An asteroid that slammed into the Sudan desert on October 7, 2008, shot out lots of little space rocks holding a precious secret: diamonds that likely formed billions of years ago inside the embryo of a now-decimated planet. "We think that there were probably many larger "parent" bodies in the early solar system, which have since been destroyed, so a since-destroyed body the size of Mercury is reasonable", he says. The planet would have been about the size of between Mercury and Mars. Because diamonds are forged at huge pressures and temperatures, typically deep inside the planet, the various materials that get trapped inside are quite hard to get a hold of at the surface - and diamonds can preserve them for billions of years.
The finding boosted the theory that the solar system's planets were forged from the remains of large "proto-planets".
The diamonds we're familiar with are formed when sheets of carbon called graphite - the same material in pencil lead - is squeezed to incredible pressures.
Diamonds can act as time capsules: They trap nearby minerals during the formation process and, with their strength and stability, preserve material that scientists call inclusions.
The researchers suggest all ureilite asteroids were remnants of the same proto-planet.
A chemical map shows sulfur (red) and iron (yellow) inside the inclusions in the diamond matrix. The meteorites have, in fact, been classed as ureilites - a rare type of stony meteorite that has a unique mineralogical composition, very different from that of other stony meteorites. When it exploded in the atmosphere, it scattered multiple fragments across the desert.
A microscope's view of a diamond-encrusted meteorite.
According to the researchers, this means the diamonds formed at the extreme pressure of 20 gigapscals - about 180 times as crushing as the pressure found at the bottom of the Marianas Trench, the deepest point in Earth's oceans.
The paper, published in the journal Nature Communications, reveals that asteroid 2008 TC3 may have come from an ancient planet, formed early on during the birth of the solar system, reports the Washington Post.
"Although this is the first compelling evidence for such a large body that has since disappeared, their existence in the early solar system has been predicted by planetary formation models", Dr Nabiei added.
Such planetary embryos got ejected from the solar system and either became rogue planets or smashed together. "This study provides convincing evidence that the ureilite parent body was one such large "lost" planet before it was destroyed by collisions some 4.5 billion years ago".