An oversight in a radioisotope dating technique used to date everything from meteorites to geologic samples means that scientists have likely overestimated the age of many samples, according to new research from North Carolina State University.
To conduct radioisotope dating, scientists evaluate the concentration of isotopes in a material. The number of protons in an atom determines which element it is, while the number of neutrons determines which isotope it is. For example, strontium-86 has 38 protons and 48 neutrons, whereas strontium-87 has 38 protons and 49 neutrons. Radioactive elements, such as rubidium-87 (but not strontium-86 or strontium-87), decay over time. By evaluating the concentrations of all of these isotopes in a rock sample, scientists can determine what its original make-up of strontium and rubidium were. Then, by assessing the isotope concentrations of rubidium and strontium, scientists can back-calculate to determine when the rock was formed. Read more.