What reason did Copernicus provide for the failure of astronomers to observe any annual stellar parallax?
buildToggle(‘a15′); Answer Copernicus stated that the stars must be much further away from us than previously believed hence the parallax of a star would too small to be detected. • Compare Copernicus’ model with that of Ptolemy. buildToggle(‘a16′); Answer There were several advantages of Copernicus’ model over that of Ptolemy: • It could predict planetary positions to within 2°, the same as that of Ptolemy. • Retrograde motion of planets was explained by the relative motion between them and the Earth. • Distances between planets and the Sun could be accurately determined in units of the Earth-Sun distance (ie Astronomical Units). • Orbital periods could be accurately determined. • It explained the difference between the inferior planets (Mercury and Venus) that were always observed close to the Sun and the superior ones (Mars, Jupiter and Saturn). • It preserved the concept of uniform circular motion without the need for equants. • It preserved Aristotle’s concept of real spheres nest
