If you watch the moon every night, you see its shape appear to change. Does the moon really change shape? Of course not, but its appearance from Earth certainly changes. How does this work? The answer lies within the part of the moon that receives sunlight, and the part of the moon that does not receive sunlight.

Part 1

Letís look at a diagram of the Earth moon system to figure out how this works.

Activity 1

Sunlight will shine on the side of the Earth (or moon) that faces the sun. We call this day on the side of the Earth that faces the sun, and night on the side of the Earth that does not face the sun.
Keep in mind that sunlight will illuminate the side of an object that faces it!
Click on the arrow in the corner to go to Part 2.









Part 2      

OK, so what does this have to do with moon phases?

Activity 2

Click Activity 2 above to go to the next part of the activity.
     The diagram still shows the shadows that you correctly identified before, but in this diagram, you will need to determine what the moon looks like to humans on Earth. It's all a matter of perspective.

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Enter your name:
  1. The phases of the moon are produced by:
    A)  the spin of the Earth
    B)  varying amounts of sunlight reaching the side of the moon that faces Earth
    C)  varying amounts of sunlight reaching the side of the moon that faces the sun
    D)  the orbit of the Earth around the moon

  2. At full moon:
    A)  the side of the moon facing the Earth receives no sunlight.
    B)  the side of the moon facing the Earth receives full sunlight.
    C)  the moon is between the Earth and the sun
    D)  none of these

  3. At new moon:
    A)  the side of the moon facing the Earth receives no sunlight.
    B)  the side of the moon facing the Earth receives full sunlight.
    C)  the moon is between the Earth and the sun
    D)  A and C
    E)  none of these

  4. At first and third quarter moon phases:
    A)  the moon is basically at a 90 degree angle from the sun.
    B)  half of the side of the moon we can see "shines"
    C)  A and B
    D)  none of these

  5. In the first half of the lunar cycle, the "growing" part of the moon appears on the ______ side. After full moon when the moon is waning, the illuminated part of the moon appears on the ______ side.
    A)  right, left
    B)  left, right
    C)  right, right
    D)  left, left

 

Letís summarize:

Here's a question for you! Can you see the moon sometimes in the daytime? You'll never see a full moon in the daytime sky because it rises at sunset and sets and sunrise, but you can sometimes see other phases of the moon in the daytime. It looks a little pale and washed out, but it's there.

  1. Why doesn't the moon appear as bright in the daytime as it does at night?
    A)  The moon is receiving less sunlight.
    B)  The sunlight in the atmosphere makes the moon appear less bright.
    C)  The moon does not reflect light in the daytime.

    Here's another question for you! Let's see if your brain is really on today!

  2. If you can see a full moon at your position on the Earth, what type of moon will you see if you go to exactly the opposite side of the world on the same day (24 hours)?
    A)  A new moon.
    B)  A full moon.
    C)  No moon at all.
    D)  None of these.

  3. If you see two full moons in the same month of a calendar year, the second full moon is called a:
    A)  Moon River
    B)  Blue Moon
    C)  Moonraker

    One last point: Remember that everyone on the planet will see the same phase of the moon at the same time. It is the Earth that rotates, giving us night and day.

  4. Further thought question:
    We know that tidal effect occurs primarily because of the moon orbiting the earth. The Earth's rotation is what causes the effect of two high and two low tides per day and each location. Do you think there would be a correlation between the time of moonrise and the time of high tide? Why or why not?






Part 3

This part puts everything in action and lets you observe moon moving around the earth in it's orbit.

Activity 3