Earth--The Ever-Changing Planet

• Describe how looking at the Earth at night can help us discover the most densely populated areas of the planet.
• Identify at least two major cities in each of the nighttime images.
• Describe how satellites can assist with hurricane information.
• Be able to pick out the areas where the highest waves occurred for a particular month (of 1995) when viewing the TOPEX/Poseidon wave level map.

Prior to this activity, there should be an introduction to remote sensing, color, and light. Discuss the basic parts of a remote sensing satellite, such as the platform, the sensors, and the filters. Students should have some basic understanding of the colorwheel, too. It would be a good idea to show them some examples of different types of remotely sensed images (true color, infrared, etc.). This will let them see that color can vary from image to image. These images will also help students to understand the perspective of viewing the Earth from above.

Materials:

• one set of "glasses" for each student (red, blue, or green, depending on which group they are in; see directions below)
• red, blue, and green pipe cleaners (enough to distribute several to each student)
• 10-15 sheets of green, blue, and red acetate (or overhead projector sheets)

Directions for making "glasses":

1. Cut out pieces of the acetate large enough to cover the students' eyes.

2. Give each student a different color of the acetate to use as lenses in the "glasses."

3. Spread out the pipe cleaners on a grassy area outside; they should not be hidden.

1. Divide the students into three equal groups; one group for red "glasses," one for blue, and one for green.

2. Pass out the "glasses" before going outside. Be sure the students cover their eyes with the colored "glasses" before they near the area where the pipe cleaners are located.

3. Explain the situation and the rules to the students.

a. The students will pretend they are the sensors of satellites and, as satellites do, they will search for things that they can see through their colored "glasses."

b. Students can only look through their "glasses" to find the pipe cleaners.

c. When a student sees a pipe cleaner, he or she will pick it up.

d. When the time limit (10-15 minutes) is reached, have the students look to see what everyone picked up. (You could have the students trade colors to see what happens when looking through different colored "glasses").

e. Have a discussion about why students were only able to see certain colors through their "glasses."