What Causes Day and Night?

Contributor: Hannah Brooks. Lesson ID: 12431

Do you get dizzy spinning around on a merry-go-round? Did you know you live on a ginormous merry-go-round? Why does the sun move overhead and seem to change as the seasons change? Find out what's up!


Space Science and Astronomy

learning style
personality style
Grade Level
Intermediate (3-5)
Lesson Type
Quick Query

Lesson Plan - Get It!

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Watch this time-lapse video of the sun rising and setting.

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  • Why does the sun set?
  • Where does it go?
  • Where does it come from?
  • 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.

solar system

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.

Earth's rotation

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?

Earth's rotation

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.

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