I have 2 related questions about Earth-like planets and solar systems: First question: - I don’t understand why the Earth has so much iron. - How much iron is blown off by the typical supernova in proportion to other metals? - If the proto-solarsystem was a rotating gaseous disk, should most of the iron captured by the solar system have sunk into the sun? - If so, what is all this iron doing in the Earth (proportionate to its mass)? - If the outer planets are made mostly of lighter elements, why not the Earth too? Related question: - Does it matter for life that the Earth has a mainly iron core? - Can habitable planets just as well produce a strong enough magnetic field with other liquid rotating metal cores? - Is a non-iron metal core a likely scenario for habitable planets or is there something special about iron?