Some beginning comments on the history of astronomy

• Astronomy developed (in many places) from time keeping and prediction of eclipses.
• But it is/was more important: it concerns the whole universe and mankind's place in it.
• The stars seem relatively simple (although they are not). They seem to be simply light sources fixed to a giant sphere that rotates around the earth once a day.
• The sun seems relatively simple too. It seems to be carried around with the stars once a day; and in addition it moves in a circle around the ecliptic once per year.
• But the planets are a problem. They don't stay put on the celestial sphere, and their motions are complicated.
• We begin with the ancient Greeks because our present understanding of astronomy can be traced back, step by step, to there.