K
keermalec
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Earth is the only rocky planet in our solar syem with a magnetic field. It is also the only planet with a large moon as compared to its own diameter.<br /><br />If we look at common theories of moon creation, the most plausible is Earth being hit by a large body, and expelling a lot of its mass into space. Large parts of this mass go into orbit and collide with each other, forming moonlets wich eventually form the moon.<br /><br />Now maybe that body hitting the Earth is what set the differential rotation between the inner and outer cores of the Earth, and maybe that is the origine of its magnetic field.<br /><br />If so, there will not be many earthlike planets out there as they may be similar-sized and orbiting in the habitable zone but they have little chance of having a magnetic field.<br /><br />Remember that Earth's magnetic field shields us from harmful solar radiation and prohibits the erosion of our atmosphere by solar wind.<br /><br />If Earth really is an exception, then there may be very little life in the universe after all. <div class="Discussion_UserSignature"> <p><em>“An error does not become a mistake until you refuse to correct it.” John F. Kennedy</em></p> </div>