AST-A 100 Lecture Notes - Lecture 1: Natural Philosophy, Deferent And Epicycle, Geocentric Model
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The plane of the galaxy is visible. Milky way is relatively flat compared to the width. Tars su(cid:374) a(cid:374)d the (cid:373)oo(cid:374) rise i(cid:374) the east a(cid:374)d set i(cid:374) the (cid:449)est": appears as if the dome of the sky is moving, stars appear to be at the same distance. Overhead dome is referred to as the celestial sphere. Zenith: the top of the dome, the point directly overhead. Horizon: where the dome appears to meet the earth. North star: polaris, nearest to the northern celestial pole. If you were at the north pole, your zenith would be pointing to the north star. Constellations divide the sky into regions: arbitrary patterns that appear next to each other all perspective. Zodiac contellations are the important because they lie along the ecliptic: ecliptic: path the sun takes through the sky, sun goes through the constellation about once a month, astrology assigned meaning to the zodiac constellations.