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Unformatted text preview: 1 AST 1002 Planets, Stars and Galaxies Section 1 -- MW 3:35-4:50 pm; Section 2 -- MW 5:15-6:30 pm Todays Lecture: purpose & goals Motions in the Sky 2: Motions of the Celestial Sphere Review : Lunar Phases, Eclipses, Seasons Understand the Rotation of the Celestial Sphere-- leads to the day/night cycle-- define what part of sky we can see Understand Constellations and Star names from the Sun -- leads to Eclipses Understand the stellar Magnitude Scale a tilted orbit -- leads to the Seasons Summary Prof. David Lind, FSU Physics Split class: Planetarium Cowboy Astronomer w/ Baxter Black Which star is the young man told to watch over the course of the night? Watch for how the ancients coupled the cycles in the sky to their lives. Watch for the motions of the celestial sphere. Basic Motions of Earth Rotation about an axis 24 Hours Revolution about the Sun 365.242199 Days (vernal equinox to vernal equinox) 365.256366 Days (one revolution about the Sun) Revolution about the galactic center 240 million years Motion towards Andromeda A few billion years Fig. 4-2b, p.56 2 Seasons The Earths axis Tilted by 23.5 23.5 o with respect to orbital plane. So, at any given place on Earth, the flux flux of sunlight varies from day to day. Also causes variations in length of day....
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