PHIL 160D3 Lecture Notes - Lecture 17: Circular Motion, Equant, Explanatory Power

• School: University of Arizona
• Department: Philosophy Main
• Course: PHIL 160D3
• Professor: Marc Johansen

Document Summary

The sun appears to rise and set over the course of 24 hours. Earth rotates on its axis every 24 hours. The sun appears to move through the sky over the course of a year. The earth orbits the sun every year. Distinguishing planets from stars: planets move slowly through the stars, retrograde motion, planets are brighter when in retrograde. The planets appear to move with the stars. The planets appear to move through the stars seasonally: due to apparent and genuine motion, the planets and earth both orbit the sun. Coper(cid:374)icus" epic(cid:455)cles do(cid:374)"t e(cid:454)plai(cid:374) retrograde (cid:373)otio(cid:374) (he does(cid:374)"t (cid:374)eed the(cid:373) to (cid:373)ake the explanation) Both the copernican and ptolemaic models accommodate the fact that mercury and. It is a consequence of the core model itself. The ptolemaic model does not predict this fact: it requires extra assumptions about the alig(cid:374)(cid:373)e(cid:374)t of the pla(cid:374)ets" epi(cid:272)(cid:455)(cid:272)les; the alig(cid:374)(cid:373)e(cid:374)t is a (cid:272)oi(cid:374)(cid:272)ide(cid:374)(cid:272)e. Conflicts with available data that supports geocentrism.