1. Sun-Earth System Investigation 3, Part 2
Seasons and Sun
Sun-Earth System
Investigation 3, Part 2
TG-P.97-98

2. Review
Review the following questions from “Wendy and Her Worldwide Weather Watchers”:
When one location on Earth has 14 hours of daylight, is all the rest of the world having 14 hours of daylight as well?
Is the longest day of the year the same length all over the world?
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3. Review
Is the shortest day of the year the same day all over the world?
Are the longest days always in the summer?
Are the shortest days always in the winter?
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4. OBJECTIVES
I can calculate the amount of sunlight hours there are on different days of the year.
****I can explain where the earth tilt’s towards and how it affects sunlight hours.
I can explain what influence soar angle has on heating the earth.
I can explain beam spreading.

5. What ideas do you have to explain why daylight hours change over a year?
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6. Sun-Earth Model Represent the Earth and the Sun
How should I set up the model?
Where should the Earth be? Where should the sun be?
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7. Conduct Demonstration
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8. Time for some notes….

9. Revolution The movement of one object around another
(Add to your Interactive Notebook.)
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Takes 365 days or 1 year
The Earth revolves around the Sun

10. Rotation The Earth turning on its axis
One turn on it axis takes 1 day or 24 hours
Earth has a North and South Pole
Axis is the imaginary line that if you connect the North and South Pole
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The axis is tipped over at an angle of 23.5˚

11. Rotation
How do we know where it is day and where it is night on this globe?
Day
Night
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How much of the globe is in daylight at any given time?
Always exactly half illuminated and half dark

12. North Star (called Polaris)
The North Pole ALWAYS points at the North Star.
Used as a navigation aid to seafarers and explorers for centuries
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13. Summary
Is there a part of Earth that experiences only daylight or only darkness during the year?
Above the Arctic Circle
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Below the Antarctic Circle

14. Equinox Two days during the year that day and night hours are equal
Comes from Latin meaning “equal night”
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15. Fall Equinox Spring Equinox Autumnal equinox
occurs around September 21
Fall Equinox
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Vernal equinox
occurs around March 21
Spring Equinox

16. Longest Day in the Northern Hemisphere?
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Which way is the North Pole tilted?
Toward the Sun

17. Solstices Summer Solstice Winter Solstice Around June 21
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Winter Solstice
Around June 21
The longest day of the year (most hours of sunlight)
Solstice means “sun stands still”
Around December 21
The shortest day of the year (least hours of sunlight)
…for the Northern Hemisphere.

18. North Pole is tilted neither toward nor away from the Sun
At fall equinox
North Pole is tilted neither toward nor away from the Sun
Sun is directly over the equator
Half in daylight and half in darkness
At spring equinox
Sun is directly over the equator
Day and night are equal
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At summer solstice
North Pole is tilted toward the Sun
Northern Hemisphere receives more sunlight
At summer solstice
North Pole is tilted toward the Sun
Northern Hemisphere receives more sunlight
At summer solstice
North Pole is tilted toward the Sun
Northern Hemisphere receives more sunlight
At winter solstice
North Pole is now tilted away from the Sun
Shortest day of the year

19. Seasons At fall equinox Days are getting shorter
Less exposure to light, lower temperatures
At winter solstice
Days are shortest
Less exposure to light, lower temperatures
Snow, ice, frost, etc
At summer solstice
Days are longer
Longer exposure to light produces the effects of summer
Warmer temperatures, plant growth
Seasons
At spring equinox
Days are getting longer
Exposure to light is increasing, raising temperatures
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20. Reading
Read “Seasons” starting on page 17 of your green resource book.
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Student Resource Book P.17-19

21. Multimedia Turn to “Seasonal Changes”
You will use the Sun-Earth program on fossweb.com to answer the questions labeled Seasonal Changes.
The questions are difficult, so make careful observations and concentrate.
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22. Response Sheet
After you finish the Multimedia complete Season’s and Sun Response Sheet.
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Student Lab Notebooks P.11
TG -Teacher Assessment Master p. 383/p. 426