You are just a cornucopia of misinformation.....<br /><br />To be more exact I meant they lose some off their outer gas, water and dust as they approach the Sun and get warm enough to start giving off gasses. The key word is some. Why is it so hard to imagine the outbound leg, being relatively warm, in relation to it's surroundings, the comet wouldn't attract matter that just happened to be along it's path.<br /><br /> Space is a vacuum, only in the sense there is no air, it's not empty, there's a lot of particals, molecules and simple Atoms floating around out their waiting to find something to react with. <br /><br />Draw a good orbit, that passes through the original disc of matter and a Comet lasts a long time, appearing over and over. Just look at how much gas existed in the orbits of the outer Planets for them to get so massive. What they didn't get the comets could snatch up as they past through. <br /><br />AFter hundreds to thousnad of years, they simply stop being comets......<br /><br />No they don't, they may have expended all their volatile components and don't form a tail, they don't mysteriously disapear. They remain in their orbit until they are disturbed. If they collide with another body then their Solar orbit would change, innner Solar system gravity could pull them apart and the become asteroids.<br /><br />All this tells me is matter can be in whatever orbit.<br /><br />A Some are tossed complelely out of the solar system, too. ...<br /><br />Has this ever been observed? The Sun is the only body big enough to do that and it would have to be a perfect shot to work. Not that it couldn't be done, just that it would take a lot of luck. <br /><br /> I think most matter generated by the Black Hole that became the Solar System has stayed within the Solar System, gravity over acceleration.<br /><br />Perhaps a lot of asteroids are Comets that burned of their outer layers. It's even conceivable that metallic meteors are Comet cores, just like the cores of the Planets. Ot <div class="Discussion_UserSignature"> </div>