Every morning the Sun appears in the east, crosses the sky and sets in the west. It looks as if the Sun moves around us. It is really the Earth that turns.
Key idea
The Earth spins (rotates) on its axis once about every 24 hours. The half facing the Sun has day; the half facing away has night. Because Earth spins toward the east, the Sun seems to rise in the east and set in the west.
Shadows change during the day too. In the morning and evening, when the Sun is low, shadows are long. Near noon, when the Sun is high, they are short. A shadow always points away from the Sun.
Worked example: Count the turns
How many times does the Earth spin in one week?
- It spins once a day.
- A week has 7 days.
Answer: 7 times.
Common mistake
Thinking the Sun goes around the Earth, or that night comes when the Moon covers the Sun. Night is our side of Earth turned away from the Sun.
Try it at home
- In a dark room, shine a lamp (the Sun) at a ball or an orange (the Earth). Stick a small sticker on it for your town.
- Turn the ball slowly. When is your sticker in day? In night? At sunrise?
- Outdoors, push a stick into the ground and mark the end of its shadow at breakfast, lunch and dinner. Never look straight at the Sun.
Going further. Agnes Giberne's Sun, Moon, and Stars, the Sky and Solar System lab, and Day and Night in Earth Science.