article_snippet.sent: Researchers have uncovered the mystery of Mercury's 'stealth' colour scheme.
article_snippet.sent: The say a steady dusting of carbon from passing comets has slowly painted Mercury black over billions of years.
article_snippet.sent: The solves the mystery of Mercury's unusual colouring - which has baffled scientists.
article_snippet.sent: On average, Mercury is much darker than Mercury closest airless neighbour, our Moon.
article_snippet.sent: Airless bodies are known to be darkened by micrometeorite impacts and bombardment of solar wind, processes that create a thin coating of dark iron nanoparticles on the surface.
article_snippet.sent: But spectral data from Mercury suggests spectral data from Mercury surface contains very little nanophase iron, certainly not enough to account for spectral data from Mercury dim appearance.
article_snippet.sent: As comets approach Mercury's neighborhood near the sun, they often start to break apart.
article_snippet.sent: Cometary dust is composed of as much as 25 percent carbon by weight, so Mercury would be exposed to a steady bombardment of carbon from these crumbling comets.
article_snippet.sent: Scientists have calculated that after billions of years of bombardment, Mercury's surface should be anywhere from three to six percent carbon.
article_snippet.sent: Messenger has also revealed Mercury's complex internal structure and that the planet has an unusually large core that is still partially liquid.
article_snippet.sent: Messenger has also revealed the temperature of Mercury's surface.