Why does Mercury have such a big iron core?

William McDonough, professor of geology at the University of Maryland, and Takashi Yoshizaki of Tohoku University in Japan have established a model that shows that the density, mass, and iron content of the core of a rocky planet are affected by its distance from the sun’s magnetic field

McDonough said: "The four inner planets of our solar system-Mercury, Venus, Earth, and Mars-are made up of metals and rocks in different proportions

McDonough previously developed a model of the composition of the Earth, which is a common model used by planetary scientists to determine the composition of exoplanets

McDonough’s new model shows that during the early formation of the solar system, the young sun was surrounded by a rotating cloud of dust and gas, and iron particles were attracted to the center by the solar magnetic field

Researchers have discovered that in the core of a rocky planet, the density and proportion of iron are related to the strength of the magnetic field surrounding the sun during the formation of the planet

The composition of the planet’s core is very important for maintaining the possibility of life

Using existing planetary formation models, McDonough determined the speed at which gas and dust were drawn into the center during the formation of the solar system

When the early solar system began to cool, dust and gas that had not been sucked into the sun began to gather together

When McDonough incorporated this model into the calculation of planet formation, it revealed the gradient of metal content and density, which is exactly in line with scientists' understanding of the planets in the solar system

This new understanding of the role of magnetism in the formation of planets has brought trouble to the study of exoplanets, because there is currently no way to determine the magnetism of stars from observations on Earth

McDonough said: "You can no longer just say,'Oh, the composition of a star is like this, so the planets around it must be like this

The next step in this work will be for scientists to find another planetary system like ours—a planetary system made of rocky planets far away from the central sun

Journal Reference :

1. William F.