Cairns Bain, Nuclear Africa: Long before the advent of the atomic bomb or nuclear power, mankind lived in a radioactive world. Our planet is made up of the nuclear debris of exploding stars, consisting of both the stable elements and also some long-lived radioactive isotopes of uranium, thorium and potassium. We also continue to be bombarded with cosmic rays from our own sun and from distant galaxies. Our very bodies carry a mix of radioactive materials imparted to us from Mother Nature.