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Station #1: The Reason for the Seasons The Earth turns on an imaginary axle called an axis. The axis of the earth is tilted about 23 ½ degrees. It takes the Earth 24 hours to make one complete revolution. The Earth is also revolving around the sun. At different times of the year different parts of the Earth’s surface face the sun for longer or for shorter periods of time. Most parts of the world have four such periods or seasons. They are spring, summer, autumn and winter. During the summer season, there is more daylight. In winter, there is less. In spring and autumn, the hours of light and dark are about the same. Some parts of the world have only two seasons: rainy and dry. If the Earth did not tilt on its axis, there would be no seasons. Every day would have 12 hours of light and 12 hours of dark. But since the Earth’s axis is at an angle to its orbital plane, we have summer and winter, long days and short. When the North Pole tips toward the Sun, the Northern Hemisphere has summer warmth. When the South Pole tips toward the Sun, Australia has summer and North America has winter. As the Earth swings around the Sun different parts of its surface are exposed to sunlight for different lengths of time each day. For this station, you can place the black presentation boards in a semi-circle around the season display and place a black foam poster board on top to block out the light. You can also just set up the season display on the table in front of the students. Have students stand/sit near the table and observe the model of the sun and earth in each of the four seasons. It is probably better to divide the group in half so that students are able to see the model better if they are standing around the black display boards. Have students locate the North Pole, the Northern Hemisphere and Georgia (red star). Help students answer the questions on their sheets. How long does it take Earth to complete one revolution around the sun? 365 days Is Earth’s axis of rotation straight up and down OR tilted? Tilted Have students locate the season of their birthday and describe the tilt of the Earth during the season of their birthday. Is the Northern Hemisphere tilted toward the sun, away from the sun or neither way? Station #2: Make a Refracting Telescope Astronomers study space with optical telescopes. These telescopes capture light streaming toward Earth from every corner of the universe. Today we are going to make a simple Refracting Telescope. A Refracting Telescope is a telescope that uses a convex objective lens to focus light directly into an eyepiece lens which then magnifies an image. Hand each student one small diameter cardboard tube, one large diameter cardboard tube, one thin (larger) lens that is inside a red cap, and one thicker (smaller) lens protected inside a circular piece of gray foam. Have each student place their larger lens with the red cap on one end of the larger diameter cardboard tube. Next, have students place their smaller lens with the gray foam circle into one end of the smaller diameter cardboard tube. Have students carefully slide the open end of the smaller diameter cardboard tube into the open end of the larger diameter cardboard tube. Students should hold their telescope up and look through the end opposite the red end. Have students focus on a far off object in the room (maybe one of the planets hanging from the ceiling) by sliding the small tube in and out of the larger tube until the image they are viewing is in focus. If they have trouble seeing an image take them outside and let them focus on an object in a tree behind the portables, a birdhouse or some brush in the woods. Ask the students: How do objects appear through the telescope? Objects will appear upside down and larger, because of the manner in which light traveling through the lens is bent. Ask students which lens they were looking through when the objects appeared larger? The smaller (thicker) lens Ask students if they were to look through a telescope to observe the night sky which is the better lens to look through. They should look through a thicker (convex) lens for larger images. Note: If it is hard for some students to understand the difference in lenses, show them using the two lenses provided that when placed over printed words a concave lens will not change the size of an object, while a convex lens will make an object larger. Ask students to place their telescopes on the table and answer the questions on their sheets. Provide assistance as needed. After the sheets are completed you can read the information below to them and show them pictures of different refracting and reflecting telescopes shown in the book provided. Additional Information about Telescopes Another type of optical telescope is a Reflecting Telescope. In this type of telescope light strikes a concave primary mirror at the back of the reflecting telescope and bounces back up the tube to a smaller flat angled secondary mirror, then to an eyepiece. Bigger telescopes used today are reflecting telescopes. (For example, the Hubble Space Telescope) Station #3: Model of the Solar System Explain to the students that you will be helping them to make a model of the solar system similar to the one you have for display. Divide the group in half and use both tables so there is plenty of room for student to work. Give each pair of students one long strip of black paper, a glue stick and a yardstick. In each rotation, students will make four models. Collect them and give them to the teacher to use when the class studies Space. Have students glue the half sun to the edge of the black strip of paper. Ask students to place the black paper on the table lengthwise and place the yard stick on top of the paper with the edge resting on the edge of the yellow sun. Using the chart below students should place stickers or die cuts representing the planets in order the distance from the sun listed on the chart under the heading Scale Distance from Sun (inches). Students may make a mark on the black paper with there pencil if they like before placing the sticker or die cut. Here is a description of the planet and the die cut or sticker used to represent each: Mercury – yellow ¼” sticker Venus – green ¼” sticker Earth – blue ¼” sticker Mars – red ¼” sticker Jupiter – orange large circle Saturn – red planet die cut Uranus – green circle die cut Neptune – blue circle die cut Pluto – make a small dot with a gel pen ½ inch from sun ¾ inch from sun 1 inch from sun 2 inches from sun 5 inches from sun 10 inches from sun 19 inches from sun 30 inches from sun 39 inches from sun Remind students of the memory trick to remember the order of planets: My Very Eager Mother Just Saved Us Nine Pennies If there is enough time students can label the planets and the asteroid belt with the gel markers. ½ Planet’s Diameter (rounded to nearest 1000 km) 5000 Approximate Scale Size of Planet Diameter (inches) ¼ 0.7 ¾ 12000 ½ 150 million 1 1 13000 ½ Mars 228 million 2 2 7000 ¼ Jupiter 778 million 5 5 143000 6 Saturn 1429 million 2871 million 4500 million 5900 million 10 10 121000 5 19 19 51000 2 30 30 50000 2 39 39 2000 1/8 Planet Average Distance from Sun (km) Distance from Sun in Astronomic al Units Scale Distance from Sun (inches) Mercury 58 million 0.4 Venus 108 million Earth Uranus Neptune Pluto