Image

How Old? The Carbon Knows

Karl von Reden, staff physicist, is shown working at the WHOI-based National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility. The facility is used to carbon date organic and inorganic material by measuring the isotope of carbon known as radiocarbon, or carbon-14. Radiocarbon is produced naturally by the interaction of cosmic rays with the upper atmosphere, making about one out of one trillion carbon atoms in the atmosphere and upper ocean a carbon-14 atom. Because carbon-14 decays at a known rate, scientists can accurately estimate the age of a sample from the amount of carbon-14 in it. The facility processes over 6000 samples each year for the ocean science community. (Photo by Tom Kleindinst, Woods Hole Oceanographic Institution)