Smithsonian National Air and Space Museum

The Science of Light and Shadows

Science Goals for Light and Shadows:

After explorations, students will be able to understand:

  • Most objects don’t make their own light.

  • The Sun, lamps, flashlights, and fires are all sources of light.

  • Shadows need a light source and an object.

  • Shadows show the shape of an object.

 

What is Light?

  • žLight is a form of energy and travels as a particle and a wave.
  • Humans see light in seven different colors: Red, Orange, Yellow, Green, Blue, Indigo, and Violet (ROY G BIV).
  • All objects reflect or absorb the seven different colors of light. Objects appear to be different colors based on what colors they reflect.
     

What is a Shadow?

  • žShadows need a light source and an object.
  • A shadow is light blocked by an object.
  • The object can block all or part of the light.
  • Shadows change size based on how close they are to the light source.

 

The Science of Light and Objects

  • Opaque objects block all the light.
  • žSome objects don’t block any light – like windows. These are called transparent objects.
  • žWhen an object blocks part of the light, but lets part of the light through, it is called translucent. Some translucent objects act as filters, and only let certain colors of light through. These objects create colored shadows.

See the blog “The Science of the Seasons” for more information about shadows in nature.

 

How do I explain sunrise and sunset?

Discussing the movement of the planets around the Sun can be too abstract for most learners (big and little!) This is why space science is not explored by children until the later elementary years. But as you are studying shadows, young children may begin to have questions about the Sun and the Moon. Even if it is not age-appropriate to teach space science in depth, we don’t want to teach misconceptions to our littlest learners. For curious students, here are just some ways that you can discuss the movement of the Earth, Moon, and Sun:

  • Use a globe and a light source to illustrate how the Earth moves around the Sun. Explain that when it is day time in the United States of America, it is night time on the other side of the world. 
  • Use language that is accurate but not complicated, such as "The Sun appears to move across the sky," not to be confused with "The Sun moves across the sky."  Same with the Moon. 
  • Let students know that the stars are always in the sky, even when we can not see them during the day time! This is because the Sun is SO bright! When the Sun goes away, it becomes dark and we can start to see the stars again.