In 1610, Galileo used a telescope that he made to observe the heavens. What he observed helped to prove that the new “heliocentric” model was correct.

The first thing that Galileo looked at through his telescope was the moon.

When he turned his telescope towards Jupiter, he was surprised by what he saw…

On the next night, the arrangement of the stars had changed.

As he continued to make observations, he as amazed at the way the pattern of stars would change.

Galileo decided to try to figure out what was going on.

You are going to repeat Galileo’s discovery…

…by watching & plotting how Jupiter’s escorts change position from night to night.

Choose 1 color of star—red, yellow, white, or blue to watch & plot for each night. (Write your choice on your worksheet on the line for “Color: _______.”)

Plot the location of your star by making an X on the number line showing where it is for each night.

Example: J -212 numbers = millions of miles to the left or right of Jupiter X

Night 1 J -212

Night 2 J -212

Night 3 J -212

Night 4 J -212

Predict the location of your star on night 5 by making a DOT on the number line showing where you think it will be.

Night 5 J -212 Mark the actual location with an X. Was your prediction close?

Predict the location of your star on night 6 by making a dot on the number line showing where you think it will be.

Night 6 J -212 Mark the actual location with an X. Was your prediction close?

Predict the location of your star on night 7 by making a dot on the number line showing where you think it will be.

Night 7 J -212 Mark the actual location with an X. Was your prediction close?

Predict the location of your star on night 8 by making a dot on the number line showing where you think it will be.

Night 8 J -212 Mark the actual location with an X. Was your prediction close?

Predict the location of your star on night 9 by making a dot on the number line showing where you think it will be.

Night 9 J -212 Mark the actual location with an X. Was your prediction close?

Now, play “dot-to-dot”, connecting all of the Xs in order from night 1 to night 9.

Here is what your pattern should look like if you are the red colored star.

J J J J J J J J J

Here is what your pattern should look like if you are the yellow colored star.

J J J J J J J J J

Here is what your pattern should look like if you are the blue colored star.

J J J J J J J J J

Here is what your pattern should look like if you are the white colored star.

J J J J J J J J J

Answer the questions on your worksheet. Be sure to use complete sentences.

Discussion of Results What are the objects and what are they doing?

They are moons that are orbiting around Jupiter.

Earth’s Moon, Luna

Io (red) Europa (yellow) Ganymede (blue) Callisto (white) Here are what the 4 “Galilean” moons look like...