== Hadean Atmosphere? == 

 Should there be more discussion on differences between planet Earth and other planets that led to a creation of an atmosphere sufficient to keep water vapor in and thus create oceans?  After all, if all the inner planets were a molten mass, then presumably the same conditions and processes should have appeared on each inner planet.  Yet clearly, Earth was of such a unique place, that only Earthof the inner planetsended up with sizable oceans.  What was the significant difference or differences?  More detailed discussion re distance from the sun, or magnetosphere, or asteroidal/comet impacts.