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Join Wendy and her global weather watchers to investigate daylight hours, seasons, and the Sun-Earth system. Discover how Earth's tilt affects daylight and seasons in different locations, and explore equinoxes and solstices. Unveil the mysteries of the North Star and its role in navigation. Engage in demonstrations and answer key questions to deepen your understanding of Earth's revolution and rotation. 8 Relevant
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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 • 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?
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?
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?
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?
Lengths of Days • What ideas do you have to explain why daylight hours change over a year?
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?
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?
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°.
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?
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)
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?
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.
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?
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?
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”
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.
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
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.
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?
