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Shadows

Space and time · level 1, lesson 3 of 6

A question to start

Go outside in the morning and look at your shadow. Is it long or short? Look again at lunchtime. Has it changed?

The idea

A shadow forms where something blocks the light. Your shadow always points away from the Sun.

  • In the morning and evening, the Sun is low, so shadows are long.
  • At midday, the Sun is high, so shadows are short.
  • As the Sun moves across the sky, shadows swing round.

Long ago, people used this to tell the time. A sundial has a stick whose shadow moves round a dial through the day.

morningmiddayevening

Worked examples

1. Morning. The Sun is in the east, so your shadow points west, and it is long.

2. Midday. The Sun is high, so your shadow is short and nearly under your feet.

3. A sundial. At 9 o'clock the shadow points one way; by 3 o'clock it has swung round to the other side.

Try it

  1. Which way does a shadow point?
  2. When are shadows longest?
  3. When are shadows shortest?
  4. How does a sundial tell the time?
Answers
  1. Away from the Sun.
  2. In the morning and evening, when the Sun is low.
  3. At midday, when the Sun is high.
  4. The shadow of its stick moves round the dial as the Sun moves across the sky.

Common mistake

"My shadow is always the same size." Your shadow changes all day, because the Sun is at a different height.

Where it leads