Mysteries PHYS10102s08 of the Sky - WebCT 4.1.5
4/17/08 6:46 PM
Moon phases The difficulty with this activity is mentally switching from an overview model of the solar system (drawings like #1) and how things look when we step outside (#2). So drawings throughout the activity like 1 are in overview mode (10, 13) and drawings like 2 are when looking from here (by the noodle, facing Hyalite) (16, 17, 18, 20, 23, 24, 27, 28, 31). #1: We know that we spin once on our axis (counter-clockwise) every 24 hours. Time of day is determined by the location of the Sun #2: When we stand outside, the Sun and the moon appear to move across the sky from East to West (clockwise when facing south). Again, time of day is determined by the location of the Sun. Because in 12 hours the only thing that changes the on picture at the top of page 223 is that we spin half way around, we know that through one night, the phase of the moon should not change. In class we looked at a picture all the phases of the moon as it travels around us in 1 month. The Sun was to the right, and the Earth simply turned on its axis. This picture allows us to imagine what time the moon is overhead for any phase, thus helping us estimate rise and set times. Because time of day is determined by where the Sun is in the sky, we can also use this picture to help us figure out how the sky should look if we go outside and look toward the South. It just takes a bit of practice. See slide shows from 4/3 and 4/5 for specific examples.
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