Phases of the Moon

Summary
This lab is designed to be an introduction to the scientific process. You will, using simple tools, deduce the motion of the Moon around the Earth. You will determine the direction of motion, and the reason for the phases.

The Phases of the Moon
Procedure
  1. Form a group of four with your neighbors. Choose one person to be the Moon, one person to be the Earth, one person to be the Record-keeper, and one person to be Spiff, the astronaut who observes "from above".
  2. Study the phases chart above, which shows the moon at different phases throughout the lunar cycle. Note carefully what changes about the moon from each image to the next.
  3. The Moon should pick up a styrofoam ball from the front of the room, and then everyone heads to the hallway.
  4. Spaceman Spiff goes upstairs to the balcony, and stands above his group.
  5. The 'Sun' is located at the end of the hallway, where the windows are.
  6. The Earth stands in one spot for the entire lesson (but can turn around to see the Moon). The Moon stands relative to the Earth so that the styrofoam ball appears to the Earth in each phase. The Moon must make sure that the white side of the styrofoam ball always faces towards the 'Sun'! The Earth decides when the appropriate phase is shown. Astronaut Spiff has the view from 'North' of the Earth-Moon system. He tells the recorder where the Moon is relative to the Earth (above or below, to left or right). All should try to visualize what the astronaut sees. The recorder marks the location of the Moon in the appropriate box in the table below.
Waning CrescentNewWaxing Crescent
First 1/4Waxing GibbousFull
Waning GibbousThird 1/4Waning Crescent

When you are finished, work together to answer the following questions: 1. In which direction does the Moon orbit the Earth? CLOCKWISE or COUNTERCLOCKWISE

2. For observers from the Northern hemisphere, which side of the Moon is illuminated when the Moon is just past new phase? RIGHT or LEFT

3. If you were to observe a crescent moon with the horns of the crescent pointing right, is the Moon WAXING or WANING? Hint: consider the previous question!

4. When an earth-bound person observes the Moon in its full phase, which phase of Earth is observed by a person on the Moon? NEW or FULL or SOME OTHER PHASE

5. In the following three pictures, fill in the missing piece (either in the top or the bottom panel).


6. Mars has two moons, Phobos and Deimos. In the following picture,
  1. What is the phase of Phobos as seen from Mars?
  2. What is the phase of Deimos as seen from Mars?
  3. What is the phase of Deimos as seen from Phobos?

7. For each of the following pictures, what is the time for the observer (the solid black line), what phase is the Moon in, and where is it in the observer's sky?
Time:Time:
Phase:Phase:
Location:Location:

© 1999 University of Washington
Revised: 8 August, 2001