and then there is what happen before the Sun-Terran System even formed. * A very lucky super nova explodes causing a shock wave and just the right amount of other elements, especially above the iron center point (ie Uranium). <br><br>Uranium keeping the planets core more-so molten thus a sustained magnetic field. <br><br>the right amount of silicate to heavy metal ratio makes a planet not too vulcanized or not too little. <br><br>* without the right amount of vulcanism percolating to the surface, there would be no technology enabling elements eaiser to extract let alone the nutrient life cycle. <br>And that precious magnetic field.