Diamonds recovered from the remains of a meteorite reveal the first evidence of proto-planets
Proto-planets that ranged from the size of the moon to Mars helped form terrestrial planets in our solar system
When an asteroid fell to Earth in 2008 and landed in Sudan’s Nubian Desert, researchers weren’t expecting to find diamonds from a lost planet inside.
Those remnants act like a time capsule from the early days of our solar system.
New research conducted on the meteorites collected at the site, Almahata Sitta, was published in April in the journal Nature Communications. The finding is providing a glimpse into the tempestuous nature of our solar system before terrestrial planets like the Earth and Mars were formed.
A long-held theory in astronomy theory posits that multiple proto-planets the size of the moon or Mars first populated our solar system. These planet “embryos” collided with each other, breaking apart or gaining material through those impacts, resulting in the creation of the terrestrial planets in our solar system.
But there hasn’t been any evidence of this hypothesis in the past until now.
The majority of what was recovered from the asteroid impact site is ureilite, a rare type of meteorite with high concentrations of carbon, graphite and diamonds in between grains of silicate.
Those diamonds can be formed in multiple ways, including high-energy impact, chemical-induced growth and static high pressure.
Using transmission electron microscopy, researchers analyzed the tiny crystals within the diamonds to determine how they were formed. Their research revealed that the intensely high pressures needed to create these large diamonds had to come from something much larger – like a Mercury- or Mars-size proto-planet existing in the solar system’s first 10 million years. The diameter of the proto-planet would have been between 2,485 and 3,728 miles.
But in order for this fragment to have reached us, the planet it came from was most likely destroyed by collisions, the study says.
These ureilite are all that’s been discovered of a “lost planet” that probably became part of the terrestrial planets in our system. And this is the first such relic to be found.
“When diamonds form in high pressures inside a planet, they trap some of the minerals from their environment inside them,” lead study author Farhang Nabiei, a doctoral assistant at the Earth and Planetary Science Laboratory in Lausanne, Switzerland, wrote in an email. “These are what we call inclusions. And since diamonds are the hardest natural material, they act as an excellent packaging for these mineral. Thus, the shape and composition of these inclusions are preserved inside the diamonds. That is why inclusions in terrestrial diamonds has been so important for researchers. And now we have them from interiors of another planet!”
This discovery “completely changes the picture” when it comes to understanding ureilites, Nabiei said. Before, it was believed they came from something much smaller. Now, their origin is known to be much larger, as in the size of a proto-planet.
“But there are over 480 meteorites classified as ureilites,” Nabiei said. “Our next step is to analyze other ureilite sample and see how they fit into this big picture.”