Diamond discovery hints at lost planet
SWITZERLAND: A scattering of diamonds discovered in a meteorite that landed in the Nubian desert 10 years ago points to the existence of a lost planet that used to wander the early solar system.
Scientists have long speculated that Earth and the other planets orbiting the Sun were born in a maelstrom of massive lumps of rock colliding with such force that they sometimes stuck together. The bands of diamond shot through the Almahata Sitta meteorite are said to be the first compelling evidence that this is really what happened.
The specimen is one of about 600 chunks of the TC3 asteroid, which disintegrated and rained down in lumps across a remote area of Sudan in 2008. It was the first time astronomers had detected an approaching asteroid and then tracked it as it broke up.
At the time, the find was hailed as a ‘‘Rosetta Stone’’ for space because TC3 was a relic from the formation of the solar system 4.5 billion years ago, older than the oldest rocks on Earth.
Professor Philippe Gillet and his colleagues at the Ecole Polytechnique Federale de Lausanne in Switzerland now argue that it could only have come from an ancient planet that may have been as big as Mars.
‘‘We started with a disk of dust, and finally we ended up with planets,’’ Gillet said. ‘‘In a nutshell, there was a first generation of big planets, or the embryos of planets, which populated the solar system during the first 10 to 20 million years. We have probably found the remnants of one of these first big planets.’’
Although the Almahata Sitta meteorite is mostly made up of silicon-rich minerals called olivine and pyroxene that are very common on Earth, it also contains microscopic layers of graphite, a form of carbon, interspersed with diamonds. The diamond grains are up to 100 micrometres in diameter, which is almost large enough to be seen with the naked eye and much too big to have formed in a highenergy collision.
The diamonds contain a number of nanometre-scale flaws, chiefly specks of iron-rich sulphides such as troilite and kamacite.
The researchers, who published their findings in the journal Nature Communications, say the only way to explain these impurities is that they must have solidified at the same time as the diamonds out of an incandescent soup of iron, sulphur and carbon, cooked deep inside a planet at enormous pressure. – The Times