Newsgroups: alt.pub.dragons-inn From: kring@physik.uni-kl.de (Thomas Kettenring) Subject: Re: ADMIN: The Nexus System (Size of Generica) Message-ID: <1993Aug2.020153.17022@rhrk.uni-kl.de> References: <93210.113522ASG102@psuvm.psu.edu> <1993Jul29.205309.10436@mnemosyne.cs.du.edu> Date: Mon, 2 Aug 1993 02:01:53 GMT In article <1993Jul29.205309.10436@mnemosyne.cs.du.edu>, arsmith@nyx.cs.du.edu (Alan Smith) writes: >In article <93210.113522ASG102@psuvm.psu.edu> The Dreamer writes: >> I do think that we have some >>literary licence with the moons though since there are a great variety >>of numbers, sizes, and orbits in our own solar system. >>I suggest the following: Two moons, one large one, that orbits Nexus >>and a small one that orbits the large moon. To visualize this, equate >>Nexus to our Sun. The large moon is Earth, and the small moon is our >>moon. Earth goes around the Sun. The Moon goes around Earth. >>The large moon goes around Nexus. The small moon goes around the large moon. > >Sounds wierd. I think we'd have to back the big moon away from nexus >so that we can get the little moon in orbit without gravitational interference. > >UNLESS, you want to put the tiny moon in polar orbit over the big moon. >so that at certain times of the month you'd see the little moon describing >a circle around the big one, and at other times going before-behind like >normal orbits, but in the vertical plane. Or always in a circle around the >big moon. I dunno, is there a physicist in the house? (willing to do the math) An almost-physicist... the n-body problem is right in my field, being nonlinear, but that means the math is difficult. I guess that moons around moons are not stable if the planet is close enough to the star to support life. The ratio of the distances of the respective bodies to their primaries has to be larger than something, independent of orientation, so either the sun has to be far away or the moon's moon has to be very close. The former means no life, the latter may be prevented by the Roche limit (tides destroying the small moon and making a ring out of it). Perhaps the third moon Dan Peters mentioned could have the same period as the first? An equilateral triangle Nexus-Moon1-Moon3 is a solution of the three-body problem: there are asteroids in that position regarding Sun and Jupiter. But it seems odd to me to use real physics (or my perceptions of it) in a fantasy world... I like the moon's moon, and I like the polar orbit, so bugger physics! >>So, what about other planets in the system? Are there any others that >>are inhabited? What about comets, rings, constellations, etc... In the Sorc thread, Mithrandir used planes near to Nexus: Inferno and Sorceror's mini-plane. Inferno could be on a near planet (close to the Sun?) and Sorceror's plane on one of the moons. Don't you like the idea of a portal to the moon? You go through a door and can see in the sky the continent you just came from. -- thomas kettenring, 3 dan, kaiserslautern, germany If you have to smoke and curse and drink to prove that you're grown-up, you aren't. If you have to do sports and have young mates to prove you're still young, you aren't.