Phases of the Moon

by littleBits

Published on April 23, 2014

Moon Day, July 20, is a celebration of the first day man walked on the moon in 1969. In honor of Moon Day, this project simulates the phases of the moon in a lunar month. Use the light sensor to control the moon's orbit and see the various phases of the moon, from a waxing gibbous, to a full moon, to a waning crescent!

How To Make It


Assemble your circuit. Connect the power Bit to the battery cable and 9V battery. Be sure to switch the small black switch on your power Bit to "on". Then connect power + bright led + wire + light sensor + wire + dc motor.


Find a cereal box to be the base for your project. Then cut out a piece of cardboard to the same size as your cereal box. Add a small hole in the center-top portion of your cardboard rectangle. To the closed end of the box, add the piece of cardboard to act as your sun backdrop. The hole should be near the top. You can attach using hot glue.


Now it is time to make the mechanism that the Earth and moon will spin on. Make a 3d triangle by folding a strip of cardboard twice and gluing the 2 ends together. Attach the dc motor to one face of the triangle. Tape it in place.


Attach a bbq skewer to the d-shaft of the dc motor. Use tape or try other ways of connecting to the d-shaft by checking out the dc motor tips & tricks. The bbq skewer should be sticking up at an angle. This is where your earth will sit. The actual earth is tilted at 23.4 degree angle.


Open the cereal box and tape or glue the cardboard triangle to the inside of the box. Make sure to poke a hole in the top of your box for the bbq skewer to stick out of.


Let's put all the bits in place. The light sensor should be placed on top of the box and the bright led should be positioned behind the hole on the cardboard backdrop. Now when you turn your circuit on, the bright led will shine through the hole. Tape all Bits in place.


Stick a styrofoam ball on the skewer to represent the earth. Then attach a stiff wire (you can use a coat hanger or pipe cleaner as well) to the bbq skewer. Make sure to align it with the bright led on the other end of the box. Tape or glue it in place. To the end of the wire, attach a ping pong ball. This will represent the moon.


Decorate your project! Use paint and colored paper to create a space scene.


Set the light sensor to dark mode and adjust the sensitivity so that when you turn off the lights and place your hand over the sensor, your globe spins and your moon orbits. When you remove your hand, the spinning will stop, but the light remains on.


Now you are ready to examine the different phases of the moon. At any point in the orbit, when you look at the moon from the point of view of the earth, you will see a different shadow being cast. The various shadows represent the phases of the moon. See the following diagrams for more information: Phases of the Moon

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