Why shadows change

The objective of this animation is to respond to these questions. The setting is simple to be able to isolate the effects of the light source here it is the sun on the objects here it is the tree with or without the house. While displacing the sun the shadow ellongates, retracts or disappears. The light disseminates in a straight line. It is therefore easy to understand that the shadow reproduces the silhouette of a more or less deformed object according to the position of the sun.

Try experimenting with light and shadow. Shine a light on translucent objects. The shadow created will be light or might even be colored. Try tracing a shadow onto paper. Use your hands to make shadows on a wall or learn how to make shadow puppets. All of this light travels in a straight line until it hits something. Sometimes, it travels a short distance — like when we switch on the lamp. Other times, light travels thousands of years — like the light from stars we see in the Milky Way.

It is easy to see our shadows when we are outdoors in the sunshine on a clear, bright sunny day, but do shadows form when an object blocks light from other sources? The answer is yes, but they may be difficult to see if the light source is not very bright has a low light intensity.

Shadows are also more definite sharper where there is contrast between the shadow and the lit surface, for example, a shadow on a white wall will be more easily seen.

The size of the light source can sharpen or blur the shadow. A small spotlight like a cellphone torch forms a more distinct shadow than an overhead room light, but the sharpness of the shadow changes when the torch moves away from the object. A shape of an object always determines the shape of its shadow.

However, the size and shape of the shadow can change. These changes are caused by the position of the light source. When we are outside on a sunny day, we can see how our shadows change throughout the day. When the Sun is low on the horizon, the shadows are long. When the Sun is high in the sky, the shadows are much shorter.

We can create the same effects indoors by changing the position of a torch as it shines on an object. As Earth rotates, the Sun appears higher in the sky and shadows get shorter. At noon, the Sun is overhead and objects cast short shadows or no shadow at all. The length of shadows changes as Earth rotates. In the morning, the sun is low in the eastern sky and shadows are long. At the time of sunrise if a man stands facing the east, his shadow will be towards west. At the time of sunset the shadow of an object is always in the east.

If a man stands facing the North, at the time of sunrise his shadow will be towards his left and at the time of sunset it will be towards his right. East is in the clockwise direction of rotation from north. West is directly opposite east.

In the morning, the sun rises roughly in the east and tracks upwards. Answer: Shadows are longer in the morning and evening and short in the noon because the sun rays are slanting in the morning and evening whereas at noon it is just above our head. The size of the shadow depends on the position of the object from the source of light. Look at the illustration to the right and notice the direction of the shadow is away from the source.

During midday it would be the shortest, and in afternoon it would be on the opposite side. If the sun is low in the sky 10 degrees , your shadow would be 5. The corresponding ratio at 5 degrees is So an average height person 5. At noon the sun is directly overhead, the sun rays fall vertically on the body so the shadow is very short. In the morning or in the evenings, the sun rays fall in an inclined position,so the shadows are long.

Noon is going to produce the shortest shadow of the day, though this length will vary based on the time of year and how far north or south of the equator you are.