Why does the Moon go through a Cycle of Phases?
OBJECTIVES & UNDERSTANDINGS
After completing this activity, you should be able to:
- Explain why the Moon goes through a cycle of phases.
- List the names of the eight Moon phases in order of occurrence.
- Given the current Moon phase, predict the next phase.
- Differentiate between waxing and waning phases.
- List the name(s) of the Moon phase(s) during which solar and lunar
eclipses can occur.
- Given the current Moon phase, predict the approximate time of
moonrise and moonset.
- Given the Moon phase, identify the corresponding Earth phase.
MATERIALS (supplied by classroom teacher)
- Following your instructor's
directions, complete the Moon Phase
Diagram (supplied by your instructor).
- Answer the following activity questions.
- Using materials provided by the planetarium teacher, construct a "Moon Phaser." Visit the planetarium (students
should bring the "Moon Phaser" to the planetarium).
- Why does the Moon go through a cycle of phases? (Before answering this
question, you may need to refer to a demonstration
of Moon phases.)
- Waxing and waning phases.
- During which phases does the shape of the Moon appear to grow larger
- During which phases does the shape of the Moon appear to grow smaller
- How can an observer on Earth recognize waxing from waning phases?
- Solar and lunar eclipses. (Note: Eclipses are named for the object
which cannot be seen, e.g., during a solar eclipse, you cannot see the
- During which phase(s) could a solar eclipse occur?
- During which phase(s) could a lunar eclipse occur?
- Why are solar and lunar eclipses so rare?
- You know that the Moon is much smaller than the Sun. Explain how the
disk of the Moon can block most of the light from the Sun during a total
- Is it safe to look directly at a solar eclipse? At a lunar eclipse?
- Using the following table, fill in the approximate time of moonrise
and moonset. If necessary, refer to a "Moon
- Which commonly used time unit (e.g., day, week, month, year, etc.) is
derived from the revolution of the Moon around the Earth?
For Further Thought
When the Moon is in the waning gibbous phase, to an observer on the
Moon, in which phase is the Earth?