<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>While that is one theory, I suspect the true cause is the intense solar wind, heat (breaking down molecules into lighter pieces, more easily swept away) and other intense things that happen at that distance and environment.Certainly, other stellar systems have "hot giants" at such distances, but it seems likely the only way for such a large object to be there is to have it migrate to that position, not form there.Perhaps Mercury is the end result of a process where the planet forms there, and the hot giants are a process that moves them there.It's all rather speculative at this point; after all the whole purpose of MESSENGER is to help answer these quetions!MW <br /> Posted by MeteorWayne</DIV></p><p>i would have to differ with you, I agree Mercury could have had an atmosphere and it was disipated by the Sun. The gas giants had to have a nucleus to start their formation, it might not be more then what we call an asteroid or it could have evolved from a Earth sized mass ejected into that orbit. It is all a matter of gravity. A body in a region with gasses would attract the gasses in the region it orbited in. As it grew heavier it's orbit would have moved inward and it would have attracted more gasses. </p><p>If more gasses existed where Pluto is it may have been the nucleus of a gas giant, not enough gas made it that far though, so it attracted what it could and became what it is.</p><p> </p><p>This all implies the heaviest materials are closer to the Sun, that also means material we can only produce artificially may exist on Venus or Mercury in a natural state. That also opens up the probability other matter exist there we don't have a clue about and could provide us energy without being beholding to others. </p> <div class="Discussion_UserSignature"> </div>