Moons
Chapter 18
Section 2
Lecture 1
What is a satellite?
• A satellite is a natural or artificial body that
revolves around large bodies like planets.
• All of the planets, except for Mercury & Venus,
have natural satellites called moons.
 Artificial satellite
Natural satellite 
Our Lovely Moon
• Our moon is called Luna, the Latin word for moon.
• Our moon has a lower density than Earth & samples of
lunar rocks brought back by the Apollo astronauts
suggests the moon is similar to the Earth’s mantle.
• The oldest lunar rocks are about 4.6 billion years old.
• The moon is also covered in craters.
• By counting these, we know exactly how many times the
moon has been hit .
Did Earth Have Two Moons?
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Interesting Facts
• The moon changes slightly every single night.
• There is no air, food, or liquid water on the
moon.
• The moon’s gravity is too weak to hold an
atmosphere.
• The moon reflects only 7% of the light that
falls on it.
• Every full moon has a name. The most
familiar is the harvest moon, which occurs in
the fall.
• More than 70 spacecraft have been sent to
the moon.
• 12 astronauts have walked on the surface
• Check out: Google Moon
Why do we only see
one side of the moon?
• Think about it: every time you look at the
moon, it looks the same. Same man on the
moon, same bunny rabbit, always the same.
• This is because the moon rotates at the
same rate it revolves (27 days, 7 hours,
43 minutes) - so the same side always
faces Earth.
• This is called synchronous rotation.
• There is a part of the moon we never will
see from Earth.
• There is no such thing as the dark side of
the moon because the sun shines on all sides
of the moon in turn.
How was the moon formed?
2. How was the moon formed?
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The Phases of the Moon
WAXING CRESCENT
WAXING GIBBOUS
FIRST QUARTER
NEW MOON
FULL MOON
WANING CRESCENT
WANING GIBBOUS
LAST QUARTER
Week 1
1.
New Moon -When the Moon is
roughly in the same direction as
the Sun, its illuminated half is
facing away from the Earth, and
therefore the part that faces us
is all dark. When in this phase,
the Sun and the Moon rise and
set at about the same time.
2. Waxing Crescent - As the Moon
moves around the Earth, we get
to see more and more of the
illuminated half, and we say the
moon is waxing. At first we get a
silver of it, which grows as the
days go by.
Waxing = to increase in power/brightness
Week 2
3. First Quarter - A week after
the New Moon, when the
Moon has completed about a
quarter of its turn around the
Earth, we can see half of the
illuminated part; that is a
quarter of the Moon.
4. Waxing Gibbous - During the
next week we keep on seeing
more and more of the
illuminated part of the Moon.
gibbous = almost full
Week 3
5. Full Moon - Two weeks after the
New Moon, the Moon is now half
way through it’s revolution, and
now the illuminated half coincides
with the one facing the earth, so
that we can see a full disk. At this
time the Moon rises as the Sun
sets, and it sets as the Sun rises.
6. Waning Gibbous - From now on, till
it becomes new again, the
illuminated part of the Moon
decreases, and we say that’s a
waning.
Waning = to decrease in power/brightness
Week 4
7. Last Quarter - Three weeks
after the new, we again see
half of the illuminated part.
8. Waning Crescent - Finally,
during the fourth week, the
Moon is reduced to a thin
silver crest.
Other Moons
• Many of the planets have
moons - both large and
small
• All of the gas giants
have many moons
• Many of the very small
moons may be captured
asteroids
• 4 moons are larger than
our moon: Ganymede,
Titan, Callisto & Io
3. Scientists research surface of
the Titan moon
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Eclipses
• An eclipse occurs when the shadow of one celestial body falls
on another.
• It’s all about blocking light & creating a shadow.
• Eclipses don't last longer than a few hours because both
planets or moons are moving.
• The amount of eclipse is also dependent on your location.
• The same eclipse might be a total eclipse for someone in
Brazil, but only a partial eclipse for someone in Florida.
• Why don’t we see solar and lunar eclipses every month?
– Because the moon’s orbit is titled by about 5˚
– This means the moon stays out of Earth’s shadows most of
the time, and vice versa
Lunar Eclipse
• Occurs when the Earth comes between
the sun and the moon.
• During a total lunar eclipse, the moons
often appears to turn a deep red.
• There are 2 to 3 lunar eclipses a year
• Partial lunar eclipses are a little more
common than total lunar eclipses
• Lunar eclipses are totally safe to look at.
Solar Eclipse
• Occurs when the moon comes between
the sun and the earth.
• The Moon casts a shadow over a
portion of the planet, leaving that area
in darkness.
• If you were watching from space, you
could see the shadow pass over the
surface.
• You would also notice that the Moon's
shadow only covers a part of the
planet because the Earth is much
larger than the Moon.
Solar Eclipse
• There are 1-2 solar eclipses each year.
• A total solar eclipse happens when the
Moon blocks the entire Sun.
• An annular or partial solar eclipse only
covers some of the Sun.
• There are different eclipses because
the Moon can be closer or further
away from the surface of the Earth.
• Never look directly at a solar eclipse.
• Turkey Eclipse 2006
What if we had no moon?
We’ll get to watch that movie
on Friday
BrainPops!
1.
2.
3.
4.
The Moon :click here
Moon Phases: click here
Eclipse: click here
Tides: click here
Brain Pops: The Moon
2. Moon Phases
3. Eclipse
4. Tides
Let’s talk about the moon Journal
• After we talk about the moon journal, you’ll
be going into the computer lab to watch the
4 Brain Pops that have to do with the moon.
• THEN, you’ll have some time to start
working on you Chp 18 little book that is
due next week
4. And in conclusion… here’s Bill
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