Diamonds found in the Sudanese desert have an explosive extra-terrestrial origin, researchers have announced.
They were found inside meteorites that fell to Earth in October 2008 when an asteroid slammed into the atmosphere and exploded above the Nubian Desert.
Analysis of the nanoscopic diamonds has found they formed under pressure so high they could only have been made in a planetary explosion, according to a study published in Nature Communications this week.
It provides 'rock-solid' evidence the solar system once had more planets than the eight we currently know of.
"Planetary formation models show that terrestrial planets are formed by the accretion of tens of Moon- to Mars-sized planetary embryos through energetic giant impacts," the authors say, "however, relics of these large proto-planets are yet to be found."
Their analysis suggests the planet these diamonds formed in was smashed apart more than 4 billion years ago, when the solar system was in its chaotic formation phase.
"This level of internal pressure can only be explained if the planetary parent body was a Mercury- to Mars-sized planetary 'embryo'," the study says.
And there may have been many of them.
"Mars-sized bodies (such as the giant impactor that formed the Moon) were common, and either accreted to form larger planets, or collided with the Sun or were ejected from the solar system. This study provides convincing evidence [the planet the Sudanese diamonds formed in] was one such large 'lost' planet before it was destroyed by collisions."
The moon was created when the Earth crashed into a young Mars-sized planet, many scientists now believe.