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Ohio 4-H Youth Development

Ohio State University Extension


Small Moon, Big Sun 2

This is a 4-H Solar Eclipse activity by Cynthia Canan, PhD, State 4-H STEM Specialist, Ohio State University Extension and Sara Newsome, 4-H Alumnus and STEM Student Assistant, The Ohio State University
Reviewed by: Wayne Schlingman, PhD, Director of the Arne Slettebak Planetarium, The Ohio State University, Caitlyn Romshak, Extension Educator, 4-H Youth Development, Ohio State University Extension-Harrison County and Gwen Soule, Extension Educator, 4-H Youth Development, Ohio State University Extension-Sandusky County

Topic: Space Science | Estimated time: 30 minutes | For individuals and groups (BEGINNING to INTERMEDIATE level) | PDF for PRINTING

A totalThe moon covers the sun during a solar eclipse. solar eclipse is a rare and awe-inspiring astronomical event that occurs when the moon completely covers the sun, temporarily blocking out its light. As total darkness consumes the path of totality, the temperature could drop, stars and planets could become visible, and animals could behave as if it were nighttime. But we know the moon is smaller than the sun, so how does the moon cover the sun?


  • coin (one, such as a penny, nickel, dime, or quarter)

  • measuring tape

  • masking tape

  • paper plates, any color (6 in., 9 in., and 12 in. diameter) or cutout paper circles, any color (6 in., 9 in., and 12 in. diameter)

Be sure to complete this activity in a long space, such as a hallway or gym.

What To Do

  1. Tape the 9-inch paper plate to a wall at eye level.
  2. Stand in front of the plate while holding the coin in your hand at eye level. Stretch your arm straight out in front of you and hold the coin against the 9-inch plate.
  3. Close oA youth aligns a coin with the center of a eye and look at the coin with the 9-inch plate behind it. Begin taking steps backward while holding the coin straight out. Stop when the penny appears to be the same size as the paper plate (covers the entire plate when you line up the coin and plate).
  4. Using masking tape, mark the ground where the backs of your feet have stopped.
  5. Make a copy of the chart. Measure the distance from the masking tape to the wall (plate) and write it in the Actual row of the 9-Inch Plate column of the chart. Always be sure to label the unit of measure.
      6-Inch Plate 9-inch Plate  
    Prediction (inches)      
    Actual (inches)      

    Describe your observations using this sentence frame:

Using a ____________ (type of coin), I had to step ____ inches away to cover a ____-inch plate.

  1. Replace the 9-inch plate with the 6-inch plate and predict how many inches from the wall it would take for the same coin to cover the 6-inch plate. Write your prediction in the Prediction row of the 6-Inch Plate column of the chart.
  2. Test your prediction. Find the distance needed for the coin to cover the 6-inch plate. Write this distance in the Actual row of the 6-Inch Plate column of the chart. Describe your observations using the sentence frame.
  3. Repeat steps 6 and 7 with the 12-inch plate.
  4. What do you know about the size relationship among the plates? What do you notice about the distance relationship needed for the coin to cover the different-sized plates?

Talking It Over

Write your answers to these questions and talk about them with your project helper or another caring adult. 

SHARE What happens during a solar eclipse?

REFLECT How does the distance of the sun and moon impact an eclipse?

GENERALIZE Why is the sun’s distance from Earth important to us?

APPLY Why might it be important to know the distances between planets and stars?

More Challenges

Using materials of your choice, build a model to represent the size and distance differences among the sun, moon, and Earth. Remember the proportional differences among the three and build your model to match what you just discovered.

The sun, moon, and Earth align during a solar eclipse.


We know the moon is much smaller than the sun. In fact, the moon is about 400 times smaller than the sun. This means if the sun were the size of a basketball, the moon would be about the size of a pinprick or a single dot made by a sharp pencil. How can such a small moon cover the big sun? The answer is in the distance between Earth and the sun and Earth and the moon.The moon moves across the sun.

When we look at an everyday item and hold it closer to our eyes, it will appear bigger compared to when the same item is held farther away from our eyes. The same phenomenon occurs when we observe the things in the sky from Earth: an object closer to Earth will appear to be bigger compared to the same object when it is farther away from Earth.

Even though the moon is 400 times smaller than the sun, it is also about 400 times closer to Earth compared to the sun. Because of these similar ratios in distance and size, the moon and the sun actually appear to be similar in size when we observe the sky from Earth. This is why, when the moon moves in front of the sun, the moon can cover the sun completely.

Did you know?

The moon is slowly pulling away from Earth, which means the time will eventually come when the size ratio of the moon and sun will no longer match their distance ratio. Sometime in the future, the moon will appear too small to create a total solar eclipse.


astronomical. Relating to the study of objects outside earth’s atmosphere.

path of totality. The path of the moon’s shadow across Earth’s surface.

phenomenon. An observable fact or event of scientific interest

ratio. A number that shows the relationship between two amounts.

Learn more!

Visit Eclipse on the National Geographic website to learn more about the different types of eclipses and see photographs of these phenomenon.


“How Is the Sun Completely Blocked in an Eclipse?” NASA Science Space Place.
“Eclipse: How can the little Moon hide the giant Sun?” NASA Sun-Earth Day.
For more solar eclipse activities, visit

Project skill: Understanding how size and distance affect the appearance of the Earth, moon, and sun | Life skill: Decision making | Educational standards: NGSS 3-5-ETS1-2. Generate and compare multiple possible solutions to a problem based on how well each is likely to meet the criteria and constraints of the problem | NGSS 5-ESS1-2. Represent data in graphical displays to reveal patterns of daily changes in length and direction of shadows, day and night, and the seasonal appearance of some stars in the night sky | Success indicator: Predicts and records data about distance and the sizes of objects

For more solar eclipse activities, visit