What Causes Day and Night?

Lesson Plan - Get It!

Audio:

• Have you watched the sun set or rise in person?

It can be a wonderful sight.

• Why does it happen?

The earth is a giant sphere, moving in a system of planets around the sun.

You cannot feel it, but the earth is constantly spinning, or rotating, on an axis.

The earth's axis is a central point in the planet's middle. The axis has a tilt, causing the earth to rotate at an angle.

It takes the earth 24 hours to completely rotate its axis.

• Why do you think 24 hours is an important number?

This is how we organize time — by day and night, based on the earth's rotation.

When daylight is outside, we face the sun. At nighttime, we are facing away from the sun.

• If it is daytime in the United States, what time is it halfway around the world?

If the United States is experiencing day, countries on the opposite side of the earth are experiencing night.

Our spherical earth spins on its axis once each day, causing day and night. It takes 24 hours to complete one spin, which is how we keep time.

Half of the earth receives light during that time, while the other half is in darkness.

Look at the image above.

• How might the earth's angle impact the amount of sunlight on the earth's surface?
• Do you think the North and South Poles get the same amount of sunlight? Why or why not?

Now, predict sunlight at the North and South Poles. Write your prediction on a sheet of paper.

In the Got It? section, learn more about the cause of day and night on the earth.