Unlike many of my posts, today’s project requires slightly less art and more math!
When we talk about the solar system, it’s easy to picture the planets orbiting around the sun.
Add in the earth spinning on its axis while orbiting around the sun and things start to look more complicated.
Add in the moon spinning on its axis while orbiting the earth. And the earth is also spinning on its axis while orbiting the sun—well, my head starts spinning too!
One thing that’s not easy to picture, though, is the solar system’s size.
This activity helps kids learn about the scale of the universe using common household/food objects.
Books
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If you want to avoid shopping on Amazon, I suggest checking Bookshop or your local bookstores instead.
If Pluto Was a Pea, by Gabrielle Prendergast, illustrated by Rebecca Gerlings. This is a great picture book read-along that focuses on the relative sizes of the planets in our solar system. (Fiction)
The Girl Who Named Pluto: The Story of Venetia Burney, written by Alice B. McGinty, illustrated by Elizabeth Haidle. This picture book biography offers another example of a scale model of a solar system. (Nonfiction)
The Magic School Bus: Lost in the Solar System, by Joanna Cole, illustrated by Bruce Degen. This book is a humorous way to introduce children to the key facts about the solar system. (Fiction)
Both If Pluto was a Pea or The Girl Who Named Pluto focus on models of the solar system. You can use these objects to build your model of the solar system.
Or, you can start with the Magic School Bus Story and build your own solar system using the activity outlined below:
Build a Scale Model of the Solar System:
This is a new version of an activity we did a couple of years ago. You can find the original version here. I’ve expanded the instructions, and hopefully made it easier to follow.
Materials (to show the planets’ sizes):
- A 21-inch exercise ball, or tape/chalk to mark a circle 21 inches across.
- A sesame seed or millet seed
- Two peas or small pony beads
- One peppercorn or other small seed
- Two mandarin oranges (a larger and a smaller one), or one orange and a golf ball
- Two normal/small marbles
- An open space 300 feet long or longer.
I used Exploratorium.edu’s calculator to build this model and set the sun’s size to 21 inches (or 53 cm). You can use the calculator to create a smaller model if you want. The smallest planets are already tiny at this scale, though.
I recommend using a model at least this size if you can:
For this project, you will want to use a straight sidewalk or other open area. It should be at least 300 feet long. This space will allow you to mark out the first four planets in a straight line.
If your sun is 21 inches in diameter, that’s about as big as a medium-sized exercise ball. If you have a ball this size, set it at the beginning of your solar system. If you don’t, then use tape or chalk to mark a circle 21 inches across.
Now, measure 72 feet from the sun. Place a millet seed or a sesame seed there to mark Mercury.
Measure another 63 feet (or 135 feet from the sun), and place a pea seed there to mark Venus.
Measure 53 feet further (a total of 188 feet from the sun). Place the other pea seed there to mark the earth’s position.
Measure 98 feet more (or 286 feet from the sun), and place a peppercorn there to mark Mars.
Mercury, Venus, Earth, and Mars are the four inner planets. They’re much closer to the sun than the others. If you want to continue the solar system from Mars, the distances increase astronomically!
Using this scale, Jupiter is almost seven hundred feet further on, at 978 feet from the sun. Jupiter would be the size of a mandarin orange.
(In between Mars and Jupiter is the asteroid belt—around 40,000 asteroids no larger than grains of sand at this scale.)
Beyond Jupiter is Saturn. At 1,794 feet from the sun, Saturn would be about as large as a small, peeled mandarin orange. It’s huge compared to the other planets, but still noticeably smaller than Jupiter.
Then, at 3,608 feet from the sun, Uranus would be about as big as a regular-sized marble.
Neptune would be 5,657 feet (or over a mile) from the sun. Neptune is a bit smaller than Uranus, but still about the size of a marble.
Finally, Pluto and the Kuiper Belt would be a mile-and-a-half, or 7434 feet, from the sun. It’s even smaller than Mercury, though, so it would only be the size of a grain of sand.
And that’s how you put the solar system into perspective!
Have you ever built a scale model of the solar system with your students? How did it go?
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