'Lost planet' dropped diamonds from the sky billions of years ago

Debris from a meteorite that plunged to Earth in 2008 offers strong evidence of a lost planet that once drifted through our solar system, a new study has found.

Diamonds inside a meteorite that crashed in Sudan’s Nubian Desert 10 years ago were probably created by a “proto planet” that existed about 4.55 billion years ago.

The team of scientists from France, Switzerland and Germany published their results in the latest journal of Nature Communications.

The diamonds in the meteorite have tiny crystals inside them that would need great pressure to form, said one of the study's co-authors, Philippe Gillet.

“We demonstrate that these large diamonds cannot be the result of a shock but rather of growth that has taken place within a planet," he told The Associated Press.

Calculations of the pressure needed to form such diamonds pointed to the mystery planet being at least the same size as Mercury, or possibly Mars.

Researchers have deduced that the early solar system once contained many more planet, some of which were likely little more than a mass of molten magma.

One of these embryo planets – known as Theia - is believed to have struck Earth, ejecting a large amount of debris that later formed the Moon.