At-Home STEM Activities: Hole-Punch Earth
Create a scale model of the Earth and Sun with craft supplies in your own home!
Materials
• a hole punch circle (what you normally discard when you use a hole punch)
• metric ruler
• large square of butcher paper (about 1 meter x 1 meter)
• scissors
• compass
• pencil
• calculator
tape measure (for bonus activity)
Earth's Diameter = 12,756 km
Sun's Diameter = 1,392,000 km
Earth Distance To The Sun = 149,600,000 km
Your hole punch circle represents the planet Earth.
Measure the diameter of the circle. Set up a proportion to determine the diameter of the Sun. For example, if the hole punch has a diameter of 1 cm, the following would be a way to find the scaling factor:
This scaling factor (which has no units) can be multiplied by the actual diameter of the Sun to find the size of the scaled down version. To set this up as a proportion, we can compare the two size/distance ratios and solve for the unknown diameter of the scaled down Sun, x:
Once you have found the scaled down Sun's diameter, draw it on the butcher paper. What is you'r Sun’s radius? What is its diameter?
The diameter is the distance across a circle in a straight line. The radius is half the circumference, or the distance from the circle’s center to its outside boundary (perimeter).
Once you have found your scaled-down Sun's diameter, use the compass to draw it on the butcher paper:
Use a ruler to set the distance from the point of the compass to the pencil's lead to your radius
Place the point of the compass at the center of the circle.
Draw the circle by turning the compass 360º.
Cut out your Sun, which should be about 100 times the diameter of your hole punch Earth.
Bonus Activity:
Using the formulas above, determine the correct scaled distance between the Earth and Sun. Using a metric tape measure, mark the location of your Sun and pace out the correct distance to Earth. You can try this outside with a friend of family member: if one of you is the Sun and the other is the Earth, how far away should you stand from one another?
What's Going On?
The Sun is much larger and farther away than most people realize. The sun is about 100 Earth diameters across and about 100 Sun diameters away from Earth.
If the hole punch “Earth” is .7 cm in diameter, then the correctly scaled sun should be about 70 cm in diameter. The correct distance for this particular model would be about 70 meters!
