The age of Earth is estimated to be 4.54 ± 0.05 billion years. This age corresponds to the final stages of Earth's accretion and planetary differentiation during the early Hadean eon. Estimates are based on radiometric dating of meteoritic material—the ages of which are approached by those of the oldest-known terrestrial material and lunar samples—and accretion models consistent with observations of planet formation in protoplanetary disks.