Talk:Semi-major axis

The relation between energy and semimajor axis

Since the semimajor axis becomes infinite when the orbital energy equals the escape velocity it can be seen that the relation between the two cannot be linear. - Farred 18:29, 4 February 2013 (UTC)

You are correct. The relation is linear for elliptic orbits; I misspoke. Since we're on the nitpicking topic, you must mean orbital velocity equal to escape velocity . ChristiaanK 16:39, 5 February 2013 (UTC)

Well I knew what I was thinking. The semimajor axis becomes infinite when the orbital energy per unit mass equals 1/2 times the square of the escape velocity. And when the orbital energy is 0.99999 times that there is a very long semimajor axis elliptical orbit, but nowhere near infinite energy. I tink I have it all correkt now. - Farred 21:44, 5 February 2013 (UTC)