Planets & Solar System
Mercury inside and out Mercury has a huge core and a high concentration of core iron
The structure of Mercury Huge impact As the mantle is so thin, there may have been an impact that stripped away some of the original mantle
Bombardment The crust may have formed after the bombardment, followed by volcanic activity that resulted in lava flows Mercury contains about 30 per cent silicate materials and 70 per cent metals. Although it’s so small, this make-up also means that it’s incredibly dense at 5.427 grams per cubic centimetre, only a little bit less than the Earth’s mean density. The Earth’s density is due to gravitational compression, but Mercury has such a weak gravitational field in comparison to the Earth’s. That’s why scientists have decided that its density must be due to a large, iron-rich core. Mercury has a higher concentration of iron in its core than any other major planet in the Solar System. Some believe that this huge core is due to what was going on with the Sun while Mercury was forming. If Mercury formed before the energy output from the Sun stabilised, it may have had twice the mass that it does now. Then when the Sun contracted and stabilised, massive temperature fluctuations vaporised some of the planet’s crust and mantle rock. Or a thinner mantle and crust may have always existed due to drag on the solar nebula (the Sun’s cloud of dust
30
and gas from which the planets formed) from the close proximity to the Sun itself. Our latest information from the Messenger spacecraft supports the latter theory, because it has found high levels of materials like potassium on the surface, which would have been vaporised at the extremely high temperatures needed for the former theory.
