Solar Angles and Latitude Objectives The student will understand that the sun is not directly overhead at noon in most latitudes. The student will research and discover the latitude ir classroom and calculate the solar angles for their area for the winter and summer solstice. The student will apply their knowledge to build a model that will show the solar angles at their latitude. The student will use their model to predict where the sun will be at noon on the current date. Suggested Grade Level Tenth Subject Area(s) Math Science Technology Timeline Three 40 minute class periods: 1 st Period Background and Lesson 2 nd Period Research and Design 3 rd Period Build, Demonstrate, and Evaluation Background Teachers - Knowing where the sun is in the sky is practical knowledge for many design activities. Even at the equator the sun appears to move 47 degrees through the sky between the winter and summer solstices and that fact can have an effect on human activities. For example, a designer or technician lining up solar panels needs to know the exact portion of sky to point the panels so that they will produce the maximum current. An architect designing a home to a particular site might want to know the angle of the building s location throughout the year to create a solar advantage to heating or cooling the structure. Students Know the background above elements. Materials Protractor Ruler Cutting tool (such as scissors) Cardstock Brads or glue
Lesson 1. Vocabulary Equator The imaginary great circle around the earth's surface, equidistant from the poles and perpendicular to the earth's axis of rotation. It divides the earth into the Northern Hemisphere and the Southern Hemisphere. Latitude The angular distance north or south earth's equator, measured in degrees along a meridian, as on a map or globe. Longitude Angular distance on the earth's surface, measured east or west from the prime meridian at Greenwich, England, to the meridian passing through a position, expressed in degrees (or hours), minutes, and seconds. Polaris A star second magnitude, at the end handle Little Dipper and almost at the north celestial pole. Axis A straight line about which a body or geometric object rotates or may be conceived to rotate. Meridian An imaginary great circle on the earth's surface passing through the North and South geographic poles. All points on the same meridian have the same longitude. Celestial Equator A great circle on the celestial sphere in the same plane as the earth's equator. Solstice Either of two times year when the sun is at its greatest distance from the celestial equator. The summer solstice in the Northern Hemisphere occurs about June 21, when the sun is in the zenith at the tropic of Cancer; the winter solstice occurs about December 21, when the sun is over the tropic of Capricorn. The summer solstice is the longest day year and the winter solstice is the shortest. 2. Demonstration (30-40 minutes) There is a 90 degree angle between the rotational axis earth and the equator. The North Pole always points to the star Polaris.
Figure 1 Polaris will always appear to be above the horizon the same number of degrees latitude that you looking from. For example, if you are at 30 degrees north then Polaris will appear to be 30 degrees above the horizon. We will use this relationship to help us find the number of degrees that the sun appears in the sky above the horizon. Figure 2 As the earth orbits around the sun the angle that the sun appears in the sky will appear to move 23 ½ degrees north and south celestial equator. At the Summer solstice the sun will appear 23 ½ degrees north celestial equator. At the Winter solstice the sun will appear 23 ½ south celestial equator
Figure 3 3. Your assignment is to design and build a model using the information above and the materials provided which you will use to location of noon today. To be successful in this project, you will need to research to find the dates Summer Solstice and Winter Solstice. You will also need to find out the latitude school. You will need to use a protractor to make sure the angles of your model are. Extensions 1. Students predict angle Winter Solstice for major cities in the northern hemisphere. 2. Students modify their model so that it can be used at more than one latitude in the northern hemisphere. Evaluation The student did understand that the sun is not directly overhead at noon in most latitudes. The student did research and discover the latitude ir classroom and calculate the solar angles for their area for the winter and summer solstice. The student did apply their knowledge to build a model that will show the solar angles at their latitude. The student did use their model to predict where the sun will be at noon on the current date. Evaluation will be by the rubric included below.
Points 5 4 3 2 1 Solstices The dates Winter and Summer solstice are. One dates is wrong but in its month. Both dates are wrong but in their same month. One dates is completely wrong. Latitude Model Prediction within one to four is built ly and neatly. five within five to nine has one error. ten Resources The American Heritage Dictionary within ten to nineteen has two errors. twenty Wikipedia, the free encyclopedia, article on Solstice http://en.wikipedia.org/wiki/solstice is twenty to twenty-nine degrees off the answer. has three errors. thirty Maporama will allow you to find the Latitude and Longitude of any address worldwide. http://www.maporama.com/share/ Both dates are wrong. The latitude is more than thirty degrees in. is unusable or unfinished. could not be used. The United States Board on Geographic Names will allow you to find the Latitude of named features in the United States. http://geonames.usgs.gov/redirect.html