Astronomy and space sciencePrint
The planets spin as they orbit the Sun. It takes the Earth 24 hours to make one complete turn on its axis, so an Earth day is 24 hours long.
Different planets take different amounts of time to make one complete turn, so they have different lengths of day.
The Sun lights up one half of the Earth, and the other half is in shadow. As the Earth spins we move from shadow to light and back to shadow and so on. It is daytime in the UK when our part of the planet is in the lit by the Sun. And it is night-time in the UK when our part of the planet is facing away from the Sun.
During the day, the Sun appears to move through the sky. Remember that this happens because the Earth is spinning on its axis. In the UK if we look south and follow the path of Sun in the sky during the day, it looks like this:
The Sun appears to move from east to west. That's because the Earth is spinning towards to the east, so we see the Sun first appear there at the start of the day. The Sun 'rises' in the east and 'sets' in the west.
One way to remember which way the Earth turns is to remember "w.e. spin", which means the Earth spins from west to east.
During the night, we cannot see the Sun. But the Earth is still spinning on its axis. This means that the stars appear to move from east to west in the sky, just as the Sun does in the day.
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