How do science concepts apply to your world? Here are some questions you'll be able to answer after you read this chapter.

• How does a spacesuit work?
• Why shouldn't you park a car too close to the ocean's edge?
• Why isn't Earth covered by craters?
• Did Mars once have liquid water?
• Where, besides Earth, is life most likely to occur in our solar system?
• What lies at the outer edges of the solar system?
• Are there planets around other stars?
• Why do comets have tails?

Why Does the Sun Seem to Move?

Procedure

1. Tape a pencil to a sunny window with its point facing up.
2. Tape a sheet of paper to a desk or the floor so that the shadow of the pencil point falls on the paper. Use a compass to find east, and mark an arrow on the paper pointing to the east. CAUTION: Do not look directly at the sun.
3. Mark the position of the pencil point's shadow on the paper. Record the time of day.
4. After 10 minutes, repeat Step 3.

Think About It

1. Observing   In which direction did the shadow move between your two observations?
2. Inferring   What can you infer about the apparent motion of the sun from the movement of the shadow?
3. Drawing Conclusions   How must Earth be moving to explain the apparent movement of the sun?