Everyday Life & Technology
Why does my shadow move with me?
Puschel waves a paw, and his shadow joins in.
The short answer
Your body blocks light. Less light reaches the ground behind it: that is your shadow. When you or the light source move, the place receiving less light changes too.
Compare the light path and shadow
1. Light takes a path
A lamp sends light in different directions.
2. Less arrives behind
The blocked light does not reach part of the wall behind.
3. Different direction, different shape
Moving the lamp or object changes the light paths.
Yellow is the light source, brown the opaque object, and the wall is on the right. Grey shows where direct light is missing.
In the last picture the object is closer to the wall, making a smaller shadow. The wall itself does not move.
An imagined Wusel scene
Puschel and Flauschi investigate
Puschel spots a dark shape by his feet. Puschel“A very quiet visitor!”
He raises a paw. The shape raises one too. Flauschi“That is your shadow. Your body blocks some sunlight.”
Puschel steps sideways and the shadow moves. Puschel“What an attentive companion.”
Flauschi indicates the Sun behind them without looking into it. Flauschi“Our shadows lie on the other side, away from the light.”
They stand side by side and wave their paws. Two furry greetings appear on the ground.
Little Wusel quiz
What does a shadow need?
Choose one answer: a), b).
- a)A light source and something that blocks light.
- b)A heat source without light or an object
Show answer
Correct answer: a): A light source and something that blocks light. A light source and an object that blocks light.
Does a shadow always stay the same length?
Choose one answer: a), b).
- a)No.
- b)Yes.
Show answer
Correct answer: a): No. No. The light direction and the position of the object change it.
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
Light takes a path
A lamp sends light in different directions. In uniform air it travels straight. An opaque object blocks some of it.
Less arrives behind
The blocked light does not reach part of the wall behind. This darker area is a shadow, not a substance coming out of the object.
Different direction, different shape
Moving the lamp or object changes the light paths. The shadow moves or changes, so one body can make different shadows.
The key points again
Discovery 1
A shadow forms when an object blocks light. Less light reaches the surface behind it.
Source: [1]
Discovery 2
Your shadow changes when you move or light arrives from a different direction.
Source: [1]
Discovery 3
A low Sun can make long shadows. Shadows are not always equally dark or sharply edged.