Nuclear Planet

What is Earth? Poets say it's a celestial sapphire, a cerulean orb. Astronomers say it's a medium-size planet orbiting an average star. Some environmentalists say it's Mother. Biologists say it's life's only known home. But the most scientifically precise definition may prove to be the one that no one suspected. Earth, says geophysicist J. Marvin Herndon, is a gigantic natural nuclear power plant. We live on its thick shield, while 4,000 miles below our feet a five-mile-wide ball of uranium burns, churns, and reacts, creating the planet's magnetic field as well as the heat that powers volcanoes and continental-plate movements. Herndon's theory boldly contradicts the view that has dominated geophysics since the 1940s: that Earth's inner core is a huge ball of partially crystallized iron and nickel, slowly cooling and growing as it surrenders heat into a fluid core. Radioactivity, in this model, is just a supplementary heat source, with ...