Abstract
We review the developments in isotope chronology of the oldest extraterrestrial materials achieved in the last 10-15 years, with emphasis on high precision U-Pb and extinct radionuclide dating, and on application of these methods to the materials that formed in the first 7 million years after formation of proto-Sun, the time during which the gas and dust in the protoplanetary disc accreted or dissipated, and planetesimals and protoplanets formed. The analytical precision of isotopic dates now allows resolving events that occurred within 100 000-300 000 years of each other. The main challenges currently faced by isotope cosmochronology are matching the achieved precision with a similar level of accuracy, adapting to the growing evidence of complex isotope heterogeneity of the protoplanetary disc, extracting ages of individual events from complex rocks, and responding to growing quantity, quality and diversity of recently discovered meteorites and samples returned by space missions.