20 ACTIVITY 4 •
Parallel light rays
from the Sun
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FIGURE 4.1
• Studying the Phases of the Moon from a Privileged View
Crushed paper Moon
Crushed paper Earth
1. Starting with a new Moon, rotate the paper Earth once. If this is an accurate model, do all
locations see approximately a new Moon (that is, if we could actually "see" a new Moon)?
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1912
2. Each time Earth rotates, 1 day passes, and the Moon moves 12°. Move the Moon counter-
clockwise in its orbit, and again rotate Earth. Keep stepping through this process (rotate
Earth once, move the Moon 12°) until you get to the first quarter Moon (7.5 rotations of
Earth). Do all locations on Earth see a first quarter Moon, or very close to this phase, over
the course of one rotation of Earth? (Yes or No
3. Move the Moon and rotate Earth until the alignment is Sun-Earth-Moon (Moon on the
"Day 15" mark). What is the phase of the Moon when the system is in this configuration?
4. Do all locations on Earth see this phase, or very close to this phase, over the course of one
rotation of Earth? Yes or No
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5. Continue another 7.5 days. What is the phase of the Moon?
6. Briefly summarize your answers for questions 1-4, explaining what phases of the Moon are
observed at different locations on Earth over just one complete rotation.