View Full Version : Periods of Bodies in Solar System

2009-Jul-25, 03:15 AM
I'm personally interested in the periods of rotation and revolution for major bodies. I would like to have a feel for what goes on in our solar system. Especially, it would be nice to know about the Moon's orbit. I apologize if there is much overlap between this thread and others.

Let me specify what it is I hope to find exactly.

Ideally, this would be a program that generates output in the following format:
resonanceInfo (resonant with which other body in what ratio)

The min and max periods would be to account for the range of error.

The range for timeOfObservation would be specified in seconds since 2000AD, but equal to [200,000 yrs ago to 200,000 yrs from now].

I would like this data for the following bodies:
Moon about Earth
Moon about Sun

I would assume some of these bodies have not changed much at all during the time range of observation. Some may show a very simple relation that can be given clearly in a mathematical expression.

Do you know what the best way to go about getting this information is? It may offend, but I hope not to become bogged down in the details of this information. I have no interest in coming up with a clever scheme for divining this information from old texts, or of plugging thousands of data points into planetarium software.

I realize some of these periods may be under dispute over the given time range of observation. If so, I'd just like a best guess approach with a more-or-less fitting range of error.

Thanks in advance for any pointers. BTW, I hope to share the program as open source with appropriate credits should I ever be able to accomplish this task.

2009-Jul-25, 10:53 AM
What kind of accuracies are you expecting, especially over such a time range (+/- 200K years)?

One can obtain ephemeris information from a numerical integrator such as Solex (http://chemistry.unina.it/~alvitagl/solex/index.html) with a quoted time range of +/-150K years. Links on the page include a paper which describes the calculation techniques in detail, and a Power Basic source code which implements a less accurate version over shorter range. As for the other info you require, it is not clear what you are seeking.

2009-Jul-25, 05:17 PM
Hey, that's great, Veeger! I'm not too well informed about astro sw. I should have mentioned, ultimately I'm working on a sort of calendar system. I would like periods to be accurate as possible, including changes in the Earth solar day, lunar month, etc. An important factor is knowing the range of possible error, so that I can tell when positions of celestial bodies are truly unique, or when it may just be a sort of guess that didn't actually or won't actually occur.

2009-Jul-25, 05:24 PM
I could certainly modify the time range. I had chosen the former because it agreed with the known span of Homo sapiens. What is a very predictable span for which bodies? Thanks for any more help.