ASTR 3 Lecture Notes - Lecture 4: Geocentric Model, Scientific Method, Metonic Cycle
Document Summary
Phases of the moon"s 29. 5 day cycle. At any time, half of the moon is illuminated by the sun and half is not (it is dark) Moon casts a shadow onto the earth, by passing in front of the sun (solar) Lunar eclipses: occurs when the moon moves into the earth"s shadow. Solar eclipses only occur during new moon. Solar eclipses can total, partial, and annular. The moon orbiting is tilted 5 to ecliptic plane so that"s why we don"t have eclipses once a month. Planets usually appear to move eastward relative to the stars. But, as we pass them in our orbit, they move west relative to the stars for a few weeks or months called retrograde motion. Greeks knew that we should see stellar parallax if we orbited the sun- but they could not detect it. The apparent angular shift of a star"s position as earth orbits the sun. Reason why parallax was not detectable: 1.
