Alternate Earths: A spectrum of Earth-like planets over the course of galactic evolution.

Alternate Earths: A spectrum of Earth-like planets over the course of galactic evolution.

Event Name Alternate Earths: A spectrum of Earth-like planets over the course of galactic evolution.
Start Date 4 Sep 2018 1:00 pm
End Date 4 Sep 2018 2:00 pm
Duration 1 hour
Description

Rocky Earth-like planets are frequently suggested to be favourable targets for astrobiology, largely because 100% of known life in the galaxy comes from one. However, the basic elemental constituents of such worlds have evolved with galactic chemical evolution. In particular, it’s been suggested that the mean Si/Fe, and the abundances of heat producing radionuclides U (235 & 238), 232Th and 40K, have evolved significantly over the course of galactic evolution.

In general, the mean size of cores of rocky planets formed over the last 13 Gyr have increased - with implications for surface gravities, internal pressures and - crucially - internal dynamos and magnetic fields on these bodies. At the same time the internal heat production budget of newly-formed planets has decreased - affecting the internal temperatures, volcanism, and tectonics of these bodies. In this talk A/Prof. Neill will present numerical simulations of the evolution of typical Earth-like terrestrial planets at different times in galactic history, and explore how plate tectonics emerges on these planets (or not), and how their magnetic fields evolve. He will then speculate about the habitability of such worlds.

A/Prof Craig O’Neill has been at Macquarie for the good part of a geological epoch (the Anthropocene is a short epoch), and is currently the director of the Macquarie Planetary Research Centre. His background is in geophysics and computational fluid dynamics, which he applies in simulating the interiors of terrestrial planets. Before coming to Macquarie, he completed a PhD at Sydney University, and then a NASA-funded postdoc at Rice University in Houston, where he survived 2 hurricanes. Coincidently, he moved back to Australia soon after, to Macquarie, on an ARC postdoctoral fellowship, and later a Future Fellowship.

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