Planet Earth was built in a very tough neighborhood: a world of violent impacts, swirling clouds of debris, and heaving oceans of silicate magma and molten iron. OES postdoc Maylis Landeau is investigating these events in a novel way — with fluid dynamics experiments in the lab. Working with Hopkins graduate Ben Hirsh, former OES postdoc Renaud Deguen, and OES PI Peter Olson, and using ordinary liquids — silicone oils for magma and saline solutions for molten iron — Landeau has simulated the environment in which Earth’s central core formed, but on a vastly reduced scale. To simulate a giant impact, the team drops liquid projectiles into a two-layer liquid representing the mantle and core of the accreting Earth. The accompanying figure shows the turbulent state of an impacting core as it penetrates Earth’s core-mantle boundary in the experiment. In an article in Nature Geoscience Landeau and the team propose that seismically-imaged heterogeneity below the core-mantle boundary is a vestige left over from the giant impact that formed the Moon some four and one half billion years ago.