A study published today in Nature Communications suggests that diamonds trapped in a rare meteorite called a ureilite is evidence of long-lost planets within our solar system. These particular diamonds are believed to have originated inside a Mars-sized object.
Remains of diamond detected in fragments of the meteorite Almahata Sitta (2008 TC3)—an object almost four meters in diameter that burned up around 37 kilometers above the Nubian Desert a decade ago—reveals that the fireball may have been part of an ancient planet of the Solar System that has long since disappeared.
According to the authors of the study published in Nature Communications, the diamonds found in the fragments that were scattered on the surface require enormous pressures to form, only compatible with the birth of a planetary object.
Researchers have calculated that the formation of such crystals required a pressure above 20 gigapascals, which suggests that the supposed missing planet should have been as large as Mercury or even Mars.
Here on Earth, most diamonds are formed at around just 4.5 gigapascals.
Diamonds, Planets, and Ureilites
Theories say that these small diamonds can be formed in three different ways: by the creation of shock waves in impacts between objects in space, by a chemical process or because of the high pressures present inside planets.
Until now, scientists wondered how the ureilites of «2008 TC3» had been formed.
The researchers, led by planetary scientists Farhang Nabiei, from the École Polytechnique Fédérale de Lausanne, a research institute in Switzerland, studied the diamond inclusions inside the meteorite and discovered it contained relatively large, individual diamond crystals up to 100 μm that could not have formed under an impact event, because of such an event’s short duration, which would not allow time for such large crystals to form.
“Normally we talk about telescopes [to study space]. Here we are talking about the past, so it’s different. Here we use the electron microscope,” said Farhang Nabiei.
Evidence of a long lost planet
“Before you end up with the nine planets, you had a population of larger bodies a few thousands of kilometres in size – Mercury to Mars-size I would say – that were populating the solar system,” Professor Philippe Gillet, a geophysicist at the Ecole Polytechnique Federale de Lausanne (EPFL), told The Independent.
“These ‘proto-planets’ were colliding into each other, forming the planets we know today. These were the building blocks.”
Scientists have always considered that during the birth of the Solar System many other planets may have existed, some of them barely formed by molten masses of magma.
For example, it is believed that one of these planetary embryos, like the famous planet Theia, collided with a young planet Earth and created a large mass of debris that eventually gave rise to the Moon.
“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,” the researchers wrote in their paper.
“Mars-sized bodies 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 that the ureilite parent body was one such large ‘lost’ planet before it was destroyed by collisions.”