Shadow Clocks

Shadows don't stay the same. If you move, your shadow moves with you.

You've probably also noticed that the shadow of something that doesn't move, such as a house, can move too. Have you thought about why that happens? The light is coming from the Sun and it is being blocked by the house.

As the Sun moves, shadows of objects that stay still, will move!

Don't worry, they don't start jumping around!

But when the sun rises, shadows appear longer and in the opposite direction to the light source - this is on the right side of the object, with the sun shining on the left.

As the sun gets higher, the shadow will fall directly behind or beneath the object.

Then as the sun sets, the shadow will fall on the left side as the sun moves over to the right and finally sets. Remember, this is only true for objects that stay in one place. Objects that move - like humans and animals, depending on what way they are facing, the shadow might appear differently to this.

Many years ago, people used to use the Sun and shadows to help them tell the time, using a clock made for the sun, called: a sundial.

 

The clock face would line up with the shadow and where the shadow falls, shows what time it is! (approximately, you can't really tell minutes or seconds, but you can know the hour with a sundial!)

Another reason that using the shadow from the Sun is a great way to tell the time, is because it means we don't have to look at where the Sun is in the sky and this helps us protect our eyes. It's important to remember, we must never look directly at the Sun because it will damage our eyes.

In this worksheet we will look at why shadows change during the day, and at how this can be a useful way of telling the time.