Hi. Keppler's third law implicates that the velocity of an object orbiting around our sun is directly dependant on the object's average distance to the sun... Afterall, if the velocity of be more irregular, then no constant would exist. I realize this probably has something to do with the average centripetal force provided by the gravity of the sun... I was thinking that this is because the longer away an object is the bigger its orbit and thus the smaller the average centripetal force and thus one could assume that it is possible that the speed must be smaller as well? mass*(v^2)/r=centripetal force. But then again the radius r is also bigger if the orbit is bigger and that allows for a larger speed.. bah. And: The next sub-chapter of my physics book it is about Newton's work with gravity and using that jazz to prove keppler's laws.. So maybe I will find out eventually tho still I'd appreciate it if you people could make some simple explanations.