Earth’s Tilt, the Sun & Seasons
Earth’s 23.4° axial tilt changes both the angle of sunlight and how long the Sun stays above the horizon. These three synchronized views connect that tilt to daylight, solstices, equinoxes, and the opposite seasons in the Northern and Southern Hemispheres.
Day & Night Map
The sun is overhead at 8.0° N, 171.7° W — this is the subsolar point. 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.
Map limitation: Earth is a globe flattened into a rectangle, so shapes and distances — especially near the poles — are distorted. The Sun and Moon markers are enlarged so you can see them. Why this map is flat →
Angle of the Sun Based on the Time of the Year
This view turns Earth sideways so the cause of the seasons is easier to see. Earth’s axis keeps its 23.4° tilt while the direction toward the Sun changes through the orbit. The yellow centre line lands at the subsolar point, moving between the two tropics as the year passes.
The Sun–Earth centre line lands at 8.0° N, 15.4° short of the Tropic of Cancer. The Northern Hemisphere is leaning into the light, so its days are longer than its nights. See how tilt makes the seasons →
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.
Earth, the Sun & the Moon Through One Year
This wider view answers the missing question: where is Earth in its orbit while the daylight pattern changes? The same instant drives all three simulators. Sizes and distances are compressed to fit. The Moon’s real 5.1° orbital tilt is drawn at 18° so a near miss — or an eclipse alignment — is easier to see. Open the full Earth–Sun–Moon simulator →
Earth’s Tilt, the Sun & Seasons Instructions
These are three views of one instant, not three separate models. Move any slider, press any seasonal button, or press Play under any view and all three update together.
Start with the two solstices and compare all three views. Then choose either equinox. Ask what changed, what stayed fixed, and which hemisphere receives the longer daily path through sunlight.
Things to Try
- Read one date three ways. Choose the summer solstice. The map shows longer northern daylight, the side view puts the overhead Sun at the Tropic of Cancer, and the orbit view shows the north end of Earth leaning toward the Sun. Those are three consequences of the same geometry.
- Swap the hemispheres. Move from the summer solstice to the winter solstice. Watch what reverses and what does not. Earth’s axial tilt keeps the same size and direction; which hemisphere leans into the sunlight changes.
- Find the balance points. Compare the spring and fall equinoxes. The day/night boundary runs nearly pole to pole and the overhead Sun crosses the equator, yet Earth is on opposite sides of its orbit.
- Test the distance myth. In the orbit view, compare Earth’s distance from the Sun with the season in each hemisphere. Both hemispheres are the same distance from the Sun, but they have opposite seasons. Distance cannot be the cause.
- Follow the overhead Sun. Press Play and watch the yellow point move between the tropics. It never crosses them because their latitude is Earth’s 23.4° axial tilt written onto the globe.
- Look for an eclipse alignment. Open a known eclipse date with the year, date, and time URL variables. The Moon can line up with the Sun and Earth, but it does not change Earth’s seasons—the axial tilt and annual orbit do.
Taught one of these, or something better? Help us turn it into a lesson plan — we build them with teachers and publish them free, credited to you.
Questions About Earth’s Tilt and Seasons
What causes the seasons?
Earth’s axis is tilted about 23.4°. As Earth orbits the Sun, one hemisphere leans toward the sunlight while the other leans away. Six months later they swap. The changing angle of sunlight and length of daylight create the seasons.
Are seasons caused by Earth being closer to the Sun?
No. Both hemispheres are always the same distance from the Sun, yet they have opposite seasons. Earth is actually closest to the Sun during northern winter. Tilt changes the angle and daily duration of sunlight; distance is not the seasonal switch.
Do the solstices and equinoxes start the seasons?
They mark the starts of the astronomical seasons. The June and December solstices are the longest and shortest daylight days in each hemisphere. The March and September equinoxes have nearly equal day and night worldwide.
Why is the Moon included in a seasons simulator?
The Moon does not cause the seasons. It is included so the three-body positions stay visible on exact dates, including eclipse dates, and so students can distinguish the Moon’s monthly orbit from Earth’s yearly seasonal cycle.
Can I share a particular year, date, season, or eclipse alignment?
Yes. The simulator reads year, date, time, and season from the URL. For example, year=2024, date=2024-04-08, and time=18:18 opens that precise UTC minute in all three synchronized views.
Keep Exploring the Seasons
Use the simulators here to see the relationship, then open a focused page when you want the deeper explanation or the numbers for your own location.
Why do we have seasons? What is axial tilt? What is a solstice? What is an equinox? Focused day & night map Full Earth–Sun–Moon simulator Your daylight and seasons Use these in a lesson