![]() You also need to know the height of that landmark. Note this down on the worksheet.įor the Washington Monument Wikipedia reports: This can be measured off of digital maps (like Google Earth) or on USGS Topo Maps (either on paper or various digital interfaces), or directly with a GPS or GPS phone app at the landmark location. Note down the Latitude and Longitude of the landmark. You can work either directly off of your screen capture in a program like Paint or Photoshop, or print it out and use a pencil and ruler to make your measurements. Screen capture the satellite image you want to work with the larger the image the better, as you are going to take measurements of the shadow and want it to be as large as possible. Here, for illustration purposes we pick a prominent national landmark, the Washington Monument. It doesn't matter what landmark you pick, except that it must show a shadow on the ground in the satellite image. ![]() More often than not, we pick an image of a landmark we are familiar with or interested in, like our house or a local library or school. ![]() On the left side of the image the shadows clearly point in a different direction than those on the right hand side of an image! When were these two different images taken? Students are motivated by the same question when viewing areas that are familiar and important to them. Consider the image of an area of New York shown in the first image above. A prominent indicator is the differences in shadows from one side of an image to another. For instance, most of the areas are virtually cloudless, and the seasons indicated by trees and ground cover are not always consistent. If you look at wide area mosaics in satellite map layers, you will notice they have been made from images taken at different times. The first task is to pick a landmark that you would like to date the satellite photograph of. An introductory textbook on astronomy will discuss these changes in the context of the seasons, and how they arise from the tilt of the Earth's axis and its position in its orbit around the Sun. The exact reasons for these changes and differences underlie this project, but are not described here. it has total visibility of less than 12 hours per day.it rises and sets over the horizon at points south of the cardinal east and west directions.it reaches lower maximum altitude during the day.it is visible for more than 12 hours a dayĭuring the northern winter, the Sun's position has the properties:.it rises and sets north of the east and west cardinal directions.During the northern summer, the Sun's position has the following properties: Here we show you that measuring photographs of shadows and understanding the motion of the Sun through the sky with seasons can be used to date satellite photographs (something of interest to modern students, but not historically to farmers in ancient times).Įxamples of the Sun's motion during a day in the Northern Hemisphere are shown above for different times of year. The changes in the Sun's position in the sky depend on the date and time of day, and change how shadows are positioned on the ground. Such needs are not well suited to the modern world, where few of us are farmers, and more to the point, we have calendars. The reasons to learn about the motion of the Sun appeal to historical need - the Sun's motion is an indicator of the seasons and can be used to plan when to plant and harvest crops. Over the course of the year, the point on the horizon where the Sun rises and sets moves north and south, and its path through the sky is higher or lower in the sky depending on the season. Astronomy classes often spend time learning about the motions of celestial objects in the sky, and how those motions change over time. Our original motivation for this project was inspired by teaching introductory astronomy. If used in the classroom setting: this activity is suitable for high school science students who have a knowledge of geometry and trigonometry in the college setting, it is suitable for intro physics or astronomy students. A common question that arises in these explorations is, "when was this picture taken?" As it turns out, you can answer that question - this Instructable will show you how. A fun past time for many of us (especially our students) is looking at their own homes on these satellite images, and identifying their own cars and backyard gardens and recreation sites. If you've played around with these sites at all, you soon discover they have a satellite layer, showing high resolution images of virtually anywhere on Earth. At your fingertips, with your computer or you phone, you can instantly see a map of anywhere in the world, and find directions to your favorite coffee shop or pizzeria. One of the wonders of the Modern World is Google Maps and other online mapping services.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |