The path of the Moon in the sky
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Transcript of The path of the Moon in the sky
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The path of the Moon in the sky
The second most striking astronomical object
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If we observe the position of the Moon in the night sky, what do we find?
Instant gratification concession: Any opinions (guesses) on where you can find the Moon in
the sky?
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First phenomenon to discuss: phases of the moon
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Phases of the moon and position of the Sun…they are not independent!
Full moon is 180 degrees away from the Sun on the sky, Question: where in the sky will the full moon be at midnight?
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The reason for phases of the Moon
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Understanding the geometric reason for the phases of
the Moon allows us to immediately
understand new pictures from
distant spacecraft
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Where do we find the Moon in the nighttime sky?
In which constellations do we find it? Does it move along the
ecliptic?
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The path of the Moon in the sky
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The line of nodes of the Moon’s orbit
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You can get out your SC1 chart and check it out for yourself!
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How do we explain all of this?
What is the “physics” of the solar system which produces all of these observed phenomena?
It took the human race tens of thousands of years to reach the right answer
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The existence of the ecliptic
The Earth and the other planets orbit the Sun, in nearly the same plane for all planets
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The inner solar system 3 months from now
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February 3
May 3
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Why we see the Sun “projected against” different constellations at different times
of the year
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Then, why is the ecliptic tilted with respect to the celestial equator (the
reason for seasons)
Answer: the obliquity of the ecliptic (or more simply
“obliquity”, or even more simply, “tilt of the Earth’s axis”)
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Northern hemisphere in summer
Northern hemisphere in winter