Laurens Rossi wrote:
Hi All!

I have been searching the web for software which calculates the absolute
position of planets and the sun, which is based on the laws of gravity. All
software I found is based on the trigonometrical calculations with the
current postion and speed of the planets. These programs seem to keep the
sun as an absolute reference point and to calculate the planets' orbits.

What I'm interested in, is the motion of the sun itself related to the
position and motion of the planets.


Hi Laurens,

I'm not sure it'll do exactly what you're looking for, but libnova can
be used to make this kind of calculations.

http://libnova.sourceforge.net/

Otherwise, there are more open source libraries in the Science &
Engineering Astronomy section at http://freshmeat.net which may
contain the code you're looking for.

Best of luck,

Steve

--
Steve Maddison
Den Haag, The Netherlands
http://www.cosam.org/