In the Moon Time

Category: Learning cycle

Learning Objectives:
The student will be able to:

1. Organize and accurately record a lengthy series of observations of the Moon.
2. Derive an explanation for changes observed.
3. Produce a model which demonstrates the relative motion of the Earth, Moon and Sun. Use the model to demonstrate how the moon appears to an observer on the Earth.
4. Relate this information to calendars, to ancient theories of astronomy, to eclipses, and to the scientific methods and instruments that have changed our understanding of the Earth/Moon system.

Materials:

• Light source (such as slide projector to assist with modeling)
• Notebook
• Skyglobe shareware astronomy program (optional - Windows® shareware program)
  • Software Lab 1-800-359-998
• Computer for running Skyglobe (optional)
• Assorted spheres for modeling

Sequence and duration of each part of lesson:
Total time: 5 minutes per night for 5 weeks plus 2 class periods.

This module is intended as an introduction. Students will individually observe and record information about the Moon's phase and position in the sky at different times of night over a 5 week period. They will work in teams to compile this data and develop a model to demonstrate the apparent motion and change of phase of the Moon. They should be able to design their own data table and schedule their own observations.

This same data could be obtained from almanacs or calendars that show moon phases or from computer programs. A shareware program called Skyglobe allows you to set dates and times and watch the moon move across the sky. But these sources would best be used as supplements to the students' observations. There is no substitute for direct observation.

Exploration Phase:
Begin with an attention getter such as showing an Aztec or Mayan calendar. Explain that ancient people knew a lot about astronomy even though they did not know what a star was. "How could they learn enough to predict eclipses and other astronomical events with no telescopes? We're going to begin our study of astronomy much as they did."

Assign students to record data on the appearance of the Moon and its position in the sky at different times of the night. Allow students to determine how they will record data. Note that the moon sometimes rises very late. Some observations can be made early in the morning or even during daylight. If the moon was not up when students went to bed, it will probably still be up when they leave for school.

After about 3 days of observations, allow class time for discussion and comparison of the data charts in use. Students may benefit from comparing charts and data in teams of 3 or 4. Ask whether other students have recorded data that seems significant that they didn't think to record. Possible data include time of moon rise, height above the horizon at a fixed time, constellation the moon is near, phase, and which edge of a crescent moon is lighted. Within their teams, students may want to arrange taking turns making observations and getting together later to compile data.

(Optional) After at least 1 week of observations, Introduce the Skyglobe program and make copies available to those who can use it on their computer. This program shows the position of sun, moon, stars, and planets at any date as seen from many locations. The view can be rotated and set to move ahead in steps.

Special Computer Management Consideration: Take precautions against introducing viruses to your system when making copies of Skyglobe shareware. Copy to new or cleared disks.

Mention the project frequently over the next month.

Invention Phase : (At end of 5 weeks)
Start the discussion by asking these questions:

1. When does the full moon rise? [At sunset] How do you account for this?

2. If you look at the Moon at a certain time each night, will it be further west or further east or in the same position? How do you account for this?

3. How long does it take the Moon to orbit the Earth? Where did we get the term "month"?

4. Could we set up a metric calendar: 10 months equals 1 year, 10 weeks equals 1 month, 10 days equals 1 week...? Why or why not? [The calendar once had 10 months. September through December are still named for the roots of 7th, 8th, 9th, and 10th.] [Students may wish to research calendars that differ from ours to see if they are connected with the Moon.]

5. What causes the phases of the Moon? Is the crescent curved the same way for waxing and waning moons? How do you account for this?

6. An eclipse of the sun happens when the Moon's shadow falls on the Earth. What phase will the moon be in when there is a solar eclipse?
   
   
7. An eclipse of the moon happens when the Earth's shadow falls on the moon. What phase would go with a lunar eclipse?

Challenge each team to set up a demonstration of the relative motion of the Earth, moon, and sun that will fit their observations and can be used to demonstrate the answer to several of the questions above. [Note that their model does not have to agree with current astronomic theory.]

Expansion Phase
At the next class session, have pairs of teams give their demonstrations to each other. Discuss differences between models. Did the models help clarify their thinking? If models differed significantly, how could we determine which model is right?

Discuss the following:

1. How can you tell which apparent movement of the Moon is caused by the Earth turning and which is caused by the moon orbiting the Earth? (Discuss the difficulty early astronomers had because they started with the assumption the Earth is holding still.)

2. Is it possible that some of the other assumptions we make in science are not true? What assumptions do we make in science? (Physical laws are constant. Gravity is universal. Life is organic....)

Bring the exercise to closure by making sure all students can explain current theory using their model.

Evaluation: will be based on individual data charts and on team models and final explanations. On data charts look for a complete and well organized table of observations. Note any unique observations other students do not have. On the model look for clarity of the explanation and participation of all team members.

Related Resources: One source for Skyglobe shareware that is guaranteed virus free is the Software Lab, 1-800-359-9998.