Where do shadows go?

Shadows -  is need light before they can appear. If the light goes out, the shadow goes out too.

  A shadow is that part of an an illuminated surface which is shielded from oncoming light rays by an object through which the light cannot pass. If the source of light is small, the outline of the shadow will be sharp and pro­nounced and its shape will be that of the object producing it. If the source of light is large, the shadow is very dark in the middle (the umbra) and much lighter on the outside with indistinct outlines (the penumbra).

 Shadows cast by the sun always have a penumbra and the shape of the shadows cast varies with the position of the sun in the sky and the angle of its rays. An upright pole will cast a long shadow in the morning when the sun is rising but grows shorter as noon approaches. As the sun declines in the sky, the shadow grows longer again.

Human shadows have often had a mystical or magical significance. In the picture above you can see a masterly use of shadow to give form by the English painter Wright, of Derby.