The January 5, 2010, issue of Scientific American, headlined an article about a “Supernova star too close for comfort” to Earth. Since our solar system is in the Milky Way galaxy filled with potential supernovae and even much bigger gamma-ray bursts from much larger dying star deaths, could we be hit by a blast of gamma rays large enough to knock out our ozone layer? If that happened, all surface Earth life, including humans, would be exposed to deadly UV and gamma ray energies no longer blocked by the protective ozone layer. Has that happened before to our planet and caused one or more of the half dozen extinction events that mark life and death evolution on Earth?
