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Message started by Maastrichian on 10/04/06 at 09:48:26

Title: Fly Away Worlds
Post by Maastrichian on 10/04/06 at 09:48:26

Hi folks...

A brief question.  When I run the complete Solar System add-on, and bring the simulation time spped up quite a ways (around 8192xnormal I think) many moons fly away from their host planets (typically Titan and Callisto as notable cases, though it does vary quite a bit).  Is this just a bug in the program, or is it an actual limitation for running a simulation at high speed?  I'm assuming Titan isn't going to go winging away from Saturn in the near future! ;)


Title: Re: Fly Away Worlds
Post by Tony on 10/04/06 at 19:42:26

Hi, welcome!

The higher the time step the less stable the orbits become, starting with the tightest orbits.  Titan, with a period of about 15 days will probably hang around Saturn at a time step of 8192, but Saturn's innermost moons will be flung out of orbit.  That is because the program is constructing their orbits step by step.  If an object orbits in less than 8192 seconds, you can't possibly model its orbit at 8192 or higher.  Increase the time step more, and you'll see Mercury get ejected.  Even higher, and you can eject all the planets from the solar system.

Based upon what you're trying to do, choosing a time step is important.

Also, see this thread for more about time steps:;action=display;num=1158230793

Title: Re: Fly Away Worlds
Post by Maastrichian on 10/04/06 at 21:34:40

Ah, that clears it up quite a bit, thank you.  I should be able to run my simulations at a slower speed and still get the reults I'm looking for.  Basically, I'm modelling systems that I've made for my ArcBuilder Universe ( setting.  in most cases I've used fairly reliable system generators, but in others I've more or less winged it.  This program, I think, will promise to be invaluable for me!


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