Spark image


Where there is no light there is darkness, we call this a shadow. In fact at night we are in the shadow of the Earth.

You can see from the two diagrams that there are two types of shadow; a crisp edged one formed by a point source of light and a rather more fuzzy one that is formed by a larger source.

The region of deep, total shadow is called the UMBRA and the region of partial shadow is called the PENUMBRA. The umbra is a region where no light can get to while the penumbra is a region where some light can reach.

Click the link to show how the position of an object affects the size of its shadow. See: Shadows - size and object position

You can use shadow effects in photography to give the right atmosphere to a picture.

Shadows also explain lunar and solar eclipses and you can find out more about these in the section on astronomy.

See: Solar and lunar eclipses

© Keith Gibbs 2016