Fun and easy science experiments for kids and adults.

Moon in a box

Build a box with the Moon in it, and look at it from different directions through holes. This is an experiment about the lunar phases.

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Video

Materials

1 cube-shaped cardboard box
1 flashlight or table lamp
1 white spun cotton ball (preferably quite large)
1 pencil
1 paper clip
Sewing thread
1 knife
Tape
Decoration material (optional)

Step 1

Place the box, without a lid, upside down on the table. Use the knife to cut a square hole in the center of each side (but not on the top). Each hole should be as wide as the diameter of the spun cotton ball. Save the cut-out squares.

Step 2

Paint the spun cotton ball with the pencil, so that it resembles the Moon.

Step 3

Push three quarters of the paper clip into the spun cotton ball. Tie one end of the sewing thread to the paper clip.

Step 4

Use the pencil to make a small hole in the center of the top of the box. Lift the box a little and put the ball inside. Thread the sewing thread through the hole so that it comes out on top.

Step 5

Look into one of the holes. Adjust the height of the spun cotton ball so that it covers the opposite hole.

Step 6

When you have the correct height - tape the sewing thread to the outside of the box.

Step 7

Tape the cut-out pieces of cardboard with a piece of tape over the holes, so that they become doors you can open.

Step 8

Decorate the box if you want. Write "full moon" beneath one of the doors. Write "new moon" beneath the opposite door. Write "first quarter" and "last quarter" beneath the last two doors.

Step 9

Position the lamp so that it shines straight into the hole marked "full moon". The lamp should be about 10 cm (4 inches) from the hole. Tape this door so it stays in the open position.

Step 10

Turn off the other lights in the room. Look into the different doors and discover the different phases of the moon.

Short explanation

The Moon doesn't shine itself. It reflects light from the Sun. Half of the Moon is always illuminated by the Sun. The Moon orbits Earth. Depending on where Moon is in its orbit, we from Earth see different amounts of the Moons illuminated side.

Long explanation

The Moon makes one orbit around Earth in 29.5 days. During this time, the appearance of the Moon varies as seen from Earth - from new moon, to first quarter moon, to full moon, to last quarter moon, and then back to new moon. A new moon is when the Moon looks completely dark from Earth. A first quarter moon - and a last quarter moon - is when half the Moon looks illuminated from Earth. A full moon is when the whole Moon looks illuminated from Earth. But half the Moon is in reality always illuminated by the Sun. It's only at full moon that we see this whole side, because the Sun is then "behind" Earth.

This model shows how many different ways Earth, the Moon and the Sun can be positioned in relation to each other at different times. However, it may seem a little confusing that the observer (Earth) here moves around the Moon instead of the other way around. However, this is not really an error, it just depends on which reference point you choose to observe from.

A more true error in this model is that there is always a solar eclipse during a new moon. That is, the Moon blocks the Sun as seen from Earth. In fact, a solar eclipse would occur during every new moon if the Moon rotated around Earth in the same plane as Earth's orbit around the Sun. But the Moon's orbit is inclined 5 degrees relative to Earth's orbit around the Sun. Therefore, Earth, the Moon and the Sun only end up in line with each other between two and five times a year. Most of these times there is also no total eclipse, as only part of the Moon passes in front of the Sun. In addition, the Moon's orbit is elliptical ("oval"), which means that it's usually too far away from Earth at these times to cover the entire Sun.

Experiment

You can turn this model and demonstration into an experiment. This will make it a better science project. To do that, try answering one of the following questions. The answer to the question will be your hypothesis. Then test the hypothesis by doing the experiment.

What would happen to the lunar phases if the Moon's orbit around Earth was twice as fast?
What would happen to the lunar phases if the Moon stopped in its orbit around Earth.

Variation

There is a simpler variation of this exeperiment, where you hold the Moon in front of you and illuminate it with a flashlight. You can find this experiment here: Moon on a pen.