The more we learn about Mercury, the weirder it seems

For such a tiny planet, Mercury is a pretty big puzzle for researchers. NASA's MESSENGER probe already has revealed that the planet is surprisingly rich in elements that easily evaporate from the surface, such as sulphur, chlorine, sodium and potassium. This is incredibly odd as these kind of substances most likely would disappear during a hot or violent birth - exactly the type of birth a planet so close to the sun, such as Mercury, would have had.