Terrestrial planets are mainly composed of silicate and iron. These two immiscible components were liquid in the early stage of planets formation. Because of its higher density, iron forms the core, while silicate forms the outer shell of terrestrial planets. It is thought that Earth experienced several large impacts, including an impact with a Mars size body. After the impact, the iron core flowed through the molten silicate (magma ocean). As they were in close proximity, the two fluids exchanged heat and radio-elements. This had a significant influence on the initial thermochemical state of the Earth, hence on its further evolution. We study this event using a laboratory model experiment of the post-impact flow.