Investigating Shadows

Shadows are formed when something partially blocks a source of light, such as when a person stands in the sunlight. Observation and measurement of shadows has been used by scientists and artists alike for thousands of years.

Useful shadows

Measurement of shadow positions can help indicate the time of day using instruments such as sundials. You can learn more about making your own sundials in this PALMS blog post and this series of videos:

• Make a Nodal sundial
• Make a T Bar sundial
• Make a Gnomon sundial

Earth’s moon does not have its own source of light, but we are able to see it because the surface is illuminated by the light of the Sun. During a lunar eclipse, the Earth passes between the Sun and the Moon and we see Earth’s shadow travelling across the Moon.

Series of photos from a lunar eclipse (Image: Wikipedia Commons)

Shadows in art

Before photographs were invented, silhouettes were a popular way for people to have their image captured. The traditional method of cutting out a person’s silhouette from a dark material and mounting it on a light-coloured background became popular in the late 18^th century.

Drawing a Silhouette by Johann Rudolph Schellenberg (Image: Wikipedia Commons)

A traditional form of storytelling in several cultures is using shadow puppets. Elaborately carved puppets with moving parts are held near a piece of cloth illuminated by candles and the puppeteer moves the puppets and light sources to illustrate the story. This technique is still demonstrated today.

Indonesian shadow puppets (Image: Wikipedia Commons)

Observing shadows

You can have fun making some simple observations of shadows and your own piece of shadow art, as demonstrated in this PALMS video. The teacher notes to accompany the Investigating Shadows activity can be found here and the student worksheet can be found here.

More information

Some further information on shadows can be found on the following web pages:

• A series of activities to investigate shadows further can be found on the NZ Science Learning Hub web page.
• The Royal Society (UK) has put together an investigation featuring videos with Prof. Brian Cox about What factors affect the size of a shadow in a shadow theatre?
• This video from Crash Course Kids looks at how the position of the Sun affects shadows.
• This NASA web page explains how a solar eclipse occurs.