2. Describe
what produces the retrograde motion of Mars. What geometric arrangements
did Ptolemy use to explain this motion?
In actuality, when Earth overtakes Mars in its orbit,
Mars appears to be moving backward against the background stars. Ptolemy,
in assuming that all the planets orbit around Earth, proposed that Mars (and
other planets) made a small backward loop in its orbit, called an epicycle.
3. What major change did Copernicus make in the Ptolemaic system? Why
was this change philosphically significant?
Copernicus proposed that the planets orbit around the
Sun, instead of the Sun and planets orbiting around Earth.
7. Use Kepler's third law to determine the distance from the Sun of
a planet whose period is.
a) 5 years
A. 2.9 AUs
b) 10 years
4.6 AUs
c) 10 days
0.01 AUs