Day and Night

We all live on Earth. It is like a big, round ball. And it is spinning. This is hard to believe because we do not feel any motion. Everything stays in place because the Earth pulls everything to itself. This pull is called gravity. The Earth always spins at the same speed (about 1000 miles per hour!). The Earth spins around one time, or makes one full rotation, in 24 hours.

Light from the sun falls on one half of the spinning Earth. This half has day. The other, darker half has night. As the Earth spins, we move through the light, into the darkness, and back again. This makes day and night. Half of the Earth is always in the light and half of the Earth is always in the dark. The Earth is always spinning and that is why it is always changing.

Look at the pictures below to see how the Earth rotates and where the sun is at each time of day.

People at point A can see the sun rise.

As the Earth turns, the people move to point B.
It is the middle of the day for them.
The sun is straight up in the sky. This means it is noontime.

When the people are at C, the sun is going down. This means it is sunset.

At D it is midnight. Now it is very dark.

Twenty-four hours, or one day, will have gone by once they get back to A. The sun will rise again and a new day will be starting.

This is what we see everyday from Earth as it rotates and the sun moves across the sky. In the morning you can see the sunrise. Around noontime, the sun is straight up in the sky. At night, you can see the sunset.

Try this experiment to see how the Earth moves from day to night.

The turning Earth gives us about twelve hours of daylight and twelve hours of darkness. This gives us enough time to go to school, go to work, and play during the day and enough time to sleep at night.