Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Apogee and perigee

  1. Jan 11, 2005 #1
    i know the equation for both, apogee=a(1+e) perigee=a(1-e). i know the e stands for eccentricity, but what does the a stand for? thanks.
  2. jcsd
  3. Jan 11, 2005 #2


    User Avatar
    Science Advisor
    Homework Helper

    Since the sum of the apogee and the perigee will give you the length of the major axis of the ellipse, consider a(1+e)+a(1-e)=2a.
    So a is the length of the semi-major axis of the ellipse.

    It's the same 'a' as in the equation for an ellipse:

    (if b<a).
  4. Jan 11, 2005 #3
    thank you.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook