It seems to us that Earth stands quite stable (稳定的). But it is really m all the time. It turns around a make-believe line through its centre. We c this make-believe line Earth's axis(轴). The t ends（尽头） of Earth's axis are its poles(极). It t Earth 24 hours to travel around its axis once. We look at the sun and say it ‘rises' and t across the sky, but the sun doesn't really do so. It is the turning of E that makes us feel that the sun were moving across the sky. We can't see the Earth is moving b everything on Earth is turning around it.
As Earth moves around every 24 hours, the first half of Earth faces the sun and then the other h. When our half of Earth is f the sun, we say it is day. When our half is a from the sun, we say it is night. It is the turning of Earth that tells us when to get up and when to go to bed.
