Problem 19
As a ship comes into view over the horizon, the top appears before the rest of the ship. How does this demonstrate that Earth is spherical?
Problem 19
Draw Conclusions How would solar eclipses be different if the Moon were twice as far from Earth? Explain.
Problem 20
Predict how the information gathered by moon missions could be helpful in the future for people wanting to establish a colony on the Moon.
Problem 20
If Earth were flat, how would an approaching ship appear differently?
Problem 21
Use Variables, Constants, and Controls Describe a simple activity to show how the Moon's rotation and revolution work to keep the same side facing Earth at all times.
Problem 21
Explain why eclipses of the Sun occur only occasionally despite the fact that the Moon's rotation causes it to pass between Earth and the Sun every month.
Problem 22
Draw Conclusions Gravity is weaker on the Moon than it is on Earth. Why might more craters be present on the far side of the Moon than on the side of the Moon facing Earth?
Problem 22
Recent data from the spacecraft Lunar Prospector indicate the presence of large quantities of water in shadowed areas of lunar impact basins. Describe the hypothesis that scientists have developed to explain how this water reached the moon and how it might be preserved.
Problem 23
Recognize Cause and Effect During a new phase of the Moon, we cannot see it because no sunlight reaches the side facing Earth. Yet sometimes when there is a thin crescent visible, we do see a faint image of the rest of the Moon. Explain what might cause this to happen.
Problem 24
Describe Earth's magnetic field. Include an explanation of how scientists believe it is generated and two ways in which it helps people on Earth.
