Apparent Motion of The Sky
Let’s go outside and view the night sky (OK, a virtual sky, using digital pictures). We are going to investigate how the patterns of stars in the sky APPEAR to move as time goes by. By investigating this APPARENT MOTION of the sky, we can try to reach some conclusions about how to explain what we see. You’ll use actual digital data taken during August, 2006 by several 9th and 10th grade students who attended a Space Camp at Pine Mountain Observatory organized by OMSI, Portland. Most of their images (pictures) show the dark outline of the horizon (where sky appears to meet ground and trees), and a number of stars. Captions will explain further and will ask you investigative questions and tell you what you need to do with the data. You can just view the JPEG images posted or can download the JPEGs or the FITS images and do more detailed data analysis using a browser for JPEGs or FITSVIEW free software from the NRAO. YOU NEED TO LOOK FOR PATTERNS OF GROUPS OF STARS, like triangles, squares, or other shapes, these are called ASTERISMS. Since the view of the sky in each picture is relatively small (about 8 degrees per side), the stars you see probably belong to parts of several Constellations, but the view doesn’t allow us to show entire Constellations, that’s why you need to keep your eye out for asterisms to use as your reference. These asterisms are easy to spot in a sequence of pictures, and will show you their motion much more obviously than if you only try to spot one star.
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