1. Yo Yo Yo
Phases of the Moon, Gee
Phases of the Moon 1

2. Earth Moon System
• The average distance from the Moon to the
Earth is 384,404 km.
– Closest approach is Perigee 356,334 km.
– Farthest is Apogee 406,610 km.
• Diameter of the Moon is 3475.9 km = 0.27
diameter of the Earth (12756 km)
• Mass is 1/80th that of Earth.
• Volume 1/49th that of the Earth.
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3. Exploration of the Moon
• 3 human space flight programs:
1. Project Mercury: Alan Shepard
2. Project Gemini: 2 men in space
3. Apollo Program
• Between 1969 and 1972 six Apollo spacecraft
were sent to the moon.
• Apollo 1 disaster (fire on launch pad)
• 12 people have walked on the moon
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4. Buzz Aldrin
Apollo 11
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5. James Irwin
Apollo 15
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6. John Young
Apollo 16
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7. Harrison Schmitt
Apollo 17 (last Apollo astronaut to step foot on the moon)
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8. What is it like on the moon?
• FGravity is 1/6th that of Earth
• Not strong enough to hold gases
• No atmosphere
• Temperature Range: 135oC to -170oC
• No wind, no weather, no erosion
• Frozen ice at poles
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9. Phases of the Moon 9

10. The Lunar Surface
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11. Maria: dark surfaces, reflect little light.
-once thought to be bodies of surface water
-actually dark solidified lava
Rilles: run through maria, lava channels that
look like dry riverbeds
Craters: bowl-shaped surface depressions
-most from impacts 4 billion years ago
-some have diameters 250km across
No erosion means the surface has not changed
much in 4 billion years!
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12. Charles M Duke next to a crater
Apollo 16 (youngest person to walk on the moon)
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13. The Moon
• The Moon shines by reflected sunlight.
– On average, it reflects about 7% of the incident
light from the sun.
– The Moon appears about 400,000 times fainter
than the Sun in the sky.
• The phases of the Moon are due to the
relative position of the earth, moon and sun.
– A common misconception is that the phases of the
Moon are caused by “the shadow of the Earth on
the moon.”
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14. Phases of the Moon 14

15. Phases of the Moon 15

16. Phases of the Moon 16

17. Phases of the Moon 17

18. Phases of the Moon
Phase Moonrise Transit Moonset
New Sunrise Noon Sunset
Waxing Crescent 9 a.m. 3 p.m. 9 p.m.
First Quarter Noon 6 p.m. Midnight
Waxing gibbous 3 p.m. 9 p.m. 3 a.m.
Full Moon 6 p.m. Midnight 6 a.m.
Waning Gibbous 9 p.m. 3 a.m. 9 a.m.
Third Quarter Midnight 6 a.m. Noon
Waning Crescent 3 a.m. 9 a.m. 3 p.m.
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19. Orbit of the Moon
• The time it takes the Moon to go through its
phases is called the
synodic period and is 29.5 days.
• The time it takes the Moon to orbit the Earth
with respect to the stars is the sidereal period
and is 27.3 days.
• The orbit of the Moon is inclined by 5 degrees
with respect to the ecliptic.
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20. Lunar Lunacy
• Another common misconception is
that the Moon affects the weather, the
number of births, the number of arrests,
and the number of emergency room
admissions.
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21. Lunar Lunacy
• The astronomer George Abell studied
the birth rate as a function of the phase
of the Moon.
– He looked at 11,691 live births at the UCLA
hospital between March 17, 1974 and April
30, 1978 and found no correlation.
– He then narrowed it down to the 8,142
natural (not caesarean) births and found no
correlation.
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22. Lunar Lunacy
• The human female menstrual cycle
averages 28 days, not 29.5.
– If it is influenced by the lunar phases, then
all mammals should have the same cycle
length.
• Guinea pigs 11 days, rats and mice 5 days
• Sheep 16 days, chimpanzees 37 days
• Cows and horses 21 days
• Opossum 28 days
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23. Phases of Venus
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24. Rotation of the Moon
• The Moon always presents the same
face towards Earth.
– Another common misconception is that this
means that the Moon does not rotate.
– However, in order to keep the same face
toward Earth, the Moon must rotate once
every orbit.
– The far side of the Moon is not dark, it gets
just as much sunlight as the near side.
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25. Near Side of the Moon
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26. Far Side of the Moon
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27. Rotation of the Moon
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28. Mark Twain
• “Everyone is a Moon, and has a dark
side which he never shows to anybody.”
– Mark Twain
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29. Misconception:
Dark Side of the Moon
• The “Dark Side” of the Moon should
really be called the “Far Side.”
– The far side gets just as much light as the
near side. For example, during a new
moon, the near side of the Moon is dark,
and the far side of the Moon is fully
illuminated!
– http://www.badastronomy.com/bad/misc/dark_side.html
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30. Sorry Pink Floyd Fans…
Roger, David, Rick, and Nick got
it wrong!
One of the best selling albums of all time!
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31. Lunar Libration
• You might expect that if the Moon always
keeps the same face pointed toward Earth,
that we can only see 50% of the Moon.
– However, the Moon appears to rock back and
forth. This back and forth rocking is called
libration.
• In its elliptical orbit around Earth, the Moon moves faster
when close to the Earth and slower when farther. Since
its rotation is fairly constant, we get to see a little bit
around each limb.
• In addition, the orbit of the Moon is tilted with respect to
the ecliptic, so we get to see somewhat beyond the poles
as the Moon moves above and below the ecliptic.
• 59% of the Moon is visible Moon on Earth.
Phases of the
to us 31

32. Phases of the Moon 32

33. Misconception: The Size of
the Rising Moon
• Many people believe the rising moon is
larger than when the Moon is high
overhead.
– The Moon is actually slightly larger when it
is high overhead!
– The effect is an illusion, however, the
illusion is not well understood! See these
links for more details:
• http://www.badastronomy.com/bad/misc/moonbig.html
• http://www.lhup.edu/~dsimanek/3d/moonillu.htm
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34. Moonrise
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35. Moon Illusion
Which
circle is
larger?
They are
both the
same size!
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36. Does the size change?
• Yes
• The moon appears 10% larger during
Perigee (closer) than it does during
Apogee
• Tough to see this difference in size
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37. Interesting moon factoids
• In 1961 President John F. Kennedy said: "I believe that this
nation should commit itself to achieving the goal, before this
decade is out, of landing a man on the Moon and returning him
safely to the Earth."
• At 10:17 pm on July 20th, 1969 (six hours after landing) Neil
Armstrong took his “small step.” He was joined by fellow
astronaut “Buzz” Aldrin minutes later. Michael Collins orbited
overhead. They were part of the Apollo 11 mission.
• Armstrong really said, “This is one small step for a man,” and
not “one small step for man” as is commonly reported.
• No weather on the moon, no erosion, so something as delicate
as a footstep will last a very long time!
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38. Here fishy fishy…
Some believe that the best fishing
takes place during a full or new moon.
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39. Phases of the Moon 39