The Sun is highest in the sky at midday and casts a short shadow. In the afternoon, when the Sun is lower in the sky, the shadow is longer. The length of the shadow is also affected by the seasons. Winter shadows are longer than Summer shadows. This is because the Sun is lower in the sky in Winter. If you don't remember why have another look at what causes the seasons. The speed of the shadow depends on the length of the gnomon. For example, if the gnomon is 2 metres tall, the tip of the shadow will move about a third of its height (60cm) in an hour - 1cm per minute. The Eiffel Tower is 300 metres high. The tip of its shadow moves across the ground at a speed of about 1.5 metres per minute. This movement is due to the Earth's rotation. |
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