First, go to the NAAP site (see above) and read through the background
materials they have provided. The materials are short, easy to read and very
instructive. Next, work through the questions below using the simulators and
SkyViewCafé.
Lunar Phase Simulator
Use the simulator to answer the following questions. The simulator shows
the Earth/Moon system from above the North Pole. The Sun is off the screen to
the left. In the upper right there is a pane showing the phase of the Moon
that allows you to choose what phase you are looking at. In the lower right
there is another pane (Horizon Diagram) that shows an observer in the
Northern Hemisphere. In this pane you can watch how the Moon changes its
location in the sky relative to the Sun through the cycle of its phases.
For each of the phases listed in the table below
write down how much of the face of the Moon is lit from the point of view
from an observer on Earth. Use the Moon Phase box in the upper right of the
simulator. Also, use the “show angle” option to find the
Sun/Earth/Moon angle for each phase.
Phase
Angle
Percent
Lit
Picture
New
Moon
Waxing
Crescent
45°
14.6%
First
Quarter
Waxing
Gibbous
Full
Moon
Waning
Gibbous
Third
Quarter
Waning
Crescent
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The phrase the “dark side of the Moon”
is often used by people who don’t really know what it means. Usually
people think they mean that there is one side of the Moon that is always in
the dark and never lit by the Sun. Use the simulator to determine whether
there really is a “dark side of the Moon”. Explain what you
find out in one or two sentences.
Click the optional box marked “show lunar
landmark”. Use the simulator to find out how long it takes for the
Moon to rotate once on its axis relative to the Sun. You can measure this
by watching the landmark. Start out with it pointing directly away from the
Sun and drag the Moon through its cycle until it points exactly the same
again. How long does it take? You can read off time elapsed in the Moon
Phase pane.
While you were working on answering the previous
question you may have noticed something interesting. How long does it take
for the Moon to cycle through all of the phases, from New Moon back to New
Moon again?
Use the simulator to find out why we on Earth can
only ever see ½ of the Moon’s surface. Hint: Refer back to the
previous two questions to help you. Explain what you find out in one or two
sentences.
If the “dark side of the Moon” has any
meaning at all, what is it? Is the “dark side of the Moon”
really dark?
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Find the time of Sunrise-set and Moonrise-set for
each phase. Turn on the “show time tickmarks” option. Set the exact phase of the Moon using the menu in the upper right. Then click on the stick figure on the Earth to change the time of day. You can put the Sun or Moon on the horizon in the Horizon Diagram to find the time each rises and sets. The time of day is given in the Horizon Diagram. Give times
to the nearest hour or ½-hour.
Phase
Sunrise
Sunset
Moonrise
Moonset
New
Moon
Waxing
Crescent
First
Quarter
Waxing
Gibbous
Full
Moon
Waning
Gibbous
Third
Quarter
Waning
Crescent
Does Moonrise get later every day or earlier? The
Moon orbits the Earth in the same direction as the Earth’s rotation.
Use this information, and the simulator, to explain your answer to the
question in one or two sentences.
Use the simulator to find out whether the Full
Moon is ever visible during daylight hours. Is it? Why or why not?
Do Waxing phases (all the phases from New Moon to
Full Moon) rise before or after the Sunrise on any given day? Use the
simulator to find out.
Do Waning phases (all the phases from Full Moon to
New Moon) set before or after the Sunset on any given day? Use the
simulator to find out.
Is a Waning Crescent visible before Sunrise or in
the evening just before Sunset? What direction should you look for it (East
or West)?
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Moon Phases and the Horizon Diagram
Go back to the main page for the Lunar Phase Simulator. Now go to
Moon Phases and the Horizon Diagram [swf]. Click at the top to
Show Position Labels. Click at the bottom to show phase of moon on moon disc.
Put the Sun and the Moon at position 1 by using the sliders in the Sun
Settings and Moon Settings.
When the Sun is at position one it is 6
am and the Sun is due East at sunrise. For
each of the following Moon positions draw the phase of the Moon as you see
it in the lower right-hand corner of the simulator. Also, label the phase.
Finally, indicate whether the Moon is in the sky in the East, overhead,
West, or below the horizon.
