Create an account
the apparent motion of a relatively close object with respect to a more distant background as the location of the observer changes
noticed that planets speed-up, slow-down, and even reverse direction of motion (retrograde motion). Model contained epicycles.
each plant rides on a small _____ whose center in turn rides on a larger circle called the deferent
model accounted for retrograde motion. Lacked uniform circular motion (same speed all along the circle)
made own instruments to observe the universe. Believed that the sun and moon orbited the Earth and then all the other planets and stars orbited around the sun
Kepler's 2nd Law
draw imaginary line from planet to sun. sweeps over equal area in equal time. Distance between the planet and the sun changes as the planet orbits the sun.
Kepler's 3rd Law
planet's orbital period squared is proportional to cube of its average distance from sun
Galileo's Finding that Contradicts Ptolemy Model
phases of Venus: crescent when close to Earth, gibbous when furthest away. Concluded Venus revolves around the sun.
Please allow access to your computer’s microphone to use Voice Recording.
Having trouble? Click here for help.
We can’t access your microphone!
Click the icon above to update your browser permissions and try again
Reload the page to try again!Reload
Press Cmd-0 to reset your zoom
Press Ctrl-0 to reset your zoom
It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.
Please upgrade Flash or install Chrome
to use Voice Recording.
For more help, see our troubleshooting page.
Your microphone is muted
For help fixing this issue, see this FAQ.
Star this term
You can study starred terms together