Privileged Planet: Magnetic field (Introduction)
Our magnetic field is a result of our nickel-iron core movements plus its appears lots of uranium. This plus our atmosphere protects us from all the nasty rays that fly around the universe and the Milky Way:-http://www.nature.com/nature/journal/v520/n7547/full/520299a.html?WT.ec_id=NATURE-20150416-Note editors comments and the other link