From: utzoo!decvax!cca!REM@MIT-MC@sri-unix Newsgroups: net.space Title: Article-I.D.: sri-unix.1691 Posted: Wed Jun 9 15:52:41 1982 Received: Thu Jun 10 02:44:34 1982 From: Robert Elton MaasNote, the libration points are only points in the Earth-Moon frame of reference. In the Earth-Sun or Earth-Stars etc. frames, they aren't points, rather they're orbits around the Earth with a period of one month, the same as the moon (one synodic month if you're in the Earth-Sun system, or one siderial month if you're in the Earth-Stars system, I think, but that's irrelevant to this general point I'm making). In the Earth-Moon frame, L4 and L5 are points of minimal energy, i.e. potential wells. Thus you can either sit at the bottom of the well not moving (in that frame) or move in an orbit inside the well but around the bottom rather than exactly at it. I believe this first approximation assumes the orbit of the Moon around the Earth is circular and no other bodies purturb the potential well. Does somebody on this list have a more complete analysis that includes the non-circular motion of the Moon around the Earth (actually around the center of gravity of the Earth-Moon system) and purturbations from Sun, Venus, Mars, Jupiter etc.?