Transcript: What would you observe if you looked at the sky for a year from somewhere in the Northern hemisphere?  You'd notice that the stars rose in the east and set in the West and appeared to move about a fixed point in the Northern sky.  You'd notice that the Sun, the Moon, and the planets all traverse the same strip of the sky.  You'd notice that the stars rise and set slightly earlier everyday and that the constellations move through the entire sky in the course of a year.  You'd notice that the Sun during the summer rises slightly North of due-East, and the day is longer than twelve hours.  In the winter you'd notice the Sun rising South of due-East, and the day is shorter than twelve hours. You'd notice the constellations rising in the East and setting in the West and always preserving a fixed pattern with respect to each other.  You’d notice the regular pattern of the Lunar phases repeating every 28 or 29 days.  You’d notice the rare phenomena of eclipses and the fact that Solar eclipses are much rarer than Lunar eclipses, and neither occurs every month.  And you would notice that some of the planets follow irregular motions with the fixed constellations.  All of this you would notice by careful, naked-eye observations over the course of the year.