It's Just a Phase

Contributor: Lindsey Congalosi. Lesson ID: 13120

Have you ever noticed that the moon appears to gradually change? Did you ever wonder WHY the moon changes shape, or where it goes when it seems to disappear? Read on to find out all this and more!


Earth Science, Space Science and Astronomy

learning style
Auditory, Kinesthetic
personality style
Grade Level
Middle School (6-8), High School (9-12)
Lesson Type
Dig Deeper

Lesson Plan - Get It!


Galileo quote

On, you can look up what the moon phase was on any given day in the past or what moon phase it will be in the future, even thousands of years from now.

  • How is this website able to determine the moon phase on any possible day?

Read on to find the answer to this question and learn how you can predict the moon phases website needed.

moon phases

The moon goes through a cycle of phases. It grows bigger and bigger until it's fully lit up, and then gets smaller and smaller until we can no longer see it.

You have likely observed this cycle yourself.

  • What other observations have you made?

Let's test how much you know about the moon!

phases of the moon

To figure out how moon phases work, you must understand a little thing called perspective.

From space, the moon always looks the same. Half of the moon is lit up at all times. However, the moon looks different to us because we can only see part of the illuminated half.

moon between the earth and the sun

  • When the moon is located directly between the earth and the sun, which moon phase would be visible from earth?

Approximately two weeks later, the moon will now be on the opposite side of the earth, putting the earth directly between the sun and moon.

earth between the moon and the sun

  • Which moon phase is visible from Earth when the moon is in this location?

The best way to understand moon phases is to create a lunar model.

To do this, you need:

Once you've gathered your materials, move on to the Got It? section to create your very own moon model.

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