The formation of Earth’s core was a key moment in the evolution of our planet, and determined the starting composition of the planet’s core and mantle. In turn, this had a knock-on affect on the evolution of the Earth and the planet’s habitability. Many geochemical and geophysical aspects of Earth’s core formation remain unknown. A new study of Hf-W isotopes provides new insight into the timing and conditions under which this event occurred.

Hf-W refers to the half life of Tungsten (W) isotopes. W isotopes for the Earth have a unique signature and can be compared to those of other objects for which we have samples, such as chondrite and lunar meteorites. Such comparisons have been used to gather a range of data concerning Earth’s formation, and indicate that the accretion of the planet was rapid and occurred shortly after the origin of the Solar System.

The new study improves on previous work using simulations of planetary accretion combined with a detailed core formation model. The results provide constraints for better understanding both the formation of Earth’s core and the giant impact event that formed the Moon.

The study, “Effects of core formation on the Hf–W isotopic composition of the Earth and dating of the Moon-forming impact,” was published in the journal Earth and Planetary Science Letters. This work was supported by the Emerging Worlds Program. The NASA Astrobiology Program provides resources for Emerging Worlds and other Research and Analysis programs within the NASA Science Mission Directorate (SMD) that solicit proposals relevant to astrobiology research.