Is the map showing real time?

Yes. It opens at the current moment and repaints every minute while it is left alone. The slider moves it forward through the next seven days, and Now brings it back. Everything is computed in your browser from the sun's position — nothing is fetched from a server, and there is nothing to sign up for.

Where can I see the exact sunrise and sunset time for my town?

On the sun pages: they give sunrise, sunset, day length, twilight and a seven-day outlook for more than a thousand cities, or for any location you name. This map is the shape of the thing; those pages are the numbers.

What do Play, Now and the season buttons do?

Play runs about six hours a second so one turn of the Earth takes four seconds. Now jumps back to this moment. The season buttons jump the date to an equinox or solstice so you can see the slow lean of the year, which barely changes across the seven-day slider.

TimeAndSpace.Science

Day and Night Map

Where it is light on Earth right now, where it is dark, and the twilight in between. Drag the slider to move through the next seven days, or press play and watch the line sweep round. The same picture as the world clock's map, with time attached.

Time — seven days, hour by hour

The sun is overhead at 10.2° N, 131.3° W — the yellow marker on the map (press Now to put it on this minute). This time of year the sun is moving from summer toward fall, and days in the northern half of the world are getting shorter because Earth is tilting away from the sun in Earth’s orbit.

Play runs at about six hours a second: one full turn of the Earth takes four seconds, and the whole week about half a minute. Nothing on the map slides sideways while it runs — the shaded shape is re-solved for each moment, meridian by meridian — so the picture never runs off the edge and jumps back. The one thing that does cross the edge is the sun marker, and that is honest: this map is a cylinder cut open at the date line, so the point the sun stands over leaves at one side and arrives at the other.

What this is, and how it works

This is a live map of day and night on Earth, solved for this moment. Half the planet is in sunlight at every instant. The bright half is where the sun is above the horizon, the dark half is below, and the soft band is twilight — the sun has set but the sky is still lit, out to 18° down.

The yellow marker is the one place the sun stands straight overhead. The dashed gold lines are the tropics, at plus and minus the tilt. The curve is the terminator. Play watches it sweep west. Pick a date, or jump to an equinox or a solstice, to see the shadow change through the year. The lean is the tilt of Earth in Earth’s orbit.

Yellow markerSubsolar point — a flagpole there casts no shadow.

Soft bandTwilight, widest toward the poles.

Dark halfNight, solved per meridian, not stamped on.

Where the sun is standing, seen from the side

The map above looks down at the ground. This is the same instant from beside Earth’s orbit — parallel sunlight, and the one yellow line from the centre of the sun to the centre of the Earth. It meets the surface at the yellow marker.

That line lands at 10.2° N — 13.3° short of the Tropic of Cancer, which is as far north as it can ever get. The northern half of the world is leaning into the light, so more of it falls inside the lit half than outside, and its days are longer than its nights. That lean is the tilt of Earth in Earth’s orbit.

The two dashed chords are the tropics, at ±23.4°. They are the tilt written on the surface. Jump the map to a solstice and watch the yellow line stop there.

Tropic of Cancer, 23.4°NFurthest north the sun can stand overhead.

Tropic of Capricorn, 23.4°SThe same limit going south.

Questions this page answers

The question is the link. A short answer sits here; tap through for the drawing and the deeper pass.

What is the Tropic of Cancer? It is the circle at 23.4° north. The Sun is straight overhead there once a year, on the June solstice, and never north of it. That number is Earth’s tilt, not a climate zone someone drew.
What is the Tropic of Capricorn? It is the circle at 23.4° south — the southern twin of the Tropic of Cancer. The Sun stands straight overhead there once a year, on the December solstice, and never south of it.
What is the subsolar point? It is the one place on Earth where the Sun is straight overhead right now — where a flagpole casts no shadow. It is the yellow dot on the day/night map, and it is where the Sun-centre to Earth-centre line hits the surface.
What is the terminator? The terminator is the line between day and night — the circle on Earth where the Sun sits on the horizon. Sunrise is where you cross it going into the light; sunset is where you cross it going out.
What is Earth’s axial tilt? Earth’s spin axis is not upright. It leans about 23.4° from the vertical to its orbit. That lean is why we have tropics, polar circles, and seasons — and it barely changes from one year to the next.
What are the polar circles? The Arctic Circle and Antarctic Circle sit at 66.6° north and south — 90° minus Earth’s tilt. Inside them the Sun can stay up all day in summer, or stay down all day in winter.
What is twilight? Twilight is the time when the Sun is below the horizon but still lighting the sky. This map draws it as a soft band: from the terminator down to where the Sun is 18° below — the edge of astronomical night.
Why is this map flat? This map gives every degree of latitude and longitude the same length on the page, so meridians are straight and the terminator is honest. The cost is size: land near the poles is stretched. The picture says so, in numbers from the drawing.
Why do we have seasons? Not because Earth gets closer to the Sun. When it is summer in the United States it is winter in Australia, on the same planet, at the same distance. Seasons happen because the axis is tilted 23.4° and keeps pointing the same way all year.

Keep going

This map answers "where", to the nearest few hundred kilometres. For "when", to the minute, in your own town:

Why do we have seasons? Earth’s orbit with the tilt Why is this map flat? Glossary Sunrise & sunset for your city Tonight's moon phase What time is it there? The same line, on a globe How sunrise is worked out Using these in a lesson

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