Earth & Space
Why does it get dark in the evening?
A lamp and a globe help solve the day-and-night puzzle.
The short answer
Earth turns. The side facing the Sun has day; the other has night. Rotation carries places into and out of sunlight. The Sun does not need to travel around Earth for this.
A place turns into and out of the light
1. One half receives sunlight
The Sun lights the facing side of Earth.
2. Earth rotates
A place moves with Earth’s rotation out of light and into darkness, then back.
3. The Sun is not switched off
Earth’s turning causes the change.
The Sun stays on the left. Red marks the same place on the rotating Earth: first on the day side, then the night side, then in the light again.
The drawing shows selected times, not real sizes or distances.
An imagined Wusel scene
Puschel and Flauschi investigate
Flauschi places a globe beside a lamp. Puschel“The lamp is playing the Sun today!”
Flauschi“And the globe models Earth. These sizes and distances are not real.”
They mark a place and slowly rotate the globe. The place moves from light into shadow. Puschel“Night is arriving there.”
Flauschi“Earth keeps turning. Nobody switches the Sun off every evening.”
After another half-turn, the place is in the light again. Puschel“Good morning, little model place!”
Little Wusel quiz
What causes the daily cycle of day and night?
Choose one answer: a), b).
- a)Earth rotating.
- b)By Earth’s yearly orbit around the Sun.
Show answer
Correct answer: a): Earth rotating. Earth spins on its axis.
Is it daytime everywhere on Earth at once?
Choose one answer: a), b).
- a)No.
- b)Yes.
Show answer
Correct answer: a): No. No. Sunlight illuminates the side facing the Sun.
Word help
- rotation
- Turning around one's own axis.
- axis
- An imaginary line around which something turns; in machines it may also be a physical part.
Explore in more detail
Here you will find longer explanations and further details. You can explore them together.
Understand step by step
How it works – simply explained
One half receives sunlight
The Sun lights the facing side of Earth. The other side is in shadow, where it is night.
Earth rotates
A place moves with Earth’s rotation out of light and into darkness, then back. Rotation means turning around its own axis.
The Sun is not switched off
Earth’s turning causes the change. A lamp and rotating ball can model the idea, but their sizes and distances do not match space.
Why morning is not simultaneous everywhere
Imagine a dot for your home on an Earth globe. When rotation carries it from darkness into sunlight, day begins there. An opposite place leaves the light. The Sun need not travel around Earth each day. The picture is a snapshot; rotation changes the lighting at each place.
The key points again
Discovery 1
Earth spins on its axis. The axis is an imaginary line through the middle of Earth from the North Pole to the South Pole. One rotation takes about 24 hours.
Source: [3]
Discovery 2
The side facing the Sun receives sunlight and has daytime. The side facing away has night.
Discovery 3
Many places have a daily cycle of day and night. Near the poles, there are also periods of very long days or nights.
Source: [2]