Are you trying to simulate the gravitational interaction between all the planets? That might get real messy, depending on how good the floating point math is, and what kind of timescale its on.
Array/List/Dictionary whatever the python equivalent is; all of the objects with gravity. Do the same calculations you do to the planet you are calculating to the sun, and each of the other objects with gravity (one of the object fields should be strength). Python is actually great with large numbers(Large as in lots of digits, placement of decimal doesn't really matter). Where in java you have to use things like BigIntegers, python will handle that all automagically.
The only problem in the simulation was that Pygame acts silly when the window is dragged around. Otherwise, it would work perfectly. If I knew how to, I might even have put the calculation and drawing in separate threads. But I don't know how to do that just yet.
I love the fact that Amazon gives you the option to "Buy it Again," because clearly who doesn't need two computer cases for the same computer.
man reason my profile is the way it is! seems after level 20 it seems the spammers go after you. http://steamcommunity.com/id/PUNK_AND_GOTH/