In 1999 researchers in Germany discovered traces of iron-60 in crust from the Pacific Ocean. Because only supernovae are known to create abundant amounts of 60Fe, which has a half-life of 2.6 million years, Gunther Korschinek at the Technical University of Munich and colleagues concluded that dust from a relatively recent and nearby supernova had littered Earth’s surface with the isotope. After only a smattering of supporting evidence over the past 17 years, a burst of 60Fe research has now solidified the supernova interpretation and opened a new window for investigating how those close encounters affected Earth’s past climate and life.
Anton Wallner at the Australian National University in Canberra and colleagues expand the 60Fe record by using accelerator mass spectrometry to measure the isotope’s prevalence in crusts (including the pictured sample) and sediment cores from the Pacific, Atlantic, and Indian Oceans. The distribution and concentrations...
