What is a shadow?
A shadow is a dark shape made when something is blocking the light. To have a shadow there must be a source of light like the Sun, a light bulb, a torch or a fire. At night time there isn’t much light which is why you see fewer shadows at night than during the day.
Does everything have a shadow?
Any object that can block light can have a shadow.
Some objects are transparent like glass, these objects don’t block the light and let light pass through them. They don’t create shadows. Other objects are translucent, meaning they let light pass through a little bit like a balloon, these create small shadows. Objects that are opaque like a desk or wall don’t let light pass through at all, they have the biggest shadows of all.
- The Earth makes a shadow too, it’s called an umbra.
- Shadows are used to make shadow puppetry.
- A long time ago people made sundials, a type of huge clock that tells the time based on shadows.
- The closer an object is to the source of light, the bigger the shadow.
- If there are multiple sources of light there are multiple shadows. The parts of the shadow that overlap are darker.
- The first person to calculate the size of planet Earth used the measurement of shadows over 2000 years ago.