Luna, The Story of Our Moon

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Luna, The Story of Our Moon
Isn't She Pretty?
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Where do we Begin?
The theory of why Earth has one moon is a violent
one. We begin a long time ago, in a galaxy
really really close
Over 4 BILLION Years Ago
yikes!
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The Entire Solar System Was Young
And there were likely many more planets than
exist now.
Maybe 20 of them, some with criss- crossing
orbits.
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Earth was still forming into the big ball of rock
that we know today
Earth was crusty rock over boiling seas of lava
and a molten iron core.
One day, one of the other planets comes on
byWAY TOO CLOSE.
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The Collision is the most violent thing EVER to
happen to Earth
Oh. Snap.
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And so

• A large object collided with Earth
• The collision flung a lot of material into space
• The material collected into a sphere (gravity)
• and formed into our moon.
• Earth smoothed-over (due to its mostly liquid
• nature gravity) back into a sphere

The similarity of Earth moon rocks in both age
composition supports this theory.
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Those Crazy Moon Shapes
Are known as PHASES that describe the lit up
part of the moon
(not faces)
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A GIANT mirror
The moon does not make light. It only reflects
light from the Sun onto Earth.
light
So! This means the moon works like a giant mirror!
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The Moons Phases
(way out of scale)
Notice The half of the moon facing the Sun is
always lit. As the moon revolves around Earth,
we see a different amount of it lit up by the Sun
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Learn the Phases
We call this phase the new moon, as it starts a
new lunar cycle every month.
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A few days later
The moon moves to where people on Earth can see
just a little bit of moon on the right. This is
called the waxing crescent moon. Waxing is a word
that just means growing. The moon will get
fatter the next night
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And then a few days later
People on Earth can see the entire right half of
the moon being lit by the sun. This is the first
quarter moon (were ¼ through the cycle). Dont
call this the half moon!
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A few more days go by
Now we see quite a bit of the moon, as it
continues to wax larger, but theres still
some on the left that we cant see. We call this
weird shape waxing gibbous (gibbous more than
half).
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And the moon keeps on truckin
People on Earth now see ALL of the lit up half of
the moon. It appears as a complete circle in the
sky. This is the full moon.
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The moon keeps on going
Now this diagram gets strange. You have to
imagine yourself on the Earth looking up into
the sky at the little moon. Youd see the moon
lit up on the left with some of the right
missing. This is the waning gibbous. Waning
shrinking.
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I hope you get it now
The moon is ¾ of the way through its cycle. We
call this the third or last quarter.
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And next
The moon continues to wane smaller and smaller,
down to the waning crescent phase.
50,000,000,000 TIMES
And then the moon wanes a few more days until it
is new and starts another cycle. This has
happened about
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Review
Study this diagram once or twice
Please notice that the explanation for
moon phases has NOTHING to do with clouds,
or Earth making a shadow or anything like that.
As the moon revolves around Earth, we see
a different part of it lit up each night. Thats
it.
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That whole cycle takes
Pretty much exactly the same amount of time it
takes the moon to rotate on its axis once about
a month.
Thats why we only see parts of the same surface
of the moon all the time (and the back side that
we cant see is called the dark side.)
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Eclipses
You might think that when the moon is in
either of these two spots
that the moon or Earth would make a shadow on
the other one.
But eclipses like that are rare. Lets see why.
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Looking at things from a SIDE view
The moons orbit is tilted compared to Earths
orbit around the Sun.
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But now and then the 3 objects DO line up
Solar eclipse Sun is blocked from view, can
only happen during a new moon.
Lunar eclipse Moon is blocked from view, can
only happen during a full moon.
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Eclipse Images
Because of the scale of objects
their distances, seeing a total eclipse is a rare
event. Here are some pictures taken during
eclipses.
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Other Moon Facts
Because of its relatively small size mass,
the moon has only about 1/6 of Earths gravity.
On the moon 18 feet!!!
On Earth... 3 feet
Likewise, a 100 pound person would only weigh 17
pounds. Imagine what you could pick up!
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More Moon Facts
Thanks to its very weak gravity, the moon has no
atmosphere.
On the moon, theres no wind or weather of any
sort. Nothing. And with no air to
transmit sound waves, you cannot hear anything
(unless youre wearing your space helmet).
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More Moon Facts
Flag wiggles from vibration, not from any breeze.
These footprints will exist forever unless meteor
activity destroys them
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And you Better Wear that Space Suit

• Thanks to having no protective atmosphere
• Daytime Temperature 2200 F
• Nighttime Temperature -3000 F
• CONSTANT impacts from meteors, tiny
• huge, that create craters (and could rip your
• space suit open, too)

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More Moon Facts
The moon is 2100 miles in diameter, about ¼ the
diameter of Earth. The moon is around 240,000
miles away from Earth.
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The moons gravity is weak
but not THAT weak. Its gravity is strong enough
that its pull on Earth explains at least one
natural occurrence tides.
Watch this animation on the effect of the moon on
Earths oceans (greatly exaggerated).
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What you notice at the beach
Play on the beach for enough hours, and
youll notice the tides at work. The water level
will rise and fall (not talking about waves)
gradually until your sand castle is now
underwater.
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• Tides the change in water level of the oceans.
  
• Caused by the moons gravity pulling on ocean
  wate
• High tide ocean level is high because the moon
  is pulling on it.The opposite side of the world
  will also have high tide, to keep Earth balanced.
• 
  high tide gravity Moon pulls on
  water
  
  
• low tide
• Low tide the beach is not facing the moon or
  away from itocean level is low
• Beaches have 2 high tides and 2 low tides every
  day.
• Spring Tides difference between daily high
  low tide is greatest during the full new moons.
  
• Neap Tides difference between daily high low
  tide is least during the first last quarter
  moons.

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Youve Learned a Lot
about seasons, our moon, moon phases, tides, and
eclipses. Be proud that you understand more
about these natural phenomena than even most
HARVARD graduates!
A brief movie about students misunderstandings
about the Earth Moon. Click the VoD button on
the Website.
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THE END!