Just finished watching an interesting documentary callled 'Inside Planet Earth'.
Was very informative on such recent topics as earthquakes, solar flares etc. It give me a really good insight into the importance of the core to the earth and its magnetic field.
If the core or the magnetic field changed in anyway drastcially this could affect the earth and its systems. It seems that Mars was a life-giving planet until something made its core stop, and brought its magnetic field to be extremely weak. Evidence seems to suggest a large crater caused by an object released such an impact that MArs core became solid. Once MArs defences were down radioactive energy from space and solar flare activity would have made Mars become baron and life-less.
Anyway, I'll move on, so heres the video