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Seasons and Sun

Seasons and Sun. Investigation 3 – Part 2 Sun-Earth System. Reading. Wendy and Her Worldwide Weather Watchers Use this reading to answer the questions posed in the next few slides. Wendy and…review.

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Seasons and Sun

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  1. Seasons and Sun Investigation 3 – Part 2 Sun-Earth System

  2. Reading • Wendy and Her Worldwide Weather Watchers • Use this reading to answer the questions posed in the next few slides.

  3. Wendy and…review • 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?

  4. Wendy and…review • Is the longest 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?

  5. Wendy and…review • Which locations have the greatest number of hours of daylight on June 21? The fewest hours of daylight? • Which locations have the longest hours of daylight on December 21? The shortest hours of daylight?

  6. Wendy and…review • Alpena, Michigan, is located 45° north of the equator. How much daylight do you estimate they have on June 21? On December 21? • Boulder, Colorado, has a latitude of 40°N. Wellington, New Zealand, has a latitude of 41°S. Which city has the longest amount of daylight on June 21?

  7. Lengths of Days • What ideas do you have to explain why daylight hours change over a year?

  8. Model of the Sun-Earth System • How should I set up a model of the relationship between the Sun and Earth? • Where should the Sun be and where should Earth be?

  9. Demonstration • When one object moves around another we say that the object revolves around the other object. • Earth revolvesaround the sun. • How long does it take for the Earth to make one revolution around the Sun?

  10. Rotation • Earth has a North Pole and a South Pole. These are the north and south ends of an imaginary axle, called an axis, on which Earth rotates. • Earth does not spin straight up and down on its axis. Earth is tipped over at an angle of 23.5°.

  11. Rotation • How long does it take for Earth to rotate (turn around once) on it axis. • How do we know where it is day and where it is night on this globe? • How much of the globe is in daylight at any given time?

  12. The North Star • There is a star in the night sky called Polaris, or North Star.It is positioned directly over Earth’s North Pole. Earth’s North Pole always points to the North Star – summer, fall, winter, spring, day, and night. That’s why the North Star has been a navigation aid to seafarers and explorers for centuries. • (you will have to visualize the location of the North Star in our model)

  13. Hours of Daylight • How could we use this model to investigate the question, Why do hours of daylight differ depending on the time of year and location on Earth?

  14. Demonstration • Watch as the Earth revolves around the Sun. • Observe that the Earth will always point to the North Star. • See that at the same time Earth spins on its axis.

  15. Demonstration • At each stop, 1-4, answer the following… • Which region of Earth is getting the greatest number of hours of daylight now? • Which is experiencing the most hours of darkness? • When Earth is at this point in its revolution, what season is it in Oak Harbor?

  16. Demonstration Questions • Is there a part of Earth that experiences only daylight or only darkness? • Is there ever a time when the day and night are equal everywhere on Earth? • How many times does this happen during a revolution?

  17. Equinox • There are 2 days during the year (one revolution around the Sun) that day and night hours are equal. • These days are called equinoxes. Equinox comes from Latin, meaning “equal night”

  18. Equinox • One equinox, the springor vernal equinox, occurs around March 21st. • When do you think the other equinox occurs? • The fallor autumnal equinox occurs around September 21st.

  19. Solstices • When is the longest day of the year in the Northern Hemisphere? • Around June 21st. • Which way is the North Pole tilted, toward the Sun or away from the Sun? • Toward the Sun

  20. Solstices • The longest day of the year is the summer solstice. • Solstice means “Sun stands still.” • When is the shortest day of the year in the Northern Hemisphere? • Around December 21st. • The shortest day of the year is the winter solstice.

  21. Walk Around a Year • Lets review with a walk through the year. Pay attention to the equinoxes and solstices. • Can you identify the seasons at each stop?

  22. Seasons

  23. Seasons

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