Day night map

The subsolar point on four dates in 2026

How to use it

1. Open the page. The orange line is the terminator, the boundary between day and night at this moment.
2. The marked point is the subsolar point, where the sun is directly overhead.
3. Everything within 90° of that point is in daylight. Pan and zoom to see which places are near sunrise or sunset.
4. Reload the page to redraw both for the current time.

How the line is drawn

First the tool finds the subsolar point. Its latitude is the sun's declination and its longitude follows the time of day, corrected by the equation of time, both from NOAA's general solar position equations. The terminator is then the circle of points exactly 90° of arc, about 10,008 km, from the subsolar point.

This is the geometric terminator. Because of refraction and the sun's disk, the sky stays bright a little past the line, and twilight extends much farther.

Why the line bends through the year

At the equinoxes the subsolar point is on the equator, and the terminator runs straight from pole to pole. As the sun moves north toward June, the line tilts: the North Pole stays in daylight and the South Pole in darkness. In December the tilt reverses. On a Mercator map the tilted circle appears as a wave.

The day length by latitude guide explains how this sets the hours of daylight.

Related sun tools

For sunrise and sunset at one place, use the sunrise and sunset calculator. For the sun's direction and height right now, use the sun position calculator.

Things to notice

Around the June solstice, the area around the North Pole sits wholly on the day side and the South Pole on the night side. Around the equinoxes the line runs close to north and south.

The subsolar point moves west about 15° an hour, so reloading an hour later shifts the whole pattern west by about one time zone. Every place on a given meridian sees the same solar time. Near the December solstice the pattern reverses, with Antarctica in constant daylight and the Arctic in polar night.