I am doing my extended essay in the IB program in mathematics and my question is "How did Newton prove Keplerâ€™s conjecture that planets move in elliptical orbits, can there exist a solar system with two or three suns?" If our sun is at one focus of an ellipse then can there be another sun at the other focus? Would they be attracted to each other? What if there was a third sun? Can anyone give me any input? It would be greatly appreciated!