The idea is simple: Use the "Add" tool to stack all the Jupiter images together to come up with one image that shows the path of each of the moons. The difficult part will be keeping track of your work. You will be using the Hands-On Universe software. Although you may think of many different ways to do this, try these steps first:
The images are listed in the order they were taken. The last 6 digits in the image name tell you the time each was taken. See "Reading File Names," document in the Library for help understanding file names.
Open each of the images. Examine each image and find the moons.
It is important that you keep track of which images you have added. Have a list of the images handy and check them off as you work.
Select the first image.
Go to the Manipulation menu and click on "add"
Click on "display" and then select the second image from the pull-down menu.Don't forget to click "Display results in a new window."
Click "OK"
A new temporary window with open with your first two images added together. Keep this window active.
Select "Add" once again. This time add the third image to your temporary image. Do Not select "display results in a new window."
Continue to add each of the images to your temporary image until you have them all added together.
In order to see clearly which of the many dots on your final image was the first in the series,go to the manipulation menu and subtract the first image from the temporary image TWO times. This will make first three moons appear black.
Save this image.