Is there an applet that simulates the orbits of the planets around the sun which is based on the equation for gravitational force GMm/r^2. This equation does not allow for the position of the planet in relation to the sun. That is earth could be at declination of -12 and at a position of 90 degrees and Mars could be at declination +5 and position 270 degrees. How is the net resolution of these forces handled?