Sun, Earth and Moon
Day and night, the seasons, the phases of the Moon and eclipses all come from three movements: Earth turns around its tilted axis, Earth circles the Sun, and the Moon circles Earth.
Here you don't just read about it. You control all three in a live 3D model on a real calendar: move through the year, tilt Earth's axis, stand on the ground and watch the Sun's path. Pick a question below for a guided tour, or explore the model freely.
What do you want to find out?
What causes the seasons?
Find out why it is warm in summer and cold in winter, and why the distance to the Sun is not the reason.
8 steps · Beginner
Why does the Moon have phases?
Find out why the Moon changes its shape every month, and why Earth's shadow has nothing to do with it.
7 steps · Beginner
What causes a solar eclipse?
Find out how the Moon's shadow makes a solar eclipse, and why there isn't one at every new moon.
7 steps · Beginner
What causes day and night?
Find out why the Sun rises and sets, and why it isn't noon everywhere at the same time.
7 steps · Beginner
What causes the midnight sun and polar night?
Find out why the Sun doesn't set for weeks in the Arctic summer, and why the polar night doesn't start with a bang.
8 steps · Beginner
Why do we always see the same side of the Moon?
Find out why the Moon always shows us the same face, and what we would see if it didn't turn at all.
8 steps · Beginner
Where does the Sun rise?
Watch sunrise in Berlin through the year and find out why the Sun rises due east only twice a year and never stands overhead in Europe.
8 steps · Beginner
How this was made
This simulation was built with AI from the sources below. Before it goes online, an automated test checks every control, view and part. The positions of the Sun and Moon follow a simplified astronomical model: full moons and eclipses fall on their real dates. Sizes and distances are drawn much smaller than real unless you switch to true scale, the time is solar time without time zones, and the sunlight is measured outside the atmosphere. It may contain errors. If you find one, write to us: office@soticek.com