Go to my saved resources

Planets don’t travel in perfect circles—they follow stretched-out paths called ellipses. This idea comes from Kepler’s First Law, which tells us that a planet’s orbit around the Sun is an oval shape. That’s why sometimes a planet is closer to the Sun and sometimes it’s farther away. These changing positions also explain why we see different constellations at different times of the year!

In this project created by Ilana, a member of the Rosie Innovators STEM program for young women in high school, you’ll model planetary orbits to see Kepler’s First Law in action. Curious how planets travel through space? Gather your supplies and follow the steps below!

Step-By-Step Instructions

Step 1

Take the foam and place it down with the long side on top.

Step 2

Insert one of the golden brads about 1/3 of the way down the long side of the foam in the middle of the short side. Make sure to leave a little gap between the foam and the head of the brad.

Step 3

Insert the other golden brad about 2/3 of the way down the long side of the foam in the middle of the short side. Make sure to leave a little gap between the foam and the head of the brad.

Step 4

Take the loop of string and put it down around the brads.

Step 5

Insert the tip of the marker into the loop and pull it outward until the string is tight.

Step 6

Move the marker around the pins keeping the thread tight. This traces the orbit of the planets around the sun.

Step 7

Take out the marker from the string.

Step 8

Remove the loop of string and one of the golden brads so that only the orbit and 1 golden brad are left.

Step 9

Take one of the colorful brads and place it somewhere on the oval to represent the planet.

Step 10

Decorate the foam however you want to represent stars.

Real Women in STEM

Resource 1

Heidi B. Hammel

Heidi B. Hammel is a planetary scientist who has worked on many NASA missions, including the Gemini, Hubble, Spitzer, and Keck telescopes. She has been recognized for her communication as an active planetary scientist to the public and has been a key contributor to a more recent understanding of both planets within and outside our solar system.