Phases and Eclipses of the Moon
This material was originally created for On the Cutting Edge: Professional Development for Geoscience Faculty
and is replicated here as part of the SERC Pedagogic Service.
In this activity, students confront their misconceptions about eclipses and lunar phases, come to understand the true causes of these phenomena, practice using simple physical models to solve problems, and develop their 3-D visualizations skills.
The specific content learning objectives are:
- Demonstrate and illustrate how the relative positions of the sun, Earth and moon cause the phases of the moon as seen from Earth.
- Given a drawing or photograph of the moon in any phase, be able to correctly name that phase and draw a diagram showing the relative positions of Earth, the moon and the sun for that phase.
- Given a diagram showing any possible set of relative positions of Earth, the moon and the sun, determine the name of the moon phase and draw what the moon would look like in that phase.
- State which way the moon revolves around Earth and describe a method for figuring this out.
- Demonstrate why we always see the same side of the moon (the face side of the "man in the moon")
- Demonstrate what causes lunar and solar eclipses.
- Explain why eclipses don't happen every month.
Context for Use
Description and Teaching Materials
- Student Handout for the Activity on the Moon's Phases and Eclipses (Microsoft Word 77kB Dec14 08)
- Pop-up Moon Phase Diagram (Acrobat (PDF) 153kB Dec14 08)
- Other materials needed:
- One pencil and one 3 inch diameter Polystyrene ball per student. An ordinary Styrofoam ball will not do; the ball must be opaque. Suggested source: Molecular Model Enterprises, 116 Swift St., P.O. Box 250, Edgerton, WI 53334, (608)884-9877. Prices are under $1 each.
- One paperclip and one 7/8 inch diameter Polystyrene ball per lab table
- One overhead projector
- A single light source in the center of a darkened room
Teaching Notes and Tips
At the end of this activity, I typically assess student learning by having student groups present their answers to the rest of the class. I divide the different parts of this activity among the student groups, assigning each group to prepare illustrations and orally present their part to the rest of the class. Each presentation is then followed by a whole-class discussion.
I also ask students questions that require them to apply and extend the knowledge gained from this activity to specific situations. Here are some example questions; click on each to get the full-sized version:
I give students practice answering these questions in low-stakes ConcepTests (using clickers) or on-line practice quizzes before asking such questions on high-stakes exams.
References and Resources
The following reasonably-priced, thick (400 and 180 sheets, respectively) loose-leaf notebooks contain a wealth of classroom-tested hands-on activities, resource listings, and teaching suggestions for teaching astronomy. They are aimed at K-12 teachers, but are also very useful for college professors.
- Fraknoi, Andrew (ed), 1995, The Universe at Your Fingertips: An Astronomy Activity and Resource Notebook: The Astronomical Society of the Pacific, San Francisco.
- Fraknoi, Andrew and Schatz, Dennis (eds), [link
- https://web.archive.org/web/20180825224739/http://www.astrosociety.org/education/the-universe-at-your-fingertips-2-0/'More Universe at Your Fingertips']: The Astronomical Society of the Pacific, San Francisco.
An excellent animation that simultaneously shows the relative locations of the moon, Earth and the sun and a view of the moon from Earth can be found at the Exploring Earth web site, by McDougall Littell Publishing Company: