Does Mercury Have a big Iron Core Because its so Close to the Suns Magnetic Field?
Magnetic fields are great for lots of things  directing explorers, levitating trains, and containing nuclear fusion reactions are just an example of what these invisible forces can do. Now we can ascribe another feature to magnetic fields  they can give planets a rocky core. That is the result from research done by Dr. William McDonough at the University of Maryland and Dr. Takashi Yoshizaki from Tohoku University. The pair developed a model that was published in Progress in Earth and Planetary Sciences that show how the suns magnetic field controlled the gradient of raw materials that the planets were formed out of. We are still studying the suns magnetic field  and the Solar Orbiter spacecraft is a key part of the effort. One of the outcomes of their research was a correlation between a newly formed planets density and proportion of iron and the strength of the stars magnetic field during that planets formation. Though without experimental controls the research is unable to show causation, it makes logical sense that iron, which is magnetic, would be affected by the massive magnetic fields emitted by a young star. Our own solar system is a reasonable example of this  Mercury, despite being the smallest planet, has an iron core that makes up  of its mass. of their weight in their cores while Mars clocks in at .  UT Video discussing the planetary formation process. The cores themselves arent created by magnetic fields though. Magnetisms impact is more subtle, drawing chunks of iron together into newly formed protoplanetary balls. Gravitational forces then take over in driving the dense iron into the core of the planet, where it either melted or cooled, depending on a variety of other planetary formation factors. U  Those planetary formation factors apply not only in our own solar system, but around the myriad stars that house extrasolar planets. Unfortunately there is currently no way to detect the magnetic field of remote stars, so it would be impossible to include that data to try to understand exoplanet formation in existing systems. But it is possible to infer what planets are made out of based on their emitted spectra and their estimated density. Even Mars had a stronger magnetic field at one point, caused by its iron core, which might itself have been caused by the Suns magnetic field. Credit: NASA/JPL/GSFC  Density estimates will play a key factor in future exploration of this topic. Dr. McDonough and his colleagues are looking to extrasolar planetary systems to confirm their theory. They are interested in whether the density of planets decreases and they get farther away from the sun. If they do, its a strong hint that magnetic forces might be causing heavier elements (i.e. iron) to move in towards the star. For now the biggest impact this work will have is on modeling and future models of planetary formation. With luck they will be able to confirm their theory in other solar systems, and solidify the importance of magnetic fields in planetary formation. Magnetism! Its Big Iron Core May Be Due to Magnetism! SlashGear  Mercurys large iron core is thanks to the suns magnetic field  Lead Image   Cutaway image of Mercury showing the size of its core. Credit  NASA Goddard Space Flight Center