How do radioactive isotopes in meteorites help scientists estimate Earth’s age?

Scientists estimate Earth’s age to be approximately 4.6 billion years by using radioactive isotopes found in meteorites to determine when these bodies first formed. Because meteorites and Earth condensed from the same solar nebula at roughly the same time, their isotopic histories are linked.1

The process relies on radioactive decay, where a parent isotope decays into a stable daughter isotope at a constant, known rate. By measuring the ratio of these parent and daughter atoms within a sample, scientists can calculate the time elapsed since the material solidified. Common methods include rubidium–strontium and uranium–lead dating.21

Specifically, researchers often use the isochron method, which plots isotopic ratios to determine the age of formation. When the growth curve of terrestrial lead isotopes is extrapolated back in time, it coincides with the age measured in meteorites, confirming their shared origin in the early solar system.31