Paper Plate Education
"Serving the Universe on a Paper Plate"

Activity: Milky Way Galaxy

The following text is excerpted from GLPA Proceedings, 1992, p. 85; used with permission:

Background: Our sun is the nearest star of over 100 billion orbiting a central point. This group is called our Milky Way Galaxy because we see it as a band of light going across the sky, once thought of as a band of milk. Most of the stars we see are near-by neighbors of our sun. A few bright stars are more distant.

Material: 2 paper plates

tape

pencil

In some of the activities, we straighten out the wrinkles in the plates. Do not do so for this activity. Place the 2 plates together so the curved part of each faces toward each other. Tape them around the edge. Now you have something looking like a discus. Find a point about 2/3 the way out from the center. This is where our sun is located. The disk of the galaxy is abut 120,000 LY (light years) across and our sun is about 30,000 LY from the center. The outer arms are about 1,000 LY thick. The inner bulge is like a ball at the center of your model. The bulge is 12,000 LY across and 10,000 LY thick. Label the LY measurements on your paper plate model. Find other material to make a model to scale showing the central bulge. Globular Clusters are spheres of stars in several groups above and below the plane of the galaxy. It takes about 250,000,000 years for our sun to go around the galaxy center. Draw a time line around your plate and mark events that happened in the last 250 million years.

Teacher key: Written history 5 to 10,000 years ago

Earliest humans 2 to 3 million years ago

Dinosaurs died out 65 million years ago

(end of Cretaceous - 1/4 orbit)

All continents together—Pangaea—300 million years ago—slightly over one orbit

Life changes from reptiles to dinosaurs during just one orbit of the sun around the galaxy.

Oldest rocks at the Grand Canyon—7 orbits ago of the sun around the galaxy

First bacteria formed about 10 orbits ago

Information: Most of the objects in the galaxy are blocked by gas and dust so we are unable to see them in visible light. Astronomers now use infrared telescopes and radio telescopes to get information of what is behind the dust. Many other galaxies have black holes at their center. Current research is trying to see what is at the center of our galaxy. Sagittarius is a constellation we see in the summer looking south. A part of it looks like a teapot. Just west of the spout from the teapot is the direction of the center of our galaxy.

Extension: You can draw spiral arms on the plates representing the arms of our galaxy and label them using a map from an astronomy book such as NIGHTWATCH by Terence Dickinson. Study other galaxies and compare them to ours. Find pictures made of our galaxy in other forms of energy than visible light.

Contributed by Wayne James.

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