A diamond-bearing space rock that exploded in Earth's atmosphere in 2008 was part of a lost planet from the early solar system, a study suggests.
The parent "proto-planet" existed billions of years ago before breaking up in a collision and would have been about as large as Mercury or Mars, an article in the journal Nature Communications said.
It argued that the pressures necessary to produce diamonds of this kind could only occur in planet of this size.
Using high-definition microscopy, researchers measured the composition of diamonds locked up in rocks left scattered in the Nubian desert of northern Sudan after the asteroid 2008 TC3 hit the atmosphere.
The measurements provided "the first compelling evidence for such a large body that has since disappeared", the research team wrote.
The finding boosted the theory that the solar system's planets were forged from the remains of large "proto-planets".
The meteorites from this collision fall into a category of space rocks called ureilites, which account for less than one percent of objects that collide with Earth. Researchers suggested ureilite asteroids could be remnants of the same proto-planet.