What changed
Light arrives at a new angle.
A hemisphere tilted toward the Sun receives more direct light for more hours. Tilt it away and the same light spreads across a larger surface for fewer hours.
Observe · The yearly pattern
Why do seasons change?
Earth keeps the same 23.5° tilt as it circles the Sun. That tilt changes the angle of sunlight and the length of each day—not distance from the Sun.
Learning objectiveConnect axial tilt, sunlight angle, and daylight length to the season experienced in either hemisphere.
Start with the tiltOne axis. Four seasons.
23.5° axial tilt
Lesson progress
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02 · Experiment
Move through the year.
Pick a season and hemisphere. Watch Earth move to the matching orbital position, then compare the noon Sun angle and approximate daylight at 40° latitude.
Earth–Sun model
Northern Hemisphere · June solstice
Axis stays parallel
What stayed constant
The axis keeps pointing the same way.
Earth does not wobble back and forth each season. Its axis stays nearly parallel as the planet travels around the Sun, changing which hemisphere leans into the light.
03 · Checkpoint
Test the pattern.
Choose one answer in each card. Feedback appears immediately and stays only in this page—nothing is submitted or saved.
Question 01
What is the main cause of Earth’s seasons?
Pick the factor that changes sunlight angle and day length.
Question 02
When it is summer in the north, what is happening in the south?
Think about which hemisphere is leaning toward the Sun.
Question 03
What happens to daylight as summer approaches?
Use the daylight reading from the experiment as evidence.
04 · Summary
Keep the tilt. Change the view.
Spring
Day and night are close to equal. Direct light begins shifting north as days lengthen.
Summer
The north tilts toward the Sun, producing its longest days and highest noon Sun.
Autumn
Day and night return near balance while direct light shifts south and days shorten.
Winter
The north tilts away from the Sun, bringing its shortest days and lowest noon Sun.
Earth’s axis is tilted 23.5° relative to its orbit.
Direct, long-lasting sunlight delivers more energy.
The hemispheres experience opposite seasons.