A new study from Caltech and the UC Davis College of Letters and Science shows that giant impacts can dramatically lower the internal pressure of planets, a finding that could significantly change the current model of planetary formation.
The impacts, such as the one that is thought to have caused the formation of the earth's moon roughly 4.5 billion years ago, could cause random fluctuations in core and mantle pressures that would explain some puzzling geochemical signatures in Earth’s mantle.
"Previous studies have incorrectly assumed that a planet's internal pressure is simply a function of the mass of the planet, and so it increases continuously as the planet grows. What we've shown is that the pressure can temporarily change after a major impact, followed by a longer term increase in pressure as the post-impact body recovers. This finding has major implications for the planet's chemical structure and subsequent evolution," says Simon Lock, postdoctoral researcher at Caltech and lead author of a paper explaining the new model that was published by Science Advances on September 4. Lock authored the paper with colleague Sarah Stewart, professor of planetary science at UC Davis and a 2018 MacArthur Fellow.
— Adapted from a press release by Robert Perkins, Caltech News.