Seasons and Day Length
Watch Earth go once round the Sun with its axis tilted, and see how the tilt, not the distance from the Sun, makes the seasons. Pick a latitude and a tilt, then follow how long the Sun is up each day and how high it climbs at noon through a whole year. Near the poles the Sun stays up all day in summer and never rises in winter. Set the tilt to 0° and the seasons disappear. The two halves of the world have opposite seasons.
Preview — sign up free to change the numbers yourself
What you can adjust
- Tilt of Earth's axis
- 0 – 45 °
- Latitude
- -80 – 80 °
How far Earth's axis leans from straight up. Earth's is 23.4°. At 0° there are no seasons at all, and a bigger tilt makes the seasons more extreme.
How far you are from the equator. Positive is north and negative is south: 52 is about London, −34 about Sydney, 0 is the equator. The two halves of the world have opposite seasons.
About this simulation
What it shows
Earth goes once round the Sun in 12 seconds with its axis tilted the same way all year. Graphs show how many hours the Sun is up each day and how high it climbs at noon at your latitude, with the date, season and sunlight beside them.
The key idea
Seasons come from the tilt, not from distance. When your half of the world leans toward the Sun, the Sun climbs higher and stays up longer, so it is summer. Earth is actually closest to the Sun in early January. The two halves of the world have opposite seasons.
Try this
Set Latitude to 70 and watch the Sun stay up all day in summer and never rise in winter. Then set Tilt of Earth's axis to 0 and the seasons vanish.
A simple model: Earth's path is drawn almost circular and not to scale, and daylight is counted from when the middle of the Sun is on the horizon, so it ignores the few minutes that the air's bending of light adds. Sunlight is the daily average at the top of the air.