| MadSci Network: Astronomy |
Mercury consists of a large iron core covered with a rocky mantle and crust. This outer layer presumably consists of rather ordinary silicates, not unlike what the Earth’s crust is made of. Such material has a melting point of 1200 K (927 degrees C) or higher, so even though Mercury is very hot at 720 K (447 degrees C), it is nowhere near hot enough to melt rock.
Although it is farther from the Sun, Venus is even hotter than Mercury. But it, too, doesn’t reach the temperatures necessary to melt rock.
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