Transcript Unit 8_Lesson 3

Joke of the day
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Q: How do you know when the Moon is going
broke?
A: When it’s down to its last quarter!
Agenda
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Catalyst
Go over homework
Review of Moon Phases
Lesson on Eclipses
Exit Ticket
Objective for the day
By the end of the day…
 SWBAT define and describe the
reasons for a solar and lunar eclipse.
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SWBAT distinguish between a total and
partial lunar eclipse and a total and
partial solar eclipse.
Eclipses in history and myth
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Have been recorded in Chinese and Egyptian
history over 4,000 years ago.
In ancient China, the solar and lunar eclipses were
regarded as heavenly signs that foretell the future
of the Emperor.
Over four millenniums ago, two Chinese astrologers
were murdered as they failed to predict a solar
eclipse.
Chinese Myth
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The ancient Chinese believed that
solar eclipses occur when a
legendary celestial dragon devours
the Sun.
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Also believed that this dragon attacks
the Moon during lunar eclipses.
It was a tradition to bang drums
and pots and make loud noises
during eclipses to frighten that
dragon away. They thought without
the sun, there would be no life.
Extra credit
opportunity!
What is an eclipse?
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An eclipse occurs when the sun,
Earth, and Moon line up
perfectly.
Key Point #1: The revolution
of the Moon causes eclipses.
They occur when Earth or the
moon temporarily blocks the
sunlight from reaching the other.
Eclipses happen every year.
Lunar Eclipse
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Key Point #2: A lunar eclipse occurs when the Earth
is between the Sun and the moon. The Earth’s
shadow falls on the moon.
The Earth has a shadow from the Sun, just like
anything on Earth casts a shadow when sunlight
shines on it.
Umbra vs. Penumbra
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Umbra: the darkest part of the Earth’s or moon’s shadow.
Penumbra: the larger part of Earth’s or the moon’s
shadow.
Total vs. Partial Lunar Eclipse
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Total Lunar Eclipse: When the moon is totally in the
Earth’s umbra.
Partial Lunar Eclipse: When the moon is only
partially in the Earth’s umbra and partially in the
penumbra.
Why does the moon appear red?
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While the Moon remains completely within Earth’s
umbral shadow, indirect sunlight still manages to
reach and illuminate it. However, this sunlight must
first pass deep through Earth’s atmosphere, which
filters out most the blue colored light.
The remaining light is a deep red or orange in color
and is much dimmer than pure white sunlight. Earth’s
atmosphere also bends or refracts some of this light
so that a small fraction of it can reach and
illuminate the Moon.
Star Advertiser
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“A total lunar eclipse will take place early on Dec. 10.
As seen from the islands, the moon will be in total
eclipse for about 45 minutes, 4:10 to 4:55 am.
The partial phase of the lunar eclipse will begin at
about 2:45 a.m., as the moon starts to enter the deep
inner shadow (umbra) of Earth. By 4:10 a.m., the
eclipse will be total.”
Solar Eclipses
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Key Point #3: A solar eclipse occurs when the Moon
moves directly between the Sun and Earth and casts
its shadow over part of Earth.
Total vs. Partial Solar Eclipse
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Depends on where on the Earth someone sees the solar eclipse.
Total Solar Eclipse: A solar eclipse as seen from someone
in the Moon’s umbra.
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The Sun is completely blocked by the moon.
Partial Solar Eclipse: A solar eclipse as seen from
someone only in the Moon’s penumbra.
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Part of the sun is visible from Earth.
Total Solar Eclipse
Partial Solar Eclipse
Solar Eclipses: A coincidence?
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Some say we are “lucky” to be able to see solar
eclipses.
The distance from the Sun to the Earth is about 400
times the distance from the Earth to the moon.
The moon is about 400 times smaller than the Earth.
This means that during a solar eclipse, the moon and
sun appear to be the same size!
If the distance of mass of the moon were any larger
or smaller, solar eclipses would not look so perfect.
When does a lunar eclipse occur?
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Think-Pair-Share: We discussed moon phases last
class period.
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which moon phase would a lunar eclipse occur?
 Why doesn’t an eclipse occur every time we have this
moon phase?
When does a lunar eclipse occur?
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Key Point #4: A lunar eclipse can only occur
during a full moon.
When does a solar eclipse occur?
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Think-Pair-Share: We discussed moon phases last
class period.
 During
which moon phase would a solar eclipse occur?
When does a solar eclipse occur?
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Key Point #5: A solar eclipse can only occur
during a new moon.
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Exit Ticket
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1) Draw a simple picture that shows the orientation
of the Sun, Earth, and Moon during a total lunar
eclipse.
2) What is the difference between a total solar
eclipse and a partial solar eclipse?