Moon at 1
______________
Phase
Circle one:
E
W overhead below horizon
Moon at 8
______________
Phase
Circle one:
E
W overhead below horizon
Moon at 7
______________
Phase
Circle one:
E
W overhead below horizon
Moon at 6
______________
Phase
Circle one:
E
W overhead below horizon
Moon at 5
______________
Phase
Circle one:
E
W overhead below horizon
Moon at 4
______________
Phase
Circle one:
E
W overhead below horizon
Moon at 3
______________
Phase
Circle one:
E
W overhead below horizon
Moon at 2
______________
Phase
Circle one:
E
W overhead below horizon
Use the slider to move the Sun to position 5. When
the Sun is at position five it is 6 pm and
the Sun is due West at sunset. For each of the following Moon positions draw
the phase of the Moon as you see it in the lower right-hand corner of the
simulator. Also, label the phase. Finally, indicate whether the Moon is in
the sky in the East, overhead, West, or below the horizon.
Moon at 5
______________
Phase
Circle one:
E
W overhead below horizon
Moon at 4
______________
Phase
Circle one:
E
W overhead below horizon
Moon at 3
______________
Phase
Circle one:
E
W overhead below horizon
Moon at 2
______________
Phase
Circle one:
E
W overhead below horizon
Moon at 1
______________
Phase
Circle one:
E
W overhead below horizon
Moon at 8
______________
Phase
Circle one:
E
W overhead below horizon
Moon at 7
______________
Phase
Circle one:
E
W overhead below horizon
Moon at 6
______________
Phase
Circle one:
E
W overhead below horizon
Use the slider to move the Sun to position 6. When
the Sun is at position six it is 9 pm and
the Sun is about 45° below the western horizon. For each of the following Moon positions
draw the phase of the Moon as you see it in the lower right-hand corner of
the simulator. Also, label the phase. Finally, indicate whether the Moon is
in the sky in the East, overhead, West, or below the horizon.
Moon at 6
______________
Phase
Circle one:
E
W overhead below horizon
Moon at 5
______________
Phase
Circle one:
E
W overhead below horizon
Moon at 4
______________
Phase
Circle one:
E
W overhead below horizon
Moon at 3
______________
Phase
Circle one:
E
W overhead below horizon
Moon at 2
______________
Phase
Circle one:
E
W overhead below horizon
Moon at 1
______________
Phase
Circle one:
E
W overhead below horizon
Moon at 8
______________
Phase
Circle one:
E
W overhead below horizon
Moon at 7
______________
Phase
Circle one:
E
W overhead below horizon
What phases of the Moon are always above the
horizon at 6 am (sunrise)?
What phases of the Moon are always above the
horizon at 6 pm (sunset)?
What phases of the Moon are always above the
horizon at 9 pm?
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SkyViewCafé
Go to SkyViewCafé.com and start the interactive planetarium. Go to the Ecliptic tab (which shows the paths of the Sun, Moon and planets as if the Earth stood still). Be sure to click the box that says
“Enlarge Sun/Moon”. Use the blue arrows at the top to go to the
next New Moon. Note the location of the Sun and Moon. Now use the arrow
buttons on the keyboard and the digits of the date/time box to move forward
one day at a time. Keep going until you reach another New Moon.
How long did it take to get the Moon back to its
starting point?
How long did it take to get to a second New
Moon?
What happened to the position of the Sun in the
meantime while you cycled the Moon around through its phases?
Why does the apparent position of the Sun
move?
The Moon orbits the Earth every
271/3 days as measured against the stars. The cycle
of the Moon’s phases is longer than that: 29½ days. Use the
information you gathered in answering the last few questions to explain why
it takes longer to cycle through the phases than for the Moon to go once
around the Earth.
Use only your brain for this one: Sherlock Holmes interviewed the key
witness in a murder trial. He found that the witness claimed to have
recognized the perpetrator by the light of the Moon on the night of the
murder. The witness said that she saw the murderer at 11 pm on the night of October 21, 2008. When you check your
moon phase calendar you find that it was the night of the Third Quarter.
Sherlock Holmes decided that the witness is hiding something and may even
be a suspect herself. Why?
