At-home STEM Activities: Alexander Calder-inspired Moon Phases Mobile
Alexander Calder (1898-1976) was an American artist who was a pioneer in kinetic art. He created sculptures that moved, some using motors and other just moving in response to any motion in the air around them. Calder’s sculptures that relied only on air were called “mobiles.” His mobiles were either free-standing or hanging pieces of art made of punched-out aluminum sheeting and wires.
Calder’s Maripose, 1960 (image credit: bonhams.com)
Part of the beauty of Calder’s mobiles is the serenity in the balance of each of the metal shapes. The visual harmony of his sculptures is the result of both Calder’s artistic vision and a basic geometric property of any object—center of gravity.
Center of gravity is the average location of the weight of an object. In flight, objects rotate around their center of gravity, so determining where the center of gravity is is very important when designing airplanes and rockets. You can find the center of gravity of an object by finding the point where it balances.
try finding the center of gravity of a pen or pencil by balancing it on your finger
Let’s use the property of center of gravity to create our own mobile like Alexander Calder!
Moon Phases Mobile
Materials:
Thin cardboard (like from a cereal box)
Round objects to trace
Pencil
Paint
Paintbrush and water (to wash off the brush)
Pin
Wire
Needle nose pliers
String
Instructions:
1. Trace circles onto your cardboard and cut out the shapes.
2. Paint one side of your circles to look like the phases of the moon. Wait for the paint to dry and paint the other side of the circles.
3. While the paint is drying, cut four piece of wire, each about 5 inches. Once all the painted circles are dry, use the needle to poke two holes about 0.25 inches apart in each circle.
4. Now we’ll create the bottom tier of the mobile. Insert one end of the wire into the hole closest to the edge of the “new moon” circle.” Bend the wire into a 90 degree angle about 0.5 inches from the end, then make a second bend the distance between the two holes.
5. Insert the wire into the second hole, and use the needle nose pliers to bend and secure the wire. Repeat this process with the “crescent moon” circle.
6. Find the center of gravity of the bottom tier by balancing it on the end of the pliers. When you find the balancing point, twist the wire to form a loop.
7. Repeat step 5 with the “half-moon” circle. Twist the other end of the wire into the loop of the first tier.
8. Find the center of balance of the second tier and twist a loop at that point.
9. Repeat step 7 and 8 with the remaining two circles, the “gibbous moon” and the “full moon” circles.
10. Tie a string to the loop of the top tier. Hang your mobile and make any adjustments to the wires to get your mobile to look how you want.
Your mobile is done—enjoy your physics-based art!
Take this activity further with your own creativity
Come up with your own design, use other materials to make your mobile, or make it more elaborate with more tiers
