessarily mean the Sun is at its highest point.
Limits to keep in mind
The map approximates solar declination and the equation of time. It does not model observer altitude, terrain, clouds, refraction or twilight stages. Near polar regions and the boundary, consult a dedicated sunrise/sunset calculation and local observations. NOAA is a reference for calculation principles and limitations, not a live forecast provider for this service.
Official references
If you find an error in an explanation or example, please let us know on the contact page. Report an error