Investigation 4.1b: Understanding the Motions of the Stars and Constellations Across the Sky

You know that stars and constellations seem to move across the sky. How fast do they move? Locate a bright star that you can easily watch appear over the horizon, a building, or any easily identifiable reference point. Record the time that it just comes into view at your reference point. Do you think the star will appear at the same time every night? Repeat your observation and again record the time three days later. Does the star come into view at the same time? If not, what is the difference? Make five observations approximately three days apart, and take the average. Wha does this number represent? Remember that the Earth travels 360° in one rotation, and the amount of time one rotation takes is commonly accepted as 24 hours.