Mercury has been found to have a dark side with graphite, a crystalline form of carbon commonly found in pencils, being the source of the mysterious dark colouration of the planet’s surface.

The study, published this week in Nature Geoscience, was led by a team from the Johns Hopkins University Applied Physics Laboratory in the US, which analysed measurements collected by NASA’s Messenger spacecraft as it went through its final orbits of Mercury.

The findings not only test theories of early planetary formation but may offer an explanation of the amount of carbon here on Earth.

Helen Maynard-Casely says that the discovery came as a surprise and may change our view on the how the solar system was formed, and the current model of predicting the presence of carbon, including here on Earth.

“Carbon’s been a very tricky element to pin down, even on Earth, and it is a puzzle to discover what has happened to our carbon. There’s a thought now that a lot of the carbon on Earth is trapped further down within the interior and that we are missing a lot of minerals. There is currently a bit of a worldwide hunt for these,” she said.

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